Non-Return Valve NV654

Non-return valve for the prevention of unintended gas mixtures, for flow rates up to 11,059 scfh (air), up to 870 psi, G 1/8

  • safety element: non-return valve [NV]
  • every non-return valve 100% tested
  • ultra-low opening pressures (approx. 0.435 psi), ultra-low pressure drop
  • small and light: 0.55 X 1.64 inches, 1.56 oz
  • up to 870 psi working pressure (O2: up to 435 psi)
  • air max. 11,059 scfh (free flow-off)

This model is also available in Stainless Steel

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    WITT  non-return valves (check valves) for reliable protection against dangerous reverse gas flow. Every  non-return valve (check valve) 100% tested.


    • a spring-loaded  non-return valve (check valve) prevents a reverse flow of gases which could lead to unwanted gas mixtures
    • low pressure drops – using complex valve assembly with low opening pressures (approx. 30 mbar)
    • no leaks – using a spring-loaded valve assembly with elastomer sealing
    • diverse applications – useful for many technical gases
    • reduce installation costs – the spring-loaded valve is not affected by gravity and may be installed in any orientation
    • compact design, small mounting dimensions

    Operation / Usage:

    • non-return valves (check valves) are used to protect equipment and pipelines against dangerous reverse gas flow
    • WITT  non-return valves (check valves) may be mounted in any position / orientation
    • the maximum ambient / working temperature is 60 °C / 140 °F


    • annual testing of the  non-return valve (check valve) and body leak tightness is recommended
    • WITT is happy to supply special test equipment
    • non-return valves (check valves) are only to be serviced by the manufacturer

    Company certified to ISO 9001 and PED 2014/68/EC Module H
    Designed for Oxygen Service in accordance with EIGA 13/20 and CGA G-4.4: Oxygen Pipeline and Piping Systems
    Cleaned for Oxygen Service in accordance with EIGA 33/18 and CGA G-4.1: Cleaning of Equipment for Oxygen Service


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    Test Rig 722

    Test Rig 722

    For the annual testing of WITT flashback arrestors and check valves