Ask the Expert Question-and-Answer Archive

by Ron Joseph

December, 2002

Fouling of Abatement Control Equipment by Overspray

Q. My plant has a problem with a rotary concentrator + thermal oxidizer system used in paint spray booth emission control. The adsorbent is contaminated with paint overspray and the supplier says it is because we changed to a lower cost prefilter ahead of the adsorbent cassettes instead of that recommended by the system supplier. Is this possible or is this just an excuse for design deficiencies?

A. The prefilters used in rotary concentrator + thermal oxidizer systems are very critical to system operation by keeping the adsorbent free of paint overspray. If you change prefilter suppliers or change to less efficient prefilters for the sake of lowering your expenses, you need to make sure that both the prefilter supplier and your concentrator system supplier agree that the replacement filters will do the same job. In addition, the lower cost prefilters may need to be changed more often than the original filters so there may be no cost savings by changing the prefilter type.

Since the cost of contaminating your VOC abatement control devices far exceeds the cost of prefilters, you should not stint, but purchase only ones that have high particulate capture efficiency. Having said that, you must also bear in mind that the pressure differential (pressure drop) across the filters might increase as the filter efficiency increases. Therefore, before changing to new more efficient filters you should first insure that you will not impede the performance of the spray booth/abatement control system.

This question has been answered by Robert Kenson an associate of Ron Joseph & Associates, Inc.