Prevention of Electrostatic Fires During Spray Painting
In automotive manufacturing plants, the air during spray painting operations often contains significant amounts of flammable gases released from paints, thinners, and solvents. Although ventilation systems are installed, exhaust rates often fall short of requirements, allowing these flammable gases to reach explosive concentration limits. Should an electrostatic discharge produce a spark, it can easily trigger a fire or explosion. The workspace inevitably accumulates overspray, and paint residue builds up inside exhaust ducts; should a fire break out, it could spread rapidly.
The paints and thinners used in spraying are materials with high electrical resistivity, making them prone to generating and accumulating static electricity. Paint flows rapidly through the supply lines. During application, compressed air forces the paint through the spray gun's nozzle; with operating pressures typically ranging from 3 to 4 kgf/cm² and flow velocities often exceeding 3 meters per second, static electricity is readily generated. Spray guns, operators, and workpieces are often electrically isolated from the ground, preventing static charges from dissipating. Although the spray gun itself is metal, it is connected to the air pump via plastic or rubber hoses, effectively insulating it from the ground. Similarly, operators usually wear rubber-soled work shoes with high electrical resistance, insulating them from the ground as well. Workpieces made of non-metallic materials-or metal parts mounted on supports or pads with poor conductivity-are also prone to static accumulation. To prevent fires caused by static buildup, spray guns should be equipped with static discharge mechanisms, such as effective grounding systems.
Operators should ideally wear anti-static shoes with low electrical resistance; when spraying non-metallic workpieces, continuous spraying time should not exceed 90 seconds. The spray booth must be well-ventilated to minimize the accumulation of flammable gases, and overspray residue should be removed regularly. Provided it does not compromise quality, water may be sprayed in the workshop to increase indoor humidity, which helps reduce static accumulation.