Spectrophotometric method for contamination control of gas media filters
Abstract
Abstract The possibility of measuring air filter contamination by colourimetry methods is investigated. It is found that the optical density D rel , measured relative to a clean filter surface can be used to assess filter contamination with coloured contaminant. This indicator is convenient for the specific weight of the contaminant in the range of 5-50 g/m 2 for substances with a density ρ < 1 g/cm 3 , and for the specific weight of the contaminant 10-250 g/m 2 for ρ > 1. It is shown that in case of a colour dust contaminated filter, the most reliable indicator is the colour difference ΔE of the contaminated surface relative to the clean one. The analysis of colour charts a*b*, a*L* and b*L* constructed in the CIE L*a*b*-1976 system shows that the lightness value ΔL* is appropriate to measure dark contaminants, and the value ΔE is acceptable for light contaminants.