How do I Calculate CFM for a Spray Booth Exhaust Fan?

An exhaust fan is necessary to achieve proper spray booth airflow.

When you are designing a spray booth, it is vital that the proper amount of airflow is available. A spray booth should have an exhaust fan that is rated at the proper cubic feet per minute (CFM) rating to ensure that airflow is always at the optimal rate. While special equipment is available that can test the concentration of specific solvents, the National Fire Protection Association's estimated sufficient airflow velocity of 100 feet per minute can be used to calculate a sufficient CFM rating for your exhaust fan.

Things You'll Need

• Tape measure
• Calculator

Instructions

1. Use a tape measure to determine the height and width of your spray booth face in feet.

2. Multiply the height and width together to get the area in square feet. For instance, a 10-foot by 10-foot face would have an area of 100 feet.

3. Multiply the area by the National Fire Protection Association airflow figure of 100 feet per minute to get the CFM needed for an exhaust fan in the spray booth. For instance, our example of a 100-square-foot area would need a fan with a rating of at least 10,000 CFM to adequately ventilate the booth.

Tips & Warnings

• Proper airflow in a paint booth is important to ensure both that the painter is safe and that the paint finish turns out as desired.

References

• Finishing News: Calculating Spray Booth Air Flow