Jump to main content.


Rectangular Duct Wall Effects


You will need Adobe Acrobat Reader to view some of the files on this page. See EPA's About PDF page to learn more about PDF, and a link to the free Adobe Acrobat Reader.

EPA is allowing the use of an optional rectangular duct wall effects conditional test method CTM-041 (PDF) (17 pp., 45 K) for source personnel that perform flow monitor relative accuracy testing in a rectangular stack or duct.

As further described below, CTM-041 must be approved as an alternative before a source may use it to meet Federal requirements under 40 CFR Parts 60, 61, 63 or 75. Additional information on conditional test methods is available on EPA Emission Measurement Center Web site.

The Designated Representative (DR) or Authorized Account Representative (AAR) of a Part 75 or NOx SIP Call-affected unit may submit to the appropriate address below a one time, written request to use CTM-041 that may cover all of the units for which the DR or AAR is responsible. At a minimum, the written request must contain the plant name, unit ID, stack/pipe ID, ORISPL number, and the start date and time that the rectangular duct wall effects will be applied to the flow data.

Personnel of a Part 75 or NOx SIP Call-affected unit may provisionally use CTM-041 starting in the quarter that the written request is submitted, but not prior to the fourth quarter 2003. Wall effects adjusted data resulting from a provisionally approved request will be considered valid quality-assured data (retroactive to the start date and time of the rectangular duct wall effects adjustment), provided that EPA approves the request. We anticipate that EPA will likely approve each written request. However, all approvals will be conditioned with the following language: "The rectangular duct cross-sectional area may not be adjusted to account for any build-up of particulate matter or other material in the bottom of the duct when calculating stack gas volumetric flow."

Part 75 or NOx SIP Call-affected units using CTM-041 must use the Reporting Instructions (9 pp., 45 K).

For performing CTM-041 calculations:

EPA encourages personnel using CTM-041 at any Part 75 or NOx SIP Call-affected unit to download and run the special rectangular duct wall effects version of MDC version 4.2.51 prior to submitting each quarterly report.

For Part 75 or NOx SIP Call-affected units, the written request to use CTM-041 should be sent to:

Regular Mail:
USEPA
Clean Air Markets Division, Mail Code: 6204J
1200 Pennsylvania Avenue, N.W.
Washington, D.C. 20460
Attn: John Schakenbach

Overnight Mail:
USEPA
Clean Air Markets Division, Mail Code: 6204J
1310 L Street, N.W.
Washington, D.C. 20005
Attn: John Schakenbach

For any other sources wishing to use the methodology, a written request should be sent to:

Regular Mail:
USEPA
OAQPS, EMAD
Mailroom - Mail Code: D205-02
Research Triangle Park, NC 27711
Attn: Conniesue B. Oldham

 


Local Navigation


Jump to main content.