Flashback Arrestors

Mods-if this is deemed not truck related, no problem-remove it please.
Learned Folks
My mate has just come back from industrial China, and advises that flashback arrestors are fitted only on acetylene lines.
He was advised this is industry standard and approved.
It's a long time since I waved an oxy set around, but I recall arrestors being on both Oxy and Acetylene.
I only saw it once, but it was enough to frighten the bejesus outa me-the hose on fire, making it's way back to the bottle bank.
Not my doing I might add, can't remember what caused it, but I'm still here.
Now that I'm at it-hoses were "glued" together weren't they? So if one caught fire, the other one would too.
In my mate's case, it was a large industrial site, not a small isolated workshop.
There were no bottles-bulk storage some way away, gases piped-either hard or soft piped, or a combination of both, then manifolds with branches leading off to the various work sites.
Don't have all the pipe and branch details, so can't explain any better-yet.
But even then, two hoses from each manifold to the torch at the work site are together, and again, fire in one means fire in both.
I see ESAB and the like still sell arrestors for both Oxy and Acetylene.
I think WorkSafe or whatever their name is in each state still demands both lines have arrestors.
What are your thoughts on this China practice?
(Never mind the Jubilee clips-are these legal in Oz? Some places demand crimps. I hope the "bandages" on hoses are for identification, and not repairs!)


Thanks in advance.
Cheers

It would be good to see what the risks of explosion are,

Neither the gas in the oxy or acetylene bottles will burn by themselves without the other, Acetylene leaking draws oxygen from surrounding air enough to keep burning, cook the hoses and cause general fire. It will not explode. If it is helped by melting the adjoining oxy hose you have a good fire but no explosion,

You need a perfect mixture, depending on fuel (petrol/oxygen about 16:1) to get an explosion and even then unless it is restricted you get a big poof instead of a big bang. A really big poof in cases like house gas explosions where there is heaps of correct mixture floating around before ignition. That is why you can weld a full petrol tank if you are game, with only a possibility of a "gentle" fire from the filler neck as the internal mixture is far too rich to explode.

Leads to the question, what function does the blow=back valve perform? Only works when the bottle runs out and the sniff of acetylene remaining is just enough to create the correct explosive mixture inside the bottle?

Expert opinion please.

lang

Hi Lang
Leads to the question, what function does the blow=back valve perform?
Are you referring to the non-return valves?
Yes, expert opinion please
Cheers

Well nothing definite but the Carlisle Tech College had some display Oxy cylinders that had exploded from acetylene going back into them and the flash back igniting them.

Seems to only happen with a very low Oxy cylinder and a fairly full Acetylene.
As Acetylene are filled with a porous substance I doubt very much you can get one of them to explode from flash back
Cheers Steve

Lang wrote
"That is why you can weld a full petrol tank if you are game, with only a possibility of a "gentle" fire from the filler neck as the internal mixture is far too rich to explode."

Thanks all the same, i'll leave that to someone else who hasn't got much to live for.

"Thanks all the same, i'll leave that to someone else who hasn't got much to live for."



My father lost half the hair on his head doing this once..... The right half.... At the time he was somewhat lucky.... But we look back on it theses days and piss ourselves laughing about it.... Best bit was him having to shave the other half off ....

Ive had plenty of explosions cutting up old trucks.......sometimes you get a loud whistling sound,then the fuel tank goes boom.....even when the tanks had no petrol for years....Plenty of flashbacks too cutting up double and triple rail chassis.....you just ignore the burns,or you get nothing done...The govt used flashback arresters on everything.....waste of time ,and moneyIMHO......Havent had acetylene for 40 years...its for rich people.......but when I was working,the crawlers used the workshop of a weekend,never closed the valves,empty G size every Monday morning.....must be $250 for a G acetylene now.........LP gas is just as good,at $25 a cylinder.

Can't imagine the circumstances where you'd have sufficient acetlyene pressure to overcome the oxy reg and enter the bottle.
I used to cut with about 5psi of acetylene and even a dead empty oxy still has more pressure than that.

Flashbacks that Ive had burn into the nozzle of the cutting torch,if you arent quick,the mixer inside the torch will burn up.........its caused by the nozzle getting blocked by slag.....easy cutting up dirty stuff........sand is a nightmare......the stuff melts into a sticky mess,and blocks the nozzle........and melted sand doesnt half burn if it get on you.

en.wikipedia.org/wiki/Flashback_arrestor