The choice of compressor took a lot of research. Basically you need to decide the maximum flow rate you might need, and then the size of tank. But to do this you also have to consider how you are planning to prime the parts, because this will effect the choice of spraygun and protective mask. These items will probably take the largest flow rate.
I decided on an Acid Etch primer, nasty stuff so needed an air mask to keep the horrible potions out of my lungs! I chose an Iwata AZ3 HTE2 AV Gravity Spraygun and a DeVilbiss VIZI-601 Air-Fed Visor Outfit. These items combined need about 14 cfm.
The larger the tank the less often the pump has to recharge. This is important if you have the compressor sited in the workshop, since they make a lot of noise. Belt driven compressors seem to produce the least noise (unless you pay loads of dosh for a Screw Type). I chose 150 litres, which seems to work well for the air tools. When using the pneumatic squeezer the pump cuts in about once a day! Using air drills about 3 times a day, and with high flow items such as a die grinder much more often.
Anyway, I chose a Clarke XEV16/150 Industrial Air Compressor. I registered with Machine Mart and purchased the unit when they were running a “Vat Free” promotion : )
When spraying using the air fed mask the setup just copes!