About Compressed Air

Overview

Air that is compressed to pressures greater than that of the atmospheric pressure of 1 Bar. Compressed air, also know as an industry’s fourth utility is used in almost every industry today. The standard pressure at which compressed air applications are typically used is 100 psig or 7 Bar. This pressure enables the air to be used as a motive force instead of electricity in a wide variety of application making the utility safer and more convenient.

Generation of Compressed Air

Compressor takes in air from the atmosphere and compresses the atmospheric air to the desired pressure. A wide range of compressors are used in industries today. Examples of compressor types include: Centrifugal, Reciprocating, Screw etc.

Contaminated Compressed Air

Compressed air from a compressor is always ridden with moisture and dirt. Such contaminants adversely affect the performance of the application in which compressed air is used. Contaminants in compressed air include moisture, oil and dirt. The bad effects of contaminants can be seen in many forms:

Rusting and Leaking of Compressed Air Lines.
Pressure drop due to clogging and build up.
Reduced efficiency/ mal-function of application due to build-up.
Product rejection due to Poor quality.
Excessive maintenance and repair of machinery using the compressed air.

Moisture damage is one of the most serious problems facing the compressed air industry. Problems caused by moisture alone include:

Erosion/ Corrosion of compressed air lines, machinery and system.
Moisture emulsifies with lubrication to form gum which attracts contaminant particles, eventually leading to clogs in the system.
Moisture promotes bacterial and fungal growth along the lines.
Ice formation can take place leading to blockage of line.

Compressed air from a compressor is always ridden with moisture and dirt. Such contaminants Commercial effects of contaminants can be translated as:

A large pressure drop due to contamination is loss of costly power.
Increased product rejection is wastage of time and input material.
Rusting/Corrosion leads to increased capital costs.
Increased maintenance leads to loss of production due to shut-down and service costs.

Source of Contaminants

The source of majority of the contaminants can be blamed on the fuel of the compressor air itself – “Atmospheric Air”. Atmospheric Air is never dry or clean. Certain contaminants such as oil are a result of the lubrication in the compressors. How does the density of the moisture in compressed air increase? Due to compression of the atmospheric air to a higher pressure e.g. 7 Bar, the volume of the compressed air is reduced to 1/7th of the original amount. As shown in the schematic; although the volume of the air is reduced, the moisture or dirt density increases. The content of moisture in the compressed volume doesn’t change. But, the amount of moisture entering the entire system increases with the ability of the system to accommodate 7 times more atmospheric air in the compressed form. Hence, the amount of moisture in the system increases by 7 times the amount for air that is compressed to 7 Bar.

Overview

Generation of Compressed Air

Contaminated Compressed Air

Source of Contaminants

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