DSS058: Firefighter Education in Combustible Dust Incident Response with Glen Saraduke

In this episode of the DustSafetyScience Podcast, we interview Glen Saraduke, owner of Saraduke Technical Services in Lakewood, Colorado, about firefighter education in combustible dust incident response.

Glen is a fire protection engineer (FPE) with over 20 years of experience. He is also a former firefighter and fire marshall. In his current role, he does code consulting, fire investigation, expert witness input, independent commissioning of fire systems, and related fire safety services, one of which is educating local fire departments on potential incident scenarios involving 3D printing systems.

In this episode, he answers the following questions:

How aware are fire departments about combustible dust hazards in 3D printing?
Does the process involve special firefighting challenges?
What are the hazards involved in 3D printing?
How can we better prepare firefighters to respond to dust fires and explosions?

How Aware are Fire Departments About Combustible Dust Hazards in 3D Printing?

Glen recalled that when he first became involved in the 3D printing environment three or four years ago, the fire authorities didn’t fully understand the process or the equipment, but they knew enough to get a fire protection engineer involved.

“It’s a complex process,” he said. “The 3D metal printing machines were relatively new and they’re actually changing as we speak. They started out a little more primitive, and a lot of the processes have been refined to reduce what I call the open powder time. And so the fire departments typically just weren’t aware of these machines.”

He pointed out that the printers were sold to clients who didn’t always tell the local authorities that they were installing the printer, so the only time the fire department saw one was when they were on an inspection. It’s a situation that he tries to change with his consulting business.

Does the Process Involve Special Firefighting Challenges?

Glen explained that fire suppression can be an issue with metals like aluminum and titanium. Normal sprinklers can’t be used with significant amounts of those powders because their reactivity produces hydrogen when they’re on fire, but firefighters are understandably cautious about removing sprinklers from a building.

3D printing machines should be installed in a non-combustible space so they can be allowed to burn out if necessary. They can also be suppressed by a Class D fire extinguisher. Firefighters remain uncomfortable with the technology but then again, it’s a relatively new one.

“It spans not just NFPA 484, but 652 and 654 and some other codes too, like NFPA 70,” Glen explained. “You also have to deal with all those questions like: is it a Class 2 Division 2 area? Are the machines made in Europe, where they have ATEX ratings? What’s the ATEX rating equivalent to? [I] help navigate all those things for the fire authorities and the building officials.”

He explained that the powder used in 3D printing tends to burn in one of two ways. The first is when a high-energy source ignites it and causes it to burn relatively slowly. The second is when it gets airborne and is presented with an ignition source. In both cases, you risk a flash fire and explosion.

In other industries, these accelerations have been caused by:

A backdraft when you cut a hole in the side of a hopper
Dust falling from rafters
Walls or equipment falling onto a dusty floor

On May 2, 2018, there was a large fire at a magnesium die-casting facility in Eaton Rapids, Michigan. A fire marshal was in the building when the sprinklers went off and triggered an explosion in the magnesium recycling chute. One employee was thrown against a door frame and broke his shoulder while another suffered severe lacerations.

“Somebody shooting an ABC extinguisher at a small powder fire on a 3D printer bed can create a catastrophic result,” Glen warned. “The other issue that’s not addressed well by the codes is argon on the metal printers.”

Dewar or bulk argon tanks are typically used outside a building to supply argon to these printers. The NFPA 69-compliant arrangement is to have a laser that’s inerted with argon do the welding inside the printer. However, the issue is that there are bulk argon pipes throughout the building supplying these printers.

“What we’ve recommended in the past, which isn’t a code requirement yet but is a policy in some cities, is that any time they’re using CO2 or nitrogen for plastic printers or argon, they want an A2 monitoring system,” Glen said. “Piping can pass through spaces that are not often accessed so that argon could sit there for quite a while if it leaks.”

These leaks could cause an asphyxiation hazard, an outcome that facility operators need to be more aware of.

What are the Hazards Involved in 3D Printing?

Glen stated that 3D printer manufacturers are moving toward the development of disposable particulate filters. These filters capture size-reduced particulate at the back of the machine. Aluminum and titanium powder is very sensitive to ignition and can spontaneously ignite.

At one time, machine operators used to try to clean the filters and fires resulted. While disposable filters are becoming more common, there are some metal printer manufacturers that still make reusable filters, which present an extra risk for firefighters.

Another consideration is the migration of powder over time. “We really try to stress to the clients that just straight code compliance is not always adequate, and that they really have to think about having dropped ceilings and gaskets and protecting electrical (sources) if they’re in the same room, just because we know from experience dust likes to migrate,” Glen said. “If you can’t get to it to see it or clean it, then it can create an issue later. So we really try hard to go a little conservative on how we protect from dust migration over degrees.”

The industry seems to be moving toward an enclosed filter on the back of the machine, which is under an argon blanket. When they remove the filter, they don’t clean it. They valve it off, so it’s constantly under that argon, even after it’s removed from the machine and placed in a storage area until it’s disposed of as hazardous materials.

“The other thing the industry (is addressing) is open powder time,” Glen explained. “In the past, they’ve used more manual methods to load powder and then clean the machine while having it open. So there’s quite a bit of time when it’s open.

“The newer machines have powder modules or some equivalent where the actual D.O.T. containers are inserted into the machine and are opened under argon. So really, you’re reducing that open powder time. That’s going to help a lot in terms of fire risk and lowering that chance of any issue.”

How Can We Better Prepare Firefighters to Respond to Dust Fires and Explosions?

Glen recommended that when 3D metal printers are installed, qualified and experienced fire protection engineers or SMEs be involved for the duration of the project. He also encouraged transparency and general education of local authorities and firefighters as the project progresses.

“You don’t want to just get the fire marshal in there to look at things. You really have to get the guys and women from fire stations to come out. We want to make sure they get their hands on the equipment and open up a machine so they can see what the powder bed looks like and where the powder is stored. So that’s important. And then, of course, any changes in materials or processes should be evaluated by the FPE and the fire department if necessary.”

Conclusion

Glen pointed out that the codes support and require an information exchange between fire authorities and equipment owners, but it doesn’t always happen. It’s a situation that has to change.

“I really try to stress that because I know I’m not going to be there when that incident happens. I want to make sure the firefighters know how to deal with it and limit damage and protect people.”

If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Glen Saraduke directly:
Email: [email protected]
LinkedIn: https://www.linkedin.com/in/glen-saraduke-cfei-pe-52b30010

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.