25 October 2004
PAINT SPRAY BOOTHS
FUNCTION. Paint spray booths provide surface finishing capabilities for a
wide range of parts, equipment, and vehicles. Paint spray booth sizes range from bench
type units for painting small parts, to large walk-in booths or rooms for painting vehicles,
tractors or large equipment. Design aircraft maintenance hangars in accordance with
Chapter 10 of this UFC.
OPERATIONAL CONSIDERATIONS. During paint spray operations, paint
is atomized by a spray gun and then deposited on the object being painted. Depending
on the application equipment and spray method used, transfer efficiencies vary greatly.
Transfer efficiency is the amount of paint solids deposited on a surface divided by the total
amount of paint sprayed, expressed as a percentage.
a. Use equipment with a high transfer efficiency, such as electrostatic or
high volume low pressure (HVLP) spray guns, to reduce overspray.
Overspray is the paint that is sprayed but not deposited on the surface
being painted. This equipment not only saves in paint cost, but also
reduces volatile organic compound (VOC) emissions and maintenance
b. Warm the paint before applying, whenever possible. This lowers the
paint viscosity enabling spray painting at a lower pressure, thereby
minimizing the amount of overspray generated. The lower viscosity also
decreases the quantity of solvent used to thin the paint prior to spraying.
This results in reduced solvent consumption and VOC emissions.
Painting Equipment Types. Spray-painting equipment must conform to
national, state, and local emission control requirements. One of these requirements is
transfer efficiency. Five primary types of paint spraying equipment and their typical
transfer efficiencies include:
1. Conventional air spray (25 percent transfer efficiency).
2. Airless spray (35 percent transfer efficiency).
3. Air-assisted airless spray (45 percent transfer efficiency).
4. Electrostatic spray (65 percent transfer efficiency).
5. High volume/low pressure (HVLP) spray (up to 75 percent transfer
DESIGN CRITERIA. Design or procure paint spray booths in accordance
with the general technical requirements in Chapter 2 of this UFC and the specific
requirements in this Chapter.
Walk-in Spray Paint Booths. The ventilation system for a walk-in booth
is mainly to prevent fire and explosion. A well-designed ventilation system will also