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Appendix A                                                                                  Gas RATA Observation Sheet

3.  RATA Observations (cont.)

RATA Checks


Does the stack test equipment setup match that required by the reference method?

O2/CO2/MW- RM3 or RM3a

H2O - RM4 (wet bulb-dry bulb technique may not be used to correct dry basis measurements in determining emission rate)

SO2 - RM6 or RM6c

NOx - RM7, RM7E, or RM20

Check the traverse point locations for the reference method tests, and the sampling location dimensions.  The stack dimensions should be based on measurements not drawings.   Gas tests should use at least 3 traverse points.  Check PS2 in Part 60, App. B.  Units with wet scrubbers may use a shorter measurement line than required by PS2 if minimal stratification is demonstrated, and moisture and gas systems may use a single point if the stratification test is passed (App. A, ' 6.5.6).

Has a stratification test been performed and passed?

Stratification testing is required for units wishing to use fewer traverse points under the alternatives allowed by App. A, ' 6.5.6(a) and (b).  Stratification testing is described in App. A, ' -

For a NOx RATA using the instrumental RM 7E, is the NOx converter efficiency documented through a performance test?  A NOx converter efficiency test is required if the NO2 concentration is greater than 5 ppm.  The efficiency test is described in RM 20.

Check the reference method calibration gases used for instrumental methods.  The calibration gas certificate should show:

 !EPA Protocol gases or other Part 75 certified gases.

 !Concentrations which match that used in the bias/drift check calculations.

 !Expiration date after the RATA

The regulator gauge should show a cylinder pressure >150 psi.

Check the results of the pretest linearity check of the reference method analyzer.  Were the calibration gases injected at the same pressure and temperature as the stack gases?  Difference between the calibration gas value and response should be within 2% of the span for the linearity test.  Otherwise the test is repeated until passed.  No adjustments can be made to the analyzer after the linearity check.

Record and check the span of the reference method analyzers.  A test run is invalid if a measured concentration exceeds the span. (Method 6C, Sec. 2.1)


Part 75 Field Audit Manual - July 16, 2003                                                                                                       Page A-15

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