DSS040: How to Run Effective Dust Explosion Training Sessions With Dr. Chris Bloore

In this episode of the DustSafetyScience Podcast, we talk to Dr. Chris Bloore about how to run an effective dust explosion training session.

This is Chris’s third appearance on the podcast. In Episode #38, he discussed the New Zealand Code of Practice for handling combustible dust, and in Episode #31, he shared his insights on hygiene and explosion safety in food handling industries. Today, Chris explains how to run an effective dust explosion training session. In the process, he answers the following questions:

What are the basic elements of an effective dust explosion training program?
Who are the audience members?
How can we tailor a program to different audiences?

Chris became involved in dust explosion research and training during the late 1980s, when a catastrophic explosion took place in New Zealand. He worked with the New Zealand dairy industry to develop the New Zealand code of practice and, later, the joint Australian New Zealand standard.

In 2000, the Australian dairy industry began holding the IChemE (Institution of Chemical Engineers) training course on dust hazards. Chris was involved in delivering the course in several areas, which was eventually adopted by the New Zealand Qualifications Authority and became unit standard 16311 in their system. Over the years, it was modified for presentation in different countries, but the primary audience continued to be spray dryer operators.

What Should Be Included in a Training Program?

Chris said that his training sessions usually begin with an overview of the fire triangle and deflagration pentagon, which states that you need a fuel, an oxidizer (typically air) and heat to get a fire going, followed by dispersion of the dust or powder and confinement.

“Without confinement it’s not such a hazard,” he explained. “If it’s in a confined space, obviously it will attempt to escape… and that’s when you get serious issues with damaged equipment and harm to people.”

He pointed out that some plants have dust clouds present by design: the creation of a combustible dust cloud is a feature of the equipment. Since it can’t be avoided, controlling ignition sources like sparks and hot screws becomes crucial.

“A very significant part of the course is going to be ignition sources,” Chris said. “What are they? Which ones are important? Which ones are less important in each context?”

Understanding the dust characteristics can answer these questions. Some materials, like cornstarch, are extremely hazardous because they have a very high KST value. They explode quickly and creates a lot of pressure in a very short time. Other products, like coffee creamer, burn more slowly, so the pressure rise is slower, although, as Chris put it, “You still don’t want to be there when it happens.”

After prevention, he recommended that courses go over steps that mitigate the effects of an explosion, like venting, suppression, and isolation.

Who Are The Different Audiences?

Chris explained that when his course first came out, the primary audience was spray dryer operators. These people ran two or three spray dryers from a control room, where they relied on the heavily mediated information on their computer screens to tell them what was going on. Over time, additional audience members included:

Maintenance personnel
Packaging staff
Product laboratory staff

“These are people who, for a short part of each working day, are potentially exposed to the risk,” Chris said. “They need to be aware that there are hazards and if they spot anything that doesn’t look right, they should report it immediately.”

He found that people who work in plants where the dust is the side effect of the process are often not as alert to the hazard as they should be. One example might be medium-density fibreboard plants.

While housekeeping is a key part of controlling the hazard in dust fire or explosion situations, Chris acknowledged that addressing unnecessary dust creation is also crucial.

“They can reduce the amount of housekeeping needed by reducing the amount of fugitive dust,” he said.

Chris identified static electricity as another issue. “If you watch a YouTube clip about an incident, 80% of the time the local fire chief will say that static electricity was suspected. In the food industry, static is really not much of a hazard because the minimum ignition energy for most food products is very high. You’re not going to get blown to bits by a static spark, whereas if you were handling plastic pellets in an injection molding situation, you can stroke a cat in the next room and the static will set it off. There have been horrendous fatal accidents from static-sensitive materials.”

According to Chris firefighters present a unique challenge. They understand the fire triangle and are fully equipped with the technology needed to fight fires, but their awareness of the deflagration pentagon may not be as high. Sometimes they have inadvertently created dust clouds that led to explosion and injury.

“With firefighters I try and differentiate between the response that’s appropriate for a fire and the response appropriate for a deflagration which is something they’re not generally well-trained in,” Chris explained.

Other course participants include:

The manufacturers of spray dryers, powder sifters, pneumatic conveying equipment, and dust collectors
Attorneys representing companies that might be having problems with the regulatory authorities
Regulators who inspect plants for compliance
Insurers

When training a group that appears to be hesitant about applying what they’ve learned, Chris uses demonstrations to convince them about the seriousness of combustible dust hazards. Taking a length of plastic tubing with a funnel on the end of it, he puts a few spoonfuls of powder into the funnel and then, from a safe distance, blows the powder over a naked flame from a blowtorch. The fireball that results can be anywhere from a couple of meters long to six or eight feet long depending on the product.

“We did some work with a major coffee creamer manufacturer some years ago,” Chris recalled. “The workers said but our product wouldn’t (create a dust hazard), but we got a 20-foot flame that burned quite long and slow and generated a lot of heat. It certainly got their attention, so a live demonstration is really good. They feel the heat and realize that if (the flame) was in a confined space, it would be deeply unpleasant and possibly fatal. So it really does get your attention.”

Conclusion

When the New Zealand dairy industry formed the New Zealand Dairy Code of Practice for the spray dryers, it worked with the fire service, the Insurance Council, the New Zealand Dairy Board, and a research institute to come up with something that would work for the whole industry.

“There’s definitely a role for it in different industries,” Chris said. “Some industries, like grain handling, are everywhere in the world yet it’s pretty much the same technology, they experience very similar issues and there’s a lot to be gained by working together.”

Once that happens on a more regular basis, the rate of progress will go up.

If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Chris Bloore directly:
Email: [email protected]
LinkedIn: https://www.linkedin.com/in/chrisbloore/

If you have questions about the contents of this or any other podcast episode, you can go to our ‘Questions from the Community’ page and submit a text message or video recording. We will then bring someone on to answer these questions in a future episode