Power & Temperature Control Equipment

Compressed Air Glossary

Ambient air — The air around or surrounding you.

Aftercoolers — Heat exchanger that cools discharge air from the compressor (provides the most effective means of removing moisture from compressed air approximately. 70% of water is removed).

Air-cooled compressors — Atmospheric air is circulated to cool the unit and /or the compressed air.

Air end — Compression chamber (chamber where air is compressed).

Approach temperature — Temperature above ambient.

Boosters — Increase air pressure (usually four times inlet PSI).

Boss hose fitting — Threaded fitting to connect hose from compressor or extend the length of hose used to flow gases.

Chicago Fitting (crows foot) — 1/4 turn fitting that can connect hose to the compressor or extend the length of hose used to flow gases.

CFM — Cubic feet per minute.

Centrifugal compressors — Compression of air/gas through turning impellers.

Condensate — Liquid discharged from compressor and /or air treatment equipment.

Dew point — Temperature that moisture changes from vapor to liquid.

Dew point suppression — Temperature below ambient.

Dynamic-type compressors — Air or gas is compressed by rotating vanes or impellers.

Filters — Devices that separate and /or remove undesired liquids and particulates from compressed air.

High-pressure air — Compressed air above 150 PSI.

Instrument-quality (IQ) air — Treated compressed air from an oil-flooded compressor (aftercooled, filtered).

Low-pressure air — Compressed air 150 PSI or lower.

Multicasting compressors — One motor can run two or more compression chambers.

Multistage compressor — Compressor with two or more stages.

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Microns — Measurement used to define particulates in the air stream (one micron = one millionth of a meter, about one eighth the thickness one human hair).

Oil-flooded air — Compressed air produced by a compressor that utilizes lubricating oil in the compression cycle.

Oil-free air — Compressed air produced by a compressor with no oil present in the compression cycle.

Oil separator — Device used in an oil-flooded system to recycle oil back to the air end.

OSHA valve — Valve used to depressurize a system when pressure drop is noticed.

PSI — Pounds per square inch (unit for pressure of compressed air).

Particulates — Any solid material, such as dirt, rust, weld fines, pollen, etc., that is in the air stream.

PPM — Parts per million, measurement of the oil present in compressed air.

Receivers — Tanks used to store compressed air and help dampen discharge line pulsations.

Reciprocating compressor — A piston in a cylinder produces compression.

SCFM — Standard cubic feet per minute.

Standard air — Air at a temperature of 68° F, 14.70 PSI atmospheric pressure, and relative humidity of 36% (per ASME). In the gas industry, temperature is 60° F.

Standard compressed air — Untreated compressed air from an oil-flooded system (not after-cooled or filtered).

Rotary compressors — Compression is produced by the positive action of rotating elements.

Two-stage compressors — Two-compression chambers (initial to intermediate) with one air discharge.

Whipcheck — Safety cable used to restrain air hoses if an end breaks.

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