The compressed air leaving a compressor contains considerable quantities of water vapor. If the untreated air is supplied into the distribution lines, the moisture would condense to liquid water as it gets cooled. Condensed water is a major cause of downtime in compressed air systems. Air quality which was good enough for the old hand controlled valves or wide tolerance air tools is just not dry enough when used in today's sophisticated air systems. Water causes rust, pitting, blockages and freezes ups, with resultant component failure and product rejection. The only way to prevent condensation of water in airlines is to lower the dew point of the air in the system. It is less expensive to own and operate an air dryer than it is to live with the problems it can prevent. Drying compressed air doesn't cost . . . it saves.