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View Full Version : OT: Mystery solved...It's not thieves breaking in. It's .......



winchman
04-09-2013, 05:35 AM
The door to the equipment room for the building where the welding shop is located is on the outside in the breezeway. In the past several months, the door has been found forced open several times with some damage to the locks and hinges. School officials thought it was someone breaking in to steal the copper pipe or possibly a homeless person looking for a warm place to stay. They installed a security camera to monitor the activity around the door. There was already an alarm system on the door.

Early yesterday morning, the alarms went off. The replay of the video showed the double doors swinging open violently, but no other activity. An inspection of the room showed another set of double doors was buckled outward and the upper part of a concrete block wall was cracked and displaced about an inch. It was obvious something very bad had happened in the room.

An inspection of the gas line for the hot water boiler revealed a very small gas leak. The boiler is on a timer, so it's off all night, and comes on early. Apparently enough gas had been collecting in the room to cause minor explosions when the boiler lit off.

The thing that puzzles me is why the explosions were so small. It seems like a 15 by 20-foot room with a twelve-foot ceiling filled with a combustible mixture of gas would do a LOT more damage.

mf205i
04-09-2013, 06:17 AM
Absolutely amazing. I know a guy that, after he had his kitchen remodeled, would occasionally find the cabinet doors open. It drove him and the contractor nuts trying to figure it out. They too were convinced that somebody was messing with them. Finally somebody noticed the faintest odor of natural gas. The stove connection was leaking and the gas would build up and occasionally ignite, opening the doors but no fire. It just goes to show that if you live long enough that eventually you will see the impossible, TWICE! You must be living right as you are so fortunate that nobody was injured or killed.
Take care, Mike

vpt
04-09-2013, 08:11 AM
The furnace in my old house always lit off with a bang and the door to the furnace room would shutter.

I have a very small leak on the valve before my water heater right now. I have been putting it off for awhile now but I think I should get to replacing that valve.

cameron
04-09-2013, 08:41 AM
Some years ago the juvenile court building in Ottawa blew up, killing the night watchman.

A small gas explosion in the furnace blew the furnace door open. The gas supply pipe had a vertical leg within the arc of the door swing and this was ruptured.

The safety system shut down for fifteen minutes and then attempted a re-light.

Jaakko Fagerlund
04-09-2013, 08:57 AM
..and yet again one more reason for me to not get a gas line to my house, ever. Though gas heating or cooking is quite rare in residential homes around here, but still.

One just wonders why there is no leak detectors installed in the rooms that have the gas lines?

gcude
04-09-2013, 09:31 AM
One of the worst gas explosion disasters occurred in 1937 in New London, Texas:

http://www.youtube.com/watch?v=aKt01p3DJRw

KiddZimaHater
04-09-2013, 09:32 AM
When I replaced my central heat/AC unit 3 years ago, the service tech asked me, "Did you know you have a gas leak here?"
Uhhhh ....NO.
But, come to think of it, I had been smelling the faintest whiff of gas for about 10 years before the replacement.
OOPS....:o
Lucky I don't smoke.

Peter.
04-09-2013, 10:08 AM
Some things you just can't make up.

I was working on changing the road deck in a large tunnel once and another guy grabbed me and took me over to his machine, a trailer-mounted drill-rig weighing about 750kg. We both stood and watched the threads unscrew as the drill was turning and cutting. The drill was turning clockwise, half a tonne of weight on it and the thread was 1.25" BSP right-hand thread, standard on all the equipment. It un-screwed under load right in front of us, we stopped the machine, lifted the drill, screwed the drill back on by hand half a dozen turns until it seated then set it drilling again and watched it very slowly un-screw again whilst it was cutting. You could see the jack-legs start to wobble as it lifted the weight of the machine.

I adjusted the engine RPM and the phenomenon went away. Tried to re-produce it so I could get some video (D'oh!) but couldn't make it happen again.

My only guess was that the slight wobble in the bit was making machine wobble and the male thread 'walk' up the flanks of the female thread at just the right rpm. I dunno. People don't believe either of us when we tell them and I doubt I would accept it from someone if I heard it myself had I not witnessed it with my own eyes.

firbikrhd1
04-09-2013, 10:12 AM
..and yet again one more reason for me to not get a gas line to my house, ever. Though gas heating or cooking is quite rare in residential homes around here, but still.

