Aerosol Photometer Sample Flow Less Than 28.3 lpm

Reduction of the photometer sample flow to a level outside the tolerance limits, while using the internal reference settings for the 100% baseline response, results in a moderate increase in displayed % Leakage value. This higher value is the result of velocity changes of the aerosol passing through the light scattering chamber’s area of observation. The reduced velocity results in a more conservative evaluation of the filter under test. If actual upstream aerosol samples are used to establish a 100% baseline response (ratiometric mode), the unit’s aerosol response is self-correcting for the decreased flow rate and standard accuracy conditions maintained.