Flash back arrestors

galadduin

galadduin

Joined
Dec 25, 2004
Messages
1,363
For my under construction forge i bought a 100 pound propane tank (thats huge!!! :D ) Now designing the connections. Brand new regulator with manometer, valves etc. , they look safe, the feel is good. But do i need any "flashback arrestor"? It may would make the system safer i thought.

The local shop guy said propane connection doesnt need any.

I couldnt find any 1/4 or 1/8" brass nippel for the Ron Reil type atmospheric burner and did make burner from 8 mm (= 0.31496062992125984 inch) brass nippel. Is this OK?
 
If a propane burner acts at all like an oxy/act burner you will hear a horid clicking/poping noise if the flame starts to burn back. It might be hard to find a check valve that will work properly at the low psi most propane systems run at. That said I will add that I am a fan of check valves in general.

WS
 
But my financial situation hates unnecessary things, but i am scared to death with this explosive thingies around me, and hi-temp etc... If its worthy i will buy that stuff... Any know-how, advice would be handy... :confused:
 
For what its worth, you can't be too safe, but I haven't seen a check valve mentioned in any forge plans or on anyones forge. Don't have one on mine and haven't had any problems with back flashes.
The guy at the gas distribution place where I bought all the plumbing for mine talked like there was a chance of burning up the hose if the forge got to drawing more BTU's than the gas was supplying, but said it wouldn't go beyond the regulator. I haven't had a bit of trouble though.
 
Thanks Matt. I think, umm.... Yes i will buy that too :grumpy: . Your right, it wont be safe enough but as you mentioned it will be safer, i wont burn the hose means for me "SAFER"... And I love this word... :D
 
I don't think its that big a deal really, but whatever it takes to make you comfortable while running the equipment. Make sure you read the specs on whatever you buy. Your probably not going to run the forge over 5-6 psi (I run mine around 1 psi :D) Dont' want to spend the money on something if it doesn't do anything at the pressure your using.
You could just put a needle valve right at the burner so that you can shut the gas off from there. While your running the forge the fire is actually clear out at the end of the burner if its tuned right. You can hold the back half of the burner on my forge with your bare hand when the forge is up to full heat. Its only when you shut it off that the flame comes back up the burner and I've never had it act like it was flashing. If you've got a needle valve right there you put a break right there when you shut it down.
 
I run a 100# tank (for years) and this is the way I have it setup. Male fitting going into the tank - ball valve-manifold with quick connect/females ( so I can run forge and burners to heat up oil)male connector-ball valve ( this is to forge)- regulator- needle valve- quick connect female. Then I have a Hi-pressure hose with quick connects to the forge.
 
Matt thanks, thats a good tip. I will check the working range. ( I have a needle vlv. there.)

I want to implement the way you do Mr. I.G. . I didnt think that i might want to use another burner: I was too excited when I made my burner that it was the only burner i would need in my life :footinmou . Thanks showing me the obvious...
 
galadduin said:
Matt thanks, thats a good tip. I will check the working range. ( I have a needle vlv. there.)

I want to implement the way you do Mr. I.G. . I didnt think that i might want to use another burner: I was too excited when I made my burner that it was the only burner i would need in my life :footinmou . Thanks showing me the obvious...
Click to expand...
Good luck and post a pic when you got it completed. My welding forge has a blower on it and I can weld a 4 to 5 psi.
I feel that with a blower burner you have a wide range of adjustments. I have pic's on my website of how to build it.
;)
 
I've never had any trouble with my system- simply a regulator attached to the tank, and the hose running to my 2" blower pipe. Just make sure you turn the blower on before you turn on the propane and light it. (I've got friends that do this step in reverse, and it makes me shudder and wish I was'nt there). Having said that however, I must admit that what I've added thus far doesn't address your question of flashback-we're assuming that positive pressure from the fuel source, coupled with a flow of air from your blower, should negate any chance of flashback, but strange, deadly things happen despite our best intentions. Sometimes billions of dollars of technology and the pre-eminent experts in the field aren't enough to avoid disaster (remember the Columbia space shuttle?). So the best advice I would offer is that of a previous reply- you can't be too safe. It is a given when working with oxy-acetylene that flash arrestors are in place. And insofar as propane forges are concerned, I remember going to an informal meeting once of some local blacksmiths, an informal ABANA members gathering, in which forge safety was discussed. We were presented with a photo of a forge that had blown up due to improper use; I can only guess how much more severe the carnage would have been, had the propane cylinder itself blown. And be aware also, that current military "wisdom" has shown that fuel-air explosives are the next best thing to a nuclear blast. LOTS of potential mayhem in that 100-pounder.
Excuse my long reply, just my 2-cents worth, as this is a fairly important topic.
 
gijaney said:
I've never had any trouble with my system- simply a regulator attached to the tank, and the hose running to my 2" blower pipe. Just make sure you turn the blower on before you turn on the propane and light it. (I've got friends that do this step in reverse, and it makes me shudder and wish I was'nt there). ...
Click to expand...

I made an athmospheric forge that does fit my expectations, but my next project will be a "forced-air" welding relatively small forge. Therefore your reply is very on-topic. I have to admit i am scared of this forge building thing but i have to go on. "Fear doesnt earn money!" :). Thanks for your reply, sir.
 
No flash back protector should be needed for a propane atmospheric burner.If a back pressure was forced on the line by a chamber burst,the diaphragm would close.If the flame backed into the hose,which is virtually impossible at atmospheric pressure,The hose would burn through,but the flame would stop at the regulator.
The biggest danger is in an explosion in the forge chamber by igniting it after it is already full of gas.Always remember, "FLAME FIRST,GAS SECOND",and you will not get the BAM when lighting your forge.
 
I have a cutoff valve at my burner, which makes me feel secure. I'm not nearly as organized as IG though, everything comes apart with wrenches in my wretched shop. :D
 
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