One just wonders why there is no leak detectors installed in the rooms that have the gas lines?

Personally I love using gas for cooking and heating water. As to the risks, I have no doubt I exceed the risks of a gas explosion killing me every time I drive whether in my truck or on the motorcycle. Anedcotally, I would guess that the risks of being killed or hurt in a gas explosion are far less than the risks of being killed on the street, here in S. Florida anyway. Given that gas has an odor-ant, mercaptan, to warn of leaks and that the odor of mercaptan mixed in gas is detectable to the human olfactory system at concentrations far less than the flammable range, small leaks are detectable far sooner than when they are a hazard. Certainly there are instances where gas could collect undetected in areas not frequented by humans and that does pose an increased risk.
Electric appliances also have risks and an electrical hazard is far less detectable prior to injury/death than gas. We all use it regardless of it's inherent risks, without a thought, every day.
However that risk can be mitigated to a great extent with adequate ventilation and detection systems. For me, any many others, using gas in a no brainier for convenience, efficiency, cost and safety, just as electricity is something I wouldn't want to be without.

Black_Moons
04-09-2013, 10:40 AM
..and yet again one more reason for me to not get a gas line to my house, ever. Though gas heating or cooking is quite rare in residential homes around here, but still.

One just wonders why there is no leak detectors installed in the rooms that have the gas lines?

I do wonder that myself. I know they are on boats. And I have seen the sensors they are only like $50~70 quanity 1 (raw sensor, mind you, not an alarm)

Still, seems worth it to me.

My last house, the furance would often 'fawoof' when lighting up.. And sometimes a loud bang.

I think the reason why there was 'so little damage' in the OP story is that not very much of the volume of the building was at the right mixture range for combustion before it ignites. (Indeed, with very still air it might not mix right period, both too rich and lean will prevent combustion)

Peter.
04-09-2013, 10:47 AM
Gas-fired cookers and central heating is the norm in many UK towns and cities. You don't see buildings blowing up on a regular basis, but then we don't get any real earthquakes either.

A.K. Boomer
04-09-2013, 11:24 AM
when you think of all the masses involved it's actually pretty safe stuff.


good post WM

Harvey Melvin Richards
04-09-2013, 11:35 AM
I have friends that built a new cabin in the mountains. After having the cabin for only a few years, the propane built up in it and exploded, destroying the entire cabin. The explosive force moved a neighbor's cabin 10" sideways (knocked loose from the foundation). My friends still own the naked foundation. Investigators seemed to think there was a bad propane regulator, but it kinda disappeared.

Mike Nash
04-09-2013, 11:38 AM
Given that gas has an odor-ant, mercaptan, to warn of leaks and that the odor of mercaptan mixed in gas is detectable to the human olfactory system at concentrations far less than the flammable range, small leaks are detectable far sooner than when they are a hazard.

Except for those who don't smell it. Google it. As we get older our sense of smell typically declines and I've seen mentioned where over half of people 60 and older can't smell a gas leak.

Weston Bye
04-09-2013, 11:53 AM
Except for those who don't smell it. Google it. As we get older our sense of smell typically declines and I've seen mentioned where over half of people 60 and older can't smell a gas leak.

Yep, that would be me...

saltmine
04-09-2013, 12:12 PM
Years ago, out in the "Granola State" (Wut ain't fruits & nuts is flakes) A friend of mine was attempting to fix a motorcycle tire in his garage. Not having a tire pump or an air compressor, he decided to fill the tire from the propane tank on his dad's barbecue....hoping that it would be sufficient to get him to a garage or gas station where he could use regular air to fill the tire properly. Well, as luck would have it, the innertube had two punctures instead of one (which he patched). Interrupted by a phone call, he left the inflated tire leaning up against the bike, and rushed into the house to answer the phone. The phone call was punctuated by a loud bang. When he went to see what the noise was, he found that the water heater had lit off, and the propane had ignited, blowing the closed garage door across the street, the motorcycle ended up, sitting upright, minus it's rear tire, in the middle of the street. We eventually found the bike's rear wheel perched on a neighbor's roof.

derekm
04-09-2013, 02:28 PM
Its not only gas that explodes, You can get smoke to explode. The wifes taken up bee keeping and as resident pyromaniac I get to light it. Then you close it up and pump the bellows to get smoke. If you get the smoke level just right you can blow the lid off with small explosion.

