Question for all you gas welders

Well, I couldn't resist so I rigged up a couple of types. The one that worked best so far was Mapp gas, 4 feet of 1/2" tubing, a T with compressed air on 1 side and a fitting with a 3/32" hole in it. In other words, a long skinny forge burner.

Works pretty well. Got new tanks, on to the next childish adventure! :o
 
Walt2 said:
I saw a demostration one time where a fly was put in a plexiglass container(approx. 4"x4"x6") with the bottom being open. It was sitting on a piece of 1/2" glass on a table. The container had a fitting on one end where a hose could be connected. Oxygen was introduced to the inside of the container under low pressure. When the concentration reached a certain level--BOOM. The oil on the flies body reacted with the O2. It was correctly stated above about never using anything for O2 that has had compressed air in it. :eek: :eek:
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OK :confused:

but answer this
why don't we blow up in an o2 tent in the hospital? they can and will use pure O2
or those people that wear o2 tubes in there nose, we have oil on us too. :confused: O2 is not flammable it is an accelerant you need a heat source or spark for the fuel to burn,,, the fly was the fuel.
 
I don't think the "O2" from the hospital is really 100% O2. I think its mixed so that its kind of like the air we breathe only a little richer on the O2. Normal air is only something like 28% O2. Don't think the oxygen tent ever gets a rich enough mix to go kaboom :eek: I could be wrong though.
 
Dan Gray said:
OK :confused:

but answer this
why don't we blow up in an o2 tent in the hospital? they can and will use pure O2
or those people that wear o2 tubes in there nose, we have oil on us too. :confused: O2 is not flammable it is an accelerant you need a heat source or spark for the fuel to burn,,, the fly was the fuel.
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Actually thats not quite right. O2 is a required part of the combustion reaction.Hydrogen and oxygen mix, burn, and leave the the by product H2O. Sometimes Carbon or other elements are added and you get other byproducst as well like Co2.
CH4+O2=CO2+H2O
Heat is the catalyst, makes the reaction take place.All you need are the proper ratios of elements and stomething to start the reaction.
 
Hospital "nasal cannula" oxy, bottled medical oxygen, and that which comes from an oxygen concentrator is about 95-99% pure oxygen. I know this for certain, as I've watched them check my concentrator and bottles. You don't breathe in pure oxygen, however, because it's naturally mixed with air as you breath in around the tube. If I remember correctly, "normal" breathing is about 20 liters per minute, and supplemental oxygen runs from about 1-3LPM depending on one's condition. You may be right that an oxygen tent is of lesser concentration because that's all you're breathing. Concentration in normal atmosphere is around 21%.

You raise an interesting point, Dan, and have my few remaining synapses firing! I'm not exactly certain why the fly ignites, but I know it does, too, as I've seen the same type of experiment on the tube! Something interesting to think about. Thanks!

There have been cases of people on too much oxygen that have "spontaneously combusted" without any apparent ignition source whatsoever.
 
The demonstration that I saw was put on by a provider of welding supplies. O2 and Acetylene being two of the items they supplied. I spent over 40 yrs. in the welding profession and have seen other demonstrations of how little oil or grease it takes to react with O2. I once had an individual thinking he was doing a prank put grease on the nut that attaches a O2 regulator onto the bottle, thinking that I would get it on my hands. This was a potential bomb looking for a place to blow. The company determined who the individual was by someone who saw him do it, informing them who did it and he was terminated on the spot. This was a very serious violation of both company and MSHA safety rules.
 
Maybe there's something in the oil that reacts with O2, generating heat? Combustion is just one reaction, others might take place first. I suppose there's always a question of static charge as well :confused:
 
Did the fly just sponteniously combust or did it move then explode? I'm thinking a spark of static electricity could have been the trigger.
 
The demonstration was presented as being the amount of oil on a fly was enough to react with the oxygen. I forgot to mention that this was an MSHA sponsored demonstration by the welding supply co.
 
:eek:
interesting
I use the shop O2 once in a while for my migraines,, it supplies o2 to my brain when the blood is restricted from it (what I have of a brain anyway.) during an onset of one.
but Mike has a point about the mix of air..


matt O2 is a required part of the combustion reaction as reg air has o2 in it for sure weather in air or by itself but
o2 is not in any way a flammable gas, it's an accelerant , that is right on the O2 bottle

my dad had almost died a few years ago with a bad lung infection and if I recall he had almost pure O2 to get he saturation up fast 100 % ? this I don't know but it was close to it.
they may call it 100% in the hospital for all I know? :confused:
but still you have the air around the tubes..
 
