Powder coating is a type of coating in which a spray gun spreads the powder electrostatically on the surface of article. The powder may be the thermoplastic or thermoset polymer.
According to PCB (Pollution Control Board), direct exhaust of powder to atmosphere via cyclone is harmful to human and to the environment. Hence, AFU (After Filter Unit) is suggested for further separation of powder particles which has exhausted from cyclone. The particle size of powder is 5 microns or less. Normally, powder manufacturer maintains the particle size of powder below 5 microns. This unit contains filters which arrest the powder particles and fresh air is exhausted in atmosphere.