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Flash Arrestor
Series 8491 - Brass


The new 8491 Series re-settable flashback arrestors offer four (4) safety devices in each unit. Safety features include protection against flashbacks with a wide range of mixtures of oxygen or air with flammable gases including hydrogen, acetylene, methane, and LPG gases. The design includes a built-in non-return (check) valve to stop reverse flow and a thermal shut off which stops gas flow in the event a of hose or pipe line fire. An easily re-settable pressure control stops gas flow in the event of reverse flow or a flashback that creates 10 psig back pressure. This feature alerts the user that a reverse flow or a flashback of greater than 10 psig has occurred. These units are easily re-set by pulling up on the pressure control ring (shown at right), no disassembly of the gas line or special tools are needed. The 8491 Series high flow capacity makes them suitable for a broad range of applications (see flow table). Units are UL listed and meet ISO 5175, EN 730, BS 6158, and AS 4603 standards.


  • 100% flashback tested after assembly.
  • UL listed and meets strict international standards.
    UL Approved Working Pressures:
    Acetylene @15.0 psig
    Hydrogen/oxygen @50.0 psig
    Hydrogen/air @150.0 psig
    LPG @50.0 psig
    Oxygen @143.0 psig
  • Alerts user by shutting off gas flow in the event of a reverse flow or flashback exceeding 10 psig back pressure (captures back pressure in the housing, no flame or gas is exhausted to the atmosphere).
  • Stainless steel flame barrier positively extinguishes flame within the housing.
  • Checks reverse flow and provides positive shut-off of reverse flow over 10 psig.
  • Thermal cut-off @ 165°C.
  • Built-in 100 micron stainless steel sintered filter on inlet.
  • High flow capacity (see flow performance table).

Materials of Construction

Body: Alloy 360 brass
Internals: brass
Flame barrier: stainless steel
Elastomers: Neoprene

Working Pressure

Gas Pressure psig
Acetylene 15.0 22.0
Hydrogen/oxygen 50.0 58.0
Hydrogen/air 150.0 -
Methane/LPG 50.0 72.0
Oxygen 143.0 217.0

Flow Performance

Inlet Press. psigAir Flow SCFH
7.3 231.0
14.5 465.0
21.8 725.0
36.3 1041.0
2.5 1933.0

How To Order

Model Gas Service Inlet Outlet
8491-F flammables 1/4" NPT female 1/4" NPT female
8491-O oxidizers 1/4" NPT female 1/4" NPT female
8491-FL flammables 9/16-18 LH female 9/16-18 LH male
8491-OR oxidizers 9/16-18 RH female 9/16-18 RH male