Here is some safety info from Eastern Propane Co.
https://eastern.com/customer-information-center/propane-safety-tips/checking-your-propane-gas-tank
Generally speaking:
* Try to avoid storing the containers where the temps will exceed 120ºF. esp in closed areas, where leaking propane will accumulate.
* If temps exceed 120ºF, pressure builds up inside the cylinder, which may cause the pressure relief valve to release propane.
* If the pressure relief valve starts releasing propane, the accumulated gas could cause a fire or explosion, esp if it's in an enclosed space.
* Propane gas is heavier than air, and will accumulate on the floor (unless there's something to stir it up).
* If you have to store propane cylinders in your van, pay attention when you open the door and see if you notice any odor. Opening a slider door is probably more likely to cause a spark/explosion than opening a regular door.
* If you do smell the odor, stop whatever else you're doing and open the van and let the gas escape.
* When the gas has dissipated, find the source of the problem and deal with it.
* Don't approach your van (with propane inside) with a lit cigarette.
* Actually, this would be a good time to stop smoking, altogether. The savings alone will pay for a LOT of propane. Currently, the average price of one pack of cigarettes is about $5.50, which is perilously close to the price of TWO 1-LB TANKS OF PROPANE.