Coating processes bring together air and atomized chemical compounds, which can create hazardous conditions.
The primary function of a spray booth is to reduce the likelihood of fires and explosions. Although operator safety is among the highest priorities, it is not a function of spray booths to protect the operator from overspray contamination. Some people assume that a spray booth is an emission control device that must comply with Environmental Protection Agency (EPA) standards. A spray booth’s primary function is not as an emission control device.
Spray Booth Classifications
Spray booth classifications are outlined in NFPA 33. The NFPA classifies booth areas according to the type of electrical equipment and other possible ignition sources that can be safely used within those areas.
Class 1: Flammable gasses and vapors
Class 2: Combustible dusts
Divisions 1 and 2: Locations in the classified area in which these flammable gasses, vapors and dusts are handled
Class 1 Division 1: Areas inside the spray booth and ductwork
Class 1 Division 2: Any area within a 10-foot radius of the open face of a spray booth (When the spray gun is not interlocked with the exhaust fan)
Class 1 Divisions 2: When the spray gun and fan are interlocked, any area extending 5 feet from the open face of a spray booth (This area also extends 3 feet from a conveyor opening and includes the area above the ceiling of the booth)
Equipment located in the Class I, Division 1 atmosphere must be classified as explosion-proof. No electrical items should be inside a spray booth. Electrical equipment in the Class I, Division 2 atmosphere must be UL listed and must not produce sparks under normal operating conditions.