How Flashback Creates Explosion In Gas Cylinders?

venting/purging of the explosive fumes to open air, though not the best but is better than the alternative. Where it is an enclosed space such as the piping on the stove.

There is also reasons of having a backflow preventer on items such as oxy/acetylene tanks. On the acetylene tank if the valve would fail. acetylene gas will self ignite just from the frition of the gas exiting the valve unregulated.

Flash backs carry oxygen to the cylinder and make mixture of fuel and oxygen which is most explosive and as the flash back increases the temperature locally, explosion takes place.

A typical gas combustion apparatus uses the original Bunsen jet which is a venturi that is allowed to travel into a tube with a variable air sleeve. You open the jet, adjust the sleeve to get a mixture that burns with a blue flame as it exits from the combustion orifices. Too much of an opening in the air sleeve air can allow the venturi to draw in too much air and the flame will blow out. Too little air and the velocity in the mixing tube falls below the flame front propagation speed and the plane of combustion moves towards the jet where gas is injected.

A little adjustment by hand quickly makes the correct flame.

all you need to know about a Bunsen burner

Leaking gas from a combustible gas tank is always dangerous JUST where the gas and air mix. A small spark may ignite it. But the danger is not in the beginning "in" the tank, its external, at least at first, as the tank may crack from the heat of burning or a small explosion...

To my mind, the MOST dangerous gas tanks of all are Oxygen tanks, something a tiny bit wrong with the tank or the valve and you may have the equivalent of a 500KG WW2 bomb exploding. A small Oxygen tank exploding can take a complete house down.......

When I think just how many pensioners have a 5 or 10 Kg Oxygen bottle just lying around.....my mother was a prime example!!! Its a wonder that there are not more accidents. I kept telling my mother what NOT to do, she simply was a) overpowered by the infos and b) simply not interested.....She used to "flood" her bedroom so that she did not need to wear the twin jets.....and had a gas heating system downstairs.....which if it had got a good whiff of oxygen, might have exploded....

Then you are a good theoretical person, but totally unpractical......

Lets start with Oxygen 101, please read the info on the following links, it should help you to understand better the dangers of Oxygen:-

http://ezinearticles.com/?The-Danger-of-Oxygen-Tanks!&id=4037874

http://www.portableoxygen.org/o2safety.html

Obviously you did not read all the links I sent you or you might have modified your post a lot little. The notes that Oxygen can react adversely with many quite normal everyday things should be taken very seriously by all concerned....

Obviously you have been lucky in your job up to now unless you do actually follow all the recommended safety precautions that an anaesthetist should know and hold to. I guess you follow them, or someone else does it for you.

But I do find that as a professional Oxygen user, you should be the first one here recommending the necessary safety precautions, whereas you come over as though there is nothing to worry about......safe that is not!!

Now that is REALLY worrying......

By the way, do you play the Lottery? You should!!

Your points regarding the cooking gas cylinders are quite correct.

However re Oxy Acet cylinders, the pressure in an acetylene cylinder varies over a wide range but would be unusual to be lower than the regulated Oxy pressure not the Oxy cylinder pressure.

What can happen without flash back arrestors or leaky arrestors any restriction after the mixing point or too high an Oxy pressure and a low Acet pressure, as you say can cause oxygen to flow up and mix in the acetylene line and regulator, this mix can burn back or if in the correct proportions it could explode the acetylene regulator this would be the low pressure regulating stage not the high pressure section of the regulator. There is a possibility that the shock of the explosion could cause a sympathetic reaction in the high pressure section of the Acetylene regulator causing the gas to decompose but it would not be oxygen getting into the cylinder.

If that Acetylene cylinder starts to vibrate and jump around run like hell, or that is where you will go.

GA.

Hi AG,

I'm going to have to go with phph001 and LAA_Lucke on this one. While safety precautions do need to be followed, in my mind, an oxygen cylinder is not as dangerous as a propane or acetylene cylinder.

If you have a massive propane or acetylene discharge, there is atmospheric oxygen always present. If you have a massive oxygen discharge, you will most likely not have a gaseous fuel with which to make a combustible mixture.

