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Ian B
12-01-2005, 09:37 AM
On oxy acetylene sets, where should the flash back arrestors go?

- On the torch, to protect the hose?

- On the gauge, to protect the bottles in case a hose ruptures / catches fire?

- Both?

- Both, but different types?

Thanks,

Ian

Wirecutter
12-01-2005, 10:14 AM
I heard once that Thorozine is a good flashback arrestor, but you can't just get that anywhere. I believe it's administered by injection. http://bbs.homeshopmachinist.net//biggrin.gif

Sandy H
12-01-2005, 10:40 AM
On the torches we used at school, the flashback arrestors were at the very back of the torch, right in front of the hose.

Sandy.

david_r
12-01-2005, 11:49 AM
Ian,
Victor puts then on the torch. That's where I'd put them. I would only install one set of flashback arrestors. I wouldn't bother with check valves as I don't see how it is possible for the gas to flow backwards unless it is a multiple torch setup.

I wonder how many millions of feet of O/A weld were put down without either installed? Man, those were dangerous times.

[This message has been edited by david_r (edited 12-01-2005).]

Evan
12-01-2005, 11:59 AM
Mine are on the regulator outputs. The idea is to prevent blowing up the regulator.

Timleech
12-01-2005, 01:17 PM
There are two types, one designed for fitting to the regulator output, the other for fitting inline near the torch. The ones for the reg end give more degrees of protection than the little inline ones, but don't ask me what they are. A bit of web digging should reveal all.

Best protection is to use both. I use the resettable type on the regulators, and Witt quick couplers

http://www.wittgas.com/pdf/SK_100_englisch.pdf
at the torch end. These allow an easy swap between cutting torch, welding torch and straight-line cutting machine, and have built-in non-return valves.

Tim

jlach
12-01-2005, 09:27 PM
I have been using oxy acetylene equipment for the past 35 years, although we didn't always have spark arrestors, they were installed on the torch. When they are installed on the torch, everything is protected,hose, guages and bottles. I once saw a blow back where the acetylene hose had holes blown about ten different spots over a fifty foot length. I would go for the "on torch installation."

ricksplace
12-01-2005, 09:49 PM
I have them both at the torch and the tanks. If hot slag falls on a hose and ruptures it, the torch arrestors won't do you much good. Get both -cheap peace of mind.

Rick

ps. there are different types for tanks and torch.

spope14
12-01-2005, 10:04 PM
Mine are on the tanks at the regulator. The school has a contract with the gas supplier, thus they do the switch outs of the tanks for me. They installed the arrestors as well. This is called liability arresting as well. They tend to like this installation method as well as they are sure of the tank condition upon shipping to my site, and taking back the bottles.

[This message has been edited by spope14 (edited 12-01-2005).]

Ian B
12-02-2005, 01:08 AM
Thanks for the input guys,

This was all brought about by a recent incident we had here offshore; a contractor's torch flashed back and damaged the hose. It turned out that his "flash back arrestor" was in fact a quick coupling, and - not surprisingly - it didn't stop the flash back!

We're now trying to sort the equipment out, and want to get it right. I'm strongly leaning towards putting arrestors on both ends of the hose. Good to know that different types are needed on the two ends.

Ian

Warren
12-02-2005, 05:42 AM
The typical set up for Oxy-fuel safty puts the flashback arrestors at the regulators & safty check valves at the torch handle

Western Enterprises has a reverse flow check valve built in the flash arrstor as well

http://www.westernenterprises.com/enterprises/PDFS/wi25.pdf

scroll to bottom of page

Your Old Dog
12-02-2005, 06:24 AM
Ricksplace, thanks for the slag reminder. I was feeling pretty smug with my arrestors on my torche handle http://bbs.homeshopmachinist.net//biggrin.gif Guess I'll go pick up a set for the gauges as well. It's cheap insurance against mayhem.

Timleech
12-02-2005, 08:34 AM
There are some video clips for downloading at

http://www.wittgas.com/e_frames-videodownload.htm

which look as though they might be interesting. I don't have sound on my computer at the moment, so don't get the full benefit.

Tim