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.
In case you missed it, NFPA published their new COM DUST standard last month. This FIRST edition of NFPA 652, Standard on Combustible Dusts (link to free access), was issued by the Standards Council on August 18, 2015, with an effective date of September 7, 2015. NFPA 652, Standard on the Fundamentals of Combustible Dust, provides the general requirements for management of combustible dust fire and explosion hazards and directs the user to NFPA’s industry- or commodity-specific standards, as appropriate:
WARNING - this video shows the ignition of the dust cloud and people within the dust cloud on fire and trying to escape. The sights and sounds of this video ARE VERY GRAPHIC in nature, but shows the hazards of Corn Starch and its ease to ignite.
Corn Starch has one of the lowest MIE's in the Combustible Dust family. We do not yet know the ignition source, but a high wattage concert light bulb or a lit cigarette would be enough to ignite this cloud of corn starch.
As you watch this video, remember the five (5) things that have to be present for a COM DUST incident:
The U.S. Chemical Safety Board (CSB) completed a study of combustible dust hazards in late 2006, which identified 281 combustible dust incidents between 1980 and 2005 that killed 119 workers and injured another 718. Based on these findings, the CSB recommended OSHA pursue a rulemaking on this issue. OSHA has previously addressed aspects of this risk. For example, on July 31, 2005, OSHA published the Safety and Health Information Bulletin, ‘‘Combustible Dust in Industry: Preventing and Mitigating the Effects of Fire and Explosions.’’ Additionally, OSHA implemented a Combustible Dust National Emphasis Program (NEP) on March 11, 2008, launched a new Web page, and issued several other guidance documents. However, the Agency does not have a comprehensive standard that addresses combustible dust hazards. OSHA will use the information gathered from the NEP to assist in the development of this rule.