By Ron Marshall, Compressed Air Challenge (CAC)
Compressed air filters are often-forgotten items that can affect the quality of your air supply and—surprisingly—the efficiency of your overall system. You can’t afford to overlook them.
Air compressors ingest atmospheric air from the compressor room, pass it through an inlet filter, and compress it to a space about 1/7th the original size. This process generates large amounts of heat that must be removed by some type of cooler. When this is done, moisture is squeezed and condensed out of the air and mostly eliminated by a water separator. While it’s inside the compressor, though, the air also picks up small amounts of the equipment’s lubricant. Any dust in the air as it passed the inlet filter remains, but in a denser form due to the reduction in volume.
Water, lubricant, and dust particles that aren’t filtered out before they reach the air dryer will travel to points unknown throughout the system. Among other things, such contaminants could then ruin your product or clog the internal pneumatic circuits of expensive production equipment. That’s why compressed air filtration is so important.
Fortunately, there are many different types and styles of filtering solutions in the marketplace, ranging from very coarse elements that remove large particles to very fine ones that remove tiny dust particles and minute traces of lubricant and water. Unfortunately, all filters present a restriction to the flow of air that leads to the development of pressure differential.
Pressure differential consumes energy in compressed air systems. About 1% of additional power is required for every 2 psi higher compressor-discharge pressure. Thus, filters need to be chosen wisely. Note, too, that there’s usually a balance between the need for clean air and the cost of compressor operation. In general, the finer your filtering, the higher your energy costs.
That said, who chooses your filters and why? Frequently it’s the compressor supplier—who might have somewhat of a vested interest in supplying your operations with filter elements for years to come. Often, you’ll find a train of multiple filters installed in a compressor room, from coarse to fine, sometimes in multiple groups before and after the air dryer. These types of units can represent the biggest pressure differential in a plant.
For more information on compressed air topics and related training through the Compressed Air Challenge (CAC), visit compressedairchallenge.org, or contact Ron Marshall directly at firstname.lastname@example.org.