Do you have a wood shop or a metalworking shop at your school? If so, then you also have combustible dust, which might be putting your students and even your school building at risk.

If it isn’t captured and contained properly, combustible dust can cause fires and explosions. In talking with education professionals, we’ve discovered that most of them are unaware of these risks, so they aren’t taking the necessary steps to mitigate them.

This article provides an overview of the following:

• What combustible dust is and the risks it poses
• Where combustible dusts are found in schools
• How to clean properly to eliminate combustible dust hazards

What is combustible dust?

Combustible dust is any fine material that can catch fire and explode if it becomes airborne and meets an ignition source. The trick is that just about any material can become combustible under the right conditions.

As a powerful illustration of this concept, watch this short video, that shows how common household powders like coffee, pepper and flour can create fires and explosions. (Nilfisk did not produce this video, nor do we recommend you try something like this at home.)

There are typically two parts to a combustible dust explosion:

• The primary explosion. This is what was demonstrated in the video — airborne dust meets a heat source and causes a small explosion. 
• The secondary explosion. This is the scary one. If an area is dusty, for example, if dust has accumulated on elevated surfaces like the tops of cabinets, the primary explosion can disturb that dust and cause it to become airborne. If this dust also ignites, it can generate an explosion big enough to level a building. That’s exactly what happened in one of the biggest dust explosions of all time — in 2008, a series of combustible dust explosions made their way through the Imperial Sugar Company facility in Georgia, killing 38 people and injuring another 14. In that case, the dust hazard was caused by another seemingly innocuous material: sugar.

Where are combustible dusts found in schools?

If you’re starting to worry about your teacher’s lounge going up in flames, put your mind at ease. Dust must accumulate to a certain level before it becomes a danger, and the sugar or powdered creamer in your cafeteria or breakroom probably won’t ever get there.

However, there are two areas where schools, particularly high schools and vocational schools, are likely to have combustible risks: wood shops and metalworking shops. 

Both wood dusts and metal dusts are highly combustible. They are such a concern that the National Fire Protection Agency has issued individual standards for each of these environments:

• NFPA 664: Standard for the Prevention of Fires and Explosions in Wood Processing and Woodworking Facilities
• NFPA 484: Standard for Combustible Metals

How to eliminate combustible dust hazards

Now for the good news! While combustible dust has the potential to be very dangerous, it’s also very easy to control: remove the dust and you eliminate the hazard.

And what’s the best way to remove the dust? Vacuuming!

However, there is one caveat —  not just any vacuum will do. 

Remember that combustible dust explosions happen when airborne dust meets  an ignition source. Standard vacuum cleaners, especially commercial shop-style vacs, should never be used to collect combustible dust because they can actually cause explosions by providing an ignition source: static electricity.

That’s why, another standard, NFPA 652: Standard on the Fundamentals of Combustible Dust, outlines requirements for vacuum cleaners used in these environments. They include:

• Vacuums must be constructed from conductive materials.
• Hoses must be conductive or static dissipative.
• All conductive components must be bonded and grounded.
• Dust-laden air must not pass through the fan or blower.

When cleaning equipment is designed according to these standards, it won’t accidentally cause the very disaster it’s meant to prevent.

We know this is a lot of information, and if you’re learning about combustible dust for the first time, it might be overwhelming. We’re here to help. Nilfisk makes a variety of vacuum cleaners that meet all of the  requirements for use in areas with combustible dust. For more information or if you’d like help finding a vacuum cleaner that meets your school’s needs, get in touch.