You should read the links that I posted recently, one of them explains the difference in terms of fire danger with regard to pure oxygen and atmospheric oxygen as a percentage of air......its makes easy reading!!

Adding extra oxygen to air makes it dangerous VERY quickly.

Andy, perhaps I should make the message clear. When I work with oxygen, I follow all the recommended procedures, and teach them, too. When, however, I am posed the question as to whether oxygen cylinders are more dangerous than any other kind of cylinder, that has nothing to do with my oxygen operating procedures. It is a risk assessment. My assessment of that risk is that a cylinder full of fuel gas is intrinsically more dangerous than a cylinder of oxygen, even when correct operating procedures are followed. You may differ in that opinion, but I suggest that your opinion should not be based only on the misuse of oxygen.

the only thing I see lethal is if the cylinder is dropped and the valve breaks off.

http://www.youtube.com/watch?v=tyINNUaXa8Q

This is only a scuba tank.

I checked out "oxygen cylinder explosion" on YouTube, simply mind boggling. Look here:-

http://www.youtube.com/watch?v=9lw_fhNAIQc

http://www.youtube.com/watch?v=RxeMxc42Kn0&feature=related

http://www.youtube.com/watch?v=D7QpSfvyOek&feature=fvwrel

http://www.youtube.com/watch?v=ey10rW8Q4_k&feature=related

http://www.youtube.com/watch?v=zFyqilT0ld0&feature=related

And the quick way to light your Barbecue:-

http://www.youtube.com/watch?v=UjPxDOEdsX8&feature=related

http://www.youtube.com/watch?v=SaBghGKAOBo&feature=related

http://www.youtube.com/watch?v=uUmLe9WCXX0&feature=related

Enough?

When I first heard about it, I was talking to my shop instructor about compressed air, and he mentioned about the O-tank on a ocy,acytlene tank would go off like a torpedo.

I took his word for it, and repeated it in class which I took allot of ribbing and called a BS'er. they could believe it. fortunately the instrutor walked in, and not only proclaimed that I was telling the truth, but if he caught anyone trying it, he would personally call their mother to set one less plate setting at the kitchen table.

At least some of those kromags filmed thier stupidity.

I have heard allot of people on oxygen light up......and after others put the fire out they'll plead ignorance.

Apollo 1 is a good example of what will happen in an oxygen environment. http://en.wikipedia.org/wiki/Apollo_1

They are both dangerous, no question.

Even inert gas cylinders need to be treated with respect and kept away from heat!!!!! The explosion may not have fire as a component, but heavy chunks of cylinder passing through your body still hurt!!

But even quite normal everyday things that you would not think of possibly causing a fire or explosions, can, in the event of an Oxygen leak cause major damage/danger.

Its really the problem that the average person on the street would be extremely careful with cylinders of combustible gases, but might treat Oxygen as only being "pure" air.......

As a completely odorless gas, it is impossible to detect Oxygen by smell.....so no prior warning at all.....

Most combustible gases either have a smell, or have an artificial smell added.....therefore easily detected!! (unless you have a bad cold!!)

I received an oxygen tank from a freind who closed his dentist operations. I have a "Little Torch" and the regulators for oxygen and the other gas which, in my case, is propane. I want to learn how to braze but haven't gotten around to it yet. I had the oxygen tank tested and then filled. It is stored in my air conditioned tool room. A lot of time has passed. Is it safe?

John

Hi John I cant see why you should have any problem, you are storing it in a dry atmosphere, the cylinders are quite rugged.

If it was tested you will have a certificate which will indicate when retesting is required.

As a precaution against gas loss if you are storing for long periods [ valves can have slow leaks] I would screw a plug into the cylinder valve instead of leaving the regulator on the cylinder.

ok, thanks. I keep the regulators in a clean sealed box not on the tank. I like the idea of a plug. Are they readily available?

Regards

John

They should be available from your local industrial gas equipment suppliers or check back with your cylinder test people,

If you are asking me personally, I would not have it in the house, just in case that an unrelated fire caused it to explode......

In the (extremely) unlikely event of a valve failure, you might also need to look for a new house....

Why take risks? Butput it out of the house as long as you don't need it for breathing , you surely are not going to weld in the house?