Within the frame, you have the motor (electric, diesel, or gas) the compressor block, a small filtration system and the drain for the moisture separators. In general, the unit will have a base and frame, with open sides and front. Filled to 3000-4500 PSI the canisters are small while also having a reasonable capacity.Īn open frame compressor has all the necessary features and none of the frills. Paintball and PCP air rifles are another common applications of high pressure compressed air.