[[pp. 61943-61992]] Amendments for Testing and Monitoring Provisions

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: October 17, 2000 (Volume 65, Number 201)]
[Rules and Regulations]
[Page 61943-61992]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr17oc00-14]

[[Continued from page 61942]]

[[Page 61943]]

17.0 Tables, Diagrams, Flowcharts, and Validation Data
[GRAPHIC] [TIFF OMITTED] TR17OC00.243

BILLING CODE 6560-50-C

[[Page 61944]]

Method 12--Determination of Inorganic Lead Emissions From
Stationary Sources

Note: This method does not include all of the specifications
(e.g., equipment and supplies) and procedures (e.g., sampling and
analytical) essential to its performance. Some material is
incorporated by reference from other methods in this part.
Therefore, to obtain reliable results, persons using this method
should have a thorough knowledge of at least the following
additional test methods: Method 1, Method 2, Method 3, and Method 5.

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Inorganic Lead Compounds as lead 7439-92-1 see Section 13.3.
(Pb).
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of inorganic lead emissions from stationary sources, only as specified
in an applicable subpart of the regulations.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 Particulate and gaseous Pb emissions are withdrawn
isokinetically from the source and are collected on a filter and in
dilute nitric acid. The collected samples are digested in acid solution
and are analyzed by atomic absorption spectrophotometry using an air/
acetylene flame.

3.0 Definitions. [Reserved]

4.0 Interferences

4.1 Copper. High concentrations of copper may interfere with the
analysis of Pb at 217.0 nm. This interference can be avoided by
analyzing the samples at 283.3 nm.
4.2 Matrix Effects. Analysis for Pb by flame atomic absorption
spectrophotometry is sensitive to the chemical composition and to the
physical properties (e.g., viscosity, pH) of the sample. The analytical
procedure requires the use of the Method of Standard Additions to check
for these matrix effects, and requires sample analysis using the Method
of Standard Additions if significant matrix effects are found to be
present.

5.0 Safety

6.0 Equipment and Supplies

6.1 Sample Collection. A schematic of the sampling train used in
performing this method is shown in Figure 12-1 in Section 18.0; it is
similar to the Method 5 train. The following items are needed for
sample collection:
6.1.1 Probe Nozzle, Probe Liner, Pitot Tube, Differential Pressure
Gauge, Filter Holder, Filter Heating System, Temperature Sensor,
Metering System, Barometer, and Gas Density Determination Equipment.
Same as Method 5, Sections 6.1.1.1 through 6.1.1.7, 6.1.1.9, 6.1.2, and
6.1.3, respectively.
6.1.2 Impingers. Four impingers connected in series with leak-free
ground glass fittings or any similar leak-free noncontaminating
fittings are needed. For the first, third, and fourth impingers, use
the Greenburg-Smith design, modified by replacing the tip with a 1.3 cm
(\1/2\ in.) ID glass tube extending to about 1.3 cm (\1/2\ in.) from
the bottom of the flask. For the second impinger, use the Greenburg-
Smith design with the standard tip.
6.1.3 Temperature Sensor. Place a temperature sensor, capable of
measuring temperature to within 1 deg.C (2 deg.F) at the outlet of
the fourth impinger for monitoring purposes.
6.2 Sample Recovery. The following items are needed for sample
recovery:
6.2.1 Probe-Liner and Probe-Nozzle Brushes, Petri Dishes,
Graduated Cylinder and/or Balance, Plastic Storage Containers, and
Funnel and Rubber Policeman. Same as Method 5, Sections 6.2.1 and 6.2.4
through 6.2.7, respectively.
6.2.2 Wash Bottles. Glass (2).
6.2.3 Sample Storage Containers. Chemically resistant,
borosilicate glass bottles, for 0.1 N nitric acid (HNO3)
impinger and probe solutions and washes, 1000-ml. Use screw-cap liners
that are either rubber-backed Teflon or leak-free and resistant to
chemical attack by 0.1 N HNO3. (Narrow mouth glass bottles
have been found to be less prone to leakage.)
6.2.4 Funnel. Glass, to aid in sample recovery.
6.3 Sample Analysis. The following items are needed for sample
analysis:
6.3.1 Atomic Absorption Spectrophotometer. With lead hollow
cathode lamp and burner for air/acetylene flame.
6.3.2 Hot Plate.
6.3.3 Erlenmeyer Flasks. 125-ml, 24/40 standard taper.
6.3.4 Membrane Filters. Millipore SCWPO 4700, or equivalent.
6.3.5 Filtration Apparatus. Millipore vacuum filtration unit, or
equivalent, for use with the above membrane filter.
6.3.6 Volumetric Flasks. 100-ml, 250-ml, and 1000-ml.

7.0 Reagents and Standards

Note: Unless otherwise indicated, it is intended that all
reagents conform to the specifications established by the Committee
on Analytical Reagents of the American Chemical Society, where such
specifications are available; otherwise, use the best available
grade.

7.1 Sample Collection. The following reagents are needed for
sample collection:
7.1.1 Filter. Gelman Spectro Grade, Reeve Angel 934 AH, MSA 1106
BH, all with lot assay for Pb, or other high-purity glass fiber
filters, without organic binder, exhibiting at least 99.95 percent
efficiency (0.05 percent penetration) on 0.3 micron dioctyl phthalate
smoke particles. Conduct the filter efficiency test using ASTM D 2986-
71, 78, or 95a (incorporated by reference--see Sec. 60.17) or use test
data from the supplier's quality control program.
7.1.2 Silica Gel, Crushed Ice, and Stopcock Grease. Same as Method
5,

[[Page 61945]]

Sections 7.1.2, 7.1.4, and 7.1.5, respectively.
7.1.3 Water. Deionized distilled, to conform to ASTM D 1193-77 or
91, Type 3 (incorporated by reference--see Sec. 60.17). If high
concentrations of organic matter are not expected to be present, the
potassium permanganate test for oxidizable organic matter may be
omitted.
7.1.4 Nitric Acid, 0.1 N. Dilute 6.5 ml of concentrated
HNO3 to 1 liter with water. (It may be desirable to run
blanks before field use to eliminate a high blank on test samples.)
7.2 Sample Recovery. 0.1 N HNO3 (Same as in Section
7.1.4 above).
7.3 Sample Analysis. The following reagents and standards are
needed for sample analysis:
7.3.1 Water. Same as in Section 7.1.3.
7.3.2 Nitric Acid, Concentrated.
7.3.3 Nitric Acid, 50 Percent (v/v). Dilute 500 ml of concentrated
HNO3 to 1 liter with water.
7.3.4 Stock Lead Standard Solution, 1000 g Pb/ml.
Dissolve 0.1598 g of lead nitrate [Pb(NO3)2] in
about 60 ml water, add 2 ml concentrated HNO3, and dilute to
100 ml with water.
7.3.5 Working Lead Standards. Pipet 0.0, 1.0, 2.0, 3.0, 4.0, and
5.0 ml of the stock lead standard solution (Section 7.3.4) into 250-ml
volumetric flasks. Add 5 ml of concentrated HNO3 to each
flask, and dilute to volume with water. These working standards contain
0.0, 4.0, 8.0, 12.0, 16.0, and 20.0 g Pb/ml, respectively.
Prepare, as needed, additional standards at other concentrations in a
similar manner.
7.3.6 Air. Suitable quality for atomic absorption
spectrophotometry.
7.3.7 Acetylene. Suitable quality for atomic absorption
spectrophotometry.
7.3.8 Hydrogen Peroxide, 3 Percent (v/v). Dilute 10 ml of 30
percent H2O2 to 100 ml with water.

8.0 Sample Collection, Preservation, Storage, and Transport

8.1 Pretest Preparation. Follow the same general procedure given
in Method 5, Section 8.1, except that the filter need not be weighed.
8.2 Preliminary Determinations. Follow the same general procedure
given in Method 5, Section 8.2.
8.3 Preparation of Sampling Train. Follow the same general
procedure given in Method 5, Section 8.3, except place 100 ml of 0.1 N
HNO3 (instead of water) in each of the first two impingers.
As in Method 5, leave the third impinger empty and transfer
approximately 200 to 300 g of preweighed silica gel from its container
to the fourth impinger. Set up the train as shown in Figure 12-1.
8.4 Leak-Check Procedures. Same as Method 5, Section 8.4.
8.5 Sampling Train Operation. Same as Method 5, Section 8.5.
8.6 Calculation of Percent Isokinetic. Same as Method 5, Section
8.6.
8.7 Sample Recovery. Same as Method 5, Sections 8.7.1 through
8.7.6.1, with the addition of the following:
8.7.1 Container No. 2 (Probe).
8.7.1.1 Taking care that dust on the outside of the probe or other
exterior surfaces does not get into the sample, quantitatively recover
sample matter and any condensate from the probe nozzle, probe fitting,
probe liner, and front half of the filter holder by washing these
components with 0.1 N HNO3 and placing the wash into a glass
sample storage container. Measure and record (to the nearest 2 ml) the
total amount of 0.1 N HNO3 used for these rinses. Perform
the 0.1 N HNO3 rinses as follows:
8.7.1.2 Carefully remove the probe nozzle, and rinse the inside
surfaces with 0.1 N HNO3 from a wash bottle while brushing
with a stainless steel, Nylon-bristle brush. Brush until the 0.1 N
HNO3 rinse shows no visible particles, then make a final
rinse of the inside surface with 0.1 N HNO3.
8.7.1.3 Brush and rinse with 0.1 N HNO3 the inside
parts of the Swagelok fitting in a similar way until no visible
particles remain.
8.7.1.4 Rinse the probe liner with 0.1 N HNO3. While
rotating the probe so that all inside surfaces will be rinsed with 0.1
N HNO3, tilt the probe, and squirt 0.1 N HNO3
into its upper end. Let the 0.1 N HNO3 drain from the lower
end into the sample container. A glass funnel may be used to aid in
transferring liquid washes to the container. Follow the rinse with a
probe brush. Hold the probe in an inclined position, squirt 0.1 N
HNO3 into the upper end of the probe as the probe brush is
being pushed with a twisting action through the probe; hold the sample
container underneath the lower end of the probe, and catch any 0.1 N
HNO3 and sample matter that is brushed from the probe. Run
the brush through the probe three times or more until no visible sample
matter is carried out with the 0.1 N HNO3 and none remains
on the probe liner on visual inspection. With stainless steel or other
metal probes, run the brush through in the above prescribed manner at
least six times, since metal probes have small crevices in which sample
matter can be entrapped. Rinse the brush with 0.1 N HNO3,
and quantitatively collect these washings in the sample container.
After the brushing, make a final rinse of the probe as described above.
8.7.1.5 It is recommended that two people clean the probe to
minimize loss of sample. Between sampling runs, keep brushes clean and
protected from contamination.
8.7.1.6 After ensuring that all joints are wiped clean of silicone
grease, brush and rinse with 0.1 N HNO3 the inside of the
from half of the filter holder. Brush and rinse each surface three
times or more, if needed, to remove visible sample matter. Make a final
rinse of the brush and filter holder. After all 0.1 N HNO3
washings and sample matter are collected in the sample container,
tighten the lid on the sample container so that the fluid will not leak
out when it is shipped to the laboratory. Mark the height of the fluid
level to determine whether leakage occurs during transport. Label the
container to identify its contents clearly.
8.7.2 Container No. 3 (Silica Gel). Note the color of the
indicating silica gel to determine if it has been completely spent, and
make a notation of its condition. Transfer the silica gel from the
fourth impinger to the original container, and seal. A funnel may be
used to pour the silica gel from the impinger and a rubber policeman
may be used to remove the silica gel from the impinger. It is not
necessary to remove the small amount of particles that may adhere to
the walls and are difficult to remove. Since the gain in weight is to
be used for moisture calculations, do not use any water or other
liquids to transfer the silica gel. If a balance is available in the
field, follow the procedure for Container No. 3 in Section 11.4.2.
8.7.3 Container No. 4 (Impingers). Due to the large quantity of
liquid involved, the impinger solutions may be placed in several
containers. Clean each of the first three impingers and connecting
glassware in the following manner:
8.7.3.1. Wipe the impinger ball joints free of silicone grease,
and cap the joints.
8.7.3.2. Rotate and agitate each impinger, so that the impinger
contents might serve as a rinse solution.
8.7.3.3. Transfer the contents of the impingers to a 500-ml
graduated cylinder. Remove the outlet ball joint cap, and drain the
contents through this opening. Do not separate the impinger parts
(inner and outer tubes) while transferring their contents to the
cylinder. Measure the liquid volume to within 2 ml. Alternatively,
determine the weight of the liquid to within 0.5 g. Record in the log
the volume or weight of the liquid present, along with a

[[Page 61946]]

notation of any color or film observed in the impinger catch. The
liquid volume or weight is needed, along with the silica gel data, to
calculate the stack gas moisture content (see Method 5, Figure 5-6).
8.7.3.4. Transfer the contents to Container No. 4.

Note: In Sections 8.7.3.5 and 8.7.3.6, measure and record the
total amount of 0.1 N HNO3 used for rinsing.

8.7.3.5. Pour approximately 30 ml of 0.1 N HNO3 into
each of the first three impingers and agitate the impingers. Drain the
0.1 N HNO3 through the outlet arm of each impinger into
Container No. 4. Repeat this operation a second time; inspect the
impingers for any abnormal conditions.
8.7.3.6. Wipe the ball joints of the glassware connecting the
impingers free of silicone grease and rinse each piece of glassware
twice with 0.1 N HNO3; transfer this rinse into Container
No. 4. Do not rinse or brush the glass-fritted filter support. Mark the
height of the fluid level to determine whether leakage occurs during
transport. Label the container to identify its contents clearly.
8.8 Blanks.
8.8.1 Nitric Acid. Save 200 ml of the 0.1 N HNO3 used
for sampling and cleanup as a blank. Take the solution directly from
the bottle being used and place into a glass sample container labeled
``0.1 N HNO3 blank.''
8.8.2 Filter. Save two filters from each lot of filters used in
sampling. Place these filters in a container labeled ``filter blank.''

9.0 Quality Control

9.1 Miscellaneous Quality Control Measures.

9.2 Volume Metering System Checks. Same as Method 5, Section 9.2.

10.0 Calibration and Standardizations

Note: Maintain a laboratory log of all calibrations.

10.1 Sampling Equipment. Same as Method 5, Section 10.0.
10.2 Spectrophotometer.
10.2.1 Measure the absorbance of the standard solutions using the
instrument settings recommended by the spectrophotometer manufacturer.
Repeat until good agreement (3 percent) is obtained between
two consecutive readings. Plot the absorbance (y-axis) versus
concentration in g Pb/ml (x-axis). Draw or compute a straight
line through the linear portion of the curve. Do not force the
calibration curve through zero, but if the curve does not pass through
the origin or at least lie closer to the origin than 0.003
absorbance units, check for incorrectly prepared standards and for
curvature in the calibration curve.
10.2.2 To determine stability of the calibration curve, run a
blank and a standard after every five samples, and recalibrate as
necessary.

11.0 Analytical Procedures

11.1 Sample Loss Check. Prior to analysis, check the liquid level
in Containers Number 2 and Number 4. Note on the analytical data sheet
whether leakage occurred during transport. If a noticeable amount of
leakage occurred, either void the sample or take steps, subject to the
approval of the Administrator, to adjust the final results.
11.2 Sample Preparation.
11.2.1 Container No. 1 (Filter). Cut the filter into strips and
transfer the strips and all loose particulate matter into a 125-ml
Erlenmeyer flask. Rinse the petri dish with 10 ml of 50 percent
HNO3 to ensure a quantitative transfer, and add to the
flask.

Note: If the total volume required in Section 11.2.3 is expected
to exceed 80 ml, use a 250-ml flask in place of the 125-ml flask.

11.2.2 Containers No. 2 and No. 4 (Probe and Impingers). Combine
the contents of Containers No. 2 and No. 4, and evaporate to dryness on
a hot plate.
11.2.3 Sample Extraction for Lead.
11.2.3.1 Based on the approximate stack gas particulate
concentration and the total volume of stack gas sampled, estimate the
total weight of particulate sample collected. Next, transfer the
residue from Containers No. 2 and No. 4 to the 125-ml Erlenmeyer flask
that contains the sampling filter using a rubber policeman and 10 ml of
50 percent HNO3 for every 100 mg of sample collected in the
train or a minimum of 30 ml of 50 percent HNO3, whichever is
larger.
11.2.3.2 Place the Erlenmeyer flask on a hot plate, and heat with
periodic stirring for 30 minutes at a temperature just below boiling.
If the sample volume falls below 15 ml, add more 50 percent
HNO3. Add 10 ml of 3 percent H2O2, and
continue heating for 10 minutes. Add 50 ml of hot (80 deg.C, 176
deg.F) water, and heat for 20 minutes. Remove the flask from the hot
plate, and allow to cool. Filter the sample through a Millipore
membrane filter, or equivalent, and transfer the filtrate to a 250-ml
volumetric flask. Dilute to volume with water.
11.2.4 Filter Blank. Cut each filter into strips, and place each
filter in a separate 125-ml Erlenmeyer flask. Add 15 ml of 50 percent
HNO3, and treat as described in Section 11.2.3 using 10 ml
of 3 percent H2O2 and 50 ml of hot water. Filter
and dilute to a total volume of 100 ml using water.
11.2.5 Nitric Acid Blank, 0.1 N. Take the entire 200 ml of 0.1 N
HNO3 to dryness on a steam bath, add 15 ml of 50 percent
HNO3, and treat as described in Section 11.2.3 using 10 ml
of 3 percent H202 and 50 ml of hot water. Dilute
to a total volume of 100 ml using water.
11.3 Spectrophotometer Preparation. Turn on the power; set the
wavelength, slit width, and lamp current; and adjust the background
corrector as instructed by the manufacturer's manual for the particular
atomic absorption spectrophotometer. Adjust the burner and flame
characteristics as necessary.
11.4 Analysis.
11.4.1 Lead Determination. Calibrate the spectrophotometer as
outlined in Section 10.2, and determine the absorbance for each source
sample, the filter blank, and 0.1 N HNO3 blank. Analyze each
sample three times in this manner. Make appropriate dilutions, as
needed, to bring all sample Pb concentrations into the linear
absorbance range of the spectrophotometer. Because instruments vary
between manufacturers, no detailed operating instructions will be given
here. Instead, the instructions provided with the particular instrument
should be followed. If the Pb concentration of a sample is at the low
end of the calibration curve and high accuracy is required, the sample
can be taken to dryness on a hot plate and the residue dissolved in the
appropriate volume of water to bring it into the optimum range of the
calibration curve.

[[Page 61947]]

11.4.2 Container No. 3 (Silica Gel). This step may be conducted in
the field. Weigh the spent silica gel (or silica gel plus impinger) to
the nearest 0.5 g; record this weight.
11.5 Check for Matrix Effects. Use the Method of Standard
Additions as follows to check at least one sample from each source for
matrix effects on the Pb results:
11.5.1 Add or spike an equal volume of standard solution to an
aliquot of the sample solution.
11.5.2 Measure the absorbance of the resulting solution and the
absorbance of an aliquot of unspiked sample.
11.5.3 Calculate the Pb concentration Cm in g/
ml of the sample solution using Equation 12-1 in Section 12.5.
Volume corrections will not be required if the solutions as
analyzed have been made to the same final volume. Therefore,
Cm and Ca represent Pb concentration before
dilutions.
Method of Standard Additions procedures described on pages 9-4 and
9-5 of the section entitled ``General Information'' of the Perkin Elmer
Corporation Atomic Absorption Spectrophotometry Manual, Number 303-0152
(Reference 1 in Section 17.0) may also be used. In any event, if the
results of the Method of Standard Additions procedure used on the
single source sample do not agree to within 5 percent of
the value obtained by the routine atomic absorption analysis, then
reanalyze all samples from the source using the Method of Standard
Additions procedure.

