Compressors reciprocating direct acting

Positive-Displacement Compressors Reciprocating compressors are built in different sizes (up to about one megawatt refrigeration capacity per unit). Modern compressors are high-speed, mostly direct-coupled, single-acting, from one to mostly eight, and occasionally up to sixteen cylinders. 

The piston rod used in a reciprocating-compressor cylinder can fail if overstressed. The stress experienced by the piston rod is a direct function of the AP developed by the cylinder. That is because on one side of the piston, we have the suction pressure and on the other side of the piston, we have the discharge pressure. The AP times the area of the piston is therefore the force acting on the piston. Excessive force will break the piston rod. 

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