This video should be viewed in conjunction with training in combustible wood dust
hazard recognition and mitigation controls.
If employers train workers and supervisors to recognize and control the hazards associated with combustible wood dust,
what you are about to see doesn’t need to happen.
Whether you’re working in a sawmill or a wood shop,
there exists in every corner and every crevice a potentially explosive danger.
And it only takes a single spark to ignite.
Wood dust is a by-product of all types of wood manufacturing, and can range in size from large chips to very fine dust.
Regardless of its size, all wood dust is potentially combustible,
but it’s the fine wood dust that can become an explosive hazard.
What conditions are necessary to make fine wood dust explosive?
There must be an ignition source.
This could be as simple as a hot surface or a spark from an electrical device.
Then, the fine wood dust must be dispersed into the air.
This dispersion mixes the wood dust with oxygen— another ingredient necessary to cause an explosion.
The final ingredient is a fully or partially contained structure or building.
Without regular housekeeping, fine wood dust will spread and settle in corners, on rafters,
light fixtures, and ducting, as well as in and around electrical equipment,
such as fuse boxes and motors.
Combustible wood dust is so dangerous that a mere handful
can create a fireball that can engulf a worker.
While a single handful can be deadly, it is the chain reaction that follows that can cause massive destruction.
When the first explosion happens, an initial shock wave will disperse any dust in the immediate area.
This dispersion is critical, as it creates a process known as deflagration.
This new dust in the air will ignite, causing another explosion,
which in turn creates another shock wave, dislodging more dust.
This process causes an explosive fireball, moving faster and farther as it builds.
The fireball will travel outward, catching and igniting everything in its path.
Each consecutive explosion, although fractions of a second apart, amplifies the magnitude of the fireball,
exponentially gaining strength, size, and power as it travels through an enclosed area.
In a wood manufacturing plant where these conditions are present,
the destructive power is potentially enormous.
A combustible wood dust explosion can occur inside any work area that is fully or partially enclosed
or contained by walls, equipment, or other objects.
The key to preventing dust explosions is stopping combustible wood dust from accumulating
to hazardous levels, particularly in hidden areas and on hard-to-clean elevated surfaces.
These measures need to be supported by the controlling of all sources
that could ignite a fire or explosion.
For more information go to worksafebc.com