12.0 Data Analysis and Calculations

12.1 Nomenclature.

Am = Absorbance of the sample solution.
An = Cross-sectional area of nozzle, m\2\ (ft\2\).
At = Absorbance of the spiked sample solution.
Bws = Water in the gas stream, proportion by volume.
Ca = Lead concentration in standard solution, g/ml.
Cm = Lead concentration in sample solution analyzed during
check for matrix effects, g/ml.
Cs = Lead concentration in stack gas, dry basis, converted
to standard conditions, mg/dscm (gr/dscf).
I = Percent of isokinetic sampling.
L1 = Individual leakage rate observed during the leak-check
conducted prior to the first component change, m\3\/min (ft\3\/min)
La = Maximum acceptable leakage rate for either a pretest
leak-check or for a leak-check following a component change; equal to
0.00057 m\3\/min (0.020 cfm) or 4 percent of the average sampling rate,
whichever is less.
Li = Individual leakage rate observed during the leak-check
conducted prior to the ``ith'' component change (i = 1, 2, 3 * * * n),
m\3\/min (cfm).
Lp = Leakage rate observed during the post-test leak-check,
m\3\/min (cfm).
mt = Total weight of lead collected in the sample,
g.
Mw = Molecular weight of water, 18.0 g/g-mole (18.0 lb/lb-
mole).
Pbar = Barometric pressure at the sampling site, mm Hg (in.
Hg).
Ps = Absolute stack gas pressure, mm Hg (in. Hg).
Pstd = Standard absolute pressure, 760 mm Hg (29.92 in. Hg).
R = Ideal gas constant, 0.06236 [(mm Hg) (m\3\)]/[( deg.K) (g-mole)]
{21.85 [(in. Hg) (ft\3\)]/[( deg.R) (lb-mole)]}.
Tm = Absolute average dry gas meter temperature (see Figure
5-3 of Method 5), deg.K ( deg.R).
Tstd = Standard absolute temperature, 293 deg.K (528
deg.R).
vs = Stack gas velocity, m/sec (ft/sec).
Vm = Volume of gas sample as measured by the dry gas meter,
dry basis, m\3\ (ft\3\).
Vm(std) = Volume of gas sample as measured by the dry gas
meter, corrected to standard conditions, m\3\ (ft\3\).
Vw(std) = Volume of water vapor collected in the sampling
train, corrected to standard conditions, m\3\ (ft\3\).
Y = Dry gas meter calibration factor.
H = Average pressure differential across the orifice meter
(see Figure 5-3 of Method 5), mm H2O (in. H2O).
= Total sampling time, min.
l = Sampling time interval, from the beginning of
a run until the first component change, min.
i = Sampling time interval, between two successive
component changes, beginning with the interval between the first and
second changes, min.
p = Sampling time interval, from the final (n\th\)
component change until the end of the sampling run, min.
w = Density of water, 0.9982 g/ml (0.002201 lb/ml).
12.2 Average Dry Gas Meter Temperatures (Tm) and
Average Orifice Pressure Drop (H). See data sheet (Figure 5-3
of Method 5).
12.3 Dry Gas Volume, Volume of Water Vapor, and Moisture Content.
Using data obtained in this test, calculate Vm(std),
Vw(std), and Bws according to the procedures
outlined in Method 5, Sections 12.3 through 12.5.
12.4 Total Lead in Source Sample. For each source sample, correct
the average absorbance for the contribution of the filter blank and the
0.1 N HNO3 blank. Use the calibration curve and this
corrected absorbance to determine the Pb concentration in the sample
aspirated into the spectrophotometer. Calculate the total Pb content
mt (in g) in the original source sample; correct
for all the dilutions that were made to bring the Pb concentration of
the sample into the linear range of the spectrophotometer.
12.5 Sample Lead Concentration. Calculate the Pb concentration of
the sample using the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.244

12.6 Lead Concentration. Calculate the stack gas Pb concentration
Cs using Equation 12-2:
[GRAPHIC] [TIFF OMITTED] TR17OC00.245

Where:

K3 = 0.001 mg/g for metric units.
= 1.54 x 10-\5\ gr/g for English units

12.7 Stack Gas Velocity and Volumetric Flow Rate. Calculate the
average stack gas velocity and volumetric flow rate using data obtained
in this method and the equations in Sections 12.2 and 12.3 of Method 2.
12.8 Isokinetic Variation. Same as Method 5, Section 12.11.

13.0 Method Performance

13.1 Precision. The within-laboratory precision, as measured by
the coefficient of variation, ranges from 0.2 to 9.5 percent relative
to a run-mean concentration. These values were based on tests conducted
at a gray iron foundry, a lead storage battery manufacturing plant, a
secondary lead smelter, and a lead recovery furnace of an alkyl lead
manufacturing plant. The concentrations encountered during these tests
ranged from 0.61 to 123.3 mg Pb/m\3\.
13.2 Analytical Range. For a minimum analytical accuracy of
10 percent, the lower limit of the range is 100 g.
The upper limit can be extended considerably by dilution.
13.3 Analytical Sensitivity. Typical sensitivities for a 1-percent
change in absorption (0.0044 absorbance units) are 0.2 and 0.5
g Pb/ml for the 217.0 and 283.3 nm lines, respectively.

14.0 Pollution Prevention. [Reserved]

15.0 Waste Management. [Reserved]

16.0 Alternative Procedures

16.1 Simultaneous Determination of Particulate and Lead Emissions.
Method

[[Page 61948]]

5 may be used to simultaneously determine Pb provided: (1) acetone is
used to remove particulate from the probe and inside of the filter
holder as specified by Method 5, (2) 0.1 N HNO3 is used in
the impingers, (3) a glass fiber filter with a low Pb background is
used, and (4) the entire train contents, including the impingers, are
treated and analyzed for Pb as described in Sections 8.0 and 11.0 of
this method.
16.2 Filter Location. A filter may be used between the third and
fourth impingers provided the filter is included in the analysis for
Pb.
16.3 In-Stack Filter. An in-stack filter may be used provided: (1)
A glass-lined probe and at least two impingers, each containing 100 ml
of 0.1 N HNO3 after the in-stack filter, are used and (2)
the probe and impinger contents are recovered and analyzed for Pb.
Recover sample from the nozzle with acetone if a particulate analysis
is to be made.

17.0 References

Same as Method 5, Section 17.0, References 2, 3, 4, 5, and 7, with
the addition of the following:

1. Perkin Elmer Corporation. Analytical Methods for Atomic
Absorption Spectrophotometry. Norwalk, Connecticut. September 1976.
2. American Society for Testing and Materials. Annual Book of
ASTM Standards, Part 31: Water, Atmospheric Analysis. Philadelphia,
PA 1974. p. 40-42.
3. Kelin, R., and C. Hach. Standard Additions--Uses and
Limitations in Spectrophotometric Analysis. Amer. Lab. 9:21-27.
1977.
4. Mitchell, W.J., and M.R. Midgett. Determining Inorganic and
Alkyl Lead Emissions from Stationary Sources. U.S. Environmental
Protection Agency. Emission Monitoring and Support Laboratory.
Research Triangle Park, NC. (Presented at National APCA Meeting,
Houston. June 26, 1978).
BILLING CODE 6560-50-P

[[Page 61949]]

18.0 Tables, Diagrams, Flowcharts, and Validation Data
[GRAPHIC] [TIFF OMITTED] TR17OC00.246

BILLING CODE 6560-50-C

[[Page 61950]]

Method 13A--Determination of Total Fluoride Emissions From
Stationary Sources (Spadns Zirconium Lake Method)

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Total fluorides as Fluorine.... 7782-41-4 Not determined.
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of fluoride (F-) emissions from sources as specified in the
regulations. It does not measure fluorocarbons, such as Freons.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary

Gaseous and particulate F- are withdrawn isokinetically
from the source and collected in water and on a filter. The total
F- is then determined by the SPADNS Zirconium Lake
Colorimetric method.

3.0 Definitions [Reserved]

4.0 Interferences

4.1 Chloride. Large quantities of chloride will interfere with the
analysis, but this interference can be prevented by adding silver
sulfate into the distillation flask (see Section 11.3). If chloride ion
is present, it may be easier to use the specific ion electrode method
of analysis (Method 13B).
4.2 Grease. Grease on sample-exposed surfaces may cause low
F- results due to adsorption.

5.0 Safety

5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of the
safety problems associated with its use. It is the responsibility of
the user of this test method to establish appropriate safety and health
practices and to determine the applicability of regulatory limitations
prior to performing this test method.
5.2 Corrosive Reagents. The following reagents are hazardous.
Personal protective equipment and safe procedures are useful in
preventing chemical splashes. If contact occurs, immediately flush with
copious amounts of water at least 15 minutes. Remove clothing under
shower and decontaminate. Treat residual chemical burn as thermal burn.
5.2.1 Hydrochloric Acid (HCl). Highly toxic. Vapors are highly
irritating to eyes, skin, nose, and lungs, causing severe damage. May
cause bronchitis, pneumonia, or edema of lungs. Exposure to
concentrations of 0.13 to 0.2 percent can be lethal in minutes. Will
react with metals, producing hydrogen.
5.2.2 Sodium Hydroxide (NaOH). Causes severe damage to eye tissues
and to skin. Inhalation causes irritation to nose, throat, and lungs.
Reacts exothermically with limited amounts of water.
5.2.3 Sulfuric Acid (H2SO4). Rapidly
destructive to body tissue. Will cause third degree burns. Eye damage
may result in blindness. Inhalation may be fatal from spasm of the
larynx, usually within 30 minutes. May cause lung tissue damage with
edema. 1 mg/m\3\ for 8 hours will cause lung damage or, in higher
concentrations, death. Provide ventilation to limit inhalation. Reacts
violently with metals and organics.

6.0 Equipment and Supplies

6.1 Sample Collection. A schematic of the sampling train used in
performing this method is shown in Figure 13A-1; it is similar to the
Method 5 sampling train except that the filter position is
interchangeable. The sampling train consists of the following
components:
6.1.1 Probe Nozzle, Pitot Tube, Differential Pressure Gauge,
Filter Heating System, Temperature Sensor, Metering System, Barometer,
and Gas Density Determination Equipment. Same as Method 5, Sections
6.1.1.1, 6.1.1.3 through 6.1.1.7, 6.1.1.9, 6.1.2, and 6.1.3,
respectively. The filter heating system and temperature sensor are
needed only when moisture condensation is a problem.
6.1.2 Probe Liner. Borosilicate glass or 316 stainless steel. When
the filter is located immediately after the probe, a probe heating
system may be used to prevent filter plugging resulting from moisture
condensation, but the temperature in the probe shall not be allowed to
exceed 120 14 deg.C (248 25 deg.F).
6.1.3 Filter Holder. With positive seal against leakage from the
outside or around the filter. If the filter is located between the
probe and first impinger, use borosilicate glass or stainless steel
with a 20-mesh stainless steel screen filter support and a silicone
rubber gasket; do not use a glass frit or a sintered metal filter
support. If the filter is located between the third and fourth
impingers, borosilicate glass with a glass frit filter support and a
silicone rubber gasket may be used. Other materials of construction may
be used, subject to the approval of the Administrator.
6.1.4 Impingers. Four impingers connected as shown in Figure 13A-1
with ground-glass (or equivalent), vacuum-tight fittings. For the
first, third, and fourth impingers, use the Greenburg-Smith design,
modified by replacing the tip with a 1.3-cm (\1/2\ in.) ID glass tube
extending to 1.3 cm (\1/2\ in.) from the bottom of the flask. For the
second impinger, use a Greenburg-Smith impinger with the standard tip.
Modifications (e.g., flexible connections between the impingers or
materials other than glass) may be used, subject to the approval of the
Administrator. Place a temperature sensor, capable of measuring
temperature to within 1 deg.C (2 deg.F), at the outlet of the fourth
impinger for monitoring purposes.
6.2 Sample Recovery. The following items are needed for sample
recovery:
6.2.1 Probe-liner and Probe-Nozzle Brushes, Wash Bottles,
Graduated Cylinder and/or Balance, Plastic Storage Containers, Funnel
and Rubber Policeman, and Funnel. Same as Method 5, Sections 6.2.1,
6.2.2 and 6.2.5 to 6.2.8, respectively.
6.2.2 Sample Storage Container. Wide-mouth, high-density
polyethylene bottles for impinger water samples, 1 liter.
6.3 Sample Preparation and Analysis. The following items are
needed for sample preparation and analysis:
6.3.1 Distillation Apparatus. Glass distillation apparatus
assembled as shown in Figure 13A-2.
6.3.2 Bunsen Burner.

[[Page 61951]]

6.3.3 Electric Muffle Furnace. Capable of heating to 600 deg.C
(1100 deg.F).
6.3.4 Crucibles. Nickel, 75- to 100-ml.
6.3.5 Beakers. 500-ml and 1500-ml.
6.3.6 Volumetric Flasks. 50-ml.
6.3.7 Erlenmeyer Flasks or Plastic Bottles. 500-ml.
6.3.8 Constant Temperature Bath. Capable of maintaining a constant
temperature of 1.0 deg.C at room temperature conditions.
6.3.9 Balance. 300-g capacity, to measure to 0.5 g.
6.3.10 Spectrophotometer. Instrument that measures absorbance at
570 nm and provides at least a 1-cm light path.
6.3.11 Spectrophotometer Cells. 1-cm path length.

7.0 Reagents and Standards

Unless otherwise indicated, all reagents are to conform to the
specifications established by the Committee on Analytical Reagents of
the American Chemical Society, where such specifications are available.
Otherwise, use the best available grade.
7.1 Sample Collection. The following reagents are needed for
sample collection:
7.1.1 Filters.
7.1.1.1 If the filter is located between the third and fourth
impingers, use a Whatman No. 1 filter, or equivalent, sized to fit the
filter holder.
7.1.1.2 If the filter is located between the probe and first
impinger, use any suitable medium (e.g., paper, organic membrane) that
can withstand prolonged exposure to temperatures up to 135 deg.C (275
deg.F), and has at least 95 percent collection efficiency (5 percent
penetration) for 0.3 m dioctyl phthalate smoke particles.
Conduct the filter efficiency test before the test series, using ASTM D
2986-71, 78, or 95a (incorporated by reference--see Sec. 60.17), or use
test data from the supplier's quality control program. The filter must
also have a low F- blank value (0.015 mg F-/cm\2\
of filter area). Before the test series, determine the average
F- blank value of at least three filters (from the lot to be
used for sampling) using the applicable procedures described in
Sections 8.3 and 8.4 of this method. In general, glass fiber filters
have high and/or variable F- blank values, and will not be
acceptable for use.
7.1.2 Water. Deionized distilled, to conform to ASTM D 1193-77 or
91, Type 3 (incorporated by reference--see Sec. 60.17). If high
concentrations of organic matter are not expected to be present, the
potassium permanganate test for oxidizable organic matter may be
deleted.
7.1.3 Silica Gel, Crushed Ice, and Stopcock Grease. Same as Method
5, Sections 7.1.2, 7.1.4, and 7.1.5, respectively.
7.2 Sample Recovery. Water, as described in Section 7.1.2, is
needed for sample recovery.
7.3 Sample Preparation and Analysis. The following reagents and
standards are needed for sample preparation and analysis:
7.3.1 Calcium Oxide (CaO). Certified grade containing 0.005
percent F- or less.
7.3.2 Phenolphthalein Indicator. Dissolve 0.1 g of phenolphthalein
in a mixture of 50 ml of 90 percent ethanol and 50 ml of water.
7.3.3 Silver Sulfate (Ag2SO4).
7.3.4 Sodium Hydroxide (NaOH), Pellets.
7.3.5 Sulfuric Acid (H2SO4), Concentrated.
7.3.6 Sulfuric Acid, 25 Percent (v/v). Mix 1 part of concentrated
H2SO4 with 3 parts of water.
7.3.7 Filters. Whatman No. 541, or equivalent.
7.3.8 Hydrochloric Acid (HCl), Concentrated.
7.3.9 Water. Same as in Section 7.1.2.
7.3.10 Fluoride Standard Solution, 0.01 mg F-/ml. Dry
approximately 0.5 g of sodium fluoride (NaF) in an oven at 110 deg.C
(230 deg.F) for at least 2 hours. Dissolve 0.2210 g of NaF in 1 liter
of water. Dilute 100 ml of this solution to 1 liter with water.
7.3.11 SPADNS Solution [4,5 Dihydroxyl-3-(p-Sulfophenylazo)-2,7-
Naphthalene-Disulfonic Acid Trisodium Salt]. Dissolve 0.960
0.010 g of SPADNS reagent in 500 ml water. If stored in a
well-sealed bottle protected from the sunlight, this solution is stable
for at least 1 month.
7.3.12 Spectrophotometer Zero Reference Solution. Add 10 ml of
SPADNS solution to 100 ml water, and acidify with a solution prepared
by diluting 7 ml of concentrated HCl to 10 ml with deionized, distilled
water. Prepare daily.
7.3.13 SPADNS Mixed Reagent. Dissolve 0.135 0.005 g
of zirconyl chloride octahydrate (ZrOCl2 8H2O) in
25 ml of water. Add 350 ml of concentrated HCl, and dilute to 500 ml
with deionized, distilled water. Mix equal volumes of this solution and
SPADNS solution to form a single reagent. This reagent is stable for at
least 2 months.

8.0 Sample Collection, Preservation, Storage, and Transport

8.1 Pretest Preparation. Follow the general procedure given in
Method 5, Section 8.1, except that the filter need not be weighed.
8.2 Preliminary Determinations. Follow the general procedure given
in Method 5, Section 8.2, except that the nozzle size must be selected
such that isokinetic sampling rates below 28 liters/min (1.0 cfm) can
be maintained.
8.3 Preparation of Sampling Train. Follow the general procedure
given in Method 5, Section 8.3, except for the following variation:
Assemble the train as shown in Figure 13A-1 with the filter between the
third and fourth impingers. Alternatively, if a 20-mesh stainless steel
screen is used for the filter support, the filter may be placed between
the probe and first impinger. A filter heating system to prevent
moisture condensation may be used, but shall not allow the temperature
to exceed 120 14 deg.C (248 25 deg.F).
Record the filter location on the data sheet (see Section 8.5).
8.4 Leak-Check Procedures. Follow the leak-check procedures given
in Method 5, Section 8.4.
8.5 Sampling Train Operation. Follow the general procedure given
in Method 5, Section 8.5, keeping the filter and probe temperatures (if
applicable) at 120 14 deg.C (248 25 deg.F)
and isokinetic sampling rates below 28 liters/min (1.0 cfm). For each
run, record the data required on a data sheet such as the one shown in
Method 5, Figure 5-3.
8.6 Sample Recovery. Proper cleanup procedure begins as soon as
the probe is removed from the stack at the end of the sampling period.
Allow the probe to cool.
8.6.1 When the probe can be safely handled, wipe off all external
particulate matter near the tip of the probe nozzle, and place a cap
over it to keep from losing part of the sample. Do not cap off the
probe tip tightly while the sampling train is cooling down as this
would create a vacuum in the filter holder, thus drawing water from the
impingers into the filter holder.
8.6.2 Before moving the sample train to the cleanup site, remove
the probe from the sample train, wipe off any silicone grease, and cap
the open outlet of the probe. Be careful not to lose any condensate
that might be present. Remove the filter assembly, wipe off any
silicone grease from the filter holder inlet, and cap this inlet.
Remove the umbilical cord from the last impinger, and cap the impinger.
After wiping off any silicone grease, cap off the filter holder outlet
and any open impinger inlets and outlets. Ground-glass stoppers,
plastic caps, or serum caps may be used to close these openings.
8.6.3 Transfer the probe and filter-impinger assembly to the
cleanup area.

[[Page 61952]]

This area should be clean and protected from the wind so that the
chances of contaminating or losing the sample will be minimized.
8.6.4 Inspect the train prior to and during disassembly, and note
any abnormal conditions. Treat the samples as follows:
8.6.4.1 Container No. 1 (Probe, Filter, and Impinger Catches).
8.6.4.1.1 Using a graduated cylinder, measure to the nearest ml,
and record the volume of the water in the first three impingers;
include any condensate in the probe in this determination. Transfer the
impinger water from the graduated cylinder into a polyethylene
container. Add the filter to this container. (The filter may be handled
separately using procedures subject to the Administrator's approval.)
Taking care that dust on the outside of the probe or other exterior
surfaces does not get into the sample, clean all sample-exposed
surfaces (including the probe nozzle, probe fitting, probe liner, first
three impingers, impinger connectors, and filter holder) with water.
Use less than 500 ml for the entire wash. Add the washings to the
sample container. Perform the water rinses as follows:
8.6.4.1.2 Carefully remove the probe nozzle and rinse the inside
surface with water from a wash bottle. Brush with a Nylon bristle
brush, and rinse until the rinse shows no visible particles, after
which make a final rinse of the inside surface. Brush and rinse the
inside parts of the Swagelok fitting with water in a similar way.
8.6.4.1.3 Rinse the probe liner with water. While squirting the
water into the upper end of the probe, tilt and rotate the probe so
that all inside surfaces will be wetted with water. Let the water drain
from the lower end into the sample container. A funnel (glass or
polyethylene) may be used to aid in transferring the liquid washes to
the container. Follow the rinse with a probe brush. Hold the probe in
an inclined position, and squirt water into the upper end as the probe
brush is being pushed with a twisting action through the probe. Hold
the sample container underneath the lower end of the probe, and catch
any water and particulate matter that is brushed from the probe. Run
the brush through the probe three times or more. With stainless steel
or other metal probes, run the brush through in the above prescribed
manner at least six times since metal probes have small crevices in
which particulate matter can be entrapped. Rinse the brush with water,
and quantitatively collect these washings in the sample container.
After the brushing, make a final rinse of the probe as described above.
8.6.4.1.4 It is recommended that two people clean the probe to
minimize sample losses. Between sampling runs, keep brushes clean and
protected from contamination.
8.6.4.1.5 Rinse the inside surface of each of the first three
impingers (and connecting glassware) three separate times. Use a small
portion of water for each rinse, and brush each sample-exposed surface
with a Nylon bristle brush, to ensure recovery of fine particulate
matter. Make a final rinse of each surface and of the brush.
8.6.4.1.6 After ensuring that all joints have been wiped clean of
the silicone grease, brush and rinse with water the inside of the
filter holder (front-half only, if filter is positioned between the
third and fourth impingers). Brush and rinse each surface three times
or more if needed. Make a final rinse of the brush and filter holder.
8.6.4.1.7 After all water washings and particulate matter have
been collected in the sample container, tighten the lid so that water
will not leak out when it is shipped to the laboratory. Mark the height
of the fluid level to transport. Label the container clearly to
identify its contents.
8.6.4.2 Container No. 2 (Sample Blank). Prepare a blank by placing
an unused filter in a polyethylene container and adding a volume of
water equal to the total volume in Container No. 1. Process the blank
in the same manner as for Container No. 1.
8.6.4.3 Container No. 3 (Silica Gel). Note the color of the
indicating silica gel to determine whether it has been completely
spent, and make a notation of its condition. Transfer the silica gel
from the fourth impinger to its original container, and seal. A funnel
may be used to pour the silica gel and a rubber policeman to remove the
silica gel from the impinger. It is not necessary to remove the small
amount of dust particles that may adhere to the impinger wall and are
difficult to remove. Since the gain in weight is to be used for
moisture calculations, do not use any water or other liquids to
transfer the silica gel. If a balance is available in the field, follow
the analytical procedure for Container No. 3 in Section 11.4.2.

