The purpose of this Listserv is to clarify the test run acceptance criteria for EPA Method 201A (M201A) used to determine filterable PM-10 and/or filterable PM-2.5.   Below is a list of the criteria:

1.         The acceptable cut size for the PM-10 cyclone is between 9 µm and 11 µm.

2.         The acceptable cut size for the PM-2.5 cyclone is between 2.25 µm and 2.75 µm.

3.         The overall isokinetics for the test run must be between 80% and 120%.

4.         As per Section 8.3.4(b), 21% of individual traverse points, rounded to the nearest whole number, may lie outside of the acceptable isokinetic range of 80% to 120%.   For a 12 point traverse, that is 3 points.
            a.         Precise dwell times must be recorded for each point in order to get accurate calculations of isokinetics.
            b.         Precise meter volume readings must be recorded for each point in order to get accurate calculations of isokinetics.

5.         As per Section 8.5.5(b), these are the acceptable number of traverse points allowed outside of the ∆Pmin and ∆Pmax range:
            a.         When testing for PM-2.5 alone, 16% of points, rounded to the nearest whole number, are allowed outside the ∆Pmin and ∆Pmax range.  For a 12 point traverse, that is 2 points.
            b.         When testing for PM-10 alone, 8% of points, rounded to the nearest whole number, are allowed outside the ∆Pmin and ∆Pmax range.  For a 12 point traverse, that is 1 point.
            c.         When testing for PM-10 and PM-2.5 combined, 8% of points, rounded to the nearest whole number, are allowed outside the ∆Pmin and ∆Pmax range.  For a 12 point traverse, that is 1 point.

Prior to this Listserv, Item #4, above was unclear and not enforced by BTS.  Recent conversations with EPA’s Emissions Measurement Center personnel have resolved this issue.  Going forward, all M201A test runs will be required to meet this criterion. 

All stack test reports must include proof that all five of the acceptance criteria listed above have been met.