Re: OT: (consumer) propane tanks

It looks to me as if this situation is covered by Code 58 of the National Fire Prevention Association code (which is probably incorporated "by reference" into most local codes).

">I guess that if the flames hit the container, it can explode, and that

Yup. It's a double-acting bomb.

The first boom is when the cylinder ruptures from overpressure. It's like any metal tank exploding - it could throw metal shrapnel for quite some distance. If the valve fails before the cylinder wall does, it can turn the cylinder into a jet-propelled projectile.

The second boom is when the propane (or butane or etc.) mixes with the air sufficiently and then flashes into flame. It becomes a fuel/air bomb, which does damage both by the force of the explosion, and by the huge amount of heat released by a large flame-front.

One of the big hazards of storing fuel-gas indoors is that effect #2 can happen as a result of any leak from the storage cylinder. It doesn't take an external fire or flame. A leaking valve, or a big cylinder which falls over and damages or breaks off the valve assembly, can convert a building into a time-bomb in very short order. Any spark then sets off the explosion... flipping a wall light switch on or off can be all it takes. Demolished buildings are the result.

Youtube has plenty of clips - for example see

On 12/15/2023 6:24 PM, Don Y wrote: <snip>

The problem is that propane gas is heavier than air, so it doesn't readily dissipate like natural gas would.

Dunno. Ed

More info....

Virginian Fire code:

Cylinders shall be secured in a lockable, ventilated metal cabinet or other approved enclosure. Cylinders shall be accessible only by authorized personnel or by use of an automated exchange system in accordance with Section 6109.15.1. A sign shall be posted on the entry door of the business operating the cylinder exchange stating "DO NOT BRING LP-GAS CYLINDERS INTO THE BUILDING" or similar approved wording. An emergency contact information sign shall be posted within 10 feet (3048 mm) of the cylinder storage cabinet. The content, lettering, size, color and location of the required sign shall be as required by the fire code official.

There is a difference.

If the container bursts, the gas is not mixed with sufficient oxygen to burn very fast or explosively (not as big as it could be). On the other hand, a bottle leaking can produce a mixture of gas and oxygen that is indeed explosive.

My father, who worked on a refinery, said that the huge empty fuel tanks were more dangerous than the full ones. The former had a mixture of fuel and air, they could explode.

We have a similar regulation in Mass.

And don't forget the Insurance Company. After your business vanishes in a big explosion, your friendly Insurance Agent is suddenly unfriendly.

Joe Gwinn

Depends on how the fire marshal feels that day; there do tend to be different options they have in that regard.

Well, both. Different citations, though. ("Sale to a minor" and "Minor in possession of...")

Better to "lose" one moron semi-customer than the store.

Tank has to get *out* of the store somehow; and if the "customer" is being a petulant little brat about it, then it's most likely gonna be a store employee getting it out ...

If it was the smaller places around here (True-Value affiliates), the employee would probably be fired on the spot (or at least we would've been back when I was a kid working at one...)

Woshhhh! :-) Big flame or explosion.

You know that if the room is totally filled with gas, it can not explode? :-)

There is a proportion of gas and air that explodes. If the proportion is not met, it burns fast, or very very fast, but doesn't explode.

You may remember that a carburettor car with the motor soaked in gasoline doesn't start. You had to let the car stand for half an hour before trying again. Or push the accelerator to the end, not moving it, then turn the key, so that it ventilated. After a while you could try to start it for real.

Here, we have two bottles of butane on the kitchen, one connected, one spare. If the bottle gives way in the middle of cooking, we just switch the bottle, which here is a minute, 15" if you are on a hurry. We have a quick disconnect/connect device :-)

Then we replace the empty bottle at a leisure.

Things get interesting with the shower hot water if the bottle gives way just in mid shower, you are alone, and you have to get out to the garden to switch the bottles with your hair full of shampoo in winter ;-)

Yeah, BTDT.

What was that? :-?

Quite possibly.

Oh, yes!

Some modern water flash heaters have automatic regulation. They increase or decrease the gas output automatically to try keep the water temperature constant.

I don't have that in this place. I did a mistake when I purchased the last one when replacing the previous (broken) one. It is not only the problem of someone using the water at the same time, but that the temp varies a lot if you try to use less water.

:-)