ARCHIVED REPORTS_REMOVAL ACTION COMPLETION REPORT

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(see Section 8.3) after an elapsed time (ET) of one minute or more, and apply the following relationship: ET>_500/TWA For example,if TWA =2.5 mg/m3, then ET_:200 minutes (approximately 3 hours). If the TWA value changes significantly as the run proceeds,recalculate the required ET accordingly. At the end of the run (after time ET has elapsed),record TWA,ET and the flow rate Q used to sample the air. Weigh the filter on an analytical balance and obtain Om, the mass increment due to the collected particles. Calculate the average gravimetric concentration C, as follows: C = 1000 Am/ETxQ Compare the recorded value of TWA and the calculated value C, and calculate the calibration factor to be programmed into the personalDataRAM (see Section 9.0) as follows: CAL FACTOR = C/TWA For example,if C was found to be 3.2 mg/m3, and TWA had been determined to be 2.5 mg/m3, the CAL FACTOR equals 1.28.Select this value on the PC, as described in Section 9.0. This completes the gravimetric calibration of the personalDataRAM for a specific aerosol. 13.3 Scattering Coefficient Calibration Users interested in using the personalDataRAM for scattering coefficient measurements (e.g.,for atmospheric visibility monitoring) should contact the factory. A special primary Rayleigh scattering calibration for such purpose can be performed by NUE. 13.4 Internal Span Check The zeroing procedure (see Section 8.1) and the resulting normal diagnostic display of "CALIBRATION: OK" (step 2) informs the user that the instrument's calibration agrees with the original factory setting. This is an internal span check that consists of an automatic comparison between the initial (factory) optical background of the personalDataRAM (registered in its non-volatile memory), and the current optical background sensed during the zeroing sequence. 14.0 PARTICLE SIZE CLASSIFICATION (model pDR-1200 only) 31