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Emission Measurement Center
Method 201A - PM10 and PM2.5 (In-stack, CRS)
FREQUENTLY ASKED QUESTIONS (FAQS) for Method 201A
For FAQs about the revised Method 201A (December 2010 revisions), click HERE.
Can you use Method 201A in stacks that contain liquid droplets or are saturated with water vapor?
Method 201A cannot be used to measure emissions from stacks that have entrained moisture droplets (e.g., a wet scrubber stack), since these stacks may have water droplets larger than the cut size for the PM10-sizing device. To measure PM10 in stacks where water droplets are known to exist, EPA’s Technical Information Document ( TID-009: Methods 201 and 201A in Presence of Water Droplets) recommends use of Method 5 of Appendix A to 40 CFR part 60 (or a comparable method) and consideration of the particulate catch as PM10 emissions.
What changes were made in the 12-1-2010 revision to Method 201A, what comments did the Agency receive, and what were the Agency's responses to those comments?
The greatest change that was made to Method 201A was the addition of a cyclone to provide particle sizing at 2.5 um aerodynamic diameter. The preamble to the promulgated test method provides a summary of the less significant revisions that were made, the comments of greatest significance, and the responses to those comments. A copy of the promulgation preamble is located here. A copy of the Response to Comments document is available here.
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