For whatever it is worth -propane is one of the safest fuel you can get.
It will not blow up like gasoline vapors in open tank and due to freezing itself any accidental burning is self-controlled.
Years ago on the plant I was working on - forklift operator managed to ignite 4 tons propane tank. The feeding hose burned thru and the flame overheated the big tank. Tank had top safety lid about a foot diameter that blew up and the escaping propane ignited. The flame was over 50' high.
The plant got evacuated and several fire engines show up, only to stand by and wait for the propane to burn out. The freeze-controlled burn out lasted over 1/2 hr and with only tank lost, nothing more happen.
The management let us take the rest of the day off.
