With a desiccant dryer, water vapor is removed through absorption and adsorption processes. In the event compressed air lines are exposed to temperature below 32° F (or 00 C), the use of desiccant dryer is required to eliminate the hazard of compressed air line freezing.
Refrigerant type air dryers are the most economical compressed air dryers in terms of initial purchase price, cost of installation, and operation. Within a refrigerant air dryer, compressed air is cooled, water vapor is condensed into liquid water where it is mechanically separated and drained from the compressed air system. Refrigerant air dryers are supplied with automatic condensate drains.
Note: An aftercooler and/or dryer can be supplied within a stand-alone air compressor package eliminating the additional field expense of installation (piping and wiring).
A properly sized dryer will prevent liquid water within a compressed air system. All dryers are rated for inlet conditions of 100° F, 100% relative humidity, and 100 psi. Increasing inlet pressure and lowering inlet temperature will improve dryer efficiency.
Once liquid condensate has been removed from the compressed air stream through the effective use of an after cooler and dryer, a compressed air filter is recommended for removal of solid particulates, aerosol mists, and gaseous vapors.
A compressed air filter is designed with a replaceable element that allows contaminants to impinge upon the elements surface area. As the element becomes wetted, filtration efficiency actually improves. As liquids, aerosols and particulates randomly collide on small diameter fibers, the filtration process coalesced invisible contamination into larger droplets that gravitate to the base of the filter housing.
Lastly, liquids are drained from the filter through a drain valve. Compressed air filters are designed for specific applications. A properly sized and positioned compressed air filter eliminates contaminants from passing downstream. An electric drain provides a reliable alternative to floattype, gravity-feed drains that corrode and clog over time. Electric drains can be viewed as a lowcost alternative to manually draining system. Operation of all drains should be checked regularly to avoid costly loss of compressed air.