This is a contradiction to me.

i see stores stock small propane cylinders inside all the time.
as long as your garage or shed doesn't get too warm inside, i see no reason to not store them in a ventilated closed space.

You don't have to live at the stores.

The biggest problem with propane is that it is heavier than air.
If it leaks it will fill up basements, floor drains and any other low spots. That means a pool of propane gas sitting there waiting to be lit.
That is one reason why it must not be inside any structure or even near basement windows.
Tho other reason is that you don't want exploding propane tanks if there is a fire in your house.
(Natural gas is lighter than air and just floats away, but you still don't want it inside a building.
EDIT: If you google natural gas and propane gas explosions you will see why.)


The reasons they dont apply that to one pound cannisters is that they don't figure a pound of propane is enough to do any harm, and it would be impossible to enforce anyhow.

I don't know what the leaky small propane canister problem is from except cheap manufacturers.

I cant see any harm in storing small propane cylinders on theire sides.
The contents are liquid, with an expansion space containing gas/vapour.
The cylinders must however be used the right way up, with the valve or connection at the top. If a cylinder was put to use the wrong way up, liquid rather than gas could enter the burner and cause it to flare up, with risk of fire or damage to the appliance.

I would advise against storing propane indoors in a home or attached garage.
As pointed out above the containers sometimes leak, and this leakage is liable to pool in low areas, any spark from a furnace, sump pump, refrigerator etc could then cause a disasterous explosion.

If circumstances make indoor storeage unavoidable then use only well known brands, and keep as far away as possible from ignition sources. Consider buying a leak detector, these are available from marine suppliers and are intended to detect any collection of gas in boat bilges.

I noticed that the article says to store the propane cylinders standing and then shows the forklift type racked on their side.
It then mentions that you want the pressure relief valve above the liquid level so you don't spray freezing cold liquid propane out of it if it pops.
What it fails to point out is that the small barbecue type bottles combine the relief valve with the fuel valve, so they have to be stored upright to get the valve away from the liquid fuel.

Regarding forklifts: I seem to recall (vaguely) that those cylinders are designed for horizontal storage. The relief valve should be designed to contact the vapour space. And isn't there a pin in the frame that ensures they're sitting the right way when they're installed?

For all others, I would say vertical storage only. IIRC, if a propane tank vents liquid, it is venting 250 times more fuel than if it was venting vapour. That's a whole lotta 'boom.'

Yes there is a locking pin so the cylinder only goes on one way with the relief valve at 12 o'clock.

It is supposed to be an idiot proof system...

"...venting vapour. That's a whole lotta 'boom.'..."

Actually, the venting prevents the boom. It gives more of a whoosh. I once watched a motorhome burn to the ground. RV burning, every so often the propane tank would reach a certain temp/pressure and vent, creating a flame thrower effect out to the side for a few seconds. Temp/pressure went down, so did the flame thrower. Few minutes later, here came the flame thrower for a few seconds. On and off 'til the tank was empty.

I guess that in an enclosed space you could get a boom, which would be bad news...

Guess I wasn't entirely clear -- venting liquid is 'boom city.'

A while ago some idiot 'entrepreneur' was reselling propane bottles that had been modified for agricultural use (marking foam for agricultural applications). The valve was attached to a tube that went to the *bottom* of the tank. If you connected that to a BBQ, you would get pure liquid propane, and if you hit the igniter you would singe more than your eyebrows.