9.0 Quality Control

9.1 Miscellaneous Quality Control Measures.

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
8.4, 10.1..................... Sampling Ensure accurate
equipment leak- measurement of stack
check and gas flow rate and
calibration. sample volume.
10.2.......................... Spectrophotometer Evaluate analytical
calibration. technique,
preparation of
standards.
11.3.3........................ Interference/ Minimize negative
recovery effects of used
efficiency check acid.
during
distillation.
------------------------------------------------------------------------

9.2 Volume Metering System Checks. Same as Method 5, Section 9.2.

10.0 Calibration and Standardization

Note: Maintain a laboratory log of all calibrations.

10.1 Sampling Equipment. Calibrate the probe nozzle, pitot tube,
metering system, probe heater, temperature sensors, and barometer
according to the procedures outlined in Method 5, Sections 10.1 through
10.6. Conduct the leak-check of the metering system according to the
procedures outlined in Method 5, Section 8.4.1.
10.2 Spectrophotometer.
10.2.1 Prepare the blank standard by adding 10 ml of SPADNS mixed
reagent to 50 ml of water.
10.2.2 Accurately prepare a series of standards from the 0.01 mg
F-/ml standard fluoride solution (Section 7.3.10) by
diluting 0, 2, 4, 6, 8, 10, 12, and 14 ml to 100 ml with deionized,
distilled water. Pipet 50 ml from each solution, and transfer each to a
separate 100-ml beaker. Then add 10 ml of SPADNS mixed reagent (Section
7.3.13) to each. These standards will contain 0, 10, 20, 30, 40, 50,
60, and 70 g F-(0 to 1.4 g/ml),
respectively.
10.2.3 After mixing, place the blank and calibration standards in
a constant temperature bath for 30 minutes before reading the
absorbance with the spectrophotometer. Adjust all samples to this same
temperature before analyzing.
10.2.4 With the spectrophotometer at 570 nm, use the blank
standard to set

[[Page 61953]]

the absorbance to zero. Determine the absorbance of the standards.
10.2.5 Prepare a calibration curve by plotting g
F-/50 ml versus absorbance on linear graph paper. Prepare
the standard curve initially and thereafter whenever the SPADNS mixed
reagent is newly made. Also, run a calibration standard with each set
of samples and, if it differs from the calibration curve by more than
2 percent, prepare a new standard curve.

11.0 Analytical Procedures

11.1 Sample Loss Check. Note the liquid levels in Containers No. 1
and No. 2, determine whether leakage occurred during transport, and
note this finding on the analytical data sheet. If noticeable leakage
has occurred, either void the sample or use methods, subject to the
approval of the Administrator, to correct the final results.
11.2 Sample Preparation. Treat the contents of each sample
container as described below:
11.2.1 Container No. 1 (Probe, Filter, and Impinger Catches).
Filter this container's contents, including the sampling filter,
through Whatman No. 541 filter paper, or equivalent, into a 1500-ml
beaker.
11.2.1.1 If the filtrate volume exceeds 900 ml, make the filtrate
basic (red to phenolphthalein) with NaOH, and evaporate to less than
900 ml.
11.2.1.2 Place the filtered material (including sampling filter)
in a nickel crucible, add a few ml of water, and macerate the filters
with a glass rod.
11.2.1.2.1 Add 100 mg CaO to the crucible, and mix the contents
thoroughly to form a slurry. Add two drops of phenolphthalein
indicator. Place the crucible in a hood under infrared lamps or on a
hot plate at low heat. Evaporate the water completely. During the
evaporation of the water, keep the slurry basic (red to
phenolphthalein) to avoid loss of F-. If the indicator turns
colorless (acidic) during the evaporation, add CaO until the color
turns red again.
11.2.1.2.2 After evaporation of the water, place the crucible on a
hot plate under a hood, and slowly increase the temperature until the
Whatman No. 541 and sampling filters char. It may take several hours to
char the filters completely.
11.2.1.2.3 Place the crucible in a cold muffle furnace. Gradually
(to prevent smoking) increase the temperature to 600 deg.C (1100
deg.F), and maintain this temperature until the contents are reduced to
an ash. Remove the crucible from the furnace, and allow to cool.
11.2.1.2.4 Add approximately 4 g of crushed NaOH to the crucible,
and mix. Return the crucible to the muffle furnace, and fuse the sample
for 10 minutes at 600 deg.C.
11.2.1.2.5 Remove the sample from the furnace, and cool to ambient
temperature. Using several rinsings of warm water, transfer the
contents of the crucible to the beaker containing the filtrate. To
ensure complete sample removal, rinse finally with two 20-ml portions
of 25 percent H2SO4, and carefully add to the
beaker. Mix well, and transfer to a 1-liter volumetric flask. Dilute to
volume with water, and mix thoroughly. Allow any undissolved solids to
settle.
11.2.2 Container No. 2 (Sample Blank). Treat in the same manner as
described in Section 11.2.1 above.
11.2.3 Adjustment of Acid/Water Ratio in Distillation Flask. Place
400 ml of water in the distillation flask, and add 200 ml of
concentrated H2SO4. Add some soft glass beads and
several small pieces of broken glass tubing, and assemble the apparatus
as shown in Figure 13A-2. Heat the flask until it reaches a temperature
of 175 deg.C (347 deg.F) to adjust the acid/water ratio for
subsequent distillations. Discard the distillate.

Caution: Use a protective shield when carrying out this
procedure. Observe standard precautions when mixing
H2SO4 with water. Slowly add the acid to the
flask with constant swirling.

11.3 Distillation.
11.3.1 Cool the contents of the distillation flask to below 80
deg.C (180 deg.F). Pipet an aliquot of sample containing less than
10.0 mg F- directly into the distillation flask, and add
water to make a total volume of 220 ml added to the distillation flask.
(To estimate the appropriate aliquot size, select an aliquot of the
solution, and treat as described in Section 11.4.1. This will be an
approximation of the F- content because of possible
interfering ions.)

Note: If the sample contains chloride, add 5 mg of
Ag2SO4 to the flask for every mg of chloride.

11.3.2 Place a 250-ml volumetric flask at the condenser exit. Heat
the flask as rapidly as possible with a Bunsen burner, and collect all
the distillate up to 175 deg.C (347 deg.F). During heatup, play the
burner flame up and down the side of the flask to prevent bumping.
Conduct the distillation as rapidly as possible (15 minutes or less).
Slow distillations have been found to produce low F-
recoveries. Be careful not to exceed 175 deg.C (347 deg.F) to avoid
causing H2SO4 to distill over. If F-
distillation in the mg range is to be followed by a distillation in the
fractional mg range, add 220 ml of water and distill it over as in the
acid adjustment step to remove residual F- from the
distillation system.
11.3.3 The acid in the distillation flask may be used until there
is carry-over of interferences or poor F- recovery. Check
for interference and for recovery efficiency every tenth distillation
using a water blank and a standard solution. Change the acid whenever
the F- recovery is less than 90 percent or the blank value
exceeds 0.1 g/ml.
11.4 Sample Analysis.
11.4.1 Containers No. 1 and No. 2.
11.4.1.1 After distilling suitable aliquots from Containers No. 1
and No. 2 according to Section 11.3, dilute the distillate in the
volumetric flasks to exactly 250 ml with water, and mix thoroughly.
Pipet a suitable aliquot of each sample distillate (containing 10 to 40
g F-/ml) into a beaker, and dilute to 50 ml with
water. Use the same aliquot size for the blank. Add 10 ml of SPADNS
mixed reagent (Section 7.3.13), and mix thoroughly.
11.4.1.2 After mixing, place the sample in a constant-temperature
bath containing the standard solutions for 30 minutes before reading
the absorbance on the spectrophotometer.

Note: After the sample and colorimetric reagent are mixed, the
color formed is stable for approximately 2 hours. Also, a 3 deg.C
(5.4 deg.F) temperature difference between the sample and standard
solutions produces an error of approximately 0.005 mg F-/
liter. To avoid this error, the absorbencies of the sample and
standard solutions must be measured at the same temperature.

11.4.1.3 Set the spectrophotometer to zero absorbance at 570 nm
with the zero reference solution (Section 7.3.12), and check the
spectrophotometer calibration with the standard solution (Section
7.3.10). Determine the absorbance of the samples, and determine the
concentration from the calibration curve. If the concentration does not
fall within the range of the calibration curve, repeat the procedure
using a different size aliquot.
11.4.2 Container No. 3 (Silica Gel). Weigh the spent silica gel
(or silica gel plus impinger) to the nearest 0.5 g using a balance.
This step may be conducted in the field.

12.0 Data Analysis and Calculations

Carry out calculations, retaining at least one extra significant
figure beyond that of the acquired data. Round off figures after final
calculation. Other forms of the equations may be used, provided that
they yield equivalent results.
12.1 Nomenclature.

[[Page 61954]]

Ad = Aliquot of distillate taken for color development, ml.
At = Aliquot of total sample added to still, ml.
Bws = Water vapor in the gas stream, portion by volume.
Cs = Concentration of F- in stack gas, mg/dscm
(gr/dscf).
Fc = F- concentration from the calibration curve,
g.
Ft = Total F- in sample, mg.
Tm = Absolute average dry gas meter (DGM) temperature (see
Figure 5-3 of Method 5), deg.K ( deg.R).
Ts = Absolute average stack gas temperature (see Figure 5-3
of Method 5), deg.K ( deg.R).
Vd = Volume of distillate as diluted, ml.
Vm(std) = Volume of gas sample as measured by DGM at
standard conditions, dscm (dscf).
Vt = Total volume of F- sample, after final
dilution, ml.
Vw(std) = Volume of water vapor in the gas sample at
standard conditions, scm (scf)

12.2 Average DGM Temperature and Average Orifice Pressure Drop
(see Figure 5-3 of Method 5).
12.3 Dry Gas Volume. Calculate Vm(std), and adjust for
leakage, if necessary, using Equation 5-1 of Method 5.
12.4 Volume of Water Vapor and Moisture Content. Calculate
Vw(std) and Bws from the data obtained in this
method. Use Equations 5-2 and 5-3 of Method 5.
12.5 Total Fluoride in Sample. Calculate the amount of
F- in the sample using the following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.247

Where:

K = 10-3 mg/g (metric units)
= 1.54 x 10-5 gr/g (English units)

12.6 Fluoride Concentration in Stack Gas. Determine the
F- concentration in the stack gas using the following
equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.248

12.7 Isokinetic Variation. Same as Method 5, Section 12.11.

13.0 Method Performance

The following estimates are based on a collaborative test done at a
primary aluminum smelter. In the test, six laboratories each sampled
the stack simultaneously using two sampling trains for a total of 12
samples per sampling run. Fluoride concentrations encountered during
the test ranged from 0.1 to 1.4 mg F-/m\3\.
13.1 Precision. The intra- and inter-laboratory standard
deviations, which include sampling and analysis errors, were 0.044 mg
F-/m\3\ with 60 degrees of freedom and 0.064 mg
F-/m\3\ with five degrees of freedom, respectively.
13.2 Bias. The collaborative test did not find any bias in the
analytical method.
13.3 Range. The range of this method is 0 to 1.4 g
F-/ml.

14.0 Pollution Prevention. [Reserved]

15.0 Waste Management. [Reserved]

16.0 Alternative Procedures

16.1 Compliance with ASTM D 3270-73T, 80, 91, or 95 (incorporated
by reference--see Sec. 60.17) ``Analysis of Fluoride Content of the
Atmosphere and Plant Tissues (Semiautomated Method) is an acceptable
alternative for the requirements specified in Sections 11.2, 11.3, and
11.4.1 when applied to suitable aliquots of Containers 1 and 2 samples.

17.0 References

1. Bellack, Ervin. Simplified Fluoride Distillation Method. J.
of the American Water Works Association. 50:5306. 1958.
2. Mitchell, W.J., J.C. Suggs, and F.J. Bergman. Collaborative
Study of EPA Method 13A and Method 13B. Publication No. EPA-300/4-
77-050. U.S. Environmental Protection Agency, Research Triangle
Park, NC. December 1977.
3. Mitchell, W.J., and M.R. Midgett. Adequacy of Sampling Trains
and Analytical Procedures Used for Fluoride. Atm. Environ. 10:865-
872. 1976.
BILLING CODE 6560-50-P

[[Page 61955]]

18.0 Tables, Diagrams, Flowcharts, and Validation Data
[GRAPHIC] [TIFF OMITTED] TR17OC00.249

[[Page 61956]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.250

BILLING CODE 6560-50-C

Method 13B--Determination of Total Fluoride Emissions From
Stationary Sources (Specific Ion Electrode Method)

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Total fluorides as Fluorine.... 7782-41-4 Not determined.
------------------------------------------------------------------------

2.0 Summary

Gaseous and particulate F- are withdrawn isokinetically
from the source and collected in water and on a filter. The total
F- is then determined by the specific ion electrode method.

3.0 Definitions. [Reserved]

4.0 Interferences

Grease on sample-exposed surfaces may cause low F-
results because of adsorption.

5.0 Safety

5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method does not purport to address
all of the safety problems associated with its use. It is the
responsibility of the user of this test method to establish appropriate
safety and health practices and to determine the applicability of
regulatory limitations prior to performing this test method.
5.2 Corrosive Reagents. The following reagents are hazardous.
Personal protective equipment and safe procedures are useful in
preventing chemical splashes. If contact occurs, immediately flush with
copious amounts of water at least 15 minutes. Remove clothing under
shower and

[[Page 61957]]

decontaminate. Treat residual chemical burn as thermal burn.
5.2.1 Sodium Hydroxide (NaOH). Causes severe damage to eye tissues
and to skin. Inhalation causes irritation to nose, throat, and lungs.
Reacts exothermically with limited amounts of water.
5.2.2 Sulfuric Acid (H2SO4). Rapidly
destructive to body tissue. Will cause third degree burns. Eye damage
may result in blindness. Inhalation may be fatal from spasm of the
larynx, usually within 30 minutes. May cause lung tissue damage with
edema. 1 mg/m\3\ for 8 hours will cause lung damage or, in higher
concentrations, death. Provide ventilation to limit inhalation. Reacts
violently with metals and organics.

6.0 Equipment and Supplies

6.1 Sample Collection and Sample Recovery. Same as Method 13A,
Sections 6.1 and 6.2, respectively.
6.2 Sample Preparation and Analysis. The following items are
required for sample preparation and analysis:
6.2.1 Distillation Apparatus, Bunsen Burner, Electric Muffle
Furnace, Crucibles, Beakers, Volumetric Flasks, Erlenmeyer Flasks or
Plastic Bottles, Constant Temperature Bath, and Balance. Same as Method
13A, Sections 6.3.1 to 6.3.9, respectively.
6.2.2 Fluoride Ion Activity Sensing Electrode.
6.2.3 Reference Electrode. Single junction, sleeve type.
6.2.4 Electrometer. A pH meter with millivolt-scale capable of
0.1-mv resolution, or a specific ion meter made
specifically for specific ion electrode use.
6.2.5 Magnetic Stirrer and Tetrafluoroethylene (TFE) Fluorocarbon-
Coated Stirring Bars.
6.2.6 Beakers. Polyethylene, 100-ml.

7.0 Reagents and Standards

8.0 Sample Collection, Preservation, Storage, and Transport

Same as Method 13A, Section 8.0.

9.0 Quality Control

9.1 Miscellaneous Quality Control Measures.

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
8.0, 10.1..................... Sampling Ensure accurate
equipment leak- measurement of stack
check and gas flow rate and
calibration. sample volume.
10.2.......................... Fluoride Evaluate analytical
electrode. technique,
preparation of
standards.
11.1.......................... Interference/ Minimize negative
recovery effects of used
efficiency-check acid.
during
distillation.
------------------------------------------------------------------------

9.2 Volume Metering System Checks. Same as Method 5, Section 9.2.

10.0 Calibration and Standardizations

Note: Maintain a laboratory log of all calibrations.

10.1 Sampling Equipment. Same as Method 13A, Section 10.1.
10.2 Fluoride Electrode. Prepare fluoride standardizing solutions
by serial dilution of the 0.1 M fluoride standard solution. Pipet 10 ml
of 0.1 M fluoride standard solution into a 100-ml volumetric flask, and
make up to the mark with water for a 10-\2\ M standard
solution. Use 10 ml of 10-\2\ M solution to make a
10-\3\ M solution in the same manner. Repeat the dilution
procedure, and make 10-\4\ and 10-\5\ M
solutions.
10.2.1 Pipet 50 ml of each standard into a separate beaker. Add 50
ml of TISAB to each beaker. Place the electrode in the most dilute
standard solution. When a steady millivolt reading is obtained, plot
the value on the linear axis of semilog graph paper versus
concentration on the log axis. Plot the nominal value for concentration
of the standard on the log axis, (e.g., when 50 ml of 10-\2\
M standard is diluted with 50 ml of TISAB, the concentration is still
designated ``10-\2\ M'').
10.2.2 Between measurements, soak the fluoride sensing electrode
in water for 30 seconds, and then remove and blot dry. Analyze the
standards going from dilute to concentrated standards. A straight-line
calibration curve will be obtained, with nominal concentrations of
10-\4\, 10-\3\, 10-\2\,
10-\1\ fluoride molarity on the log axis plotted versus
electrode potential (in mv) on the linear scale. Some electrodes may be
slightly nonlinear between 10-\5\ and 10-\4\ M.
If this occurs, use additional standards between these two
concentrations.
10.2.3 Calibrate the fluoride electrode daily, and check it
hourly. Prepare fresh fluoride standardizing solutions daily
(10-\2\ M or less). Store fluoride standardizing solutions
in polyethylene or polypropylene containers.

Note: Certain specific ion meters have been designed
specifically for fluoride electrode use and give a direct readout of
fluoride ion concentration. These meters may be used in lieu of
calibration curves for fluoride

[[Page 61958]]

measurements over a narrow concentration ranges. Calibrate the meter
according to the manufacturer's instructions.

11.0 Analytical Procedures

11.1 Sample Loss Check, Sample Preparation, and Distillation. Same
as Method 13A, Sections 11.1 through 11.3, except that the Note
following Section 11.3.1 is not applicable.
11.2 Analysis.
11.2.1 Containers No. 1 and No. 2. Distill suitable aliquots from
Containers No. 1 and No. 2. Dilute the distillate in the volumetric
flasks to exactly 250 ml with water, and mix thoroughly. Pipet a 25-ml
aliquot from each of the distillate into separate beakers. Add an equal
volume of TISAB, and mix. The sample should be at the same temperature
as the calibration standards when measurements are made. If ambient
laboratory temperature fluctuates more than 2 deg.C from
the temperature at which the calibration standards were measured,
condition samples and standards in a constant-temperature bath before
measurement. Stir the sample with a magnetic stirrer during measurement
to minimize electrode response time. If the stirrer generates enough
heat to change solution temperature, place a piece of temperature
insulating material, such as cork, between the stirrer and the beaker.
Hold dilute samples (below 10-\4\ M fluoride ion content) in
polyethylene beakers during measurement.
11.2.2 Insert the fluoride and reference electrodes into the
solution. When a steady millivolt reading is obtained, record it. This
may take several minutes. Determine concentration from the calibration
curve. Between electrode measurements, rinse the electrode with water.
11.2.3 Container No. 3 (Silica Gel). Same as in Method 13A,
Section 11.4.2.

12.0 Data Analysis and Calculations

Carry out calculations, retaining at least one extra significant
figure beyond that of the acquired data. Round off figures after final
calculation.
12.1 Nomenclature. Same as Method 13A, Section 12.1, with the
addition of the following:

M = F- concentration from calibration curve, molarity.

12.2 Average DGM Temperature and Average Orifice Pressure Drop,
Dry Gas Volume, Volume of Water Vapor and Moisture Content, Fluoride
Concentration in Stack Gas, and Isokinetic Variation. Same as Method
13A, Sections 12.2 to 12.4, 12.6, and 12.7, respectively.
12.3 Total Fluoride in Sample. Calculate the amount of
F- in the sample using Equation 13B-1:
[GRAPHIC] [TIFF OMITTED] TR17OC00.251

Where:

K = 19 [(mgl)/(moleml)] (metric units)
= 0.292 [(grl)/(moleml)] (English units)

13.0 Method Performance

The following estimates are based on a collaborative test done at a
primary aluminum smelter. In the test, six laboratories each sampled
the stack simultaneously using two sampling trains for a total of 12
samples per sampling run. Fluoride concentrations encountered during
the test ranged from 0.1 to 1.4 mg F-/m\3\.
13.1 Precision. The intra-laboratory and inter-laboratory standard
deviations, which include sampling and analysis errors, are 0.037 mg
F-/m\3\ with 60 degrees of freedom and 0.056 mg
F-/m\3\ with five degrees of freedom, respectively.
13.2 Bias. The collaborative test did not find any bias in the
analytical method.
13.3 Range. The range of this method is 0.02 to 2,000 g
F-/ml; however, measurements of less than 0.1 g
F-/ml require extra care.

14.0 Pollution Prevention. [Reserved]

15.0 Waste Management. [Reserved]

16.0 Alternative Procedures

16.1 Compliance with ASTM D 3270-73T, 91, 95 ``Analysis for
Fluoride Content of the Atmosphere and Plant Tissues (Semiautomated
Method)'' is an acceptable alternative for the distillation and
analysis requirements specified in Sections 11.1 and 11.2 when applied
to suitable aliquots of Containers 1 and 2 samples.

17.0 References

Same as Method 13A, Section 16.0, References 1 and 2, with the
following addition:

1. MacLeod, Kathryn E., and Howard L. Crist. Comparison of the
SPADNS-Zirconium Lake and Specific Ion Electrode Methods of Fluoride
Determination in Stack Emission Samples. Analytical Chemistry.
45:1272-1273. 1973.

