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anybody know how to keep a lit gas from lighting the gas in a fuel tank? I'm building a hydrogen stove or burner. Answered

I need to keep the lit hydrogen from lighting the compressed tank of hydrogen. The only things between the burner and the tank is a hose and a valve.

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fozzy13

9 years ago

you need a flashback arrestor. There are tons of different ways to make one, I use an aquarium blue filter stone in some brass fittings from home depot. Probably the most popular one is the bronze wool design where you stuff a bunch of fine bronze wool into a length of pipe to stop the backward burning. If you search youtube for "flashback arrestor" you'll find countless designs. Hope this helps.

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lukedwardsfozzy13

Answer 2 years ago

So, I'll be shocked if you answer since it's been 7 years since your comment. I'll probably end up having to figure it out myself but how well do the aquarium stones work? In other words do they always prevent a flashback and if so how many flashbacks can they prevent? Do they wear out? Thanks!!

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fozzy13lukedwards

Answer 2 years ago

Normally I wouldn't respond to comments this old, but you got me by pointing it out hahha. 7 years later I'm still here.

I used the blue ones that are roughly 1/2" in diameter, and when placed in some 1/2" pipe fittings, they work very well. However they definitely wear out as the stone burns, which can be dangerous, since it's difficult to see how much of the stone has burned up. I would definitely recommend using bronze wool tightly packed in a copper or brass tube instead, as this proved to not burn. Best of luck!

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lukedwardsfozzy13

Answer 2 years ago

Thanks, lol!

Actually I'm going with a hole size of about 0.2mm which should prevent a flashback on it's own but I am also using a flashback arrestor inline at the moment.

I also plan on purchasing a few of these that a buddy of mine just informed me that he's been using for about a year now. He says the one he has, has taken over a dozen flashbacks with no sign yet of any wear let alone that it might fail.

From what I can find it's filled with died quartz sand.

http://www.ebay.com/itm/252316259639

I certainly appreciate the info though!

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lukedwardslukedwards

Answer 2 years ago

P.S.

I'm not going to buy the one I posted an ebay link to. I just posted that as an example. I hope to find out where my buddy got his since he says he only paid about $5 each for them.

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ahmad2117

8 years ago

i dont think you should use hydrogen since its too dangerous and if it gets burned the heat would be too high to grill meat on

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RPoooBear

9 years ago

yes you prvent the hydrogen from bakingup by using a small part of sigarett but just cut it in half and use plastic tubing for your fuel line

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Dr.Bill

9 years ago

another way to do this is to bubble the gas through a jar of water. back flash then only goes as far as the jar

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Dr.Bill

9 years ago

i have a friend that did this, he packed the end of the pipe with coarse steel wool not too tightly so as to stop the flow of gas

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Kiteman

9 years ago

As long as the gas flows out of the tank at the same speed as the flame burns along the gas, you're fine. As benthekahn said, if the gas is pure (i.e. contains no oxygen), then the flame will go out if it gets inside the tubing.

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___Kiteman

Answer 9 years ago

However if it contains oxygen.......BANG!
MAKE SURE YOU HAVE A WET AND OR DRY ARESTOR

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oxylight

9 years ago

In order to prevent the flame from moving up the fuel line the maximum diameter of the fuel port needs to be less than .057 cm (.0225 in). The stainless steel wool that you place outside the port is actually not a flame arrestor but a catalyst.

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oxylightUltra Computers

Answer 9 years ago

This is the small hole that the hydrogen fuel comes out of to mix with the air and burn. As long as this hole is less than .0225 inches in diameter the flame will stay out of the fuel delivery tube.

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benthekahn

9 years ago

Well if there is just hydrogen in the tank (no oxygen) then you shouldn't have any problems because hydrogen needs oxygen to ignite. Pure hydrogen will only burn once it leaves the burner and is exposed to the surrounding air. Warning, I am by no means an expert with any of this so try your stove at your own risk.

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jtobakoUltra Computers

Answer 9 years ago

Slight problem with the above-the gas can burn back through the line, it happens to welding torches and is the reason for flashback arresters on welding hoses. I've heard that some sort of laminar flow of gasses gets set up where oxygen gets in along the outside edge of the hose and flame byproducts go out the center. I've seen stainless steel wool used as a flame stop for hydrogen, the trick being that the spaces have to be too small for the flames to propagate through to the other side. Each gas has a different size, and I believe that hydrogen's is particularly small.