Safety Group 645/623N

Safety Group 645/623N

Parallel connection of 4 or 5 flashback arrestors 623N, certified to EN 730-1 / ISO 5175 for maximum flow rates

  • highest quality from the world market leader
  • safety elements: flame arrestor [FA], temperature-sensitive cut-off valve [TV], check valve [NV]
  • every arrestor 100% tested
  • 10.23 X 15.11 inches, 1,760 oz (4X), 1,240/1,840 oz (5X)
  • town gas max. 35,651 scfh (free flow-off)

Product of WITT 



Parallel connection of 4 or 5 Flashback Arrestors Model 623N
WITT Safety groups for reliable protection against dangerous reverse gas flow and flashbacks according to EN 730-1 / ISO 5175. For applications with high flow rates. Every safety group 100% tested.


  • a large surface area flame arrestor FA of stainless steel construction extinguishes any dangerous flashback entering the device in any direction
  • a temperature-sensitive cut-off valve TV extinguishes sustained flashbacks long before the internal temperature of the arrestors reaches a dangerous level
  • a spring-loaded check valve NV prevents slow or sudden reverse gas flow forming explosive mixtures in the gas supply

Operation / Usage:

  • in central gas supplies (behind the manifold pressure regulator or in a pipeline system)
  • in thermal processing systems conforming to EN 746-2 (cutting machines, furnace supply equipment)
  • WITT safety groups may be mounted in any position/ orientation in pipelines/supply pipes
  • the maximum ambient/working temperature is 70 °C / 158 °F


  • annual testing of the check valve, body leak tightness and flow capacity is recommended
  • safety groups are only to be serviced by the manufacturer


  • flange end connections (nominal diameter 32 – 65)
  • connection: two-sided female thread (G-; NPT-thread; Rc-thread)

Company certified ISO 9001and PED 97/23/EC Module H
CE-marked in accordance with PED 97/23/EC


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Safety Group 645/623N