Compressors are mechanical devices used to increase the pressure of air, gas or vapor and in the process move it from one location to another. The inlet or suction pressure can range from low subatmospheric pressure levels to any pressure level compatible with piping and vessel strength limits. The ratio of absolute discharge pressure to absolute suction pressure is the compressor pressure ratio.
Compression theory is primarily defined by the Ideal Gas Laws and the First & Second Laws of Thermodynamics. As originally conceived the Ideal Gas Law is based on the behavior of pure substances and takes the following form:
Pv = R*T
P = Absolute Pressure
v = Specific Volume
R = Gas Constant
T = Absolute Temperature
This equation is based on the laws of Charles, Boyle, Gay-Lussac and Avogadro
Note all properties should be defined in the same measuring system (for example either the English system or the metric system).
below Table sums up the two systems.