Alistair Hosie
04-09-2013, 02:44 PM
Wow you think that's bad! A friend of mine bought a house with gas fires in each room shortly after moving in he smelled gaS and called the gas board who came out right away .When looking under the floorboards the gas inspector evacuated the whole building,seems the smart arsed previous owner joined out all the pipes under the floor with woolworths garden hose pipe and jubilee clips too miserable in the wallet department to pay for a plumber.
Anyway the previous owner was taken or threatened with court action and eventually paid for everything to be put right. Have safe fun. Alistair

smalltime
04-09-2013, 05:21 PM
Even the pros get it wrong from time to time:

http://www.kansascity.com/2013/02/19/4075290/two-alarm-fire-raging-west-of.html

Black Forest
04-09-2013, 05:37 PM
We turned on the gas heater in one of our shops in Texas when we were painting with solvent based paint. The heater kept the fumes from the paint burned back so we didn't get a big build up and then an explosion! How's that for redneck?

MikeWI
04-09-2013, 06:44 PM
seems the smart arsed previous owner joined out all the pipes under the floor with woolworths garden hose pipe and jubilee clips too miserable in the wallet department to pay for a plumber.
Wow, what a coincidence. Many years ago I managed a hardware dept. and had a customer come up to me holding two fittings and he asks "do these fit together?" Now you'd think that he could just try fitting them together or even look at the dang things because it was obvious they wouldn't, but I got this sort of question all the time. So, after a few questions I find out that he just had a foundation for a house poured, and since it was going to get cold that night (and he didn't consider that the contractor knew what they were doing) he decided he was going to hang space heater in there (some sort of cover was over the whole thing) to keep it warm.

The bad part is that he had somehow talked his future neighbor into letting him tap into his gas line outside the house (bit of a trick there) and he was going to run a garden hose to the heater because "natural gas is only 3-4 psi so garden hose will work fine". After determining that this was not some sort of joke, I tried to talk him out of it, and he wouldn't hear of it. Keep in mind that he was going to use the garden hose as-is and needed to adapt the threaded hose connector to gas pipe, which is easy enough to do, but he couldn't figure it out. Those connector have a swivel joint that ain't gas tight.

I finally told him that we didn't have the right parts to do it and he left. I hope the next store he went to managed to talk sense into him. This was 30 years ago, and I still remember that guy.

Clevelander
04-09-2013, 06:54 PM
My wife swore she smelled gas from a connection I'd made though I couldn't. I'd rather be checked than be wrong so we called in the gas company with their "sniffer". Turns out my work was fine but they found three other small leaks and that the water heater connection was remarkably loose. Glad we didn't find out by the Fawwwoooof method.

vpt
04-09-2013, 07:59 PM
Wow, what a coincidence. Many years ago I managed a hardware dept. and had a customer come up to me holding two fittings and he asks "do these fit together?" Now you'd think that he could just try fitting them together or even look at the dang things because it was obvious they wouldn't, but I got this sort of question all the time. So, after a few questions I find out that he just had a foundation for a house poured, and since it was going to get cold that night (and he didn't consider that the contractor knew what they were doing) he decided he was going to hang space heater in there (some sort of cover was over the whole thing) to keep it warm.

The bad part is that he had somehow talked his future neighbor into letting him tap into his gas line outside the house (bit of a trick there) and he was going to run a garden hose to the heater because "natural gas is only 3-4 psi so garden hose will work fine". After determining that this was not some sort of joke, I tried to talk him out of it, and he wouldn't hear of it. Keep in mind that he was going to use the garden hose as-is and needed to adapt the threaded hose connector to gas pipe, which is easy enough to do, but he couldn't figure it out. Those connector have a swivel joint that ain't gas tight.

I finally told him that we didn't have the right parts to do it and he left. I hope the next store he went to managed to talk sense into him. This was 30 years ago, and I still remember that guy.



Can you do the trick of kinking the hose to stop flow while using gas? A guy could skip the shut off valve at the unit that way! More money in the pocket!

J Tiers
04-09-2013, 11:53 PM
..and yet again one more reason for me to not get a gas line to my house, ever. Though gas heating or cooking is quite rare in residential homes around here, but still.

