The Risk of Combustible Dust Explosions During Wood Flooring Manufacturing

Hardwood flooring. Homeowners like it for its durability, its warmth, and its handsome finishes. And like many modern-day amenities, hardwood flooring had humble beginnings.

Using old-growth forest trees for flooring began in the 1600s. Early American settlers who could afford to upgrade from dirt or stone installed unfinished planks on top of wooden joists. Wood was a far more comfortable and forgiving surface to stand on than its predecessors and held up well over time. It didn’t take long for solid wood became the most popular resource for domestic flooring in America.

The process of making flooring from hardwood trees hasn’t changed much since colonial times. The highest quality wood still has the tightest grain and fewest knots. A plank of wood is milled from a single piece of timber, dried, then sawed. After cutting, the wood is planed for smoothness – though some woods are subsequently distressed for an antiqued finish before being stained – then sealed for protection. Properly milled and installed, wood flooring can last for centuries.

But as with most manufactured products, there are potential indoor air quality (IAQ) and safety issues to consider. During the milling, sawing, and planing phases of hardwood manufacturing, a fine dust is created. While the presence of such small particulate matter may seem inconsequential, it is not. Wood dust is highly combustible; merely one spark can start a blaze.

For a fire to occur, rapid oxidation of materials must mix with heat or light and various fuel sources (1) as illustrated in the “Fire Triangle”:

Elements Of Fire
1. Combustible dust (fuel)
2. Ignition source (heat)
3. Oxygen in air (oxidizer)

In a typical incident, combustible material comes into contact with an ignition source, which causes a small fire. If there is nearby dust, the primary explosion will cause that dust to become airborne. Then, the dust cloud itself can ignite, causing a secondary explosion that will likely be many times the size and severity of the first. These secondary explosions have the potential to bring down entire facilities, cause vast damage, and in some cases, fatalities.

In addition, a Dust Explosion will occur when two more elements are added to the fire triangle:
4. Dispersion of dust particles in sufficient quantity and concentration
5. Confinement of the dust cloud

The potential for dust particulates to ignite and create a flash fire or explosion is a constant hazard in just about every industry. The reason is that just about everything, including wood, has the potential to be combustible when in dust form. Because they are solids, the dusts and powders that settle onto equipment, in passageways, and in nooks and crannies of a manufacturing plant, accumulate. When one particle ignites, the spark propels the settled dust back into the air where the flame from the initial fire then ignites the newly airborne material and causes successive explosions. The primary blast typically damages a limited area; secondary explosions tend to be much more devastating. (2)

Of course, not all fires cause loss and destruction. But occupational risk is present unless proper – and diligently monitored – control measures are employed. OSHA recommends the

Three C’s for fuel and dust fire avoidance (3):

Capture dust before it escapes into a work area by using properly designed, installed, approved, and maintained dust collection systems.
Contain dust within equipment, systems or rooms that are built and operated to safely handle combustible dust.
Clean work areas, overhead surfaces and concealed spaces frequently and thoroughly using safe housekeeping methods to remove combustible dusts not captured or contained.

Today, most businesses have specific industrial safety measures in place in order to avoid a fire or explosion. But such systems are only as good as the people who monitor them. Vigilance must be constant.

At AIRSInc,  we protect our customers in the wood flooring industry by capturing combustible dusts from their worksites using our stellar air cleaning products such as the DC-1000 Cyclone Dust Collector. Call us today for a free indoor air quality assessment from one of our skilled and experienced environmental specialists.