Yesterday, I began using a propane torch (which I won in a raffle; Yay!) for browning the tops of foods. My quandary is: where do I store the torch? The instructions say not to store it in your living space, and not to store it in a place which will get overly hot. That rules out the cabinet under the sink, and the backyard shed. I don't have a garage.
The simple answer is that propane cylinders should be stored outside. That's what every guide will tell you. You really shouldn't even be storing it in a garage. Your yard is the best place, and if you take the safety guidelines seriously, you probably shouldn't own a propane torch if you don't have an "outside" (i.e. you live in an apartment). Either that or you should dispose of the fuel immediately and only store the head.
There's always a risk associated with storing any pressurized gas in your home, whether it's a propane cylinder or a nitrous oxide charger that you use with a whipper. The autoignition temperature of propane is 470° C, about the same as wood and far greater than paper, so it's not just going to spontaneously combust - it needs a spark or a heat source like a burner - so don't store it on your stovetop. The real worry isn't a sudden explosion in the middle of the night but rather a gradual leak, which you can't see or hear, and don't become aware of until it's too late.
Much like most of our food-safety questions, the risks are very small and many folks choose to ignore them - but there is a risk of a fire or explosion. If you intend to store it in your house, you might want to check to make sure it's not specifically prohibited by your insurance policy, homeowner's association, etc., depending on where you live.
N.B. If you do decide to store it in your house anyway, at least keep it away from children, pets, and anything flammable. For example, in a metal toolbox on a top shelf.
Most recommendations about storing propane tanks outside are assuming you're storing quite a large amount of it (eg, 20lb tanks for a grill). Odds are a hand-torch has a 1-lb tank or smaller, which isn't quite as much of a problem, as be less likely to reach the concentrations to be explosive. (that's not to say it wouldn't be flamible ... just not explosive without the proper fuel-air ratio).
I still wouldn't store it inside, as should there be a leak in the tank, many homes have ignition sources such as pilot lights, and LP will travel into basements, being denser than air.
If your shed isn't air tight (especially if there's a poor seal well along the bottom of the door), and it doesn't get too hot in the summer time, it should be okay in there.
Personally, I keep my propane tanks under a table on my deck, so they've got lots of airflow, but they're out of direct sun and weather.
update : another word of caution : always store the canister so the relief valve is up. This typically means don't store it on its side unless you can prevent it from rolling. If you don't, and it gets warm, it will release propane (and then possible sieze up and then burst if it gets hot)
Most aerosol cans contain a reasonable propane or some other cheap hydrocarbon gas as the propellant. Many household have a cupboard full of them
The build quality of a disposable aerosol can is much lower than a propane cylinder, and they regularly leak, but how many household explosions/fires have been reported to be caused by them, basically none
Most teenagers have thrown an aerosol can into a fire, and know what energy they contain, yet they just don't cause issues under normal storage, mainly due to the specific air/fuel mixture requirements
You need a LOT of gas at a specific air/fuel mixture for it to become explosive, or even burn for any length of time. This rarely happens with even the common and large 9Kg gas cylinders
Most gas explosions/fires are cause by bad or faulty gas plumbing, and unmaintained automatic control systems, neither which exist on you kitchen gas torch
Deep frying while drunk seems to be the most hazardous kitchen activity in the fire station logs :-)