One just wonders why there is no leak detectors installed in the rooms that have the gas lines?

With an older stove, or furnace, one with a pilot light, the danger is actually LOW...... any leak, as with leaving a burner slightly "on", will cause periodic ignition, but not build up a houseful.

With the NEW stoves, the ones just before they decided to wire the igniters into the gas valves*, you could turn the gas on, and it would never light unless you pushed the igniter button, or turned the valve all the way to the end, which turns on the sparker for ignition. I am surprised that many houses didn't blow up from those murderously stupid stoves.

As for gas detectors..... I don't want a "detector".....all it does is tell you to get out before it blows.... your house still blows up. What I'd want is one that turned OFF the gs if it detected a build-up. THAT would prevent the explosion in the first place.

OLD furnaces have a sensible setup.... IF they have a pilot light. It heats a thermocouple that powers the main gas shutoff. If the pilot goes out, the thermocouple stops producing electrical current and the main gas valve closes.

New stoves are smarter again, at least some of them.... they have a heated igniter which reduces in resistance when heated by an extra ignition current. It must get to a certain temp before the gas valve has enough current to open. After ignition, the extra current is cut, and if the flame goes out, the igniter cools off and the valve automatically closes.

Leaks are a different matter. An automatic cutoff if a detector finds gas makes sense. Needs some sort of temporary bypass for minor concentrations, so heat is not out at -40C......

darryl
04-10-2013, 12:03 AM
I recall a time when we were kids being babysat. The sitter wanted to heat something in the oven and was having trouble lighting it. Gas stove, no pilot light- anyway, we used to fire it up by lighting a straw, then poking that into a hole while turning the gas knob. She wasn't getting it to light, but she had tried and there was lots of gas in there. Finally, the lit straw hit the right spot- Boom! Burnt some of her eyebrows and hair- could have been a lot worse.

Black_Moons
04-10-2013, 01:04 AM
New stoves are smarter again, at least some of them.... they have a heated igniter which reduces in resistance when heated by an extra ignition current. It must get to a certain temp before the gas valve has enough current to open. After ignition, the extra current is cut, and if the flame goes out, the igniter cools off and the valve automatically closes.

Leaks are a different matter. An automatic cutoff if a detector finds gas makes sense. Needs some sort of temporary bypass for minor concentrations, so heat is not out at -40C......

Oh yes, I loved our 'smart stove'
Untill the heater element aged and 'cooled off' with age, Untill it would just *barley* crack open the gas valve, but not enough to actualy ignite things so I came into the kitchen with a very uncooked meal and a very smelly kitchen.

For awhile I would light the stove with a gas lighter as once it was lit, the flames (and hot oven) would keep the igniter hot enough to keep functioning, but had to stop that insanity...

As far as the burner igniters when you put it to 'full', that module burnt out in a few years and we had to use a BBQ lighter since then.

My grandma has an intresting one that actualy seems to detect the flame and keeps sparking till flame is ignited at the burner you turned on.

Euph0ny
04-10-2013, 05:59 AM
I'm glad no-one was hurt in the OP's incident.

We recently switched our (1960s) house from oil-fired pulsed-air space heating plus electric water heating to bulk propane for water, heat and cooking.

I feel quite safe - the installation had to be signed off by two separate inspectors plus the accredited installer. The first thing they all checked was the supply isolation valve, which is connected to a gas detector at the lowest point where gas could accumulate. If the system detects gas, or if power is cut, the isolation valve springs shut (fail safe).

The only disadvantage is that once the valve is tripped, I have to go outside to manually reset it, which requires dismounting the regulator box cover. Given the Belgian weather, that is inevitably in the cold and/or rain. I am thinking about making a little radio-controlled solenoid "pusher" which my wife or I could actuate from indoors to reset the valve.

J Tiers
04-10-2013, 08:16 AM
Oh yes, I loved our 'smart stove'
Untill the heater element aged and 'cooled off' with age, Untill it would just *barley* crack open the gas valve, but not enough to actualy ignite things so I came into the kitchen with a very uncooked meal and a very smelly kitchen.

For awhile I would light the stove with a gas lighter as once it was lit, the flames (and hot oven) would keep the igniter hot enough to keep functioning, but had to stop that insanity...

As far as the burner igniters when you put it to 'full', that module burnt out in a few years and we had to use a BBQ lighter since then.



