It is a common fallacy that compressors with a very high pressure are required for spray painting. In fact, a moderate pressure, but with sufficient volume to meet the requirements of the air cap and any other equipment are being used.

The spray gun may require 12.5 cfm (Cubic Feet per Minute) and an air fed mask, another 3cfm, so transformer and hoses must be capable of delivering 16cfm at 6opsi.

Quick fit couplings often have a narrow orifice which will allow adequate pressure, but are too narrow to allow sufficient volume of air to the job. As a rule of thumb, use as few quick fit couplings as possible, where used use 5/16 internal diameter fittings, not % I.D.

Similarly, there will be a volume drop from excessive length of air hose and from long runs of pipework.

Compressed air pipework should not be put in by a plumber, who gets his runs level and down pipes off underneath, any condensation will end up at the gun.

Pipe runs should go uphill from the air receiver, should be 1½ inch I.D. galvanized and all drop pipes should come over the top. Tee off for apparatus and down to a drain tap.

Lack of air supply and dirty air are the main problems encountered in paint shops.