25 October 2004
often enters the paint spray booths through cracks and damages the paint finish.
Therefore, provide a mechanical replacement air system to maintain a neutral air pressure
inside the booth. This will prevent dust from entering the paint spray area. The neutral air
pressure will also prevent paint overspray and vapors from escaping the booth and
migrating into adjacent work areas. For paint mixing room replacement air, refer to the
ACGIH IV Manual, Paint Mix Storage Room, VS-75-30.
Air Distribution. Distribution of replacement air within the spray booth is
as significant as the average air velocity through the booth. Distribute the replacement
air evenly over the entire cross section of the booth to prevent turbulence or undesirable
air circulation. The preferred means of distributing the replacement air is through
perforated plate as shown in Figures 9-1, 9-2, and 9-3. See paragraph 2-4.5 for
additional replacement air design criteria.
Heating and Air Conditioning
. See paragraph 2-4.5. Most
spray booth ventilation systems have a painting mode and a curing mode. Do not re-
circulate air during the painting mode. About 10 percent of the booth airflow is from
outside the booth and 90 percent of the exhaust air is recycled during curing. Review
the paint drying requirements before specifying temperature and humidity ranges.
Refer to ANSI Z9.7 for exhaust air re-circulation requirements.
SYSTEM CONTROLS. Design system controls in accordance with
RESPIRATORY PROTECTION. See paragraph 2-7.3.