Page 385 - Praxair - Specialty Gases and Equipment Reference Guide

Accessories

Flash Arrestor

Series 8491 Flash Arrestor
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 occured.
These units are easily reset 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 U/L listed.

Standard Features
n 100% flashback tested after assembly n Automatically resets for flash backs and n Checks reverse flow and provides positive
n U/L listed and meets strict international reverse flow below 10 psig shut-off of reverse flow over 10 psig
standards: n Themal cut-off n Built-in 100 micron stainless steel
Working Pressures n Stainless steel flame barrier positively sintered filter on inlet
n Acetylene @ 15.0 psig extinguishes flame within housing n High flow capacity (see table)
n Hydrogen/oxygen @ 50.0 psig
n Hydrogen/air @ 150.0 psig n Alerts user by shutting off gas flow in
n LPG @ 50.0 psig the event of a reverse flow or flashback
n Oxygen @ 143.0 psig exceeding 10 psig back pressure (captures
back pressure in the housing, no flame or
gas is exhausted to the atmosphere)

Materials of Construction Working Pressure (U/L) Flow Performance
n Body Gas Pressure psig Inlet Pressure psig Air Flow scfh
Alloy 360 brass Acetylene 15.0 7.3 231.0
n Internals Hydrogen/oxygen 50.0 14.5 465.0
Brass
Hydrogen/air 150.0 21.8 725.0
n Flame barrier
Stainless steel Methane/LPG 50.0 36.3 1041.0
Oxygen 143.0 72.5 1933.0
n Elastomers
Neoprene
Section E – Gas Handling Equipment
Ordering Information
Connections
Model Gas Service Inlet Outlet
PRS8491-F Flammable 1/4" NPT female 1/4" NPT female
PRS8491-O Oxidizers 1/4" NPT female 1/4" NPT female
PRS8491-FL Flammables 9/16-18 LH female 9/16-18 LH male
PRS8491-OR Oxidizers 9/16-18 RH female 9/16-18 RH male

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