"Better" than the ones which fail in the way so as to blow you up..... not "good"..... PILOT LIGHTS were "good".... even if one went out, it would be a very long time before enough gas leaked for any problem. On furnaces, even that was protected against.



I feel quite safe - the installation had to be signed off by two separate inspectors plus the accredited installer. The first thing they all checked was the supply isolation valve, which is connected to a gas detector at the lowest point where gas could accumulate. If the system detects gas, or if power is cut, the isolation valve springs shut (fail safe).



That system makes a LOT of sense. Apparently Belgians are smarter than Americans. (does not take much to be smarter than an American, though)

GEP
04-10-2013, 09:54 AM
Yes gas is orderless but i tell you the stuff they put in it smells awfull in a concentrated form. Some years ago i was working across the street from a natural gas pipe line booster station a tanker truck pull in and filled a large tank all of a sudden there was this awfull smell we could not stand. I went and asked the man working there what had happened he replied we are putting the stinky stuff in the gas.

Steve Seebold
04-10-2013, 10:21 AM
It's just damned lucky no one was in the room when the explosion went off.

garagemark
04-10-2013, 10:36 AM
We turned on the gas heater in one of our shops in Texas when we were painting with solvent based paint. The heater kept the fumes from the paint burned back so we didn't get a big build up and then an explosion! How's that for redneck?

You win. Very few things more dangerous than paint solvent fumes, especially with the urethane based stuff. Even with decent (explosion proof) ventilation, I am always concerned when I have a car under paint in my homemade spray booth.

A.K. Boomer
04-10-2013, 10:58 AM
"Better" than the ones which fail in the way so as to blow you up..... not "good"..... PILOT LIGHTS were "good".... even if one went out, it would be a very long time before enough gas leaked for any problem. On furnaces, even that was protected against.


Those cook stoves were an abortion, the auto spark system should have came on the second the burner knob left the off position,,, how many kids turned on the burner to 3/4 throttle and then left the room, or people even bumping up against the knob...


Pilot lights are generally too small of an output to do anything - and there's even failsafe's on many of them, in the case of most older style heaters and water heaters they will have their supply cut if they get blown out due to the thermocouple not producing any voltage - what's more is that either of these units have a natural draw from their venting esp. water heaters that are storing hot water and have a central flue running up the center and leading to the great outdoors (although if nobody's home to realize the water is getting cooler this factor of course does not help after a long time, but no worries as the draw will continue)

That's not to say they are foolproof - nothing is - a mis-adjusted pilot light for the bottom of a gas cooking stove is about the most likely area of trouble, I think it's because they are in an area where you "should" be able to detect the odor many (like mine) do not have a safety cut-off, the thermocouple is there only to keep the main burner from lighting should there be no flame...
The stoves are also not vented to the outdoors, so there is no real draw to them and gas can build in the lower unit, there is also a nice little enclosed area to allow build up - the place you cook your goose...
You would have to have one "out - of - control" pilot light to take out a kitchen, (and one very burnt out nose not to notice anything before it happened) but all's it really takes is a fairly large one that's not lit to blow up your stove, The other safety factor here is pilot lights just don't simply "grow" overnight, so unless you have a regulator that really goes on the fritz (which you would notice in other things) or some hack that just tampered with it you should be good... again - not foolproof but pretty damn good track records when you think about it being mainstream for hundreds of millions....

ogre
04-10-2013, 01:41 PM
I wish i knew how to post a link to a story. I dint know if any of you seen the indianapolis couple that purposly blew theyre house up w natural gas and supposably a microwave on a timer but it damaged somethi.g like 70 homes i believe and 30 i think had to be torn down. Horrific amount of damage i felt from 1 house but i guess its just that dangerous. Then the guy tried to have a witness murdered to keep them from testifying. Hope he stays locked up. The explosion also killed 1 couple i believe. Giod that it happened while mist people were at work.(excuse typing,have nerve damage in hands.)

J Tiers
04-10-2013, 10:36 PM
Heard about it at the time, but it vanished from the national news........ Was someone convicted of it then? The story at the time was that the local law enforcement folks "were not satisfied" about the cause.

Mike Folks
04-10-2013, 10:51 PM
This news story? http://news.yahoo.com/authorities-3-set-deadly-ind-blast-insurance-222918721.html