If you did not watch Mythbusters religiously as I did, give the short video above a watch. It is an excellent demonstration of how a normally non-flammable material can become extremely combustible if the circumstances are right.
OSHA refers to this situation as combustible dust. The concept is that a material that is not typically combustible can become combustible if the particle size is very small and it is dispersed in air. The coffee creamer in the video from Mythbusters is a prime example of how non-combustible materials can become very combustible in the right conditions.
What is happening here is that by reducing the size of a solid material down to a fine powder or dust, you are increasing the surface area exponentially. Dispersing the dust into the air provides a lot of exposure to oxygen which is another ingredient needed for an explosion. The only thing you need now is a source of ignition like a spark or an open flame.
Shops dealing in plastic materials can be very dusty. Compounders are dealing with dusty regrind, ground mineral fillers and many finely ground additives. These can become airborne easily. Grinders or granulators also produce a lot of dust.
There are two primary things that can be done to prevent this. It is important to have ventilation systems that can remove this dust from your shop. Also, this is why it is important to keep a clean shop. Keep the floors clean, and make sure that spills are cleaned up. The best way is to use a floor cleaner regularly like the one in the picture to the right. We bought this one from Global Industrial. We affectionately refer to it as “the Zamboni”. It’s pretty easy to use and you can buy much bigger ones if you have a really large shop.
Although OSHA talks about combustible dust and many safety data sheets make mention of it, I could never really understand how this could happen. This particular episode of Mythbusters was a great illustration of how this works and how dangerous it actually is.