pölyräjähdykseksi

Pölyräjähdys, also known as a dust explosion, is a rapid combustion of finely dispersed combustible dust particles in an enclosed space. This phenomenon requires several conditions to occur simultaneously: a combustible dust, sufficient oxygen, an ignition source, dispersion of dust in the air at a concentration within the explosive limits, and confinement. The dust particles, when suspended in air, present a significantly larger surface area compared to a bulk material, allowing for very rapid oxidation and heat release.

The process begins with an initial ignition, which heats a small amount of dust. This leads to the release of flammable gases through a process called "dust cloud combustion." These gases then ignite, creating a rapid expansion of pressure and heat. If this occurs in a confined space, such as a silo, hopper, or processing equipment, the pressure wave can be amplified. This initial explosion can disturb more settled dust, creating a secondary, and often much more destructive, explosion as the newly suspended dust also ignites.

Common materials that can cause dust explosions include organic dusts like flour, sugar, starch, wood dust, and coal dust, as well as some metallic dusts. Industries prone to dust explosions include agriculture, food processing, woodworking, metalworking, and chemical manufacturing. Prevention strategies focus on eliminating one or more of the required conditions, such as controlling dust accumulation through good housekeeping, using explosion-proof equipment, inerting the atmosphere in potentially hazardous areas, and implementing explosion venting or suppression systems.