18.0 Tables, Diagrams, Flowcharts, and Validation Data. [Reserved]

Method 14--Determination of Fluoride Emissions From Potroom Roof
Monitors for Primary Aluminum Plants

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Total fluorides as Fluorine....... 7782-41-4 Not determined.
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of fluoride emissions from roof monitors at primary aluminum reduction
plant potroom groups.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 Gaseous and particulate fluoride roof monitor emissions are
drawn into a permanent sampling manifold through several large nozzles.
The sample is transported from the sampling manifold to ground level
through a duct. The fluoride content of the gas in the duct is
determined using either Method 13A or Method 13B. Effluent velocity and
volumetric flow rate are determined using anemometers located in the
roof monitor.

3.0 Definitions

Potroom means a building unit which houses a group of electrolytic
cells in which aluminum is produced.
Potroom group means an uncontrolled potroom, a potroom which is
controlled individually, or a group of potrooms or potroom segments
ducted to a common control system.

[[Page 61959]]

Roof monitor means that portion of the roof of a potroom where
gases not captured at the cell exit from the potroom.

4.0 Interferences

Same as Section 4.0 of either Method 13A or Method 13B, with the
addition of the following:
4.1 Magnetic Field Effects. Anemometer readings can be affected by
potroom magnetic field effects. Section 6.1 provides for minimization
of this interference through proper shielding or encasement of
anemometer components.

5.0 Safety

6.0 Equipment and Supplies

Same as Section 6.0 of either Method 13A or Method 13B, as
applicable, with the addition of the following:
6.1 Velocity Measurement Apparatus.
6.1.1 Anemometer Specifications. Propeller anemometers, or
equivalent. Each anemometer shall meet the following specifications:
6.1.1.1 Its propeller shall be made of polystyrene, or similar
material of uniform density. To ensure uniformity of performance among
propellers, it is desirable that all propellers be made from the same
mold.
6.1.1.2 The propeller shall be properly balanced, to optimize
performance.
6.1.1.3 When the anemometer is mounted horizontally, its threshold
velocity shall not exceed 15 m/min (50 ft/min).
6.1.1.4 The measurement range of the anemometer shall extend to at
least 600 m/min (2,000 ft/min).
6.1.1.5 The anemometer shall be able to withstand prolonged
exposure to dusty and corrosive environments; one way of achieving this
is to purge the bearings of the anemometer continuously with filtered
air during operation.
6.1.1.6 All anemometer components shall be properly shielded or
encased, such that the performance of the anemometer is uninfluenced by
potroom magnetic field effects.
6.1.1.7 A known relationship shall exist between the electrical
output signal from the anemometer generator and the propeller shaft rpm
(see Section 10.2.1). Anemometers having other types of output signals
(e.g., optical) may be used, subject to the approval of the
Administrator. If other types of anemometers are used, there must be a
known relationship between output signal and shaft rpm (see Section
10.2.2).
6.1.1.8 Each anemometer shall be equipped with a suitable readout
system (see Section 6.1.3).
6.1.2 Anemometer Installation Requirements.
6.1.2.1 Single, Isolated Potroom. If the affected facility
consists of a single, isolated potroom (or potroom segment), install at
least one anemometer for every 85 m (280 ft) of roof monitor length. If
the length of the roof monitor divided by 85 m (280 ft) is not a whole
number, round the fraction to the nearest whole number to determine the
number of anemometers needed. For monitors that are less than 130 m
(430 ft) in length, use at least two anemometers. Divide the monitor
cross-section into as many equal areas as anemometers, and locate an
anemometer at the centroid of each equal area. See exception in Section
6.1.2.3.
6.1.2.2 Two or More Potrooms. If the affected facility consists of
two or more potrooms (or potroom segments) ducted to a common control
device, install anemometers in each potroom (or segment) that contains
a sampling manifold. Install at least one anemometer for every 85 m
(280 ft) of roof monitor length of the potroom (or segment). If the
potroom (or segment) length divided by 85 m (280 ft) is not a whole
number, round the fraction to the nearest whole number to determine the
number of anemometers needed. If the potroom (or segment) length is
less than 130 m (430 ft), use at least two anemometers. Divide the
potroom (or segment) monitor cross-section into as many equal areas as
anemometers, and locate an anemometer at the centroid of each equal
area. See exception in Section 6.1.2.3.
6.1.2.3 Placement of Anemometer at the Center of Manifold. At
least one anemometer shall be installed in the immediate vicinity
(i.e., within 10 m (33 ft)) of the center of the manifold (see Section
6.2.1). For its placement in relation to the width of the monitor,
there are two alternatives. The first is to make a velocity traverse of
the width of the roof monitor where an anemometer is to be placed and
install the anemometer at a point of average velocity along this
traverse. The traverse may be made with any suitable low velocity
measuring device, and shall be made during normal process operating
conditions. The second alternative is to install the anemometer half-
way across the width of the roof monitor. In this latter case, the
velocity traverse need not be conducted.
6.1.3 Recorders. Recorders that are equipped with suitable
auxiliary equipment (e.g., transducers) for converting the output
signal from each anemometer to a continuous recording of air flow
velocity or to an integrated measure of volumetric flowrate shall be
used. A suitable recorder is one that allows the output signal from the
propeller anemometer to be read to within 1 percent when the velocity
is between 100 and 120 m/min (330 and 390 ft/min). For the purpose of
recording velocity, ``continuous'' shall mean one readout per 15-minute
or shorter time interval. A constant amount of time shall elapse
between readings. Volumetric flow rate may be determined by an
electrical count of anemometer revolutions. The recorders or counters
shall permit identification of the velocities or flowrates measured by
each individual anemometer.
6.1.4 Pitot Tube. Standard-type pitot tube, as described in
Section 6.7 of Method 2, and having a coefficient of 0.99
0.01.
6.1.5 Pitot Tube (Optional). Isolated, Type S pitot, as described
in Section 6.1 of Method 2, and having a known coefficient, determined
as outlined in Section 4.1 of Method 2.
6.1.6 Differential Pressure Gauge. Inclined manometer, or
equivalent, as described in Section 6.1.2 of Method 2.
6.2 Roof Monitor Air Sampling System.
6.2.1 Manifold System and Ductwork. A minimum of one manifold
system shall be installed for each potroom group. The manifold system
and ductwork shall meet the following specifications:
6.2.1.1 The manifold system and connecting duct shall be
permanently installed to draw an air sample from the roof monitor to
ground level. A typical installation of a duct for drawing a sample
from a roof monitor to ground level is shown in Figure 14-1 in Section
17.0. A plan of a manifold system that is located in a roof monitor is
shown in Figure 14-2. These drawings represent a typical installation
for a generalized roof monitor. The dimensions on these figures may be
altered slightly to make the manifold system fit into a particular roof
monitor, but the general configuration shall be followed.

[[Page 61960]]

6.2.1.2 There shall be eight nozzles, each having a diameter of
0.40 to 0.50 m.
6.2.1.3 The length of the manifold system from the first nozzle to
the eighth shall be 35 m (115 ft) or eight percent of the length of the
potroom (or potroom segment) roof monitor, whichever is greater.
Deviation from this requirement is subject to the approval of the
Administrator.
6.2.1.4 The duct leading from the roof monitor manifold system
shall be round with a diameter of 0.30 to 0.40 m (1.0 to 1.3 ft). All
connections in the ductwork shall be leak-free.
6.2.1.5 As shown in Figure 14-2, each of the sample legs of the
manifold shall have a device, such as a blast gate or valve, to enable
adjustment of the flow into each sample nozzle.
6.2.1.6 The manifold system shall be located in the immediate
vicinity of one of the propeller anemometers (see Section 8.1.1.4) and
as close as possible to the midsection of the potroom (or potroom
segment). Avoid locating the manifold system near the end of a potroom
or in a section where the aluminum reduction pot arrangement is not
typical of the rest of the potroom (or potroom segment). The sample
nozzles shall be centered in the throat of the roof monitor (see Figure
14-1).
6.2.1.7 All sample-exposed surfaces within the nozzles, manifold,
and sample duct shall be constructed with 316 stainless steel.
Alternatively, aluminum may be used if a new ductwork is conditioned
with fluoride-laden roof monitor air for a period of six weeks before
initial testing. Other materials of construction may be used if it is
demonstrated through comparative testing, to the satisfaction of the
Administrator, that there is no loss of fluorides in the system.
6.2.1.8 Two sample ports shall be located in a vertical section of
the duct between the roof monitor and the exhaust fan (see Section
6.2.2). The sample ports shall be at least 10 duct diameters downstream
and three diameters upstream from any flow disturbance such as a bend
or contraction. The two sample ports shall be situated 90 deg. apart.
One of the sample ports shall be situated so that the duct can be
traversed in the plane of the nearest upstream duct bend.
6.2.2 Exhaust Fan. An industrial fan or blower shall be attached
to the sample duct at ground level (see Figure 14-1). This exhaust fan
shall have a capacity such that a large enough volume of air can be
pulled through the ductwork to maintain an isokinetic sampling rate in
all the sample nozzles for all flow rates normally encountered in the
roof monitor. The exhaust fan volumetric flow rate shall be adjustable
so that the roof monitor gases can be drawn isokinetically into the
sample nozzles. This control of flow may be achieved by a damper on the
inlet to the exhauster or by any other workable method.
6.3 Temperature Measurement Apparatus. To monitor and record the
temperature of the roof monitor effluent gas, and consisting of the
following:
6.3.1 Temperature Sensor. A temperature sensor shall be installed
in the roof monitor near the sample duct. The temperature sensor shall
conform to the specifications outlined in Method 2, Section 6.3.
6.3.2 Signal Transducer. Transducer, to change the temperature
sensor voltage output to a temperature readout.
6.3.3 Thermocouple Wire. To reach from roof monitor to signal
transducer and recorder.
6.3.4 Recorder. Suitable recorder to monitor the output from the
thermocouple signal transducer.

7.0 Reagents and Standards

Same as Section 7.0 of either Method 13A or Method 13B, as
applicable.

8.0 Sample Collection, Preservation, Storage, and Transport

8.1 Roof Monitor Velocity Determination.
8.1.1 Velocity Estimate(s) for Setting Isokinetic Flow. To assist
in setting isokinetic flow in the manifold sample nozzles, the
anticipated average velocity in the section of the roof monitor
containing the sampling manifold shall be estimated before each test
run. Any convenient means to make this estimate may be used (e.g., the
velocity indicated by the anemometer in the section of the roof monitor
containing the sampling manifold may be continuously monitored during
the 24-hour period before the test run). If there is question as to
whether a single estimate of average velocity is adequate for an entire
test run (e.g., if velocities are anticipated to be significantly
different during different potroom operations), the test run may be
divided into two or more ``sub-runs,'' and a different estimated
average velocity may be used for each sub-run (see Section 8.4.2).
8.1.2 Velocity Determination During a Test Run. During the actual
test run, record the velocity or volumetric flowrate readings of each
propeller anemometer in the roof monitor. Readings shall be taken from
each anemometer at equal time intervals of 15 minutes or less (or
continuously).
8.2 Temperature Recording. Record the temperature of the roof
monitor effluent gases at least once every 2 hours during the test run.
8.3 Pretest Ductwork Conditioning. During the 24-hour period
immediately preceding the test run, turn on the exhaust fan, and draw
roof monitor air through the manifold system and ductwork. Adjust the
fan to draw a volumetric flow through the duct such that the velocity
of gas entering the manifold nozzles approximates the average velocity
of the air exiting the roof monitor in the vicinity of the sampling
manifold.
8.4 Manifold Isokinetic Sample Rate Adjustment(s).
8.4.1 Initial Adjustment. Before the test run (or first sub-run,
if applicable; see Sections 8.1.1 and 8.4.2), adjust the fan such that
air enters the manifold sample nozzles at a velocity equal to the
appropriate estimated average velocity determined under Section 8.1.1.
Use Equation 14-1 (Section 12.2.2) to determine the correct stream
velocity needed in the duct at the sampling location, in order for
sample gas to be drawn isokinetically into the manifold nozzles. Next,
verify that the correct stream velocity has been achieved, by
performing a pitot tube traverse of the sample duct (using either a
standard or Type S pitot tube); use the procedure outlined in Method 2.
8.4.2 Adjustments During Run. If the test run is divided into two
or more ``sub-runs'' (see Section 8.1.1), additional isokinetic rate
adjustment(s) may become necessary during the run. Any such adjustment
shall be made just before the start of a sub-run, using the procedure
outlined in Section 8.4.1 above.

Note: Isokinetic rate adjustments are not permissible during a
sub-run.

8.5 Pretest Preparation, Preliminary Determinations, Preparation
of Sampling Train, Leak-Check Procedures, Sampling Train Operation, and
Sample Recovery. Same as Method 13A, Sections 8.1 through 8.6, with the
exception of the following:
8.5.1 A single train shall be used for the entire sampling run.
Alternatively, if two or more sub-runs are performed, a separate train
may be used for each sub-run; note, however, that if this option is
chosen, the area of the sampling nozzle shall be the same
(2 percent) for each train. If the test run is divided into
sub-runs, a complete traverse of the duct shall be performed during
each sub-run.
8.5.2 Time Per Run. Each test run shall last 8 hours or more; if
more than one run is to be performed, all runs shall be of
approximately the same (10 percent) length. If questions
exist as to the representativeness of an 8-hour test,

[[Page 61961]]

a longer period should be selected. Conduct each run during a period
when all normal operations are performed underneath the sampling
manifold. For most recently-constructed plants, 24 hours are required
for all potroom operations and events to occur in the area beneath the
sampling manifold. During the test period, all pots in the potroom
group shall be operated such that emissions are representative of
normal operating conditions in the potroom group.

9.0 Quality Control

9.1 Miscellaneous Quality Control Measures.

------------------------------------------------------------------------
Quality Control
Section Measure Effect
------------------------------------------------------------------------
8.0, 10.0..................... Sampling Ensure accurate
equipment leak- measurement of gas
check and flow rate in duct
calibration. and of sample
volume.
10.3, 10.4.................... Initial and Ensure accurate and
periodic precise measurement
performance of roof monitor
checks of roof effluent gas
monitor effluent temperature and flow
gas rate.
characterization
apparatus.
11.0.......................... Interference/ Minimize negative
recovery effects of used
efficiency check acid.
during
distillation.
------------------------------------------------------------------------

9.2 Volume Metering System Checks. Same as Method 5, Section 9.2.

10.0 Calibration and Standardization

Same as Section 10.0 of either Method 13A or Method 13B, as
applicable, with the addition of the following:
10.1 Manifold Intake Nozzles. The manifold intake nozzles shall be
calibrated when the manifold system is installed or, alternatively, the
manifold may be preassembled and the nozzles calibrated on the ground
prior to installation. The following procedures shall be observed:
10.1.1 Adjust the exhaust fan to draw a volumetric flow rate
(refer to Equation 14-1) such that the entrance velocity into each
manifold nozzle approximates the average effluent velocity in the roof
monitor.
10.1.2 Measure the velocity of the air entering each nozzle by
inserting a standard pitot tube into a 2.5 cm or less diameter hole
(see Figure 14-2) located in the manifold between each blast gate (or
valve) and nozzle. Note that a standard pitot tube is used, rather than
a type S, to eliminate possible velocity measurement errors due to
cross-section blockage in the small (0.13 m diameter) manifold leg
ducts. The pitot tube tip shall be positioned at the center of each
manifold leg duct. Take care to ensure that there is no leakage around
the pitot tube, which could affect the indicated velocity in the
manifold leg.
10.1.3 If the velocity of air being drawn into each nozzle is not
the same, open or close each blast gate (or valve) until the velocity
in each nozzle is the same. Fasten each blast gate (or valve) so that
it will remain in position, and close the pitot port holes.
10.2 Initial Calibration of Propeller Anemometers.
10.2.1 Anemometers that meet the specifications outlined in
Section 6.1.1 need not be calibrated, provided that a reference
performance curve relating anemometer signal output to air velocity
(covering the velocity range of interest) is available from the
manufacturer. If a reference performance curve is not available from
the manufacturer, such a curve shall be generated.
For the purpose of this method, a ``reference'' performance curve
is defined as one that has been derived from primary standard
calibration data, with the anemometer mounted vertically. ``Primary
standard'' data are obtainable by: (a) direct calibration of one or
more of the anemometers by the National Institute of Standards and
Technology (NIST); (b) NIST-traceable calibration; or (c) Calibration
by direct measurement of fundamental parameters such as length and time
(e.g., by moving the anemometers through still air at measured rates of
speed, and recording the output signals).
10.2.2 Anemometers having output signals other than electrical
(e.g., optical) may be used, subject to the approval of the
Administrator. If other types of anemometers are used, a reference
performance curve shall be generated, using procedures subject to the
approval of the Administrator.
10.2.3 The reference performance curve shall be derived from at
least the following three points: 60 15, 900
100, and 1800 100 rpm.
10.3 Initial Performance Checks. Conduct these checks within 60
days before the first performance test.
10.3.1 Anemometers. A performance-check shall be conducted as
outlined in Sections 10.3.1.1 through 10.3.1.3. Alternatively, any
other suitable method that takes into account the signal output,
propeller condition, and threshold velocity of the anemometer may be
used, subject to the approval of the Administrator.
10.3.1.1 Check the signal output of the anemometer by using an
accurate rpm generator (see Figure 14-3) or synchronous motors to spin
the propeller shaft at each of the three rpm settings described in
Section 10.2.3, and measuring the output signal at each setting. If, at
each setting, the output signal is within 5 percent of the
manufacturer's value, the anemometer can be used. If the anemometer
performance is unsatisfactory, the anemometer shall either be replaced
or repaired.
10.3.1.2 Check the propeller condition, by visually inspecting the
propeller, making note of any significant damage or warpage; damaged or
deformed propellers shall be replaced.
10.3.1.3 Check the anemometer threshold velocity as follows: With
the anemometer mounted as shown in Figure 14-4(A), fasten a known
weight (a straight-pin will suffice) to the anemometer propeller at a
fixed distance from the center of the propeller shaft. This will
generate a known torque; for example, a 0.1-g weight, placed 10 cm from
the center of the shaft, will generate a torque of 1.0 g-cm. If the
known torque causes the propeller to rotate downward, approximately
90 deg. [see Figure 14-4(B)], then the known torque is greater than or
equal to the starting torque; if the propeller fails to rotate
approximately 90 deg., the known torque is less than the starting
torque. By trying different combinations of weight and distance, the
starting torque of a particular anemometer can be satisfactorily
estimated. Once an estimate of the starting torque has been obtained,
the threshold velocity of the anemometer (for horizontal mounting) can
be estimated from a graph such as Figure 14-5 (obtained from the
manufacturer). If the horizontal threshold velocity is acceptable [15
m/min (50 ft/min), when this technique is used], the anemometer can be
used. If the threshold velocity of an anemometer is found to be
unacceptably high, the anemometer shall either be replaced or repaired.
10.3.2 Recorders and Counters. Check the calibration of each
recorder and counter (see Section 6.1.2) at a minimum of three points,
approximately spanning the expected range of velocities. Use the
calibration

[[Page 61962]]

procedures recommended by the manufacturer, or other suitable
procedures (subject to the approval of the Administrator). If a
recorder or counter is found to be out of calibration by an average
amount greater than 5 percent for the three calibration points, replace
or repair the system; otherwise, the system can be used.
10.3.3 Temperature Measurement Apparatus. Check the calibration of
the Temperature Measurement Apparatus, using the procedures outlined in
Section 10.3 of Method 2, at temperatures of 0, 100, and 150 deg.C
(32, 212, and 302 deg.F). If the calibration is off by more than 5
deg.C (9 deg.F) at any of the temperatures, repair or replace the
apparatus; otherwise, the apparatus can be used.
10.4 Periodic Performance Checks. Repeat the procedures outlined
in Section 10.3 no more than 12 months after the initial performance
checks. If the above systems pass the performance checks (i.e., if no
repair or replacement of any component is necessary), continue with the
performance checks on a 12-month interval basis. However, if any of the
above systems fail the performance checks, repair or replace the
system(s) that failed, and conduct the periodic performance checks on a

3-month interval basis, until sufficient information (to the
satisfaction of the Administrator) is obtained to establish a modified
performance check schedule and calculation procedure.

Note: If any of the above systems fails the 12-month periodic
performance checks, the data for the past year need not be
recalculated.

11.0 Analytical Procedures

Same as Section 11.0 of either Method 13A or Method 13B.

12.0 Data Analysis and Calculations

Same as Section 12.0 of either Method 13A or Method 13B, as
applicable, with the following additions and exceptions:
12.1 Nomenclature.

A = Roof monitor open area, m\2\ (ft\2\).
Bws = Water vapor in the gas stream, portion by volume.
Cs = Average fluoride concentration in roof monitor air, mg
F/dscm (gr/dscf).
Dd = Diameter of duct at sampling location, m (ft).
Dn = Diameter of a roof monitor manifold nozzle, m (ft).
F = Emission Rate multiplication factor, dimensionless.
Ft = Total fluoride mass collected during a particular sub-
run (from Equation 13A-1 of Method 13A or Equation 13B-1 of Method
13B), mg F- (gr F-).
Md = Mole fraction of dry gas, dimensionless.
Prm = Pressure in the roof monitor; equal to barometric
pressure for this application.
Qsd = Average volumetric flow from roof monitor at standard
conditions on a dry basis, m\3\/min.
Trm = Average roof monitor temperature (from Section 8.2),
deg.C ( deg.F).
Vd = Desired velocity in duct at sampling location, m/sec.
Vm = Anticipated average velocity (from Section 8.1.1) in
sampling duct, m/sec.
Vmt = Arithmetic mean roof monitor effluent gas velocity, m/
sec.
Vs = Actual average velocity in the sampling duct (from
Equation 2-9 of Method 2 and data obtained from Method 13A or 13B), m/
sec.

