ST. PETERSBURG — Greg Sullivan saw the explosion before he heard it.
The 58-year-old retired welder was sitting down to his morning tea and cookie when he saw the condominium behind his unit shake like a bomb had detonated. The walls bulged, then came a single, concussive blast.
Sullivan called 911 and ran to his neighbor's unit and kicked in the back door, already cracked from the explosion. Through the haze and dust he saw a man lying across the threshold of the front door, his head in the lap of a woman, bright red blood pooling.
Sullivan tried to turn the man over to apply a tourniquet, but when he saw the extent of the injuries, he knew it was too late.
"It was a completely devastating wound," he said Sunday.
Russell Vanhorn II, 23, an Iraq War veteran, was the victim of the peculiar fatal explosion, according to police and his father, Russell Sr., who has his own questions.
"Something ain't right because some of those tanks he had were pretty new," said Vanhorn Sr., 55, of Hills, Iowa.
Vanhorn was rushed to St. Petersburg General Hospital where he was pronounced dead.
Vanhorn had been carrying the scuba tank into the parking lot of the condo complex at 5865 37th Ave. N, said St. Petersburg Fire and Rescue Lt. Joel Granata. The tank burst, blowing out the condo's door and windows and damaging vehicles within a 100-foot debris field.
The explosion occurred about 6:50 a.m. A man and woman inside the unit when the explosion took place were not injured.
While scuba tanks have exploded from time to time and caused serious injuries, it is highly unusual for the explosions to result in death.
"We have a dive master and he came out to examine the tanks," Granata said. "Right now it's under investigation."
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Vanhorn, who is from Cedar Rapids, Iowa, learned to scuba dive while serving in the Marine Corps. He trained when he was stationed at Camp Pendleton in California, his father said.
He moved to Holiday from Iowa a little over a year ago, a few months after he left the service.
A good friend of his lived in the area, his father said, and he wanted to begin a career in scuba diving, a brother, Justin Warnke, said.
Vanhorn Sr. hopes to lay his son to rest in Iowa later this week.
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Doug Jackson, vice president of Bill Jackson's Shop For Adventure in Pinellas Park, said Sunday he can remember only one incident of an exploding scuba tank in the last 30 years — when a Lakeland man lost his legs in 1981 after a tank he was filling with air burst.
There have been more recent tank explosions, but none fatal. A 17-year-old Palm Beach County boy lost half his left hand when a tank he was inspecting exploded in 1998. In 2000, a 66-year-old Key Largo man lost a leg when a tank he was filling burst.
Jackson wondered if the cause of Sunday's explosion is the same as the 1981 Lakeland incident — recent exposure to heat.
In the Lakeland case, the tank had recently been refinished. Exposure to high heat, 300 degrees or so, can cause aluminum to crystallize and become brittle, Jackson said.
"If it were to be crystallized by a heat source, it would be a ticking time bomb," he said.
Scuba tanks are made of either steel or aluminum. Scuba industry standards call for the tanks, usually filled to about 3,000 pounds per square inch of pressure, to be visually inspected yearly for signs of corrosion or defects. Federal law requires more thorough hydrostatic tests every five years.
Hydrostatic tests involve placing the tanks in explosion-proof chambers and filling them to 5,000 pounds of pressure per square inch. The inspection stickers should be clearly visible on all tanks, Jackson said.
Pressurized air tanks are federally regulated, Jackson said. In 1994, federal authorities issued a safety advisory warning of potential cracking in tanks made from a certain aluminum alloy. There were three incidents of tanks made from that alloy exploding, according to a 1998 South Florida Sun-Sentinel article, but none fatal.
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The parking lot was still littered with glass Sunday afternoon as police and fire rescue personnel sifted through the remaining scuba gear. Insulation and frayed planks of wood hanging from blown-out windows.
The unit's screen door rested between trees more than 50 feet away. The man and the woman who survived the blast sat on the pavement, talking to each other and police intermittently, and shaking their heads. They declined to comment.
Times Staff Writer Jamal Thalji contributed to this report.