Dan Gray said:
:eek:
interesting
I use the shop O2 once in a while for my migraines,, it supplies o2 to my brain when the blood is restricted from it (what I have of a brain anyway.) during an onset of one.
but Mike has a point about the mix of air..


matt O2 is a required part of the combustion reaction as reg air has o2 in it for sure weather in air or by itself but
o2 is not in any way a flammable gas, it's an accelerant , that is right on the O2 bottle

my dad had almost died a few years ago with a bad lung infection and if I recall he had almost pure O2 to get he saturation up fast 100 % ? this I don't know but it was close to it.
they may call it 100% in the hospital for all I know? :confused:
but still you have the air around the tubes..
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Technically that is sort of true, but its not a safe practice to take it literally. Combustion is a chemical reaction. It requires more than one elemnt to take place, if you start with O2 and end with O2 you have no reaction. The same could be said for Hydrogen and any other element. Oxygen compounds are flammable and that is what the danger is. thats the reason they put you in a tent at the hospital, its a controlled environment, so they know what is mixing with the oxygen.
The reason Oxygen doesn't burn coming right out of the tank is that the compounds it needs to mix with aren't usually (sometimes they are) present in the atmosphere. Acetylene on the othe hand, burns when mixed with oxygen, since there is already oxygen in the air, it will burn in natural air. So they call it flammable. Oxygen will do the same thing with many of the compounds present in a workshop, thats why you have to be really careful.
Oxygen doesn't really accelerate anything. It balances the equation. If you have 4hydrogen molecules and 1 oxygen molecule you end up with 2 unused hydrogen molecules. 4H2+O2=2H2+H2O+H2O. If you add another oxygen molecule now you've got enough for a complete reaction. 4H2+2O2=H2O+H2O+H2O+H2O. The complete reaction is much stronger!
Thats what your doing when you tune the flame of a torch, balance the oxygen and acetylene for a complete reaction.
So while its true that if you started with a vacuum and pumped it full of pure oxygen, it wouldn't burn, its not safe to say that oxygen won't burn and go pumping your shop full of it! You don't know what it will mix with :eek:
 
Matt Shade said:
Technically that is sort of true, but its not a safe practice to take it literally. Combustion is a chemical reaction. It requires more than one elemnt to take place, if you start with O2 and end with O2 you have no reaction. The same could be said for Hydrogen and any other element. Oxygen compounds are flammable and that is what the danger is. thats the reason they put you in a tent at the hospital, its a controlled environment, so they know what is mixing with the oxygen.
The reason Oxygen doesn't burn coming right out of the tank is that the compounds it needs to mix with aren't usually (sometimes they are) present in the atmosphere. Acetylene on the othe hand, burns when mixed with oxygen, since there is already oxygen in the air, it will burn in natural air. So they call it flammable. Oxygen will do the same thing with many of the compounds present in a workshop, thats why you have to be really careful.
Oxygen doesn't really accelerate anything. It balances the equation. If you have 4hydrogen molecules and 1 oxygen molecule you end up with 2 unused hydrogen molecules. 4H2+O2=2H2+H2O+H2O. If you add another oxygen molecule now you've got enough for a complete reaction. 4H2+2O2=H2O+H2O+H2O+H2O. The complete reaction is much stronger!
Thats what your doing when you tune the flame of a torch, balance the oxygen and acetylene for a complete reaction.
So while its true that if you started with a vacuum and pumped it full of pure oxygen, it wouldn't burn, its not safe to say that oxygen won't burn and go pumping your shop full of it! You don't know what it will mix with :eek:
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:D
I'm going to babble in layman terms OK :D
no different than electronic fuel injection
you have an O2 sensor in the exhaust (after the fuel is burnt) to monitor the ratio of o2 in the exhaust
on a car, air mixing with gas and a rate of about 14:1
change the air to 95% o2 and the ratio has to change to get the same burn
of a 14:1 mixture on the family car, could be now at 2:1 ?
the converter changes carbon monoxide into
carbon-dioxide and H2O you still have O2 in there with hydrogen and the two will part ways before long.
heat, fuel and oxygen
you will not have fire without any one of the three in one form or the other,
other than a star such as the sun but that isn't fire, it's nuclear reaction
and I'm not getting into that.
O2
will not burn
it may be converted by heat but it won't burn,

it is safe to say don't mix O2 with something you don't want going up in smoke faster than a blink of an eye, in the right conditions
tid bit
molecules
change one molecule in margarine and you can get plastic I heard that one..

hey what were we talking about ?? :confused:
 
Well...I started this so I guess I'd better jump in. To be short, Dan is correct. To be long winded:

"Oxygen does not burn, but oxygen supports combustion. A fire which will burn in air will burn explosively in pure oxygen. A material which will not burn in air may burn very well in pure oxygen- for example the metal in the oxygen cylinder or the regulator.

Oxygen is stored at high pressures. A typical cylinder of gaseous oxygen will be pressurized to 2,200 psig.

Released suddenly, as when a valve is broken off, there is enough power to drive a heavy cylinder through a concrete wall.

Sudden release of this very high pressure into an enclosed space (as when a cylinder valve is opened too rapidly) allows rapid compression. The result is heat which can raise the temperature inside if a regulator to thousands of degrees instantaneously, and make the outside so hot you can't touch it.

