Hand held propane torch exploded in my neighborhood

This morning, we heard an explosion next door, and we were told by the police and fire department, that it was a gas torch exploding. The
plumbers were apparently working in the basement and a hand held propane tank & torch exploded in the plumbers hand! Miraculously, no one was hurt. The explosion was very loud and we thought a tree limb had fallen on our house. My wife met the plumbers boss on the way out of the street and he informed her that that was indeed what happened. Pretty scary. The people in the house across the street from the accident said it felt like their house had lifted off the foundation for a moment. The plumbers stumbled out to the street and sprawled on the grass until the paramedics arrived. One the guys shirt was torn and he was in a daze but no other injuries. Has anyone ever heard of this before? -Mike St. Louis
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Given that propane in a tank is liquid I'd have thought that a burst tank in conjunction with an ignition source would make for a pretty serious local fire, not something the user would walk away from. However perhaps there was a propane or other gas leak leading to an explosive mixture which the torch ignited, that seems more consistent with a house-shaking bang.
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mlcorson writes:

Nonsense. Propane in a cylinder cannot explode, as no oxygen is present.
Something else happened.
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On Thu, 02 Aug 2007 17:37:57 -0500, Richard J Kinch

========Exactly.
More plausible scenario.
Plumber puts propane torch in tool box. Torch has slight leak or was not turned off completely. Over night the propane level in the tool box rises. Plumber opens tool box, and lights torch close to tool box so he can put his sparker back in the box. Accumulated propane and air in the tool box ignite. Tool box offers enough retention/resistance to result in a perceived explosion rather than a simple "whunf."
Anybody check to see if the toolbox that was square and about 2 cubic feet is now round and about 5 cubic feet? Is a tote tray embedded in the basement ceiling?
Unka' George [George McDuffee] ===========Merchants have no country. The mere spot they stand on does not constitute so strong an attachment as that from which they draw their gains.
Thomas Jefferson (1743-1826), U.S. president. Letter, 17 March 1814.
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wrote:

Uh, George, they outlawed the smallest refillable cylinders some years ago in PA after two of them exploded in use. These were the same size as the disposable cylinders you get in hardware stores. I had a couple of them for years.
I don't suppose there's much chance it was a refillable cylinder, but you know the hazard with those things, if you don't purge them when you refill 'em. And lots of people didn't purge them.
-- Ed Huntress
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The scenario doesn't require a refillable cylinder. I once took the torch off a disposable cylinder and noticed a slight hissing sound.... I was just really happy I heard it!
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A cylinder needs only to be purged before it is filled for the very first time. Subsequent refills do not need a purge.

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wrote:

Well, it happens I once had a discussion about this with a fishing buddy who happened to be a technician for Pargas in PA, and I asked him how air could get in those cylinders. He said that one problem is that the filler valves could be opened and people often left the empty cylinders open. Air would fill the cylinder and then they'd just put in more gas. If you do that a few times you have a bomb. Thus, whether it's an accurate description of what happens or not, the state decided after two explosions not to allow uncertified people to fill tanks. Not that you could stop it completely, but the ones refilled at home the most were the smallest ones.
That's what I'm going on. I have no direct experience with an explosion or other problem with those things. I purged mine every time I filled them. I wish I still had them.
-- Ed Huntress
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I respect your thoughts on the subject but have you ever seen a BBQ tank purged before it is filled ( after the initial purge) ?
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wrote:

Doesn't need to be- the valve on a propane tank doesn't allow air to enter at atmospheric pressure and vessel pressure is always higher than atmospheric. Most fuel gas cylinders are valved this way.
I used to work with transfilling compressed gases (medical oxygen) and a vacuum purge was mandatory because the valving , if left open, would allow room air to enter an empty cylinder.
-Carl
--
The future isn't what it used to be.



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wrote:

Yup! I purge all my outdated tanks before I use them for air tanks. Gerry :-)} London, Canada
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Ed Huntress writes:

This is superstition. The headspace of a 13 oz refilliable cylinder contains about 30 milligrams of propane vapor at an ideal 1:25 fuel:air ratio, assuming maximum headspace (no liquid). The energy from combusting 30 milligrams of C3H8 doesn't even amount to a child's firecracker.
Now if a cylinder leaks 13 oz of liquid into a confined space, and happens to mix in the right proportions with air and then ignite, then you have a potential whump. But that's not a cylinder exploding.
Purging is needed to avoid overpressure in the vessel from non-condensible gases in the headspace.
Think about it. If fuel-air headspaces were such a hazard, then every lawnmower gasoline can and automobile gas tank would be a bomb. You don't see them being outlawed like a puny propane refillable.
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You *DO KNOW*, don't you, that brass fittings are readily available for those folks who wish to fill those little cylinders from their larger propane tanks?
I've seem them advertised for sale in more than one flyer/catalog form the discount tool sales joints.
Flash
(Somehow, that moniker seems SOOooo appropriate to a thread l;ike this Sorry, I just couldn't resist))

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Kink sez:
"Nonsense. Propane in a cylinder cannot explode, as no oxygen is present."
And he sez, again:
"Think about it. If fuel-air headspaces were such a hazard, then every lawnmower gasoline can and automobile gas tank would be a bomb. You don't see them being outlawed like a puny propane refillable."
Tell that to the NTSB examiners of TWA Flight 800. Their report: An explosion of the center wing fuel tank (CWT), resulting from ignition of the flammable fuel/air mixture in the tank. The source of ignition energy for the explosion could not be determined with certainty, but, of the sources evaluated by the investigation, the most likely was a short circuit outside of the CWT that allowed excessive voltage to enter it through electrical wiring associated with the fuel quantity indication system. Contributing factors to the accident were the design and certification concept that fuel tank explosions could be prevented solely by precluding all ignition sources and the design and certification of the Boeing 747 with heat sources located beneath the CWT with no means to reduce the heat transferred into the CWT or to render the fuel vapor in the tank nonflammable.
Bob Swinney
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Follow up: Unfortunately, I had to leave town this same afternoon, and was unable to find out more information about this incident. I will be back Tuesday. I plan to call the fire department, talk to the neighbhors and possibly the plumbers. I'll check to see if there is an article in the local newspaper. I will post back after I get more facts. -Mike
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Robert Swinney wrote:

Most lawnmowers don't have wiring in their gas tanks.
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"Robert Swinney" wrote: Tell that to the NTSB examiners of TWA Flight 800. Their report:

^^^^^^^^^^^^^^^^^^ Bob, you need to separate in your mind the tanks filled with pressurized fuel, and tanks that have liquid fuel and an airspace above the liquid. The tanks on your car, your lawnmower and TWA flight 800 are vented--as fuel is consumed, air goes in. If the air vent on your car's gas tank gets plugged, the tank will collapse under atmospheric pressure. A Bernzomatic tank is filled with liquid fuel and fuel vapor. No air. As fuel is used, more evaporates, but no air goes in.
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Robert Swinney writes:

You might want to consider the difference in scale and containment between combustion inside a 13 oz propane bottle versus an aircraft fuel tank.
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Sorry, Richard ! I just couldn't let it go by.
Bob Swinney
Robert Swinney writes:

You might want to consider the difference in scale and containment between combustion inside a 13 oz propane bottle versus an aircraft fuel tank.
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Pansies. JR Dweller in the cellar
mlcorson wrote:
The people in the house across the street from the

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