Reciprocating Compressors – Some Definitions

Bore:

Cylinder diameter

Stroke:

Distance via which the piston moves. The two extreme places of the piston are termed as head-end and crank-end dead centers.

Clearance Volume (Cl):

Volume occupied by the fluid whenever the piston is at head-end dead centre.

Piston Displacement (PD):

Volume, a piston sweeps up through.

Compression Ratio (rv):

The ratio of cylinder volume with the piston at a crank-end dead centre to the cylinder volume by the piston at head-end dead centre.

Single-acting:

Where only one side of the piston is employed.

Double-acting:

Where both sides of the piston are employed.

Mechanical Efficiency:

Brake work / Indicated work that give a sign of Indicated work losses taking place among the piston and driving shaft.

Volumetric Efficiency:

Is a measure of the efficiency of the machine with regard to gas handling.