The Triangle reminds us that for a fire to occur, you must have Fuel, Oxygen, and Heat. Oxygen related fires are unique because the high concentration of oxygen allows virtually anything (metal fragments, dust, dirt) to act as fuel.

The Heat of Compression provides the necessary heat for fire to start- a cylinder valve opened too rapidly raises temperatures into the thousands of degrees.

Another source of heat, friction can be caused by the sudden motion of particles inside your equipment- as when a cylinder valve is first thrown open.

Hydrocarbons are oils and greases. (gasoline is a hydrocarbon, and so is the oil from your skin and a fly.) They are the ideal fire starters, because they ignite almost spontaneously in O2.'
 
I wish I could take credit for it all Mike. I had to do a little research...notice the quotes :o
 
peter nap said:
I wish I could take credit for it all Mike. I had to do a little research...notice the quotes :o
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who has more fun than knife makers :D :D


collectors with a lot of extra money maybe? :confused: :D
 
You guys don't seem to understand my point. I said that Oxygen COMPOUNDS are flammable. It isn't consumed by the fire, its part of a chemical reaction that converts it into something else. This reaction is highly exothermic, thats about the only difference between it and any other reaction.
Oxygen also reacts very easily with other materials, forming those compounds which ARE flammable. Oxygen is a necessary part of the reaction, and a balanced reaction is more powerful, so obviously flooding it with oxygen will garauntee that everything else completely reacts which gives off more heat.
So technically oxygen isn't flammable, it won't burn by itself, neither will a lot of other things that burn like hell in the right mix. It should not be treated that way though, because the stuff it makes IS flammable .
 
Matt Shade said:
You guys don't seem to understand my point. I said that Oxygen COMPOUNDS are flammable. It isn't consumed by the fire, its part of a chemical reaction that converts it into something else. This reaction is highly exothermic, thats about the only difference between it and any other reaction.
Oxygen also reacts very easily with other materials, forming those compounds which ARE flammable. Oxygen is a necessary part of the reaction, and a balanced reaction is more powerful, so obviously flooding it with oxygen will garauntee that everything else completely reacts which gives off more heat.
So technically oxygen isn't flammable, it won't burn by itself, neither will a lot of other things that burn like hell in the right mix. It should not be treated that way though, because the stuff it makes IS flammable .
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?? :confused: O2 can't make anything it is what it is..
, it can mix with other things like
Hydrogen say 1 part added to 2 parts Oxygen = H2O :) now you have something else.
technically oxygen isn't flammable, technically speaking or other wise.
if it were we wouldn't have to heat our coffee up :) and that shower would burn without the water heater :) OK I'm having fun now :)
I think I know what your saying
permanganate alone is Ok
but add Sugar to it and you've got a problem
will sugar burn ?
will Permanganate burn?
sure in the right situation
but not like the two mixed together. :)
we use permanganate with water (H2O) very safe
though it has oxygen in it.
it has to be mixed making something else..

OK Matt I'll stop pulling your chain now :footinmou :)
 
Matt, not being a wiseass, but I DO understand your point. I don't necessarily agree with the way you've described it, but I do understand. I was a technician then chemist for 32 years, so some of it stuck. ;) I suppose I still are one, though perhaps not a good one, despite being retired. :)

I think the definition of flammability could be described as a substance having the potential to become the primary reactant in a highly exothermic oxidation reaction that becomes self sustaining once sufficient exogenous energy has provided activation energy for initiation. It's the self-sustaining part that's of importance here. Iron will "burn" provided energy continues to be applied. Take away the external energy source, though, and the reaction slows back down and just becomes rusting once again. Cool down the "flammable" reaction and it can't provide it's own energy anymore and the fire dies.

Burning is not something that takes place AFTER an oxygen compound is formed, it IS the oxidation reaction itself. (That doesn't mean that oxygen-bearing compounds cannot be flammable, of course. Acetone or ether would be good examples. Iron oxide, on the other hand, isn't.) Visible flames are oxidation of subsequent byproducts from the intial reaction and very heated "soot" in the case of a carbon-bearing compounds. Burn something like methanol, for instance, and the conversion is so complete in one reaction there aren't flames per se, just heat given off. The final products, such as water and CO2 when discussing a carbonaceous reactant, are obviously not flammable.

Since you mentioned reaction equations and kinetics, another explanation: in a campfire, the wood is in much higher concentration than the rate-limiting oxygen from air. Increase the concentration of the oxygen and the fire becomes more violent. This can be easily demonstrated by the fact of when I smoke a cigaret I get an ember on the end. However, when I'm smoking with the oxy tube stuck in my nose, every once in awhile the end of the cigaret will burst into flame. Albeit a little dangerous, it's a really good demonstration of reaction kinetics based on reactant concentrations! :D Another good example would be hooking a blower up to a coal fire!

Well, I've probably taken this far afield, and am not looking to argue, so I'll shut up and let this return to Don's bottles.... ;)
 
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