That was part of our gas course. It was an exam question on
the school's exam and the department of labour's final exam.

funny how a NG leak in a empty house blew up that house and the 1 beside it. the house was vacant, water and electric cut off, but the gas co had not made it to cut gas off. 2 days later, BOOM. according to the local fire chief, it was caused by the NG building up and exploding. that is where i get my info. maybe he was wrong, maybe the old school thinking he was trained by was, i dunno.

i cannot find anything to back my post up, and much that backs up yours.

You know, I have never heard anyone claim (at least not that I recall) that gas can spontaneously combust once it reaches a certain concentration. Interesting that some people believe that.

Good information.

I'll have to find the thread in question and read it.

Here is the bottom line. N.G. DOES NOT EXPLODE BY ITSELF WHEN BUILT UP. IT NEVER HAS AND NEVER WILL. NEITHER DOES PROPANE. It has to have an ignition source and be at the right persentage. There was a guy that blew up houses to collect insurance. He would buy a house loosen the gas pipe to the furnace, go the the bar at the other end of town,cause a ruccus or fight so everyone remembered him and phone the home. BANG. He got caught when the house had an electronic phone and the neibours smelled gas. It didn't blow. We were taught that in gas school. There is L.E.L. and U.E.L and nothing in between. Our instuctors can't lie to us. It's a very serious liability issue. Besides we would flunk the department of labour exam. They are god. No licence. How do you think they weld up a 5 lb. gas line in a trench on a city street ? Ive seen it done. The guy goes down there with breathing equipment and strikes an arc. Bang. The ground above him is on fire but he is perfectly safe down in the trench. I wouldn't do it,
but i now know it can be done and how it is done. The only
thing i know of to date that can self combust with and only
with too much pressure is acetaline. That is why there is only 500 lbs in a tank or lay it on it's side and use it.
Oxygene will self combust, actually explode if oil is spilled on the regulator. Powdered chlorine, as in swimming
pools, will explode into flames if water is spelled into it. Built up N.G. and propane will never explode by itself
unless it is within it's limits and has an outside ignition
source. That is gosple. End of debate. I just about forgot.
I reread the above post. I know my fire commisioner. When
they say faulty wiring or gas explosion it is arson but they can't prove it. They say that so they are out of it and now it's up to the insurance investigators.

"Oxygene will self combust, actually explode if oil is spilled on the regulator. "

The oxygen is not causing the fire, the oil is.
Once the oil is consumed the fire goes out.

Oxygen is NOT combustible by itself.
Is is an oxidizer that can lower the ignition point of fuels depending on the fuel and the concentration.

A smoldering cigarette will burst into open flames in an oxygen rich environment.
The person smoking IS going to drop the thing immediately, hopefully before there hair catches on fire.
Where it lands is the next problem.

Oxygen, oil, who cares. When they are mixed its spontaneous
combustion. Everyone knows oxygen doesn't burn, i hope. It's grade 7 science. Oil, yes. Nit picking, maybe ? But have you ever seen air burn ? Yes the air we breath. Anyone that works in a smelter knows what i'm talking about. If i wasn't standing in front of the furnace and watching it i wouldn't beleive it.

Got to have four things to have a fire:

Heat, Fuel, Oxygen, and a Battalion Chief. Take away any one and you can't have a fire.

"Everyone knows oxygen doesn't burn, i hope. It's grade 7 science."

I think you would be very surprised.
A lot of people must have slept through science class.

And yes, if you heat air hot enough you can force the nitrogen to 'burn' and form various NOx compounds.

what with my bad memory, I don't even recall 7th grade, if oxygen doesn't burn why then do they post those no smoking signs near oxygen tanks, and not to bring up bad moments, but didn't they have a punctured oxygen tank on one of the space shots that resulted in an explosion., and seriously, thanks for advancing my education.

A smoldering fire (like a cigarette) near an oxygen rich environment will burst into open flames.
The smoker may get burned, or drop the cigarette lighting something else on fire.

The puncture of the oxygen tank in and of itself is dangerous, especially when it is the oxygen you are supposed to breath.

The failure was actually in a fuel cell, cutting there electric power and heat.

The LEM was used to provide power and oxygen for the rest of the ride.

Thanks for the back up Brickeyee. Anyone remember the old
flash bulds that were in the old Browny 126 cameras ? The
flash bulb was full of steel wool and oxygen. The battery
caused the wool to glow and the oxygen caused a mass flash.
Poof. you saw red spots for 1/2 hour. (actually any flash bulb for that matter ). I remember that in grade 7 science.
Stunk up the whole class. Our teach would only do it once in the same day. What i should have said is oxygen supports
combustion.

The example of the house blowing up could well have been caused by the pilot light on a gas appliance. Some fire investigators are experts. But they will often assert a cause even if they are not sure. Usually electrical gets blamed, not always accurately so. A pressure from the explosion of just 1/2 PSI can wreck a house. The pressure lifts it slightly, the foundation is pushed out, the house falls over/onto the failed foundation and falls apart. Do the math to prove the 1/2 PSI.