Expert blames grain elevator deaths on stuck bearing Rub apparently heated moving belt, igniting dust

August 20, 1998|By KNIGHT RIDDER/TRIBUNE

WICHITA, Kan. -- The June 8 explosions that killed seven people at the DeBruce Grain elevator started in a tunnel when a bearing on a conveyor belt apparently locked up, according to an expert investigating the incident.

That set off a chain of events that produced heat to ignite highly explosive grain dust, said Vernon Grose, one of six experts hired by the Occupational Safety and Health Administration.

The initial blast set off explosions that continued throughout the elevator, killing seven people dead and injuring nine. The explosions at the elevator just south of Wichita were the nation's deadliest in 15 years.

Tom Marple, head of the OSHA office in Wichita, declined to comment about the cause of the first explosion. Grose confirmed reports by three others close to the investigation about where and how the explosion started. He said the evidence is not final but strongly indicates the first explosion started in the No. 2 tunnel, at the south end and east side of the elevator.

Conveyor belts ride on rollers that keep the belts aligned. When the bearing on the conveyor belt locked up in the tunnel, it caused a roller to freeze as well. As the belt continued to move over the stopped roller, Grose said, it wore the roller away. As the belt and the roller rubbed, the roller grew hot and ignited dust that had collected on the moving belt.

There was enough dust in the air above the belt and on the tunnel walls to trigger a series of explosions, Grose said.

The fireball that resulted traveled in two directions: north to the head house and south until it blew out the south end of the elevator. Grose said the bearing probably locked up because it had not been lubricated.

"You've got to lubricate those things just like you would lubricate a car," he said. "It's proper maintenance."

When the explosion occurred, Howard Goin, one of the workers killed, was lubricating bearings in tunnel No. 1. He had not reached tunnel No. 2, where the explosion started, Grose said.

Grain industry safety experts say the secondary explosions would not have occurred without significant amounts of dust present. In earlier reports by the Wichita Eagle, workers and others described dust conditions they considered dangerous.

A spokesman for DeBruce Grain Inc. said the company's investigators have not found an ignition source and DeBruce had not been told by any government agency an ignition source had been found.

The dust-collection system in the tunnel was not functioning, according to workers and others interviewed for an earlier report in the Wichita Eagle. A dozen or more parts known as hoods were either missing or broken, so they could not draw dust out of the air as grain moved along the conveyor belts, they said.

DeBruce did not dispute this. It said then the dust system was not effective or critical to safety, and that cleaning crews hired by the company were more effective.

OSHA's Marple would not comment on whether DeBruce violated any of the federal agency's regulations, saying the investigation is not complete. OSHA has until Dec. 8 to release its report if it finds violations.

Pub Date: 8/20/98

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