compressor A mechanical device 1. to provide the desired pressure for chemical and physical reactions, 2. to control boiling points of fluids, as in gas separation, refrigeration, and evaporation, 3. to evacuate enclosed volumes, 4. to transport gases or vapors, 5. to store compressible fluids as gases or liquids under pressure and assist in recovering them from storage or tank cars, and 6. to convert mechanical energy to fluid energy for operating instruments, air agitation, fluidization, solid transport, blowcases, air tools, and motors