Friendly Reminder – LaserHawk 360 PM Instrument QA Requirement
Available now, TML offers calibration filters that meet all three Audit point specifications. A zero filter cannot be used for this test if you evaluate accuracy using equation 2-1a which will result in a divide by zero error. We have a 16.7 percent filter available for Audit point 1.
40CFR60, Appendix F, Procedure 2 includes quality assurance testing for PM instruments. Section 10.1 defines the ACA testing requirement. An "Absolute Correlation Audit (ACA)" means an evaluation of your PM CEMS response to a series of reference standards covering the full measurement range of the instrument.
You must challenge your PM CEMS with an audit standard or an equivalent audit reference to reproduce the PM CEMS's measurement at three points within the following ranges:
| Audit point | Audit range |
| 1 | 0 to 20 percent of measurement range |
| 2 | 40 to 60 percent of measurement range |
| 3 | 70 to 100 percent of measurement range |
You must then challenge your PM CEMS three times at each audit point and use the average of the three responses in determining accuracy at each audit point. Use a separate audit standard for audit points 1, 2, and 3. Challenge the PM CEMS at each audit point for a sufficient period of time to ensure that your PM CEMS response has stabilized.
What are the criteria for excessive ACA error?
Your PM CEMS is out of control if the results of any ACA exceed ±10 percent of the average audit value, as calculated using Equation 2-1a, or 7.5 percent of the applicable standard, as calculated using Equation 2-1b, whichever is greater.
How do I calculate ACA accuracy?
You must use either Equation 2-1a or 2-1b to calculate ACA accuracy for each of the three audit points. However, when calculating ACA accuracy for the first audit point (0 to 20 percent of measurement range), you must use Equation 2-1b to calculate ACA accuracy if the reference standard value (Rv) equals zero.
Where:
ACA Accuracy = The ACA accuracy at each audit point, in percent,
RCEM
= Your PM CEMS response to the reference standard, and
RV
= The reference standard value.
Where:
ACA Accuracy = The ACA accuracy at each audit point, in percent,
CCEM
= The PM concentration that corresponds to your PM CEMS response to the reference standard, as calculated using the correlation equation for your PM CEMS,
CRV
= The PM concentration that corresponds to the reference standard value in units consistent with CCEM, and
Cs
= The PM concentration that corresponds to the applicable emission limit in units consistent with CCEM.
