GALLATIN, TN -- As part of its ongoing investigation into two fatal and one serious combustible dust incidents at Hoeganes Corp.of Gallatin, the U.S. Chemical Safety Board (CSB)  conducted combustibility tests of metal dust samples it collected after the first incident on January 31.

The accompanying video shows two different tests -- the first clip is filmed at normal speed followed by the two tests filmed in slow motion at 1,000 frames a second.

CSB said the tests confirm that two flash fires at Hoeganaes, including one which killed an employee, were fueled by combustible metal dust. The CSB said the tests confirmed the preliminary conclusions that the iron powder had accumulated throughout the facility and became airborne in combustible concentrations. A flash fire on January 31 killed one worker and seriously burned another. A similar fire occurred at the plant, which manufactures "atomized" iron powder used for auto parts and other metal products, on March 29 and caused one injury. 

A third combustible dust incident, this one fueled by hydrogen, occurred at the Hoeganaes plant May 27 after the CSB released the video of its tests. That incident killed two workers and seriously injured a third employee.

The plant reportedly reopened last week in a limited production mode.

Combustible dust, including from wood sources, is under intense scrutiny by the CSB and U.S. Occupational Safety and Health Administration, which is taking the required steps to promgulate new mandatory workplace standards.

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