I dunno about that, Bobo. I grew up in a fire family, and dad and all his buddies really knew their stuff. They studied and drilled on this stuff all the time. I wouldn't discount their expertise for a second.
Not that good LP guys aren't knowledgeable too, but the average propane monkeys don't seem to be. How many times have you had someone refill your tanks and not even bother wearing gloves or eye protection? They may have standards somehow, but I don't see it in practice, and I don't detect a lot of training or science in what they do.