Packing my stove with the cylinder connected is not a practical option for me.I would not cap a bottle that is obviously leaking but will cap in case of a small seepage that is not easy to detect.I have not bought any yet but expect that they will bleed off any small pressure build up before the cap is fully off the threads.And then what? I wouldn't want to cap a leaking propane bottle even if there was no more than 1 lb of propane left inside. I would prefer to leave it connected to a propane appliance and use the on/off knob from the appliance.
If you use a metal cap, there is way too much chance of propane being released into the air as you remove the cap, then trying to connect it to your appliance and this doesn't include if there's an ignition source in the area at the time.
This happened to me with a stove once. The weather was so cold, the fitting started to leak right as I disconnected it. The hissing and the stench were scary. So I quickly put the stove's stem with a knob back on the propane bottle and used it at the next camping outing.
Sure, the stove didn't store as well with the stem and bottle having to stay connected, but at least it was safe and I was able to minimize releasing propane into the environment.
I think the cap is meant as a safeguard BEFORE any leaking occurs, but this cap would be under some pretty good pressure. I think that's why plastic is used. They want it obvious there's a leak as the thing blows off and release the gas. Keeping it under pressure is more dangerous.
Does anyone know the regulations on this?
Now what does everyone think?