Kingston Model 305A Normally Closed, Quick Opening Valve, often referred to as a Whistle Valve has a body of heavy cast brass with internal components of machined brass. Springs are stainless steel. The standard valve disc and O-ring are Buna-N. Teflon and Viton seals are available on most sizes. Maximum working pressure, 400 psi, at 60°F. Maximum working temperature, 200°F. This valve has been in service for years on agricultural and industrial applications, for both compressed air and liquid. This valve is not recommended for steam service. Applications requiring manual operation at pressures above 150 psi, please refer to Kingston Model 305B Balanced Flow Control Valves.