Powder coating uses compressed air to fluidise and spray the powder onto the part, then to clean and purge the system. Moisture or oil in the air causes clumping, spitting and finish defects, so the air supply must be clean and dry.
Air quality requirement
Specify a pressure dew point low enough to prevent any condensation, typically -20°C or lower, with oil-free air and coalescing filtration. The air that fluidises the powder is especially sensitive, because damp powder clumps and blocks the feed.
Key applications
- Powder fluidisation and transport
- Spray gun operation and cleaning
- Booth purge and filter pulse cleaning
- Control and actuation systems
System design
Use an oil-free compressor with an adsorption dryer and point-of-use filtration at the booth. Keep lines sloped and drained, and monitor the dew point so moisture never reaches the powder system during humid weather.