Non-Return Valve NV800

Non-Return Valve NV800

Non-return valve for the prevention of unintended gas mixtures, for flow rates up to 494,176 scfh (air)

  • safety element: non-return valve [NV]
  • every non-return valve 100% tested
  • protects against flashbacks for fuel gas-compressed air-mixtures
  • offer minimum pressure drops – using complex valve assembly with low opening pressures (approx. 0.087-0.116 psi)
  • dirt filter (100 μm) on gas inlet
  • maybe mounted in any position/orientation
  • 7.8 X 13.65 inches, 800 oz

Product of WITT 




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, NV800 approx. 6 – 8 mbar
  • no leaks – using a spring-loaded valve assembly with elastomer sealing
  • stainless steel filter (100 μm) in the gas inlet protects the non-return valve (check valve) against dirt contamination, 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 according to EN 746-2
  • non-return valves (check valves) are proved in accordance with EN 730-2. They may also be used as a safety device to protect against flashbacks (proved in accordance with EN 730-1 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) and body leak tightness is recommended
  • non-return valves (check valves) are only to be serviced by the manufacturer

Company certified to ISO 9001 and PED 97/23/EC Module H
CE-marked in accordance with PED 97/23/EC
Cleaned for Oxygen Service according to EIGA IGC Doc 13/12/E: Oxygen Pipeline and Piping Systems



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Non-Return Valve NV800