These flanged, heavy duty, piston type check valves control the flow of refrigerant. Valves open wide for flow in the direction of the arrow shown on the valve body and close when a reverse flow occurs. These are suitable for compressor or pump discharge, hot gas lines and pulsating pressure applications including side port to screw compressors. These valves have metal to metal seat. Suitable for R717 (Ammonia), R744 (CO2), HCFC & HFC.