12.2 Isokinetic Sampling Check.
12.2.1 Calculate the arithmetic mean of the roof monitor effluent
gas velocity readings (vm) as measured by the anemometer in
the section of the roof monitor containing the sampling manifold. If
two or more sub-runs have been performed, the average velocity for each
sub-run may be calculated separately.
12.2.2 Calculate the expected average velocity (vd) in
the duct, corresponding to each value of vm obtained under
Section 12.2.1, using Equation 14-1.
[GRAPHIC] [TIFF OMITTED] TR17OC00.252

Where:

8 = number of required manifold nozzles.
60 = sec/min.

12.2.3 Calculate the actual average velocity (vs) in
the sampling duct for each run or sub-run according to Equation 2-9 of
Method 2, using data obtained during sampling (Section 8.0 of Method
13A).
12.2.4 Express each vs value from Section 12.2.3 as a percentage
of the corresponding vd value from Section 12.2.2.
12.2.4.1 If vs is less than or equal to 120 percent of
vd, the results are acceptable (note that in cases where the
above calculations have been performed for each sub-run, the results
are acceptable if the average percentage for all sub-runs is less than
or equal to 120 percent).
12.2.4.2 If vs is more than 120 percent of
vd, multiply the reported emission rate by the following
factor:
[GRAPHIC] [TIFF OMITTED] TR17OC00.253

12.3 Average Velocity of Roof Monitor Effluent Gas. Calculate the
arithmetic mean roof monitor effluent gas velocity (vmt)
using all the velocity or volumetric flow readings from Section 8.1.2.
12.4 Average Temperature of Roof Monitor Effluent Gas. Calculate
the arithmetic mean roof monitor effluent gas temperature
(Tm) using all the temperature readings recorded in Section
8.2.
12.5 Concentration of Fluorides in Roof Monitor Effluent Gas.
12.5.1 If a single sampling train was used throughout the run,
calculate the average fluoride concentration for the roof monitor using
Equation 13A-2 of Method 13A.
12.5.2 If two or more sampling trains were used (i.e., one per
sub-run), calculate the average fluoride concentration for the run
using Equation 14-3:
[GRAPHIC] [TIFF OMITTED] TR17OC00.254

Where:

n = Total number of sub-runs.
12.6 Mole Fraction of Dry Gas.
[GRAPHIC] [TIFF OMITTED] TR17OC00.255

12.7 Average Volumetric Flow Rate of Roof Monitor Effluent Gas.
Calculate the arithmetic mean volumetric flow rate of the roof monitor
effluent gases using Equation 14-5.
[GRAPHIC] [TIFF OMITTED] TR17OC00.256

Where:

K1 = 0.3858 K/mm Hg for metric units,
= 17.64 deg.R/in. Hg for English units.

13.0 Method Performance. [Reserved]

14.0 Pollution Prevention. [Reserved]

15.0 Waste Management. [Reserved]

16.0 References

Same as Section 16.0 of either Method 13A or Method 13B, as
applicable, with the addition of the following:

1. Shigehara, R.T. A Guideline for Evaluating Compliance Test
Results (Isokinetic Sampling Rate Criterion). U.S. Environmental
Protection Agency, Emission Measurement Branch, Research Triangle
Park, NC. August 1977.
BILLING CODE 6560-50-P

[[Page 61963]]

17.0 Tables, Diagrams, Flowcharts, and Validation Data
[GRAPHIC] [TIFF OMITTED] TR17OC00.257

[[Page 61964]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.258

[[Page 61965]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.259

[[Page 61966]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.260

[[Page 61967]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.261

BILLING CODE 6560-50-C

[[Page 61968]]

* * * * *

Method 15--Determination of Hydrogen Sulfide, Carbonyl Sulfide, and
Carbon Disulfide Emissions From Stationary Sources

Note: This method is not inclusive with respect to
specifications (e.g., equipment and supplies) and procedures (e.g.,
sampling and analytical) essential to its performance. Some material
is incorporated by reference from other methods in this part.
Therefore, to obtain reliable results, persons using this method
should have a thorough knowledge of gas chromatography techniques.

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Sensitivity (See Sec
Analyte CAS No. 13.2)
------------------------------------------------------------------------
Carbon disulfide [CS2]......... 75-15-0 0.5 ppmv
Carbonyl sulfide [COS]......... 463-58-1 0.5 ppmv
Hydrogen sulfide [H2S]......... 7783-06-4 0.5 ppmv
------------------------------------------------------------------------

1.2 Applicability.
1.2.1 This method applies to the determination of emissions of
reduced sulfur compounds from tail gas control units of sulfur recovery
plants, H2S in fuel gas for fuel gas combustion devices, and
where specified in other applicable subparts of the regulations.
1.2.2 The method described below uses the principle of gas
chromatographic (GC) separation and flame photometric detection (FPD).
Since there are many systems or sets of operating conditions that
represent useable methods for determining sulfur emissions, all systems
which employ this principle, but differ only in details of equipment
and operation, may be used as alternative methods, provided that the
calibration precision and sample-line loss criteria are met.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 A gas sample is extracted from the emission source and diluted
with clean dry air (if necessary). An aliquot of the diluted sample is
then analyzed for CS2, COS, and H2S by GC/FPD.

3.0 Definitions. [Reserved]

4.0 Interferences

4.1 Moisture Condensation. Moisture condensation in the sample
delivery system, the analytical column, or the FPD burner block can
cause losses or interferences. This potential is eliminated by heating
the probe, filter box, and connections, and by maintaining the
SO2 scrubber in an ice water bath. Moisture is removed in
the SO2 scrubber and heating the sample beyond this point is
not necessary provided the ambient temperature is above 0 deg.C (32
deg.F). Alternatively, moisture may be eliminated by heating the sample
line, and by conditioning the sample with dry dilution air to lower its
dew point below the operating temperature of the GC/FPD analytical
system prior to analysis.
4.2 Carbon Monoxide (CO) and Carbon Dioxide (CO2). CO
and CO2 have substantial desensitizing effects on the FPD
even after 9:1 dilution. (Acceptable systems must demonstrate that they
have eliminated this interference by some procedure such as eluting CO
and CO2 before any of the sulfur compounds to be measured.)
Compliance with this requirement can be demonstrated by submitting
chromatograms of calibration gases with and without CO2 in
the diluent gas. The CO2 level should be approximately 10
percent for the case with CO2 present. The two chromatograms
should show agreement within the precision limits of Section 13.3.
4.3 Elemental Sulfur. The condensation of sulfur vapor in the
sampling system can lead to blockage of the particulate filter. This
problem can be minimized by observing the filter for buildup and
changing as needed.
4.4 Sulfur Dioxide (SO2). SO2 is not a
specific interferent but may be present in such large amounts that it
cannot be effectively separated from the other compounds of interest.
The SO2 scrubber described in Section 6.1.3 will effectively
remove SO2 from the sample.
4.5 Alkali Mist. Alkali mist in the emissions of some control
devices may cause a rapid increase in the SO2 scrubber pH,
resulting in low sample recoveries. Replacing the SO2
scrubber contents after each run will minimize the chances of
interference in these cases.

5.0 Safety

6.0 Equipment and Supplies

6.1 Sample Collection. See Figure 15-1. The sampling train
component parts are discussed in the following sections:
6.1.1 Probe. The probe shall be made of Teflon or Teflon-lined
stainless steel and heated to prevent moisture condensation. It shall
be designed to allow calibration gas to enter the probe at or near the
sample point entry. Any portion of the probe that contacts the stack
gas must be heated to prevent moisture condensation. The probe
described in Section 6.1.1 of Method 16A having a nozzle directed away
from the gas stream is recommended for sources having particulate or
mist emissions. Where very high stack temperatures prohibit the use of
Teflon probe components, glass or quartz-lined probes may serve as
substitutes.
6.1.2 Particulate Filter. 50-mm Teflon filter holder and a 1- to
2-micron porosity Teflon filter (available through Savillex
Corporation, 5325 Highway 101, Minnetonka, Minnesota 55343). The filter
holder must be maintained in a hot box at a temperature of at least 120
deg.C (248 deg.F).
6.1.3 SO2 Scrubber. Three 300-ml Teflon segment
impingers connected in series with flexible, thick-walled, Teflon
tubing. (Impinger parts and tubing available through Savillex.) The
first two impingers contain 100 ml of citrate buffer, and the third
impinger is initially dry. The tip of the tube inserted into the
solution should be constricted to less than 3-mm (\1/8\-in.) ID and
should be immersed to a depth of at least 50 cm (2 in.). Immerse the
impingers in an ice water bath and maintain near 0 deg.C. The scrubber
solution will normally last for a 3-hour run before needing
replacement. This will depend upon the effects of moisture and
particulate matter on the solution strength and pH. Connections between
the probe, particulate filter, and SO2 scrubber shall be
made of Teflon and as short in length as possible. All portions of the
probe, particulate filter, and connections prior

[[Page 61969]]

to the SO2 scrubber (or alternative point of moisture
removal) shall be maintained at a temperature of at least 120 deg.C
(248 deg.F).
6.1.4 Sample Line. Teflon, no greater than 13-mm (\1/2\-in.) ID.
Alternative materials, such as virgin Nylon, may be used provided the
line-loss test is acceptable.
6.1.5 Sample Pump. The sample pump shall be a leakless Teflon-
coated diaphragm type or equivalent.
6.2 Analysis. The following items are needed for sample analysis:
6.2.1 Dilution System. The dilution system must be constructed
such that all sample contacts are made of Teflon, glass, or stainless
steel. It must be capable of approximately a 9:1 dilution of the
sample.
6.2.2 Gas Chromatograph (see Figure 15-2). The gas chromatograph
must have at least the following components:
6.2.2.1 Oven. Capable of maintaining the separation column at the
proper operating temperature 1 deg.C.
6.2.2.2 Temperature Gauge. To monitor column oven, detector, and
exhaust temperature 1 deg.C.
6.2.2.3 Flow System. Gas metering system to measure sample, fuel,
combustion gas, and carrier gas flows.
6.2.2.4 Flame Photometric Detector.
6.2.2.4.1 Electrometer. Capable of full scale amplification of
linear ranges of 10-9 to 10-4 amperes full scale.
6.2.2.4.2 Power Supply. Capable of delivering up to 750 volts.
6.2.2.5 Recorder. Compatible with the output voltage range of the
electrometer.
6.2.2.6 Rotary Gas Valves. Multiport Teflon-lined valves equipped
with sample loop. Sample loop volumes shall be chosen to provide the
needed analytical range. Teflon tubing and fittings shall be used
throughout to present an inert surface for sample gas. The GC shall be
calibrated with the sample loop used for sample analysis.
6.2.2.7 GC Columns. The column system must be demonstrated to be
capable of resolving three major reduced sulfur compounds:
H2S, COS, and CS2. To demonstrate that adequate
resolution has been achieved, a chromatogram of a calibration gas
containing all three reduced sulfur compounds in the concentration
range of the applicable standard must be submitted. Adequate resolution
will be defined as base line separation of adjacent peaks when the
amplifier attenuation is set so that the smaller peak is at least 50
percent of full scale. Base line separation is defined as a return to
zero (5 percent) in the interval between peaks. Systems not
meeting this criteria may be considered alternate methods subject to
the approval of the Administrator.
6.3 Calibration System (See Figure 15-3). The calibration system
must contain the following components:
6.3.1 Flow System. To measure air flow over permeation tubes
within 2 percent. Each flowmeter shall be calibrated after each
complete test series with a wet-test meter. If the flow measuring
device differs from the wet-test meter by more than 5 percent, the
completed test shall be discarded. Alternatively, use the flow data
that will yield the lowest flow measurement. Calibration with a wet-
test meter before a test is optional. Flow over the permeation device
may also be determined using a soap bubble flowmeter.
6.3.2 Constant Temperature Bath. Device capable of maintaining the
permeation tubes at the calibration temperature within 0.1 deg.C.
6.3.3 Temperature Sensor. Thermometer or equivalent to monitor
bath temperature within 0.1 deg.C.

7.0 Reagents and Standards

7.1 Fuel. Hydrogen gas (H2). Prepurified grade or
better.
7.2 Combustion Gas. Oxygen (O2) or air, research purity
or better.
7.3 Carrier Gas. Prepurified grade or better.
7.4 Diluent. Air containing less than 0.5 ppmv total sulfur
compounds and less than 10 ppmv each of moisture and total
hydrocarbons.
7.5 Calibration Gases.
7.5.1 Permeation Devices. One each of H2S, COS, and
CS2, gravimetrically calibrated and certified at some
convenient operating temperature. These tubes consist of hermetically
sealed FEP Teflon tubing in which a liquified gaseous substance is
enclosed. The enclosed gas permeates through the tubing wall at a
constant rate. When the temperature is constant, calibration gases
covering a wide range of known concentrations can be generated by
varying and accurately measuring the flow rate of diluent gas passing
over the tubes. These calibration gases are used to calibrate the GC/
FPD system and the dilution system.
7.5.2 Cylinder Gases. Cylinder gases may be used as alternatives
to permeation devices. The gases must be traceable to a primary
standard (such as permeation tubes) and not used beyond the
certification expiration date.
7.6 Citrate Buffer. Dissolve 300 g of potassium citrate and 41 g
of anhydrous citric acid in 1 liter of water. Alternatively, 284 g of
sodium citrate may be substituted for the potassium citrate. Adjust the
pH to between 5.4 and 5.6 with potassium citrate or citric acid, as
required.
8.0 Sample Collection, Preservation, Transport, and Storage
8.1 Pretest Procedures. After the complete measurement system has
been set up at the site and deemed to be operational, the following
procedures should be completed before sampling is initiated. These
procedures are not required, but would be helpful in preventing any
problem which might occur later to invalidate the entire test.
8.1.1 Leak-Check. Appropriate leak-check procedures should be
employed to verify the integrity of all components, sample lines, and
connections. The following procedure is suggested: For components
upstream of the sample pump, attach the probe end of the sample line to
a manometer or vacuum gauge, start the pump and pull a vacuum greater
than 50 mm (2 in.) Hg, close off the pump outlet, and then stop the
pump and ascertain that there is no leak for 1 minute. For components
after the pump, apply a slight positive pressure and check for leaks by
applying a liquid (detergent in water, for example) at each joint.
Bubbling indicates the presence of a leak. As an alternative to the
initial leak-test, the sample line loss test described in Section 8.3.1
may be performed to verify the integrity of components.
8.1.2 System Performance. Since the complete system is calibrated
at the beginning and end of each day of testing, the precise
calibration of each component is not critical. However, these
components should be verified to operate properly. This verification
can be performed by observing the response of flowmeters or of the GC
output to changes in flow rates or calibration gas concentrations,
respectively, and ascertaining the response to be within predicted
limits. If any component or the complete system fails to respond in a
normal and predictable manner, the source of the discrepancy should be
identified and corrected before proceeding.

8.2 Sample Collection and Analysis

8.2.1 After performing the calibration procedures outlined in
Section 10.0, insert the sampling probe into the test port ensuring
that no dilution air enters the stack through the port. Begin sampling
and dilute the sample approximately 9:1 using the dilution system. Note
that the precise dilution factor is the one determined in Section 10.4.
Condition the entire system with sample for a minimum of 15 minutes
before beginning the analysis. Inject aliquots of the sample into the
GC/FPD analyzer for analysis.

[[Page 61970]]

Determine the concentration of each reduced sulfur compound directly
from the calibration curves or from the equation for the least-squares
line.
8.2.2 If reductions in sample concentrations are observed during a
sample run that cannot be explained by process conditions, the sampling
must be interrupted to determine if the probe or filter is clogged with
particulate matter. If either is found to be clogged, the test must be
stopped and the results up to that point discarded. Testing may resume
after cleaning or replacing the probe and filter. After each run, the
probe and filter shall be inspected and, if necessary, replaced.
8.2.3 A sample run is composed of 16 individual analyses (injects)
performed over a period of not less than 3 hours or more than 6 hours.
8.3 Post-Test Procedures.
8.3.1 Sample Line Loss. A known concentration of H2S at
the level of the applicable standard, 20 percent, must be
introduced into the sampling system at the opening of the probe in
sufficient quantities to ensure that there is an excess of sample which
must be vented to the atmosphere. The sample must be transported
through the entire sampling system to the measurement system in the
same manner as the emission samples. The resulting measured
concentration is compared to the known value to determine the sampling
system loss. For sampling losses greater than 20 percent, the previous
sample run is not valid. Sampling losses of 0-20 percent must be
corrected by dividing the resulting sample concentration by the
fraction of recovery. The known gas sample may be calibration gas as
described in Section 7.5. Alternatively, cylinder gas containing
H2S mixed in nitrogen and verified according to Section
7.1.4 of Method 16A may be used. The optional pretest procedures
provide a good guideline for determining if there are leaks in the
sampling system.
8.3.2 Determination of Calibration Drift. After each run, or after
a series of runs made within a 24-hour period, perform a partial
recalibration using the procedures in Section 10.0. Only H2S
(or other permeant) need be used to recalibrate the GC/FPD analysis
system and the dilution system. Compare the calibration curves obtained
after the runs to the calibration curves obtained under Section 10.3.
The calibration drift should not exceed the limits set forth in Section
13.4. If the drift exceeds this limit, the intervening run or runs
should be considered invalid. As an option, the calibration data set
which gives the highest sample values may be chosen by the tester.

9.0 Quality Control

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
8.3.1......................... Sample line loss Ensures that
check. uncorrected negative
bias introduced by
sample loss is no
greater than 20
percent, and
provides for
correction of bias
of 20 percent or
less.
8.3.2......................... Calibration drift Ensures that bias
test. introduced by drift
in the measurement
system output during
the run is no
greater than 5
percent.
10.0.......................... Analytical Ensures precision of
calibration. analytical results
within 5 percent.
------------------------------------------------------------------------

10.0 Calibration and Standardization

Prior to any sampling run, calibrate the system using the following
procedures. (If more than one run is performed during any 24-hour
period, a calibration need not be performed prior to the second and any
subsequent runs. However, the calibration drift must be determined as
prescribed in Section 8.3.2 after the last run is made within the 24-
hour period.)

Note: This section outlines steps to be followed for use of the
GC/FPD and the dilution system. The calibration procedure does not
include detailed instructions because the operation of these systems
is complex, and it requires an understanding of the individual
system being used. Each system should include a written operating
manual describing in detail the operating procedures associated with
each component in the measurement system. In addition, the operator
should be familiar with the operating principles of the components,
particularly the GC/FPD. The references in Section 16.0 are
recommended for review for this purpose.

10.1 Calibration Gas Permeation Tube Preparation.
10.1.1 Insert the permeation tubes into the tube chamber. Check
the bath temperature to assure agreement with the calibration
temperature of the tubes within 0.1 deg.C. Allow 24 hours for the
tubes to equilibrate. Alternatively, equilibration may be verified by
injecting samples of calibration gas at 1-hour intervals. The
permeation tubes can be assumed to have reached equilibrium when
consecutive hourly samples agree within 5 percent of their mean.
10.1.2 Vary the amount of air flowing over the tubes to produce
the desired concentrations for calibrating the analytical and dilution
systems. The air flow across the tubes must at all times exceed the
flow requirement of the analytical systems. The concentration in ppmv
generated by a tube containing a specific permeant can be calculated
using Equation 15-1 in Section 12.2.
10.2 Calibration of Analytical System. Generate a series of three
or more known concentrations spanning the linear range of the FPD
(approximately 0.5 to 10 ppmv for a 1-ml sample) for each of the three
major sulfur compounds. Bypassing the dilution system, inject these
standards into the GC/FPD and monitor the responses until three
consecutive injections for each concentration agree within 5 percent of
their mean. Failure to attain this precision indicates a problem in the
calibration or analytical system. Any such problem must be identified
and corrected before proceeding.
10.3 Calibration Curves. Plot the GC/FPD response in current
(amperes) versus their causative concentrations in ppmv on log-log
coordinate graph paper for each sulfur compound. Alternatively, a
least-squares equation may be generated from the calibration data using
concentrations versus the appropriate instrument response units.
10.4 Calibration of Dilution System. Generate a known
concentration of H2S using the permeation tube system.
Adjust the flow rate of diluent air for the first dilution stage so
that the desired level of dilution is approximated. Inject the diluted
calibration gas into the GC/FPD system until the results of three
consecutive injections for each dilution agree within 5 percent of
their mean. Failure to attain this precision in this step is an
indication of a problem in the dilution system. Any such problem must
be identified and corrected before proceeding. Using the calibration
data for H2S (developed under Section 10.3), determine the
diluted calibration gas concentration in ppmv. Then calculate the
dilution factor as the ratio of the calibration gas concentration
before dilution to the diluted calibration gas concentration determined
under this section. Repeat this procedure for each

[[Page 61971]]

stage of dilution required. Alternatively, the GC/FPD system may be
calibrated by generating a series of three or more concentrations of
each sulfur compound and diluting these samples before injecting them
into the GC/FPD system. These data will then serve as the calibration
data for the unknown samples and a separate determination of the
dilution factor will not be necessary. However, the precision
requirements are still applicable.

11.0 Analytical Procedure

Sample collection and analysis are concurrent for this method (see
Section 8.0).

