A reciprocating surroundings compressor is a positive 
displacement compressor that uses a crankshaft-driven piston and cylinder to compress the air. … A two-stage compressor contains an additional step where in fact the surroundings is Piston Air Compressor compressed by another, smaller sized piston to a pressure as high as 175 PSI.
Like a little internal combustion engine, a conventional piston compressor includes a crankshaft, a connecting rod and piston, a cylinder and a valve head. … As the piston moves down, a vacuum is created above it. This allows outside atmosphere at atmospheric pressure to force open up the inlet valve and fill up the area above the piston.