DennisCA
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I've seen these lately and I wonder how long they last before having to be replaced?
A conventional flashback arrestor works, from what I understand, so that the fuel gas or oxygen travels through this sponge like web of material, it's a very heat sensitive and if there is a flashback, the material melts so fast it stops the flame front. Now because these are often mounted on he torch they can partially melt just from regular use, so they have an expiry date of 18 months or so. Given what they cost I thought this was a pretty harsh cost for any hobbyist.
From what I understand of these resettable arrestors, they are simply designed that they shut off before the heat reaches ingition temperatures. Seems to me though this only works if they are near the torch where things get hot.
But there are resettable regulator mounted arrestors and they probably won't detect any gradual heating of the fuel gas until it's too late I think and the flame front is already rushing back through the hose. Are they just that fast that they can mechanically stop the flame front, sometihng a check valve cannot? But at that point you'd probably have a hose explosion anyway. So what I am missing, or am I?
Also I wonder do they have indefinite lifespans since they are probably mechanical and doesn't rely on the on a single use sponge of metal to melt?
Another interesting thing I read is that torch mounted flashback arrestors can also help create the conditions for flashback because they restrict gas flow and pressure, regulator mounted ones can be bigger and not restrict gas flow nearly as much.
Perhaps this is why in the nordic countries the standard has been flashback arrestors on the regulator and check valves only on the torch. Guess the logic was that the hazard of a possible hose explosion is offset by the fact that a regulator mounted arrestor makes a flashback less likely to begin with.
A conventional flashback arrestor works, from what I understand, so that the fuel gas or oxygen travels through this sponge like web of material, it's a very heat sensitive and if there is a flashback, the material melts so fast it stops the flame front. Now because these are often mounted on he torch they can partially melt just from regular use, so they have an expiry date of 18 months or so. Given what they cost I thought this was a pretty harsh cost for any hobbyist.
From what I understand of these resettable arrestors, they are simply designed that they shut off before the heat reaches ingition temperatures. Seems to me though this only works if they are near the torch where things get hot.
But there are resettable regulator mounted arrestors and they probably won't detect any gradual heating of the fuel gas until it's too late I think and the flame front is already rushing back through the hose. Are they just that fast that they can mechanically stop the flame front, sometihng a check valve cannot? But at that point you'd probably have a hose explosion anyway. So what I am missing, or am I?
Also I wonder do they have indefinite lifespans since they are probably mechanical and doesn't rely on the on a single use sponge of metal to melt?
Another interesting thing I read is that torch mounted flashback arrestors can also help create the conditions for flashback because they restrict gas flow and pressure, regulator mounted ones can be bigger and not restrict gas flow nearly as much.
Perhaps this is why in the nordic countries the standard has been flashback arrestors on the regulator and check valves only on the torch. Guess the logic was that the hazard of a possible hose explosion is offset by the fact that a regulator mounted arrestor makes a flashback less likely to begin with.