Only time Ive seen an aerosol can go off Pete, was when I was a lad. One of the local Div`s had a can of expanding foam with no nozzle and was banging it on all the gates along our terrace, when it went, the can shredded and shredded his fingers too, along with loads of sticky foam in the cuts. Funny, didnt look so hard then
See a lad punture a full can of orange spray paint too after a graffiti demo, banging it on a grind rail at face height, that f***ing covered him. Seriously looked like he had been tango`d.
I think making a hole, not a tear is key, especially if there lots of gas in t