Paints & Coatings Resource Center

Ask the Expert Question-and-Answer Archive

by Ron Joseph

May, 2004

Spray Booth Design, Exhaust Filters

Q. We're trying to build a large Paint booth at our facility but we're not sure how to determine the filter area required. The booth dimensions are 25'W x 50'L x 20'H. We are considering crossdraft without air replacement. How do you go about determining the filter area required (inlet and exhaust filters) and the required exhaust fan capacity? Thank you for your help.

A. Thank you for your email. Frankly, I would ask a dedicated spray booth company to suggest the filter design for you, since spray booths companies know the pitfalls of performing these calculations.

In general you should have an airflow rate of 100 ft/min passing the face of a painter regardless of where in the spray booth the painter stands. Since the cross section of the spray booth is 25ft. x 20ft the surface area is 500 ft2. If you multiply this by 100 ft/min the volumetric airflow is 50,000 ft3. A spray booth manufacturer might tell you that you do not need as much as 50,000 ft3, (and he/she might be quite correct) but bear in mind that you need sufficient airflow to carry the paint particulates from the back of the booth all the way to the filters. If you have insufficient airflow a significant portion of the particulates will fall to the floor before they get to the exhaust filters.

You do not need to have a filter section that is 25ft. x 20ft. and can go with smaller dimensions, but you will nevertheless need to insure a that you get lamina airflow from the back of the booth all the way to the exhaust filters. Depending on the type of machinery to be painted you might need to have two exhaust sections; one in the left corner and one in the right corner of the spray booth allowing a machine to be driven out of the booth through the space between the two exhaust sections. In other words, the design of the exhaust section will depend on what you are painting, its size and the method by which you intend to bring of the machinery into or take it out of the spray booth. I have seen many different designs, some of which performed better than others.

If you would like us to assist you in writing a specification for a spray booth that manufacturers can bid on, we will be happy to do so on a fee basis. Unfortunately, without knowing more details about what you are painting I cannot give you more useful information paragraph

Please feel free to contact us at your convenience.

Best wishes,

Ron Joseph

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