http://www2.tbo.com/news/breaking-news/2011/sep/13/fatal-scuba-blast-ruled-accidental-still-a-mystery-ar-257503/
Initial medical examiners report seems to rule out 100% oxygen. At least one "expert" not happy about the online speculation...
CLEARWATER Russell Vanhorn II died Sunday as a result of injuries from a scuba tank explosion, but it's still not clear what triggered the blast, the Pinellas Medical Examiner's said.
"It seems to be a mystery," said Bill Pellan, chief investigator with the office.
The cause of death was ruled accidental.
Whether the tank had contained compressed air or more volatile pure oxygen has not been determined.
"I'm not sure we have any information as to what was in the tank," Pellan said.
Oxygen is not a combustible gas, but it accelerates combustion through oxidation when combined with flammable materials and a heat source.
Pellan said the autopsy produced no signs of a heat-generating type of explosion.
"Based on sheer friction, there was some searing," Pellan said. "There was not any burning of the tissue like you'd see in a fire."
St. Petersburg police say the blast ripped the small, aluminum scuba tank in half and blew out the valve, causing severe damage to Vanhorn's side, leg and arm.
One expert in scuba tank safety lamented the online speculation that is filling the void of information about how the blast happened.
"A lot of the information that's being posted is pure speculation," said Mark Gresham, president and CEO of Seattle-based Professional Scuba Inspections-Professional Cylinder Inspectors.
Gresham said he hopes investigators will pinpoint the triggering event for Sunday's blast because compressed air cylinders do not spontaneously explode.
"There's always got to be a cause," Gresham said.
Gresham said oxygen tank fires typically are "very, very hot", but that even an explosion involving ordinary air can be devastating.
Gresham said that under pressure, a typical 80-cubic-foot aluminum scuba tank contains 1.3 million foot-pounds of potential energy, enough to lift four 88-ton railroad locomotives one foot off the ground.
"Hand grenades are far less powerful," Gresham said.
Gresham said he keeps statistics on scuba cylinder failures and since 1972, he knows of 21 aluminum cylinders and 56 steel tanks that have ruptured for one reason or another.