The check valve is an integral part of your air compressors function.  The check valve allows air to enter the tank as the pump works, but prevents air from leaving the tank, so your tank maintains pressure.  If air is leaking through your pressure switch or pump, your check valve may need replacing.  The check valve is typically located on the top or side of your tank, and is connected to a discharge line from the pump.  There are several sizes and configurations of check valves.  At Air Compressors Plus, we stock a wide variety of check valves so when it comes time to replace your check valve, give us a call or stop by.