I recall a school trip years ago to the local fire station. Had a tour round, slid down thd pole, sat in fire engine etc etc, all good stuff for youngsters. Then demo time, big pan on floor, gallon of 4 star poured into it, then one of the crew lobbed a lit fag end in it, nothing happened, several more where ceramoniously flicked in with no effect.......along came the head man with full BA kit on and kneeled down about 10 foot away and lit a match.......BOOM........almighty fire ball......several scrsaming kids legged it and several more stood wide eyed in awe at the ensuing inferno. Water was first used to put it out......WOOSH......another fireball........absolutely awesome sight, then they spoil it by putting foam on it. They went to great lengths to show the dangers and causes of fires and I still have a healthy respect for anything that can go bang, pop, whizz or burn. But manafacturers are frightened to death if someone is stupid enough to use NAKED FLAMES near stuff, hence all the over the top precautions. As long as you can cover the source of heat or potential spark then you should be ok. Point to remember, turn things on before spraying, then let the room clear before turning off, in case of spafk from switch gear, unless you want to buy Ex rated equipment.......££££££££.
Worked in hazardous/explosive enviroments and never had any misshaps.