12.0 Data Analysis and Calculations

12.1 Nomenclature.

C = Concentration of permeant produced, ppmv.
COS = Carbonyl sulfide concentration, ppmv.
CS2 = Carbon disulfide concentration, ppmv.
d = Dilution factor, dimensionless.
H2S = Hydrogen sulfide concentration, ppmv.
K = 24.04 L/g mole. (Gas constant at 20 deg.C and 760 mm Hg)
L = Flow rate, L/min, of air over permeant 20 deg.C, 760 mm Hg.
M = Molecular weight of the permeant, g/g-mole.
N = Number of analyses performed.
Pr = Permeation rate of the tube, g/min.
12.2 Permeant Concentration. Calculate the concentration generated
by a tube containing a specific permeant (see Section 10.1) using the
following equation:
[GRAPHIC] [TIFF OMITTED] TR17OC00.262

12.3 Calculation of SO2 Equivalent. SO2
equivalent will be determined for each analysis made by summing the
concentrations of each reduced sulfur compound resolved during the
given analysis. The SO2 equivalent is expressed as
SO2 in ppmv.
[GRAPHIC] [TIFF OMITTED] TR17OC00.263

12.4 Average SO2 Equivalent. This is determined using
the following equation. Systems that do not remove moisture from the
sample but condition the gas to prevent condensation must correct the
average SO2 equivalent for the fraction of water vapor
present. This is not done under applications where the emission
standard is not specified on a dry basis.
[GRAPHIC] [TIFF OMITTED] TR17OC00.264

Where:

Avg SO2 equivalent = Average SO2 equivalent in
ppmv, dry basis.
Average SO2 equivalent i = SO2 in ppmv
as determined by Equation 15-2.

13.0 Method Performance

13.1 Range. Coupled with a GC system using a 1-ml sample size, the
maximum limit of the FPD for each sulfur compound is approximately 10
ppmv. It may be necessary to dilute samples from sulfur recovery plants
a hundredfold (99:1), resulting in an upper limit of about 1000 ppmv
for each compound.
13.2 Sensitivity. The minimum detectable concentration of the FPD
is also dependent on sample size and would be about 0.5 ppmv for a 1-ml
sample.
13.3 Calibration Precision. A series of three consecutive
injections of the same calibration gas, at any dilution, shall produce
results which do not vary by more than 5 percent from the mean of the
three injections.
13.4 Calibration Drift. The calibration drift determined from the
mean of three injections made at the beginning and end of any run or
series of runs within a 24-hour period shall not exceed 5 percent.

14.0 Pollution Prevention. [Reserved]

15.0 Waste Management. [Reserved]

16.0 References.

1. O'Keeffe, A.E., and G.C. Ortman. ``Primary Standards for
Trace Gas Analysis.'' Anal. Chem. 38,760. 1966.
2. Stevens, R.K., A.E. O'Keeffe, and G.C. Ortman. ``Absolute
Calibration of a Flame Photometric Detector to Volatile Sulfur
Compounds at Sub-Part-Per-Million Levels.'' Environmental Science
and Technology 3:7. July 1969.
3. Mulik, J.D., R.K. Stevens, and R. Baumgardner. ``An
Analytical System Designed to Measure Multiple Malodorous Compounds
Related to Kraft Mill Activities.'' Presented at the 12th Conference
on Methods in Air Pollution and Industrial Hygiene Studies,
University of Southern California, Los Angeles, CA, April 6-8, 1971.
4. Devonald, R.H., R.S. Serenius, and A.D. McIntyre.
``Evaluation of the Flame Photometric Detector for Analysis of
Sulfur Compounds.'' Pulp and Paper Magazine of Canada, 73,3. March
1972.
5. Grimley, K.W., W.S. Smith, and R.M. Martin. ``The Use of a
Dynamic Dilution System in the Conditioning of Stack Gases for
Automated Analysis by a Mobile Sampling Van.'' Presented at the 63rd
Annual APCA Meeting in St. Louis, MO. June 14-19, 1970.
6. General Reference. Standard Methods of Chemical Analysis
Volume III-A and III-B: Instrumental Analysis. Sixth Edition. Van
Nostrand Reinhold Co.

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17.0 Tables, Diagrams, Flowcharts, and Validation Data
[GRAPHIC] [TIFF OMITTED] TR17OC00.265

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Method 15A--Determination of Total Reduced Sulfur Emissions From
Sulfur Recovery Plants in Petroleum Refineries

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Reduced sulfur compounds...... None assigned... Not determined.
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of emissions of reduced sulfur compounds from sulfur recovery plants
where the emissions are in a reducing atmosphere, such as in Stretford
units.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 An integrated gas sample is extracted from the stack, and
combustion air is added to the oxygen (O2)-deficient gas at
a known rate. The reduced sulfur compounds [including carbon disulfide
(CS2), carbonyl sulfide (COS), and hydrogen sulfide
(H2S)] are thermally oxidized to sulfur dioxide
(SO2), which is then collected in hydrogen peroxide as
sulfate ion and analyzed according to the Method 6 barium-thorin
titration procedure.

3.0 Definitions. [Reserved]

4.0 Interferences

4.1 Reduced sulfur compounds, other than CS2, COS, and
H2S, that are present in the emissions will also be oxidized
to SO2, causing a positive bias relative to emission
standards that limit only the three compounds listed above. For
example, thiophene has been identified in emissions from a Stretford
unit and produced a positive bias of 30 percent in the Method 15A
result. However, these biases may not affect the outcome of the test at
units where emissions are low relative to the standard.
4.2 Calcium and aluminum have been shown to interfere in the
Method 6 titration procedure. Since these metals have been identified
in particulate matter emissions from Stretford units, a Teflon filter
is required to minimize this interference.
4.3 Dilution of the hydrogen peroxide (H2O2)
absorbing solution can potentially reduce collection efficiency,
causing a negative bias. When used to sample emissions containing 7
percent moisture or less, the midget impingers have sufficient volume
to contain the condensate collected during sampling. Dilution of the
H2O2 does not affect the collection of
SO2. At higher moisture contents, the potassium citrate-
citric acid buffer system used with Method 16A should be used to
collect the condensate.

5.0 Safety

5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of the
safety problems associated with its use. It is the responsibility of
the user of this test method to establish appropriate safety and health
practices and determine the applicability of regulatory limitations
prior to performing this test method.
5.2 Corrosive reagents. The following reagents are hazardous.
Personal protective equipment and safe procedures are useful in
preventing chemical splashes. If contact occurs, immediately flush with
copious amounts of water for at least 15 minutes. Remove clothing under
shower and decontaminate. Treat residual chemical burns as thermal
burns.
5.2.1 Hydrogen Peroxide (H2O2). Irritating
to eyes, skin, nose, and lungs.
5.2.2 Sodium Hydroxide (NaOH). Causes severe damage to eyes and
skin. Inhalation causes irritation to nose, throat, and lungs. Reacts
exothermically with limited amounts of water.
5.2.3 Sulfuric Acid (H2SO4). Rapidly
destructive to body tissue. Will cause third degree burns. Eye damage
may result in blindness. Inhalation may be fatal from spasm of the
larynx, usually within 30 minutes. May cause lung tissue damage with
edema. 3 mg/m\3\ will cause lung damage in uninitiated. 1 mg/m\3\ for 8
hours will cause lung damage or, in higher concentrations, death.
Provide ventilation to limit inhalation. Reacts violently with metals
and organics.

6.0 Equipment and Supplies

6.1 Sample Collection. The sampling train used in performing this
method is shown in Figure 15A-1, and component parts are discussed
below. Modifications to this sampling train are acceptable provided
that the system performance check is met.
6.1.1 Probe. 6.4-mm (\1/4\-in.) OD Teflon tubing sequentially
wrapped with heat-resistant fiber strips, a rubberized heating tape
(with a plug at one end), and heat-resistant adhesive tape. A flexible
thermocouple or some other suitable temperature-measuring device shall
be placed between the Teflon tubing and the fiber strips so that the
temperature can be monitored. The probe should be sheathed in stainless
steel to provide in-stack rigidity. A series of bored-out stainless
steel fittings placed at the front of the sheath will prevent flue gas
from entering between the probe and sheath. The sampling probe is
depicted in Figure 15A-2.
6.1.2 Particulate Filter. A 50-mm Teflon filter holder and a 1- to
2-mm porosity Teflon filter (available through Savillex Corporation,
5325 Highway 101, Minnetonka, Minnesota 55345). The filter holder must
be maintained in a hot box at a temperature high enough to prevent
condensation.
6.1.3 Combustion Air Delivery System. As shown in the schematic
diagram in Figure 15A-3. The rate meter should be selected to measure
an air flow rate of 0.5 liter/min (0.02 ft\3\/min).
6.1.4 Combustion Tube. Quartz glass tubing with an expanded
combustion chamber 2.54 cm (1 in.) in diameter and at least 30.5 cm (12
in.) long. The tube ends should have an outside diameter of 0.6 cm (\1/
4\ in.) and be at least 15.3 cm (6 in.) long. This length is necessary
to maintain the quartz-glass connector near ambient temperature and
thereby avoid leaks. Alternatively, the outlet may be constructed with
a 90 degree glass elbow and socket that would fit directly onto the
inlet of the first peroxide impinger.
6.1.5 Furnace. Of sufficient size to enclose the combustion tube.
The furnace must have a temperature regulator capable of maintaining
the temperature at 1100 50 deg.C (2,012 90
deg.F). The furnace operating temperature must be checked with a
thermocouple to ensure accuracy. Lindberg furnaces have been found to
be satisfactory.

[[Page 61976]]

6.1.6 Peroxide Impingers, Stopcock Grease, Temperature Sensor,
Drying Tube, Valve, Pump, and Barometer. Same as in Method 6, Sections
6.1.1.2, 6.1.1.4, 6.1.1.5, 6.1.1.6, 6.1.1.7, 6.1.1.8, and 6.1.2,
respectively, except that the midget bubbler of Method 6, Section
6.1.1.2 is not required.
6.1.7 Vacuum Gauge and Rate Meter. At least 760 mm Hg (30 in. Hg)
gauge and rotameter, or equivalent, capable of measuring flow rate to
5 percent of the selected flow rate and calibrated as in
Section 10.2.
6.1.8 Volume Meter. Dry gas meter capable of measuring the sample
volume under the particular sampling conditions with an accuracy of 2
percent.
6.1.9 U-tube manometer. To measure the pressure at the exit of the
combustion gas dry gas meter.
6.2 Sample Recovery and Analysis. Same as Method 6, Sections 6.2
and 6.3, except a 10-ml buret with 0.05-ml graduations is required for
titrant volumes of less than 10.0 ml, and the spectrophotometer is not
needed.

7.0 Reagents and Standards

Note: Unless otherwise indicated, all reagents must conform to
the specifications established by the Committee on Analytical
Reagents of the American Chemical Society. When such specifications
are not available, the best available grade shall be used.

7.1 Sample Collection. The following reagents and standards are
required for sample analysis:
7.1.1 Water. Same as Method 6, Section 7.1.1.
7.1.2 Hydrogen Peroxide (H2O2), 3 Percent by
Volume. Same as Method 6, Section 7.1.3 (40 ml is needed per sample).
7.1.3 Recovery Check Gas. Carbonyl sulfide in nitrogen [100 parts
per million by volume (ppmv) or greater, if necessary] in an aluminum
cylinder. Concentration certified by the manufacturer with an accuracy
of 2 percent or better, or verified by gas chromatography
where the instrument is calibrated with a COS permeation tube.
7.1.4 Combustion Gas. Air, contained in a gas cylinder equipped
with a two-stage regulator. The gas shall contain less than 50 ppb of
reduced sulfur compounds and less than 10 ppm total hydrocarbons.
7.2 Sample Recovery and Analysis. Same as Method 6, Sections 7.2
and 7.3.

8.0 Sample Collection, Preservation, Storage, and Transport

8.1 Preparation of Sampling Train. For the Method 6 part of the
train, measure 20 ml of 3 percent H2O2 into the
first and second midget impingers. Leave the third midget impinger
empty and add silica gel to the fourth impinger. Alternatively, a
silica gel drying tube may be used in place of the fourth impinger.
Place crushed ice and water around all impingers. Maintain the
oxidation furnace at 1100 50 deg.C (2,012 90
deg.F) to ensure 100 percent oxidation of COS. Maintain the probe and
filter temperatures at a high enough level (no visible condensation) to
prevent moisture condensation and monitor the temperatures with a
thermocouple.
8.2 Leak-Check Procedure. Assemble the sampling train and leak-
check as described in Method 6, Section 8.2. Include the combustion air
delivery system from the needle valve forward in the leak-check.
8.3 Sample Collection. Adjust the pressure on the second stage of
the regulator on the combustion air cylinder to 10 psig. Adjust the
combustion air flow rate to 0.5 0.05 L/min (1.1
0.1 ft\3\/hr) before injecting combustion air into the
sampling train. Then inject combustion air into the sampling train,
start the sample pump, and open the stack sample gas valve. Carry out
these three operations within 15 to 30 seconds to avoid pressurizing
the sampling train. Adjust the total sample flow rate to 2.0
0.2 L/min (4.2 0.4 ft\3\/hr). These flow
rates produce an O2 concentration of 5.0 percent in the
stack gas, which must be maintained constantly to allow oxidation of
reduced sulfur compounds to SO2. Adjust these flow rates
during sampling as necessary. Monitor and record the combustion air
manometer reading at regular intervals during the sampling period.
Sample for 1 or 3 hours. At the end of sampling, turn off the sample
pump and combustion air simultaneously (within 30 seconds of each
other). All other procedures are the same as in Method 6, Section 8.3,
except that the sampling train should not be purged. After collecting
the sample, remove the probe from the stack and conduct a leak-check
according to the procedures outlined in Section 8.2 of Method 6
(mandatory). After each 3-hour test run (or after three 1-hour
samples), conduct one system performance check (see Section 8.5). After
this system performance check and before the next test run, it is
recommended that the probe be rinsed and brushed and the filter
replaced.

Note: In Method 15, a test run is composed of 16 individual
analyses (injects) performed over a period of not less than 3 hours
or more than 6 hours. For Method 15A to be consistent with Method
15, the following may be used to obtain a test run: (1) Collect
three 60-minute samples or (2) collect one 3-hour sample. (Three
test runs constitute a test.)

8.4 Sample Recovery. Recover the hydrogen peroxide-containing
impingers as detailed in Method 6, Section 8.4.
8.5 System Performance Check.
8.5.1 A system performance check is done (1) to validate the
sampling train components and procedure (before testing, optional) and
(2) to validate a test run (after a run, mandatory). Perform a check in
the field before testing consisting of at least two samples (optional),
and perform an additional check after each 3-hour run or after three 1-
hour samples (mandatory).
8.5.2 The checks involve sampling a known concentration of COS and
comparing the analyzed concentration with the known concentration. Mix
the recovery gas with N2 as shown in Figure 15A-4 if
dilution is required. Adjust the flow rates to generate a COS
concentration in the range of the stack gas or within 20 percent of the
applicable standard at a total flow rate of at least 2.5 L/min (5.3
ft\3\/hr). Use Equation 15A-4 (see Section 12.5) to calculate the
concentration of recovery gas generated. Calibrate the flow rate from
both sources with a soap bubble flow tube so that the diluted
concentration of COS can be accurately calculated. Collect 30-minute
samples, and analyze in the same manner as the emission samples.
Collect the samples through the probe of the sampling train using a
manifold or some other suitable device that will ensure extraction of a
representative sample.
8.5.3 The recovery check must be performed in the field before
replacing the particulate filter and before cleaning the probe. A
sample recovery of 100 20 percent must be obtained for the
data to be valid and should be reported with the emission data, but
should not be used to correct the data. However, if the performance
check results do not affect the compliance or noncompliance status of
the affected facility, the Administrator may decide to accept the
results of the compliance test. Use Equation 15A-5 (see Section 12.6)
to calculate the recovery efficiency.

9.0 Quality Control

[[Page 61977]]

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
8.5........................... System Ensures validity of
performance sampling train
check. components and
analytical
procedure.
8.2, 10.0..................... Sampling Ensures accurate
equipment leak- measurement of stack
check and gas flow rate,
calibration. sample volume
10.0.......................... Barium standard Ensures precision of
solution normality
standardization. determination.
11.1.......................... Replicate Ensures precision of
titrations. titration
determinations.
11.2.......................... Audit sample Evaluates analyst's
analysis. technique and
standards
preparation.
------------------------------------------------------------------------

10.0 Calibration and Standardization

10.1 Metering System, Temperature Sensors, Barometer, and Barium
Perchlorate Solution. Same as Method 6, Sections 10.1, 10.2, 10.4, and
10.5, respectively.
10.2 Rate Meter. Calibrate with a bubble flow tube.

11.0 Analytical Procedure

11.1 Sample Loss Check and Sample Analysis. Same as Method 6,
Sections 11.1 and 11.2.
11.2 Audit Sample Analysis. Same as Method 6, Section 11.3.

12.0 Data Analysis and Calculations

In the calculations, retain at least one extra decimal figure
beyond that of the acquired data. Round off figures after final
calculations.
12.1 Nomenclature.

CCOS = Concentration of COS recovery gas, ppm.
CRG(act) = Actual concentration of recovery check gas (after
dilution), ppm.
CRG(m) = Measured concentration of recovery check gas
generated, ppm.
CRS = Concentration of reduced sulfur compounds as
SO2, dry basis, corrected to standard conditions, ppm.
N = Normality of barium perchlorate titrant, milliequivalents/ml.
Pbar = Barometric pressure at exit orifice of the dry gas
meter, mm Hg.
Pstd = Standard absolute pressure, 760 mm Hg.
QCOS = Flow rate of COS recovery gas, liters/min.
QN = Flow rate of diluent N2, liters/min.
R = Recovery efficiency for the system performance check, percent.
Tm = Average dry gas meter absolute temperature, deg.K.
Tstd = Standard absolute temperature, 293 deg.K.
Va = Volume of sample aliquot titrated, ml.
Vms = Dry gas volume as measured by the sample train dry gas
meter, liters.
Vmc = Dry gas volume as measured by the combustion air dry
gas meter, liters.
Vms(std) = Dry gas volume measured by the sample train dry
gas meter, corrected to standard conditions, liters.
Vmc(std) = Dry gas volume measured by the combustion air dry
gas meter, corrected to standard conditions, liters.
Vsoln = Total volume of solution in which the sulfur dioxide
sample is contained, 100 ml.
Vt = Volume of barium perchlorate titrant used for the
sample (average of replicate titrations), ml.
Vtb = Volume of barium perchlorate titrant used for the
blank, ml.
Y = Calibration factor for sampling train dry gas meter.
Yc = Calibration factor for combustion air dry gas meter.
32.03 = Equivalent weight of sulfur dioxide, mg/meq.
[GRAPHIC] [TIFF OMITTED] TR17OC00.411

12.2 Dry Sample Gas Volume, Corrected to Standard Conditions.
[GRAPHIC] [TIFF OMITTED] TR17OC00.268

Where:

K1 = 0.3855 deg.K/mm Hg for metric units,
= 17.65 deg.R/in. Hg for English units.

12.3 Combustion Air Gas Volume, corrected to Standard Conditions.
[GRAPHIC] [TIFF OMITTED] TR17OC00.269

Note: Correct Pbar for the average pressure of the
manometer during the sampling period.
12.4 Concentration of reduced sulfur compounds as ppm
SO2.
[GRAPHIC] [TIFF OMITTED] TR17OC00.270

[[Page 61978]]

Where:
[GRAPHIC] [TIFF OMITTED] TR17OC00.271

12.5 Concentration of Generated Recovery Gas.
[GRAPHIC] [TIFF OMITTED] TR17OC00.272

12.6 Recovery Efficiency for the System Performance Check.
[GRAPHIC] [TIFF OMITTED] TR17OC00.273

13.0 Method Performance

13.1 Analytical Range. The lower detectable limit is 0.1 ppmv when
sampling at 2 lpm for 3 hours or 0.3 ppmv when sampling at 2 lpm for 1
hour. The upper concentration limit of the method exceeds
concentrations of reduced sulfur compounds generally encountered in
sulfur recovery plants.
13.2 Precision. Relative standard deviations of 2.8 and 6.9
percent have been obtained when sampling a stream with a reduced sulfur
compound concentration of 41 ppmv as SO2 for 1 and 3 hours,
respectively.
13.3 Bias. No analytical bias has been identified. However,
results obtained with this method are likely to contain a positive bias
relative to emission regulations due to the presence of nonregulated
sulfur compounds (that are present in petroleum) in the emissions. The
magnitude of this bias varies accordingly, and has not been quantified.

14.0 Pollution Prevention. [Reserved]

15.0 Waste Management. [Reserved]

16.0 References

1. American Society for Testing and Materials Annual Book of
ASTM Standards. Part 31: Water, Atmospheric Analysis. Philadelphia,
Pennsylvania. 1974. pp. 40-42.
2. Blosser, R.O., H.S. Oglesby, and A.K. Jain. A Study of
Alternate SO2 Scrubber Designs Used for TRS Monitoring.
National Council of the Paper Industry for Air and Stream
Improvement, Inc., New York, New York. Special Report 77-05. July
1977.
3. Curtis, F., and G.D. McAlister. Development and Evaluation of
an Oxidation/Method 6 TRS Emission Sampling Procedure. Emission
Measurement Branch, Emission Standards and Engineering Division,
U.S. Environmental Protection Agency, Research Triangle Park, North
Carolina. February 1980.
4. Gellman, I. A Laboratory and Field Study of Reduced Sulfur
Sampling and Monitoring Systems. National Council of the Paper
Industry for Air and Stream Improvement, Inc., New York, New York.
Atmospheric Quality Improvement Technical Bulletin No. 81. October
1975.
5. Margeson, J.H., et al. A Manual Method for TRS Determination.
Journal of Air Pollution Control Association. 35:1280-1286. December
1985.
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Method 16--Semicontinuous Determination of Sulfur Emissions From
Stationary Sources

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Dimethyl disulfide [(CH3)2S2].. 62-49-20 50 ppb.
Dimethyl sulfide [(CH3)2S]..... 75-18-3 50 ppb.
Hydrogen sulfide [H2S]......... 7783-06-4 50 ppb.
Methyl mercaptan [CH4S]........ 74-93-1 50 ppb.
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of total reduced sulfur (TRS) compounds from recovery furnaces, lime
kilns, and smelt dissolving tanks at kraft pulp mills and fuel gas
combustion devices at petroleum refineries.

