Non-Return Valve NV300

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Non-return valve for the prevention of unintended gas mixtures, for flow rates up to 3260 m³/h (air), up to 16 bar, for use in thermal processing plants, certified to EN746-2

  • safety element: non-return valve [NV]
  • every non-return valve 100% tested
  • protects against flashbacks, for fuel gas-compressed air-mixtures
  • ultra-low opening pressures (approx.3.5 mbar), ultra-low pressure drop
  • ideal for biogas desulphurisation systems
  • dirt filter (100 μm) on gas inlet
  • 65 X 115-130 mm, 1.568 g

This model is also available in Stainless Steel

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


  • a spring-loaded non-return 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 NV300 – approx. 3.5 mbar
  • no leaks – using of a spring-loaded valve assembly with elastomer sealing
  • stainless steel filter (100 μm) in the gas inlet protects the non-return 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 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 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
  • WITT non-return valves may be mounted in any position / orientation
  • the maximum ambient / working temperature is 70 °C / 158 °F


  • annual testing of the non-return valve, body leak tightness and flow capacity is recommended
  • WITT is happy to supply special test equipment
  • non-return valves are only to be serviced by the manufacturer. The dirt filter may be replaced according to model by competent staff

Company certified to ISO 9001 and PED 2014/68/EC Module H
CE-marked in accordance with to PED 2014/68/EC
Cleaned for Oxygen Service according to EIGA IGC Doc 13/12/E: Oxygen Pipeline and Piping Systems

Non-Return Valve NV300 is used in following areas:

Test Rig 722

For the annual testing of WITT flashback arrestors and non-return valves


WITT Zentrale

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