Flashback Arrestor, A-Size Fittings, Direct Connection To AW1A

[jclay]

I want to add flashback arrestors directly to my AW1A torch handle connections; no intermediary fittings. The torch end fittings are fairly close together so FB arrestor diameter is limited.

Have any of you done that and if so what brand/model are you using?
Did you notice any meaningful/excessive flow resistance; do you need to bump up the regulator pressure at all?

[cicli polito]

Hi John - I use an AW1A as my main torch, and one of things I like about it is how light weight it is. A few years ago I bought the Smith H743 torch end flashback arrestors, which I really did not like. It felt like the weight of the torch doubled in my hand, and also made access to very tight / odd torch angles more difficult. As you mention, since the fittings are close together the arrestor bodies have to be thin, but long, to allow enough room for the sintered stainless inside the arrestors to do their job. These additions (weight at the handle and increased "effective" torch length) prompted me to switch.

I swapped them out for the H753 Regulator end arrestors, and installed lightweight check valves at the torch end. Never looked back since. YMMV.

As far as I know, the only torch mounted arrestors at the time I purchased mine were made by Smith, there were no aftermarkets. Smith has since been absorbed into Miller, so they now still sell the torch end arrestors as Miller H743.

I did notice a slight drop in my pressure, only about 1 PSI though. Just a nudge to the valve will get you right back to where you want it.

[jclay]

Hi John - I use an AW1A as my main torch, and one of things I like about it is how light weight it is. A few years ago I bought the Smith H743 torch end flashback arrestors, which I really did not like. It felt like the weight of the torch doubled in my hand, and also made access to very tight / odd torch angles more difficult. As you mention, since the fittings are close together the arrestor bodies have to be thin, but long, to allow enough room for the sintered stainless inside the arrestors to do their job. These additions (weight at the handle and increased "effective" torch length) prompted me to switch.

I swapped them out for the H753 Regulator end arrestors, and installed lightweight check valves at the torch end. Never looked back since. YMMV.

As far as I know, the only torch mounted arrestors at the time I purchased mine were made by Smith, there were no aftermarkets. Smith has since been absorbed into Miller, so they now still sell the torch end arrestors as Miller H743.

I did notice a slight drop in my pressure, only about 1 PSI though. Just a nudge to the valve will get you right back to where you want it.

Thanks Dan,

Western Enterprises makes the FA 80 & 81 which has A fittings. Little information is available via the Internet; I'll have to give them a call to get the OD and pressure loss information. If they don't fit I'll just use torch end check valves, but I don't mind the idea of serial flame arrestors too (I have flame arrestor/checks on the regulators).

1 psi looks about right for the Smith/Miller units and that's fine; I'm hoping the WE units will fit and cost no more than a couple of psi.

I'm good with a bit more heft and length in my torch handle but I appreciate the caution.

[Doug Fattic]

John, like Dan I have check valves on my torch handle and flashback arrestors on the regulators. As you know torch side A size arrestors are not common. TM Technologies sells them for $78 a pair. Their website doesn’t say which brand they sell or anything else. However it is easy to call them for more info. Uniweld makes filtered and unfiltered versions in an A size. Torch Tools (a web based welding supplier on Long Island, NY) has Gentec versions that are similar to Uniweld (they reference the Uniweld part numbers).

[holy-mojo]

Hi John, I started with both torch and regulator mounted flash arrestors on the fuel side and torch mounted only on the oxygen side with my AW1A torch, but found the resistance to be too high for my Oxygen Concentrator. The Propane side was fine. I've ended up removing the sintered element from the oxygen side torch mounted arrestor just to keep the hose lengths matching. This leaves two arrestors in the fuel line (probably over-cautious) and nothing on the oxygen concentrator - the stored oxygen volume is pretty low in the concentrator so the risk is quite low. Works fine now.