Note: The method described below uses the principle of gas
chromatographic (GC) separation and flame photometric detection
(FPD). Since there are many systems or sets of operating conditions
that represent useable methods of determining sulfur emissions, all
systems which employ this principle, but differ only in details of
equipment and operation, may be used as alternative methods,
provided that the calibration precision and sample line loss
criteria are met.

1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 A gas sample is extracted from the emission source and an
aliquot is analyzed for hydrogen sulfide (H2S), methyl
mercaptan (MeSH), dimethyl sulfide (DMS), and dimethyl disulfide (DMDS)
by GC/FPD. These four compounds are known collectively as TRS.

3.0 Definitions. [Reserved]

4.0 Interferences

4.1 Moisture. Moisture condensation in the sample delivery system,
the analytical column, or the FPD burner block can cause losses or
interferences. This is prevented by maintaining the probe, filter box,
and connections at a temperature of at least 120 deg.C (248 deg.F).
Moisture is removed in the SO2 scrubber and heating the
sample beyond this point is not necessary when the ambient temperature
is above 0 deg.C (32 deg.F). Alternatively, moisture may be
eliminated by heating the sample line, and by conditioning the sample
with dry dilution air to lower its dew point below the operating
temperature of the GC/FPD analytical system prior to analysis.
4.2 Carbon Monoxide (CO) and Carbon Dioxide (CO2). CO
and CO2 have a substantial desensitizing effect on the flame
photometric detector even after dilution. Acceptable systems must
demonstrate that they have eliminated this interference by some
procedure such as eluting these compounds before any of the compounds
to be measured. Compliance with this requirement can be demonstrated by
submitting chromatograms of calibration gases with and without
CO2 in the diluent gas. The CO2 level should be
approximately 10 percent for the case with CO2 present. The
two chromatograms should show agreement within the precision limits of
Section 10.2.
4.3 Particulate Matter. Particulate matter in gas samples can
cause interference by eventual clogging of the analytical system. This
interference is eliminated by using the Teflon filter after the probe.
4.4 Sulfur Dioxide (SO2). Sulfur dioxide is not a
specific interferant but may be present in such large amounts that it
cannot effectively be separated from the other compounds of interest.
The SO2 scrubber described in Section 6.1.3 will effectively
remove SO2 from the sample.

5.0 Safety

6.0 Equipment and Supplies

6.1. Sample Collection. The following items are needed for sample
collection.
6.1.1 Probe. Teflon or Teflon-lined stainless steel. The probe
must be heated to prevent moisture condensation. It must be designed to
allow calibration gas to enter the probe at or near the sample point
entry. Any portion of the probe that contacts the stack gas must be
heated to prevent moisture condensation. Figure 16-1 illustrates the
probe used in lime kilns and other sources where significant amounts of
particulate matter are present. The probe is designed with the
deflector shield placed between the sample and the gas inlet holes to
reduce clogging of the filter and possible adsorption of sample gas. As
an alternative, the probe described in Section 6.1.1 of Method 16A
having a nozzle directed away from the gas stream may be used at
sources having significant amounts of particulate matter.
6.1.2 Particulate Filter. 50-mm Teflon filter holder and a 1- to
2-micron porosity Teflon filter (available through Savillex
Corporation, 5325 Highway 101, Minnetonka, Minnesota 55343). The filter
holder must be maintained in a hot box at a temperature of at least 120
deg.C (248 deg.F).
6.1.3 SO2 Scrubber. Three 300-ml Teflon segmented
impingers connected in series with flexible, thick-walled, Teflon
tubing. (Impinger parts and tubing available through Savillex.) The
first two impingers contain 100 ml of citrate buffer and the third
impinger is initially dry. The tip of the tube inserted into the
solution should be constricted to less than 3 mm (\1/8\ in.) ID and
should be immersed to a depth of at least 5 cm (2 in.). Immerse the
impingers in an ice water bath and maintain near 0 deg.C (32 deg.F).
The scrubber solution will normally last for a 3-hour run before
needing replacement. This will depend upon the

[[Page 61984]]

effects of moisture and particulate matter on the solution strength and
pH. Connections between the probe, particulate filter, and
SO2 scrubber must be made of Teflon and as short in length
as possible. All portions of the probe, particulate filter, and
connections prior to the SO2 scrubber (or alternative point
of moisture removal) must be maintained at a temperature of at least
120 deg.C (248 deg.F).
6.1.4 Sample Line. Teflon, no greater than 1.3 cm (\1/2\ in.) ID.
Alternative materials, such as virgin Nylon, may be used provided the
line loss test is acceptable.
6.1.5 Sample Pump. The sample pump must be a leakless Teflon-
coated diaphragm type or equivalent.
6.2 Analysis. The following items are needed for sample analysis:
6.2.1 Dilution System. Needed only for high sample concentrations.
The dilution system must be constructed such that all sample contacts
are made of Teflon, glass, or stainless steel.
6.2.2 Gas Chromatograph. The gas chromatograph must have at least
the following components:
6.2.2.1 Oven. Capable of maintaining the separation column at the
proper operating temperature 1 deg.C (2 deg.F).
6.2.2.2 Temperature Gauge. To monitor column oven, detector, and
exhaust temperature 1 deg.C (2 deg.F).
6.2.2.3 Flow System. Gas metering system to measure sample, fuel,
combustion gas, and carrier gas flows.
6.2.2.4 Flame Photometric Detector.
6.2.2.4.1 Electrometer. Capable of full scale amplification of
linear ranges of 10-\9\ to 10-\4\ amperes full
scale.
6.2.2.4.2 Power Supply. Capable of delivering up to 750 volts.
6.2.2.4.3 Recorder. Compatible with the output voltage range of
the electrometer.
6.2.2.4.4 Rotary Gas Valves. Multiport Teflon-lined valves
equipped with sample loop. Sample loop volumes must be chosen to
provide the needed analytical range. Teflon tubing and fittings must be
used throughout to present an inert surface for sample gas. The gas
chromatograph must be calibrated with the sample loop used for sample
analysis.
6.2.3 Gas Chromatogram Columns. The column system must be
demonstrated to be capable of resolving the four major reduced sulfur
compounds: H2S, MeSH, DMS, and DMDS. It must also
demonstrate freedom from known interferences. To demonstrate that
adequate resolution has been achieved, submit a chromatogram of a
calibration gas containing all four of the TRS compounds in the
concentration range of the applicable standard. Adequate resolution
will be defined as base line separation of adjacent peaks when the
amplifier attenuation is set so that the smaller peak is at least 50
percent of full scale. Baseline separation is defined as a return to
zero 5 percent in the interval between peaks. Systems not
meeting this criteria may be considered alternate methods subject to
the approval of the Administrator.
6.3 Calibration. A calibration system, containing the following
components, is required (see Figure 16-2).
6.3.1 Tube Chamber. Chamber of glass or Teflon of sufficient
dimensions to house permeation tubes.
6.3.2 Flow System. To measure air flow over permeation tubes at
2 percent. Flow over the permeation device may also be
determined using a soap bubble flowmeter.
6.3.3 Constant Temperature Bath. Device capable of maintaining the
permeation tubes at the calibration temperature within 0.1 deg.C (0.2
deg.F).
6.3.4 Temperature Gauge. Thermometer or equivalent to monitor bath
temperature within 1 deg.C (2 deg.F).

7.0 Reagents and Standards

7.1 Fuel. Hydrogen (H2), prepurified grade or better.
7.2 Combustion Gas. Oxygen (O2) or air, research purity
or better.
7.3 Carrier Gas. Prepurified grade or better.
7.4 Diluent (if required). Air containing less than 50 ppb total
sulfur compounds and less than 10 ppmv each of moisture and total
hydrocarbons.

7.5 Calibration Gases

7.5.1 Permeation tubes, one each of H2S, MeSH, DMS, and
DMDS, gravimetrically calibrated and certified at some convenient
operating temperature. These tubes consist of hermetically sealed FEP
Teflon tubing in which a liquified gaseous substance is enclosed. The
enclosed gas permeates through the tubing wall at a constant rate. When
the temperature is constant, calibration gases covering a wide range of
known concentrations can be generated by varying and accurately
measuring the flow rate of diluent gas passing over the tubes. These
calibration gases are used to calibrate the GC/FPD system and the
dilution system.
7.5.2 Cylinder Gases. Cylinder gases may be used as alternatives
to permeation devices. The gases must be traceable to a primary
standard (such as permeation tubes) and not used beyond the
certification expiration date.
7.6 Citrate Buffer and Sample Line Loss Gas. Same as Method 15,
Sections 7.6 and 7.7.

8.0 Sample Collection, Preservation, Storage, and Transport

Same as Method 15, Section 8.0, except that the references to the
dilution system may not be applicable.

9.0 Quality Control

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
8.0........................... Sample line loss Ensures that
check. uncorrected negative
bias introduced by
sample loss is no
greater than 20
percent, and
provides for
correction of bias
of 20 percent or
less.
8.0........................... Calibration drift Ensures that bias
test. introduced by drift
in the measurement
system output during
the run is no
greater than 5
percent.
10.0.......................... Analytical Ensures precision of
calibration. analytical results
within 5 percent.
------------------------------------------------------------------------

10.0 Calibration and Standardization

Same as Method 15, Section 10.0, with the following addition and
exceptions:
10.1 Use the four compounds that comprise TRS instead of the three
reduced sulfur compounds measured by Method 15.
10.2 Flow Meter. Calibration before each test run is recommended,
but not required; calibration following each test series is mandatory.
Calibrate each flow meter after each complete test series with a wet-
test meter. If the flow measuring device differs from the wet-test
meter by 5 percent or more, the completed test runs must be voided.
Alternatively, the flow data that yield the lower flow measurement may
be used. Flow over the permeation device may also be determined using a
soap bubble flowmeter.

[[Page 61985]]

11.0 Analytical Procedure

Sample collection and analysis are concurrent for this method (see
Section 8.0).

12.0 Data Analysis and Calculations

12.1 Concentration of Reduced Sulfur Compounds. Calculate the
average concentration of each of the four analytes (i.e., DMDS, DMS,
H2S, and MeSH) over the sample run (specified in Section 8.2
of Method 15 as 16 injections).
[GRAPHIC] [TIFF OMITTED] TR17OC00.278

Where:

Si = Concentration of any reduced sulfur compound from the
ith sample injection, ppm.
C = Average concentration of any one of the reduced sulfur compounds
for the entire run, ppm.
N = Number of injections in any run period.
12.2 TRS Concentration. Using Equation 16-2, calculate the TRS
concentration for each sample run.
[GRAPHIC] [TIFF OMITTED] TR17OC00.279

Where:

CTRS = TRS concentration, ppmv.
CH2S = Hydrogen sulfide concentration, ppmv.
CMeSH = Methyl mercaptan concentration, ppmv.
CDMS = Dimethyl sulfide concentration, ppmv.
CDMDS = Dimethyl disulfide concentration, ppmv.
d = Dilution factor, dimensionless.

12.3 Average TRS Concentration. Calculate the average TRS
concentration for all sample runs performed.
[GRAPHIC] [TIFF OMITTED] TR17OC00.280

Where:

Average TRS = Average total reduced sulfur in ppm.
TRSi = Total reduced sulfur in ppm as determined by Equation
16-2.
N = Number of samples.
Bwo = Fraction of volume of water vapor in the gas stream as
determined by Method 4--Determination of Moisture in Stack Gases.

13.0 Method Performance

13.1 Analytical Range. The analytical range will vary with the
sample loop size. Typically, the analytical range may extend from 0.1
to 100 ppmv using 10- to 0.1-ml sample loop sizes. This eliminates the
need for sample dilution in most cases.
13.2 Sensitivity. Using the 10-ml sample size, the minimum
detectable concentration is approximately 50 ppb.

14.0 Pollution Prevention. [Reserved]

15.0 Waste Management. [Reserved]

16.0 References

1. O'Keeffe, A.E., and G.C. Ortman. ``Primary Standards for
Trace Gas Analysis.'' Analytical Chemical Journal, 38,76. 1966.
2. Stevens, R.K., A.E. O'Keeffe, and G.C. Ortman. ``Absolute
Calibration of a Flame Photometric Detector to Volatile Sulfur
Compounds at Sub-Part-Per-Million Levels.'' Environmental Science
and Technology, 3:7. July 1969.
3. Mulik, J.D., R.K. Stevens, and R. Baumgardner. ``An
Analytical System Designed to Measure Multiple Malodorous Compounds
Related to Kraft Mill Activities.'' Presented at the 12th Conference
on Methods in Air Pollution and Industrial Hygiene Studies,
University of Southern California, Los Angeles, CA. April 6-8, 1971.
4. Devonald, R.H., R.S. Serenius, and A.D. McIntyre.
``Evaluation of the Flame Photometric Detector for Analysis of
Sulfur Compounds.'' Pulp and Paper Magazine of Canada, 73,3. March
1972.
5. Grimley, K.W., W.S. Smith, and R.M. Martin. ``The Use of a
Dynamic Dilution System in the Conditioning of Stack Gases for
Automated Analysis by a Mobile Sampling Van.'' Presented at the 63rd
Annual APCA Meeting, St. Louis, MO. June 14-19, 1970.
6. General Reference. Standard Methods of Chemical Analysis,
Volumes III-A and III-B Instrumental Methods. Sixth Edition. Van
Nostrand Reinhold Co.
BILLING CODE 6560-50-P

[[Page 61986]]

17.0 Tables, Diagrams, Flowcharts, and Validation Data
[GRAPHIC] [TIFF OMITTED] TR17OC00.281

[[Page 61987]]

[GRAPHIC] [TIFF OMITTED] TR17OC00.282

BILLING CODE 6560-50-C

[[Page 61988]]

Method 16A--Determination of Total Reduced Sulfur Emissions From
Stationary Sources (Impinger Technique)

1.0 Scope and Application

1.1 Analytes.

------------------------------------------------------------------------
Analyte CAS No. Sensitivity
------------------------------------------------------------------------
Total reduced sulfur (TRS) N/A See Section 13.1.
including:
Dimethyl disulfide [(CH3)2S2]. 62-49-20
Dimethyl sulfide [(CH3)2S].... 75-18-3
Hydrogen sulfide [H2S]........ 7783-06-4
Methyl mercaptan [CH4S]....... 74-93-1
Reduced sulfur (RS) including: N/A
H2S........................... 7783-06-4
Carbonyl sulfide [COS]........ 463-58-1
Carbon disulfide [CS2]........ 75-15-0
Reported as: Sulfur dioxide (SO2). 7449-09-5
------------------------------------------------------------------------

1.2 Applicability. This method is applicable for the determination
of TRS emissions from recovery boilers, lime kilns, and smelt
dissolving tanks at kraft pulp mills, reduced sulfur compounds
(H2S, carbonyl sulfide, and carbon disulfide from sulfur
recovery units at onshore natural gas processing facilities, and from
other sources when specified in an applicable subpart of the
regulations. The flue gas must contain at least 1 percent oxygen for
complete oxidation of all TRS to SO2.
1.3 Data Quality Objectives. Adherence to the requirements of this
method will enhance the quality of the data obtained from air pollutant
sampling methods.

2.0 Summary of Method

2.1 An integrated gas sample is extracted from the stack.
SO2 is removed selectively from the sample using a citrate
buffer solution. TRS compounds are then thermally oxidized to
SO2, collected in hydrogen peroxide as sulfate, and analyzed
by the Method 6 barium-thorin titration procedure.

3.0 Definitions. [Reserved]

4.0 Interferences

4.1 Reduced sulfur compounds other than those regulated by the
emission standards, if present, may be measured by this method.
Therefore, carbonyl sulfide, which is partially oxidized to
SO2 and may be present in a lime kiln exit stack, would be a
positive interferant.
4.2 Particulate matter from the lime kiln stack gas (primarily
calcium carbonate) can cause a negative bias if it is allowed to enter
the citrate scrubber; the particulate matter will cause the pH to rise
and H2S to be absorbed prior to oxidation. Furthermore, if
the calcium carbonate enters the hydrogen peroxide impingers, the
calcium will precipitate sulfate ion. Proper use of the particulate
filter described in Section 6.1.3 will eliminate this interference.

5.0 Safety

5.1 Disclaimer. This method may involve hazardous materials,
operations, and equipment. This test method may not address all of the
safety problems associated with its use. It is the responsibility of
the user of this test method to establish appropriate safety and health
practices and determine the applicability of regulatory limitations
prior to performing this test method.
5.2 Corrosive reagents. The following reagents are hazardous.
Personal protective equipment and safe procedures are useful in
preventing chemical splashes. If contact occurs, immediately flush with
copious amounts of water for at least 15 minutes. Remove clothing under
shower and decontaminate. Treat residual chemical burns as thermal
burns.
5.2.1 Hydrogen Peroxide (H2O2). Irritating
to eyes, skin, nose, and lungs.
5.2.2 Sodium Hydroxide (NaOH). Causes severe damage to eyes and
skin. Inhalation causes irritation to nose, throat, and lungs. Reacts
exothermically with limited amounts of water.
5.2.3 Sulfuric Acid (H2SO4). Rapidly
destructive to body tissue. Will cause third degree burns. Eye damage
may result in blindness. Inhalation may be fatal from spasm of the
larynx, usually within 30 minutes. May cause lung tissue damage with
edema. 3 mg/m\3\ will cause lung damage in uninitiated. 1 mg/m\3\ for 8
hours will cause lung damage or, in higher concentrations, death.
Provide ventilation to limit inhalation. Reacts violently with metals
and organics.
5.3 Hydrogen Sulfide (H2S). A flammable, poisonous gas
with the odor of rotten eggs. H2S is extremely hazardous and
can cause collapse, coma, and death within a few seconds of one or two
inhalations at sufficient concentrations. Low concentrations irritate
the mucous membranes and may cause nausea, dizziness, and headache
after exposure.

6.0 Equipment and Supplies

6.1 Sample Collection. The sampling train is shown in Figure 16A-1
and component parts are discussed below. Modifications to this sampling
train are acceptable provided the system performance check is met (see
Section 8.5).
6.1.1 Probe. Teflon tubing, 6.4-mm (\1/4\-in.) diameter,
sequentially wrapped with heat-resistant fiber strips, a rubberized
heat tape (plug at one end), and heat-resistant adhesive tape. A
flexible thermocouple or other suitable temperature measuring device
should be placed between the Teflon tubing and the fiber strips so that
the temperature can be monitored to prevent softening of the probe. The
probe should be sheathed in stainless steel to provide in-stack
rigidity. A series of bored-out stainless steel fittings placed at the
front of the sheath will prevent moisture and particulate from entering
between the probe and sheath. A 6.4-mm (\1/4\-in.) Teflon elbow (bored
out) should be attached to the inlet of the probe, and a 2.54 cm (1
in.) piece of Teflon tubing should be attached at the open end of the
elbow to permit the opening of the probe to be turned away from the
particulate stream; this will reduce the amount of particulate drawn
into the sampling train. The probe is depicted in Figure 16A-2.
6.1.2 Probe Brush. Nylon bristle brush with handle inserted into a
3.2-mm (\1/8\-in.) Teflon tubing. The Teflon tubing should be long
enough to pass

[[Page 61989]]

the brush through the length of the probe.
6.1.3 Particulate Filter. 50-mm Teflon filter holder and a 1- to
2-m porosity, Teflon filter (available through Savillex
Corporation, 5325 Highway 101, Minnetonka, Minnesota 55343). The filter
holder must be maintained in a hot box at a temperature sufficient to
prevent moisture condensation. A temperature of 121 deg.C (250 deg.F)
was found to be sufficient when testing a lime kiln under sub-freezing
ambient conditions.
6.1.4 SO2 Scrubber. Three 300-ml Teflon segmented
impingers connected in series with flexible, thick-walled, Teflon
tubing. (Impinger parts and tubing available through Savillex.) The
first two impingers contain 100 ml of citrate buffer and the third
impinger is initially dry. The tip of the tube inserted into the
solution should be constricted to less than 3 mm (\1/8\-in.) ID and
should be immersed to a depth of at least 5 cm (2 in.).
6.1.5 Combustion Tube. Quartz glass tubing with an expanded
combustion chamber 2.54 cm (1 in.) in diameter and at least 30.5 cm (12
in.) long. The tube ends should have an outside diameter of 0.6 cm (\1/
4\ in.) and be at least 15.3 cm (6 in.) long. This length is necessary
to maintain the quartz-glass connector near ambient temperature and
thereby avoid leaks. Alternatively, the outlet may be constructed with
a 90-degree glass elbow and socket that would fit directly onto the
inlet of the first peroxide impinger.
6.1.6 Furnace. A furnace of sufficient size to enclose the
combustion chamber of the combustion tube with a temperature regulator
capable of maintaining the temperature at 800 100 deg.C
(1472 180 deg.F). The furnace operating temperature
should be checked with a thermocouple to ensure accuracy.
6.1.7 Peroxide Impingers, Stopcock Grease, Temperature Sensor,
Drying Tube, Valve, Pump, and Barometer. Same as Method 6, Sections
6.1.1.2, 6.1.1.4, 6.1.1.5, 6.1.1.6, 6.1.1.7, 6.1.1.8, and 6.1.2,
respectively, except that the midget bubbler of Method 6, Section
6.1.1.2 is not required.
6.1.8 Vacuum Gauge. At least 760 mm Hg (30 in. Hg) gauge.
6.1.9 Rate Meter. Rotameter, or equivalent, accurate to within 5
percent at the selected flow rate of approximately 2 liters/min (4.2
ft\3\/hr).
6.1.10 Volume Meter. Dry gas meter capable of measuring the sample
volume under the sampling conditions of 2 liters/min (4.2 ft\3\/hr)
with an accuracy of 2 percent.
6.2 Sample Recovery. Polyethylene Bottles, 250-ml (one per
sample).
6.3 Sample Preparation and Analysis. Same as Method 6, Section
6.3, except a 10-ml buret with 0.05-ml graduations is required, and the
spectrophotometer is not needed.

