Isentropic means constant entropy (a definition of entropy is beyond the scope of this manual). Adiabatic describes a process wherein no heat is added or…

In an isothermal process, the temperature is unchanged during compression. Although it is impossible to build a machine that will compress isothermally, isothermal performance is…

The two actual methods used to calculate thermodynamic relationships are isentropic (adiabatic) and polytropic. These calculations are the basis for determining capacity, driver size, and…

Weight flow, w, may be calculated from any conditions of interest using the following equation (derived from Equation 100-3): Refer to the nomograph in Appendix…

Flow through a compressor may be stated in a number of different ways: • MMSCFD • Moles/Hour (MPH) • SCFM • ACFM • Weight Flow…

For air compressors it is usually necessary to account for water vapor content. It is important to know the moisture content accurately when a process…

The specific gravity of the gas mixture is determined by dividing the molecular weight of the mixture by that of air.

Knowing the mole fractions in a mixture leads to calculation of several important properties of the mixture: • the molecular weight, Mm • molal specific…

Equation 100-1 defines the behavior of a “perfect” gas in terms of variables listed: pressure, temperature, volume, etc. This is a helpful starting point, although…

Positive displacement compressors perform work on the gas in a repetitive noncontinuous process. The types within this category include: • Reciprocating • Rotary – Screw…