Kingston Model 620 Automatic Drain Valve automatically removes the condensates that collect in the tank, thereby extending the life of the air receiver and downstream air equipment. It is designed for use on all compressors with an unloader port. Complete drainage is assured by double action of the valve, which opens when the compressor starts and stops. Kingston Model 620 Automatic Drain Valve offers long, trouble-free service provided through simplicity of design and the use of corrosion resisting materials. A minimum pressure of 30 PSI is required to permit this valve to function properly. Maximum operating pressure 400 PSI. Use of a Kingston Ball Valve (KBV/KMBV) is recommended on air compressors with 5 horsepower or less.