Non-Return Valve 70 / 70U

Non-return valve for the prevention of unintended gas mixtures, for flow rates up to 11,706 scfh (air), up to 232 psi, for use in thermal processing, certified to EN746-2, G 3/4 - G 1.1/2

  • safety element: non-return valve [NV]
  • every non-return valve 100% tested
  • DIN EN ISO 5175-2
  • protects against flashbacks, for fuel gas-compressed air-mixtures
  • ultra-low opening pressures (approx. 0.058 psi), ultra-low pressure drop
  • 2.44 X 5.39-6.3 inches, 50.2 - 67.16 oz

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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 back feeding of gases which could lead to unwanted gas mixtures
    • low pressure drops – using complex valve assembly with low opening pressures (approx. 4 mbar)
    • brass filter protects the non-return valve (check valve) against flashbacks, extending the service life
    • 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

    Operation / Usage:

    • non-return valves (check valves) are used to protect equipment and pipelines against dangerous reverse gas flow. Use is possible for applications in accordance with EN 746-2
    • non-return valves (check valves) are proved in accordance with DIN EN ISO 5175-2. They may also be used as a safety device to protect against flashbacks (proved in accordance with DIN EN ISO 5175-1 point 6.7), which may result from the combustion of natural gas/ LPG with air
    • the maximum ambient / working temperature is 70 °C / 158 °F


    • annual testing of the non-return valve (check valve), body leak tightness and flow capacity 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
    CE-marked in accordance with PED 2014/68/EC
    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


    Test Rig 722

    Test Rig 722

    For the annual testing of WITT flashback arrestors and check valves

    Pipeline Fittings

    Pipeline Fittings

    For flashback arrestors models 270N/NU and 623N/NU, as well as check valve model 70



    For hose or pipe connection PN 10