When to Change Finishing Booth Air Filters

You can go by air pressure or by airflow, but the limits vary depending on location. November 26, 2006

We have in our finishing department open ended finishing booths. Can anyone tell me what the reading on the manometer should be when it is time to change the filters?

Forum Responses
(Finishing Forum)
From contributor H:
I think that it should be about .5, but my booth is very old and there is not any fluid in the doohickey. I change the filters when the spray starts to hang up in the ceiling of the booth.

From contributor R:
1. After installing a new filter, turn on the fan and mark the manometer at the pressure level that is indicated.
2. Check the manometer every time the fan is turned on.
3. If the pressure reading on the manometer increases by 0.25 in. wg (inches of water gauge), then it is time to change the filter.

From contributor T:

Contributor R is right, but if you do not live in an air quality district that has the .25 rule, you can change when your average velocity has dropped below 100 lineal CFM per minute (the OSHA requirement for spray booths). Since most booths are rated to overcome .5" of static pressure, they will lose the minimum of 100' feet per minute at .5" of static. Therefore, a good rule of thumb is to change your filters at .5" of static pressure difference unless you live in a regulated area that requires the .25 rule.