Why is it necessary to dry compressed air?
The atmospheric air drawn into a compressor is a mixture of gases that also contains water vapour. The amount of water vapour air can carry varies, and is mostly dependent on temperature. As temperature increases, the air’s ability to carry moisture increases correspondingly. When compressed air is cooled the excess moisture that it can no longer carry is precipitated. This precipitant, commonly called condensate, is then removed by a downstream centrifugal separator or in the air receiver. Only the precipitated water is removed, however, and the air remains saturated (100% relative humidity). If allowed to flow into the air main in this state would cool further and condensate would be deposited in the pipework and in the consumer devices themselves, leading to corrosion and breakdown. Therefore air drying is essential to avoid loss of production and high outlay in maintenance and repair.
Contamination in a Compressed Air System
It is often believed that the level of compressed air purification equipment required in a system is dependent upon the type of compressor used. Contamination in a compressed air system originates from many sources and is not related solely to compressor lubricants.
No matter what compressor type is selected, adequate filtration and separation products will be required to remove the large volume of dirty contaminated water as well as the dirt, rust, pipescale and microbiological contamination present.