Originally Posted by CBR.worm
Any electric motor with brushes (like most drills) will spark internally. An electric motor designed for working around flammable vapors is designed differently and sealed to prevent accidental ignition. Even the power switches are different and sealed.
This was a horrible accident, and something that I could see happening easily to someone who buys a drill powered fluid pump and then uses it to pump gas. Odds are good that it won't happen, but it can. Even static electricity can be a risk in a dry atmosphere if the ratio is right.
Exactly right ^^^^^
The only fatality that I know of at the Amoco refinery in Yorktown was when a guy kept trying to start a motor in a enclosed room.... Hydrogen was building up unbeknownst to him... And the spark from the starter in that motor ignited the hydrogen... My step father told me it was very, very, hard telling the guy he was going to be all right... Knowing full well he likely was not going to make it.