A compressor running in a "start-stop" mode operates more efficiently if the pressure trapped in the compressor head and discharge line is released after each pump-up cycle. This allows smoother starts and the use of a motor with lower starting torque. The most convenient way to release this trapped pressure is to use a Load Genie® combination check and unloader valve, available only from Control Devices, Inc. Simply install this unique valve in the compressor discharge line, and the Load Genie® does the rest! The Load Genie® senses air flow when the compressor is running and closes an unloading orifice port. When airflow stops (such as when the pressure switch turns off the motor), the Load Genie® opens the unloading orifice to release head pressure, and the built-in check valve keeps receiver air from leaking back into the discharge line and compressor head. Alternative methods rely on external unloading valves mounted on the pressure switch or compressor. These external unloading valves are connected with appropriate tubing and fittings to the compressor discharge line or compressor head. A tank check valve is also required. These systems, then consist of the unloading valve, connecting tubing with appropriate fittings, a tank check valve, and the labour to install it all. It is MOST IMPORTANT to match the rated flow range of the Load Genie® with the compressor flow capacity. Also, keep in mind that as the compressor discharge pressure goes up, the flow capacity goes down. IF the flow capacity of the compressor drops below the minimum rated flow of the Load Genie®, the valve will react as if the compressor had stopped, and it will vent the discharge line. Therefore, it is better to size the Load Genie® toward the upper/maximum end of its rated flow range. Please note that based on the flow selection criteria, the inlet and outlet sizes may not match the fitting sizes found on the compressor and tank. In this case, use the appropriate reducers available in any hardware store. Model Name Inlet Size Outlet Size Min & Max Flow SCFM Lenght (mm) Hex (mm) PA48 3/4" FPT 3/4" MPT 15-48 60.3" 30.2"