Casey Equipment has several used industrial air compressors for sale, in stock, that suit many industrial compressor applications. There are reciprocating compressors and rotary screw air compressors that range from 20 CFM to 500 CFM with brands such as Sullair, Ingersoll Rand and Roots. Reciprocating air compressors work very similar to a two cycle internal combustion engine. An electric motor drives the crankshaft of the reciprocating compressor. During the down stroke of the piston, air is drawn into the cylinder through an inlet valve. The inlet valve then closes and the outlet valve opens as the piston begins its compression stroke. Rotary screw air compressors have two motor driven screws. As the air travels from the entry end of the screws, it is compressed due to progressively smaller cavities between the "threads" of the two screws. Industrial air dryers are important for any air compressor system since they remove moisture from the compressed air. There are two concepts used for air dryers, refrigeration or moisture attracting desiccant air dryers. Refrigeration air dryers cool the compressed air below the dew point which causes the moisture vapor to condense and fall out of solution as liquid. Dessicant air dryers use either silica gel or alumina which attracts the water as the compressed air passes over it. Dessicant air dryers will have two tanks, one in operation, while the other is heated to regenerate the desiccant media. Contact Casey Equipment for a quote on used industrial air compressors/used dryers for sale.