Scuba expert baffled at report of fatal tank blast

Detectives are trying to piece together what triggered a Sunday morning scuba tank explosion that killed dive instructor Russell Vanhorn II.

"We don't really know why the tank exploded," said St. Petersburg police spokesman Bill Proffitt.

"We have the tank in our custody, we're still talking to people who may know more about it, we're still trying to find parts of the tank from the scene."

The metal tank exploded just inside the front door of Vanhorn's apartment, 5875 37th Ave. N., as the 23-year-old scuba instructor and Iraq war veteran was carrying the tank out for a trip.

Two friends in other parts of the apartment were uninjured in the blast. It was powerful enough to shatter nearby car windows and send debris flying 75 feet.

"Basically, it blew in half," Proffitt said. "The regulator, or the valve on top, is still missing."

Oceanographer and marine consultant Heyward Mathews said he's never heard of a scuba tank exploding like this in his 50 years of diving.

Mathews, who teaches scuba classes at St. Petersburg College, said it's important that detectives get to the bottom of it.

"All of us in the business are waiting to find out how it could have possibly happened," Mathews said. "It defies the laws of physics."

Scuba tanks sometimes fail during the filling process or when they overheat in the sun, Mathews said, but he couldn't recall a spontaneous explosion.

"It's such a freak thing," Mathews said.

In the past, Mathews said, scuba tanks have failed for reasons including overfilling, which can cause metal fatigue, and tampering with the so-called "burst disk," a pressure-release device designed to fail before the tank does.

"That disk will perforate and dump all the air out in a matter of two or three minutes," Mathews said.

"Some cave divers will pull the screw out, put a second disk in there, screw it back down so they can fill the tank at higher pressure than it's rated for," Mathews said.

"But no reputable dive shop would ever allow that."

Police say the tank that exploded was a small one, typically used as a reserve or backup supply.

Mathews said everyone in the local diving community is talking about the fatal mishap and anxiously awaits the outcome of the police investigation.

"I'm really hoping it comes up with something solid," Mathews said Monday as he filled an empty batch of steel tanks for his students' next lesson.

"It scares the heck out of me, frankly, to have a scuba tank explode. I've got 40 of them here."