July 31, 2017 at approximately 1:00 pm. Switz City, Indiana. White Farms Inc. Overhead tank collapsed full of corn. It hit a power line on the way down and sparked the grain dust igniting the dust and causing the flash. There were no injuries!

Scenario: Some equipment manufacturers believe that all equipment used in combustible dust atmospheres, including non-electrically powered vacuum cleaners, requires NRTL listing/approval.

Question: Could OSHA clarify the NRTL listing/approval requirements for non-electrical vacuum cleaners used in combustible dust atmospheres?

Safety Order 01 Item 001

Type of Violation: Serious; $4,000

IC 22-8-1.1 Section 2: The employer did not establish and maintain conditions of work which were reasonably safe and healthful for employees, and free from recognized hazards that were causing or likely to cause death or serious physical harm to employees in that employees were exposed to combustible dust hazards:

Facility- Information to verify the installed safety equipment and/or safety design features on the combustible wood dust (Kst = 20. 75) collection system was not provided.


In November 2015, an operator at an explosives manufacturing plant was tasked with transferring aluminium grit atomised powder (aluminium powder) from a flexible intermediate bulk container (IBC) outside the plant to the hopper inside the plant. Using a pneumatically-driven vacuum suction pump and transfer pipe work (which incorporated five metres of PVC piping) the operator successfully transferred part of the powder from the IBC. When the hopper began to empty the operator resumed transferring product. Just after repositioning the suction pipe inside the IBC, he heard a loud explosion that sounded like a cartridge of explosives detonating, and felt the pipe shake violently in his hand. The operator ran inside the plant to find that the vacuum pump and chamber were on fire and had been blown off the hopper. There were spot fires of burning product. The operator used an extinguisher to put out the fires. There were no injuries. There was charring on the inside of both the vacuum chamber and transfer pipe work but not inside the hopper. It appears a dust explosion was triggered by a static discharge inside the vacuum chamber creating a flash-back through the transfer piping.

Occupational Safety and Health Administration (OSHA) has initiated rulemaking to develop a combustible dust standard for general industry. OSHA will use information gathered, including from an upcoming SBREFA panel, to develop a comprehensive standard that addresses combustible dust hazards.  CLICK HERE for the May 2016 OMB’s Office of Information and Regulatory Affairs (OIRA) posting.

I have received quite a few e-mails and phone calls asking about NFPA 652: Standard on the Fundamentals of Combustible Dust, 2016 Edition and what it means to those it applies to.  This article will try and break down the basic requirements which can be put into four (4) categories.  PLEASE NOTE, this article assumes that you already KNOW YOUR DUST is COMBUSTIBLE.

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