Danfoss NRV 19 piston-type check valve (non-return valve), OEM P/N 020-1044. Controls unidirectional refrigerant flow to prevent back-flow in commercial refrigeration and air-conditioning systems. Straightway pattern, Flare connection 3/4 in (19 mm), inlet and outlet, supplied without flare nut. Piston design, single flow. Max working pressure 46 bar (667 psig); media temperature -50 °C to 140 °C. Suitable for oil-free applications. Refrigerant compatibility is listed on the datasheet — verify against your system charge.