In today’s episode of the Dust Safety Science podcast, Niels Pedersen, Senior Application Engineer at Nederman in North Carolina, answers questions about enclosureless dust collectors. This episode is based on an ‘Ask Me Anything’ session held in the Dust Safety Academy on October 8, 2020.
Having worked at Nederman for over 15 years, Niels is an expert in combustible dust, enclosureless dust collectors, and dust collection systems. He’s also a principal member of NFPA 652 and 654 who has presented on these NFPA standards before on applications and designs at the digital Dust Safety Conference.
In this episode, Niels provides an honest and open opinion on when enclosureless dust collectors should and shouldn’t be used and answers some related questions. Next week on the podcast, we’re going to cover the second half of this “Ask Me Anything” session.
What is an Enclosureless Dust Collector?
Niels explained that the unenclosed section of these dust collectors is the filter media. There are containers that receive the dust but the actual filter media is not enclosed, so dust must accumulate on its inside. Typically, the enclosureless dust collector has a frame copied directly to the plenum of the system.
There are two configurations. With one, the inlet plenum is below the bags. The bag is held in place upright from a simple structure without any sides. Another design has a plenum at the top and the collection bags and filter media hanging down from it.
What Industries Use These Dust Collectors?
Enclosureless dust collectors have a maximum size capacity of 5000 CFM, so it is meant to handle smaller applications, smaller flows and preferably larger chips (in woodworking). It was developed to ensure combustible dust safety in smaller operations and eventually added to NFPA 654.
“With any of the applications where you’re using an enclosureless dust collector, you cannot hook it up to machines that develop sparks or are likely to develop sparks,” Niels says. “So that means any kind of metals, any kind of grinding, anything that potentially can generate sparks, should never be used. And it specifically outlined that sanders, and abrasive planers should not be used.”
NFPA 654 also specifies a limitation of 10 kilograms or 22 pounds of dust to be collected in the collector at any time, and they will have to be emptied any time this limit is reached, which affects its suitability for production lines.
Regarding placement concerns, Niels said that it depended on the design of the dust collector.
“If it starts enclosing on three sides, we start getting in trouble. (If you’re) putting it in the corner, I don’t know how much that really practically does because you’re dealing with a small amount of flow, and a smaller amount of combustible materials are accumulating.”
The regulation does say that the collector must be placed 20 feet from any place (that is) normally occupied. This means that iit must be this distance away from a saw or machine operator. If there is more than one collector, they must also be 20 feet apart.
Do These Dust Collectors Present Health / Breathability Challenges?
Niels pointed out that one of the other requirements for an enclosureless dust collector is that it cannot have a shakedown mechanism. This essentially means that there’s some amount of dust building up on the inside of the bags.
“Typically, it is not really that much. But it is a good thing that you have a dust cake on the inside because [the filter] needs a certain amount of dust to build up on the inside in order to assist the capturing of the fine particles that eventually agglomerate on it. This dust will fall off by itself, even without shaking.”
Niels added that the fans in these dust collectors are so low energy that they are unlikely to cause any fire.
“You have to have a certain amount of energy. When we’re talking sparks, it’s multiple sparks that have to be generated in order to actually generate enough energy to even initiate the fire.”
He pointed out that it’s more of a design question than a rating question.
“You have A, B, C. So generally, a “C” fan is one that has maybe provisions for that no-metal touch, a “B” fan has maybe a sparkless wheel for its aluminum wheel. And then, the “A” fan is totally sparkless. Basically, I think it is calling for a “B” style fan.”
Conclusion
Although this episode is over two years old and both technology and requirements may have changed since it originally aired, it confirms that when used for the right application, an enclosureless dust collector can add an invaluable measure of safety in an environment that might otherwise be extremely dangerous.
Be sure to check out Part Two of this two-part series on enclosureless dust collectors next week!
If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Niels Pederson directly:
LinkedIn: https://www.linkedin.com/in/niels-pedersen-1708664
Website: http://www.nfpa.org/
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.
Resources mentioned
Dust Safety Science
Combustible Dust Incident Database
Dust Safety Science Podcast
Questions from the Community
Dust Safety Academy
Dust Safety Professionals
Dust Safety Share
Companies
Nederman
Organizations
NFPA
Standards
NFPA 652
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