NRV 10s H check valves for R744 (CO2) can work as an internal relief valve when installed in parallel with GBC Ball Valves or service shut off valves, at the inlet and outlet of components to be serviced. The NRV 10s H can also be used in hot gas defrosting lines. Refrigerants: R744 (CO2). Oil: POE, PAG. Temperature range: -50 - +140 °C (-58 - +285 °F). Max. working pressure (PS/MWP): 90 bar (1305 psig). Max. test pressure: 130 bar (1885 psig). Approvals: CE and UL.