This is what's left of a man's garage after he bumped into a scuba tank while parking. From the 1/5/2011 Fayetteville Observer...
"A scuba tank explosion in a west Fayetteville home injured a nationally known videographer and his wife, who is a photographer for The Fayetteville Observer. Rick Allen bumped into a cannister of compressed oxygen in the couple's garage around 11:30 p.m. Monday, knocking it to the ground. The explosion was so strong that it blew out a wall between the garage and a bathroom, where Allen's wife, Cindy Burnham, was brushing her teeth. Allen was in critical condition Tuesday at UNC Hospitals' Jaycee Burn Center, a spokesman said. Burnham was treated for facial cuts at Cape Fear Valley Medical Center and released.
Matt Blashfield, a neighbor on Partridge Court, was watching television at home when he heard an incredibly loud blast. "At first, I thought it was Fort Bragg," he said, "but a millisecond later, I said 'no way.' " Blashfield went to the scene where a garage door was blown into the yard, along with bumpers from the couple's vehicles. One of Allen's hands was severed by the blast, but he used a garden hose with his other hand to douse flames from the flash fire."
Bottom line, there's a helluva lot of explosive power in an air tank which requires just a puncture to release.