High flow valve to provide optimum performance. Controls excess air flow (SCFM) in only one direction. Automatically senses change in air flow and shuts off the flow in the event of a surge in excess of valve flow rating thus preventing hose whip. Conforms to OSHA regulation 1926.302 (b) (7) requiring a safety device at the source of the air supply and at branch air lines. Applications include temporary plant/factory air, construction sites, shipyards or utilities. Not for use in applications where 100 percent of the available air is required, i.e. sand blast, pile driving rigs, expansion joint blow down pipes, etc. Does not prevent backflow. Construction: solid brass body and valve. Stainless steel spring and roll pin. Maximum 250 PSI working pressure. 250 degree F maximum temperature. Safety check valves operate by using the pressure differential across the valve to operate the valve and spring assembly. The pressure differential is directly related to the flow of air (SCFM) through the valve. When the pressure differential is within the operating limits - below the cutoff flow - of the unit, the force on the valve exerted by the spring is greater than that caused by the pressure differential. The valve remains open and normal operation continues. When the pressure differential is above the cutoff limit, the force on the valve exerted by the pressure differential is greater than the force exerted by the spring, and the valve closes. After the repair is made, normal operation is automatically enabled when pressure across the valve equalizes through the bleeder hole. The valve spring size can be specified by determining the air flow during normal operation and by estimating the air flow if a failure or rupture occurs.