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# How to Calculate CFM for a Paint Booth Exhaust Fan

Updated February 21, 2017

When spraying paint in a paint booth, you need to expel the fumes from the work area. In sufficiently high concentrations, the fumes will cause health problems and may even lead to serious injury. The fumes are removed from the area by use of an exhaust fan. This exhaust fan needs to be properly sized to move enough air out of the work area. Sizing is determined in CFM (cubic feet per minute) and is dependent on the paint booth's face area square footage.

Measure the length and width of the booth's face. This is the opening in the back of the booth from where the air will be expelled. The opening will span the entire work area.

Multiply the length and width together to get the booth's face area. For example, if the measurements are 8 feet by 10 feet, the booth's face area is 80 square feet.

Multiply the booth's face area by 100 feet per minute to achieve CFM. One hundred feet per minute is the guideline for air movement in the booth area. Using the example from above, 80 square feet multiplied by 100 feet per minute equals 8,000 CFM. This is the size of the fan needed.

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