All pneumatic systems operate best when the air or gas is free of contamination. However, that is an ideal state that is not often found. Virtually every industrial air system has multiple sources of contamination. Here are some examples:
Water In air lines, water exists in the form of vapor or water droplets. Water droplets form when warm compressed air cools, which happens for several reasons. The compressed air piping may pass through ambient air which is cooler than the air in the line, or droplets may form because of turbulence and expansion of the air as it passes through the pipes. Water droplets can be stopped by filters. However, water vapor is a true gas and will pass through any filter that allows the air to flow through. The problem here is that after the vapor passes through the filters it may be subjected to temperatures below the dew point which will cause the vapor to condense into water. The solution to water contamination is the installation of an air dryer, which removes water and water vapor from the air after it passes through the compressor.
Compressor Oil -- All lubricated compressors heat the air as they compress it, which can vaporize some of the lubricating oil this is present in the cylinder head. Some of this oil vapor is unavoidably carried over into the outgoing air stream. A percentage of this oil will form droplets which, like water droplets, can be removed by filtration. To a large extent, oil vapors can also be removed by coalescing filters.
Rust & Pipe Scale -- Iron pipe, used widely in air distribution piping, is guaranteed to produce rust and scale (both are forms of iron oxide). Scale is usually found in fairly large flakes. Rust will commonly scale into particle sizes from 75 microns down to 20 microns, almost never falling below 5 microns.
PULSAIR Filtration: PULSAIR engineered systems have 40 micron main air line filters, as well as a 5 micron particulate filter and a coalescing filter inside the controller. Our equipment has run successfully for years, utilizing industrial grade compressed air, sometimes without filter changes. However, filter elements are inexpensive and easy to change, therefore they are inexpensive insurance for PULSAIR. We encourage our customers to keep an eye on the filters, drain them as needed and change the elements when they begin to discolor.