I member we had an old Desoto wood body station wagon in Cleveland circa 1966. Dad was trying to find a leak in the fuel tank. Had the tank removed & was blowing air through it with Moms Hoover canister vaccuum cleaner. Even back then that Hoover vac had the capability to both suck and blow. It's nothing new ... Anyway he had it in blow mode & was splashing soapy water on the tank looking for leaks. Couldn't find any.
Then he got the bright idea to set the vac in suck mode and see if he could detect any leaks that way. This all went well'n good til the vac sucked up enough gas fumes to ignite what was compressed in the canister. That thing lit off like a rocket, went through the neighbors hedgerow & disappeared. Left a simmering trail of burnt grass behind it.
The old man scratched his head, lit his pipe and said, Well your Mother has been asking for a new vaccuum cleaner ...
