When I worked for a roofing company, we used to scare the *censored* out of the HVAC techs. Was just a normal occurrence to us, but to outsiders it apparently was frightening. We had one guy run to his ladder full sprint in a panic ... HE'S GOT A FIRE OVER THERE!! I go ... OH, walk over, and with my face inches from the flames blow it out in a couple tries, LOL! He goes ... YOU GUYS ARE F'IN NUTS and screwed down the ladder and left!! Never saw him again.
What would happen is, since we filled our own tanks at the shop, we'd fill them until the gauge stopped rolling, and the pump started straining - that's how we knew they were full. No 80% crap here ....
Time was money!
We'd be headed down the highway westbound, and when the morning sun heated the tanks up, there would be clouds of propane gas wafting out the back of the truck. We used to laugh. By the time we lugged those 40 lb'ers up on the roof, and more sun hit, they'd be spitting liquid out of the relief valve, opposite the hookup below the hand valve. We'd light our torches, and they'd be spitting liquid and shooting fire everywhere. You'd always inadvertently light the spitting relief valve on fire, because we'd all be shooting the *censored* and not paying attention .... or still drunk from the night before. There was so much propane in these tanks, we knew there was no way in hell they'd explode .... but it sure scared the crap out of strangers!