7.0 Reagents and Standards

7.1 Sample Collection. The following reagents are required for
sample analysis:
7.1.1 Water. Same as in Method 6, Section 7.1.1.
7.1.2 Citrate Buffer. Dissolve 300 g of potassium citrate (or 284
g of sodium citrate) and 41 g of anhydrous citric acid in 1 liter of
water (200 ml is needed per test). Adjust the pH to between 5.4 and 5.6
with potassium citrate or citric acid, as required.
7.1.3 Hydrogen Peroxide, 3 percent. Same as in Method 6, Section
7.1.3 (40 ml is needed per sample).
7.1.4 Recovery Check Gas. Hydrogen sulfide (100 ppmv or less) in
nitrogen, stored in aluminum cylinders. Verify the concentration by
Method 11 or by gas chromatography where the instrument is calibrated
with an H2S permeation tube as described below. For Method
11, the relative standard deviation should not exceed 5 percent on at
least three 20-minute runs.

Note: Alternatively, hydrogen sulfide recovery gas generated
from a permeation device gravimetrically calibrated and certified at
some convenient operating temperature may be used. The permeation
rate of the device must be such that at a dilution gas flow rate of
3 liters/min (6.4 ft\3\/hr), an H2S concentration in the
range of the stack gas or within 20 percent of the standard can be
generated.

7.1.5 Combustion Gas. Gas containing less than 50 ppb reduced
sulfur compounds and less than 10 ppmv total hydrocarbons. The gas may
be generated from a clean-air system that purifies ambient air and
consists of the following components: Diaphragm pump, silica gel drying
tube, activated charcoal tube, and flow rate measuring device. Flow
from a compressed air cylinder is also acceptable.
7.2 Sample Recovery and Analysis. Same as Method 6, Sections 7.2.1
and 7.3, respectively.

8.0 Sample Collection, Preservation, Storage, and Transport

8.1 Preparation of Sampling Train.
8.1.1 For the SO2 scrubber, measure 100 ml of citrate
buffer into the first and second impingers; leave the third impinger
empty. Immerse the impingers in an ice bath, and locate them as close
as possible to the filter heat box. The connecting tubing should be
free of loops. Maintain the probe and filter temperatures sufficiently
high to prevent moisture condensation, and monitor with a suitable
temperature sensor.
8.1.2 For the Method 6 part of the train, measure 20 ml of 3
percent hydrogen peroxide into the first and second midget impingers.
Leave the third midget impinger empty, and place silica gel in the
fourth midget impinger. Alternatively, a silica gel drying tube may be
used in place of the fourth impinger. Maintain the oxidation furnace at
800 100 deg.C (1472 180 deg.F). Place
crushed ice and water around all impingers.
8.2 Citrate Scrubber Conditioning Procedure. Condition the citrate
buffer scrubbing solution by pulling stack gas through the Teflon
impingers and bypassing all other sampling train components. A purge
rate of 2 liters/min for 10 minutes has been found to be sufficient to
obtain equilibrium. After the citrate scrubber has been conditioned,
assemble the sampling train, and conduct (optional) a leak-check as
described in Method 6, Section 8.2.
8.3 Sample Collection. Same as in Method 6, Section 8.3, except
the sampling rate is 2 liters/min (10 percent) for 1 or 3
hours. After the sample is collected, remove the probe from the stack,
and conduct (mandatory) a post-test leak-check as described in Method
6, Section 8.2. The 15-minute purge of the train following collection
should not be performed. After each 3-hour test run (or after three 1-
hour samples), conduct one system performance check (see Section 8.5)
to determine the reduced sulfur recovery efficiency through the
sampling train. After this system performance check and before the next
test run, rinse and brush the probe with water, replace the filter, and
change the citrate scrubber (optional but recommended).

Note: In Method 16, a test run is composed of 16 individual
analyses (injects) performed over a period of not less than 3 hours
or more than 6 hours. For Method 16A to be consistent with Method
16, the following may be used to obtain a test run: (1) collect
three 60-minute samples or (2) collect one 3-hour sample. (Three
test runs constitute a test.)

8.4 Sample Recovery. Disconnect the impingers. Quantitatively
transfer the contents of the midget impingers of the Method 6 part of
the train into a leak-free polyethylene bottle for

[[Page 61990]]

shipment. Rinse the three midget impingers and the connecting tubes
with water and add the washings to the same storage container. Mark the
fluid level. Seal and identify the sample container.
8.5 System Performance Check.
8.5.1 A system performance check is done (1) to validate the
sampling train components and procedure (prior to testing; optional)
and (2) to validate a test run (after a run). Perform a check in the
field prior to testing consisting of at least two samples (optional),
and perform an additional check after each 3 hour run or after three 1-
hour samples (mandatory).
8.5.2 The checks involve sampling a known concentration of
H2S and comparing the analyzed concentration with the known
concentration. Mix the H2S recovery check gas (Section
7.1.4) and combustion gas in a dilution system such as that shown in
Figure 16A-3. Adjust the flow rates to generate an H2S
concentration in the range of the stack gas or within 20 percent of the
applicable standard and an oxygen concentration greater than 1 percent
at a total flow rate of at least 2.5 liters/min (5.3 ft\3\/hr). Use
Equation 16A-3 to calculate the concentration of recovery gas
generated. Calibrate the flow rate from both sources with a soap bubble
flow meter so that the diluted concentration of H2S can be
accurately calculated.
8.5.3 Collect 30-minute samples, and analyze in the same manner as
the emission samples. Collect the sample through the probe of the
sampling train using a manifold or some other suitable device that will
ensure extraction of a representative sample.
8.5.4 The recovery check must be performed in the field prior to
replacing the SO2 scrubber and particulate filter and before
the probe is cleaned. Use Equation 16A-4 (see Section 12.5) to
calculate the recovery efficiency. Report the recovery efficiency with
the emission data; do not correct the emission data for the recovery
efficiency. A sample recovery of 100 20 percent must be
obtained for the emission data to be valid. However, if the recovery
efficiency is not in the 100 20 percent range but the
results do not affect the compliance or noncompliance status of the
affected facility, the Administrator may decide to accept the results
of the compliance test.

9.0 Quality Control

------------------------------------------------------------------------
Quality control
Section measure Effect
------------------------------------------------------------------------
8.5........................... System Ensure validity of
performance sampling train
check. components and
analytical
procedure.
8.2, 10.0..................... Sampling equipme Ensure accurate
nt leak-check measurement of stack
and calibration. gas flow rate,
sample volume.
10.0.......................... Barium standard Ensure precision of
solution normality
standardization. determination.
11.1.......................... Replicate Ensure precision of
titrations. titration
determinations.
11.2.......................... Audit sample Evaluate analyst's
analysis. technique and
standards
preparation.
------------------------------------------------------------------------

10.0 Calibration

Same as Method 6, Section 10.0.

11.0 Analytical Procedure

11.1 Sample Loss Check and Sample Analysis. Same as Method 6,
Sections 11.1 and 11.2, respectively, with the following exception: for
1-hour sampling, take a 40-ml aliquot, add 160 ml of 100 percent
isopropanol and four drops of thorin.
11.2 Audit Sample Analysis. Same as Method 6, Section 11.3.

12.0 Data Analysis and Calculations

In the calculations, at least one extra decimal figure should be
retained beyond that of the acquired data. Figures should be rounded
off after final calculations.
12.1 Nomenclature.

CTRS = Concentration of TRS as SO2, dry basis
corrected to standard conditions, ppmv.
CRG(act) = Actual concentration of recovery check gas (after
dilution), ppm.
CRG(m) = Measured concentration of recovery check gas
generated, ppm.
CH2S = Verified concentration of H2S recovery
gas.
N = Normality of barium perchlorate titrant, milliequivalents/ml.
Pbar = Barometric pressure at exit orifice of the dry gas
meter, mm Hg (in. Hg).
Pstd = Standard absolute pressure, 760 mm Hg (29.92 in. Hg).
QH2S = Calibrated flow rate of H2S recovery gas,
liters/min.
QCG = Calibrated flow rate of combustion gas, liters/min.
R = Recovery efficiency for the system performance check, percent.
Tm = Average dry gas meter absolute temperature, deg.K
( deg.R).
Tstd = Standard absolute temperature, 293 deg.K (528
deg.R).
Va = Volume of sample aliquot titrated, ml.
Vm = Dry gas volume as measured by the dry gas meter, liters
(dcf).
Vm(std) = Dry gas volume measured by the dry gas meter,
corrected to standard conditions, liters (dscf).
Vsoln = Total volume of solution in which the sulfur dioxide
sample is contained, 100 ml.
Vt = Volume of barium perchlorate titrant used for the
sample, ml (average of replicate titrations).
Vtb = Volume of barium perchlorate titrant used for the
blank, ml.
Y = Dry gas meter calibration factor.
32.03 = Equivalent weight of sulfur dioxide, mg/meq.

12.2 Dry Sample Gas Volume, Corrected to Standard Conditions.
[GRAPHIC] [TIFF OMITTED] TR17OC00.283

Where:

K1 = 0.3855 deg.K/mm Hg for metric units,
= 17.65 deg.R/in. Hg for English units.

12.3 Concentration of TRS as ppm SO2.
[GRAPHIC] [TIFF OMITTED] TR17OC00.284

[[Page 61991]]

Where:
[GRAPHIC] [TIFF OMITTED] TR17OC00.285

12.4 Concentration of Recovery Gas Generated in the System
Performance Check.
[GRAPHIC] [TIFF OMITTED] TR17OC00.286

12.5 Recovery Efficiency for the System Performance Check.
[GRAPHIC] [TIFF OMITTED] TR17OC00.287

13.0 Method Performance

13.1 Analytical Range. The lower detectable limit is 0.1 ppmv
SO2 when sampling at 2 liters/min (4.2 ft\3\/hr) for 3 hours
or 0.3 ppmv when sampling at 2 liters/min (4.2 ft\3\/hr) for 1 hour.
The upper concentration limit of the method exceeds the TRS levels
generally encountered at kraft pulp mills.
13.2 Precision. Relative standard deviations of 2.0 and 2.6
percent were obtained when sampling a recovery boiler for 1 and 3
hours, respectively.
13.3 Bias.
13.3.1 No bias was found in Method 16A relative to Method 16 in a
separate study at a recovery boiler.
13.3.2 Comparison of Method 16A with Method 16 at a lime kiln
indicated that there was no bias in Method 16A. However, instability of
the source emissions adversely affected the comparison. The precision
of Method 16A at the lime kiln was similar to that obtained at the
recovery boiler (Section 13.2.1).
13.3.3 Relative standard deviations of 2.7 and 7.7 percent have
been obtained for system performance checks.

14.0 Pollution Prevention. [Reserved]

15.0 Waste Management. [Reserved]

16.0 Alternative Procedures

As an alternative to the procedures specified in Section 7.1.4, the
following procedure may be used to verify the H2S
concentration of the recovery check gas.
16.1 Summary. The H2S is collected from the calibration
gas cylinder and is absorbed in zinc acetate solution to form zinc
sulfide. The latter compound is then measured iodometrically.
16.2 Range. The procedure has been examined in the range of 5 to
1500 ppmv.
16.3 Interferences. There are no known interferences to this
procedure when used to analyze cylinder gases containing H2S
in nitrogen.
16.4 Precision and Bias. Laboratory tests have shown a relative
standard deviation of less than 3 percent. The procedure showed no bias
when compared to a gas chromatographic method that used gravimetrically
certified permeation tubes for calibration.
16.5 Equipment and Supplies.
16.5.1 Sampling Apparatus. The sampling train is shown in Figure
16A-4. Its component parts are discussed in Sections 16.5.1.1 through
16.5.2.
16.5.1.1 Sampling Line. Teflon tubing (\1/4\-in.) to connect the
cylinder regulator to the sampling valve.
16.5.1.2 Needle Valve. Stainless steel or Teflon needle valve to
control the flow rate of gases to the impingers.
16.5.1.3 Impingers. Three impingers of approximately 100-ml
capacity, constructed to permit the addition of reagents through the
gas inlet stem. The impingers shall be connected in series with leak-
free glass or Teflon connectors. The impinger bottoms have a standard
24/25 ground-glass fitting. The stems are from standard 6.4-mm (\1/4\-
in.) ball joint midget impingers, custom lengthened by about 1 in. When
fitted together, the stem end should be approximately 1.27 cm (\1/2\
in.) from the bottom (Southern Scientific, Inc., Micanopy, Florida: Set
Number S6962-048). The third in-line impinger acts as a drop-out
bottle.
16.5.1.4 Drying Tube, Rate Meter, and Barometer. Same as Method
11, Sections 6.1.5, 6.1.8, and 6.1.10, respectively.
16.5.1.5 Cylinder Gas Regulator. Stainless steel, to reduce the
pressure of the gas stream entering the Teflon sampling line to a safe
level.
16.5.1.6 Soap Bubble Meter. Calibrated for 100 and 500 ml, or two
separate bubble meters.
16.5.1.7 Critical Orifice. For volume and rate measurements. The
critical orifice may be fabricated according to Section 16.7.3 and must
be calibrated as specified in Section 16.12.4.
16.5.1.8 Graduated Cylinder. 50-ml size.
16.5.1.9 Volumetric Flask. 1-liter size.
16.5.1.10 Volumetric Pipette. 15-ml size.
16.5.1.11 Vacuum Gauge. Minimum 20 in. Hg capacity.
16.5.1.12 Stopwatch.
16.5.2 Sample Recovery and Analysis.
16.5.2.1 Erlenmeyer Flasks. 125- and 250-ml sizes.
16.5.2.2 Pipettes. 2-, 10-, 20-, and 100-ml volumetric.
16.5.2.3 Burette. 50-ml size.
16.5.2.4 Volumetric Flask. 1-liter size.
16.5.2.5 Graduated Cylinder. 50-ml size.
16.5.2.6 Wash Bottle.
16.5.2.7 Stirring Plate and Bars.
16.6 Reagents and Standards. Unless otherwise indicated, all
reagents must conform to the specifications established by the
Committee on Analytical Reagents of the American Chemical Society,
where such specifications are available. Otherwise, use the best
available grade.
16.6.1 Water. Same as Method 11, Section 7.1.3.
16.6.2 Zinc Acetate Absorbing Solution. Dissolve 20 g zinc acetate
in water, and dilute to 1 liter.
16.6.3 Potassium Bi-iodate [KH(IO3)2]
Solution, Standard 0.100 N. Dissolve 3.249 g anhydrous
KH(IO3)2 in water, and dilute to 1 liter.
16.6.4 Sodium Thiosulfate
(Na2S2O3) Solution, Standard 0.1 N.
Same as Method 11, Section 7.3.2. Standardize according to Section
16.12.2.
16.6.5 Na2S2O3 Solution, Standard
0.01 N. Pipette 100.0 ml of 0.1 N
Na2S2O3 solution into a 1-liter
volumetric flask, and dilute to the mark with water.
16.6.6 Iodine Solution, 0.1 N. Same as Method 11, Section 7.2.3.
16.6.7 Standard Iodine Solution, 0.01 N. Same as in Method 11,
Section 7.2.4. Standardize according to Section 16.12.3.
16.6.8 Hydrochloric Acid (HCl) Solution, 10 Percent by Weight. Add
230 ml concentrated HCl (specific gravity 1.19) to 770 ml water.
16.6.9 Starch Indicator Solution. To 5 g starch (potato,
arrowroot, or soluble), add a little cold water, and grind in a mortar
to a thin paste. Pour into 1 liter of boiling water, stir, and let
settle overnight. Use the clear supernatant. Preserve with 1.25 g
salicylic acid, 4 g zinc chloride, or a combination of 4 g sodium
propionate and 2 g sodium

[[Page 61992]]

azide per liter of starch solution. Some commercial starch substitutes
are satisfactory.
16.7 Pre-test Procedures.
16.7.1 Selection of Gas Sample Volumes. This procedure has been
validated for estimating the volume of cylinder gas sample needed when
the H2S concentration is in the range of 5 to 1500 ppmv. The
sample volume ranges were selected in order to ensure a 35 to 60
percent consumption of the 20 ml of 0.01 N iodine (thus ensuring a 0.01
N Na2S2O3 titer of approximately 7 to
12 ml). The sample volumes for various H2S concentrations
can be estimated by dividing the approximate ppm-liters desired for a
given concentration range by the H2S concentration stated by
the manufacturer. For example, for analyzing a cylinder gas containing
approximately 10 ppmv H2S, the optimum sample volume is 65
liters (650 ppm-liters/10 ppmv). For analyzing a cylinder gas
containing approximately 1000 ppmv H2S, the optimum sample
volume is 1 liter (1000 ppm-liters/1000 ppmv).

------------------------------------------------------------------------
Approximate
Approximate cylinder gas H2S concentration (ppmv) ppm-liters
desired
------------------------------------------------------------------------
5 to 30................................................. 650
30 to 500............................................... 800
500 to 1500............................................. 1000
------------------------------------------------------------------------

16.7.2 Critical Orifice Flow Rate Selection. The following table
shows the ranges of sample flow rates that are desirable in order to
ensure capture of H2S in the impinger solution. Slight
deviations from these ranges will not have an impact on measured
concentrations.

------------------------------------------------------------------------
Critical orifice flow rate
Cylinder gas H2S concentration (ppmv) (ml/min)
------------------------------------------------------------------------
5 to 50 ppmv............................. 1500 500
50 to 250 ppmv........................... 500 250
250 to 1000 ppmv......................... 200 50
>1000 ppmv............................... 75 25
------------------------------------------------------------------------

16.7.3 Critical Orifice Fabrication. Critical orifice of desired
flow rates may be fabricated by selecting an orifice tube of desired
length and connecting \1/16\-in. x \1/4\-in. (0.16 cm x 0.64 cm)
reducing fittings to both ends. The inside diameters and lengths of
orifice tubes needed to obtain specific flow rates are shown below.

----------------------------------------------------------------------------------------------------------------
Flowrate (ml/ Altech
Tube (in. OD) Tube (in. ID) Length (in.) min) Catalog No.
----------------------------------------------------------------------------------------------------------------
\1/16\.......................................... 0.007 1.2 85 301430
\1/16\.......................................... 0.01 3.2 215 300530
\1/16\.......................................... 0.01 1.2 350 300530
\1/16\.......................................... 0.02 1.2 1400 300230
----------------------------------------------------------------------------------------------------------------

16.7.4 Determination of Critical Orifice Approximate Flow Rate.
Connect the critical orifice to the sampling system as shown in Figure
16A-4 but without the H2S cylinder. Connect a rotameter in
the line to the first impinger. Turn on the pump, and adjust the valve
to give a reading of about half atmospheric pressure. Observe the
rotameter reading. Slowly increase the vacuum until a stable flow rate
is reached, and record this as the critical vacuum. The measured flow
rate indicates the expected critical flow rate of the orifice. If this
flow rate is in the range shown in Section 16.7.2, proceed with the
critical orifice calibration according to Section 16.12.4.
16.7.5 Determination of Approximate Sampling Time. Determine the
approximate sampling time for a cylinder of known concentration. Use
the optimum sample volume obtained in Section 16.7.1.
[GRAPHIC] [TIFF OMITTED] TR17OC00.288

16.8 Sample Collection.
16.8.1 Connect the Teflon tubing, Teflon tee, and rotameter to the
flow control needle valve as shown in Figure 16A-4. Vent the rotameter
to an exhaust hood. Plug the open end of the tee. Five to 10 minutes
prior to sampling, open the cylinder valve while keeping the flow
control needle valve closed. Adjust the delivery pressure to 20 psi.
Open the needle valve slowly until the rotameter shows a flow rate
approximately 50 to 100 ml above the flow rate of the critical orifice
being used in the system.
16.8.2 Place 50 ml of zinc acetate solution in two of the
impingers, connect them and the empty third impinger (dropout bottle)
and the rest of the equipment as shown in Figure 16A-4. Make sure the
ground-glass fittings are tight. The impingers can be easily stabilized
by using a small cardboard box in which three holes have been cut, to
act as a holder. Connect the Teflon sample line to the first impinger.
Cover the impingers with a dark cloth or piece of plastic to protect
the absorbing solution from light during sampling.
16.8.3 Record the temperature and barometric pressure. Note the
gas flow rate through the rotameter. Open the closed end of the tee.
Connect the sampling tube to the tee, ensuring a tight connection.
Start the sampling pump and stopwatch simultaneously. Note the decrease
in flow rate through the excess flow rotameter. This decrease should
equal the known flow rate of the critical orifice being used. Continue
sampling for the period determined in Section 16.7.5.
16.8.4 When sampling is complete, turn off the pump and stopwatch.
Disconnect the sampling line from the tee and plug it. Close the needle
valve followed by the cylinder valve. Record the sampling time.
16.9 Blank Analysis. While the sample is being collected, run a
blank as follows: To a 250-ml Erlenmeyer flask, add 100 ml of zinc
acetate solution, 20.0 ml of 0.01 N iodine solution, and 2 ml HCl
solution. Titrate, while stirring, with 0.01 N
Na2S2O3 until the solution is light
yellow. Add starch, and continue titrating until the blue color
disappears. Analyze a blank with each sample, as the blank titer has
been observed to change over the course of a day.

Note: Iodine titration of zinc acetate solutions is difficult to
perform because the solution turns slightly white in color near the
end point, and the disappearance of the blue color is hard to
recognize. In addition, a blue color may reappear in the solution
about 30 to 45 seconds after the titration endpoint is reached. This
should not be taken to mean

[[Continued on page 61993]]

Notices For
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994

[[pp. 61943-61992]] Amendments for Testing and Monitoring Provisions

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