Dust Explosions in Flour Mills
December 12, 2022
Flour Processing Plant Engineering, Non Food Installation, Fabrications, Health & Safety
The risk of dust explosions, although relatively rare in the UK, is taken very seriously within the flour milling sector. When dust explosions do occur they can cause devastation, including injury and loss of life. Wherever there are large amounts of combustible dust, air/oxygen and an ignition source, there is always the potential for an explosion. In large amounts, the dust produced by flour and wheat products can be explosive. However research commissioned by UK Flour Millers suggests that flour is pretty low on the level of explosive dusts. UK Flour Millers use HSD Safety as its consultant, advising the industry on safe practice, needed research, legislation and standard.
Fire prevention is key in preventing dust explosions and UK Flour Millers also collects data from mills about fires they have had. They have also commissioned research into the factors which determine if a fire within the milling process is likely lead to an explosion.
Like many other carbohydrates, flour becomes explosive when its particles hang in the air as dust. Just 1 or 2 grams of dust per cubic foot of air can render the mixture ignitable, as tiny grains of flour burn instantly. If one grain ignites, it lights other grains nearby, creating a burning dust cloud with explosive force. More or less any carbohydrate dust such as flour, sugar, pudding mix, fine sawdust etc, can explode once ignited. If the flour has been mixed with wet ingredients though, you have nothing to worry about. Flour won’t explode on its own, unless you throw flour in the microwave, creating a cloud of dust, and quickly turning on the microwave. Don’t try this though, just take our word for it!
Where flour or other dusts exist in large quantities such as in processing plants, possible ignition sources must be eliminated. Risks include mechanical friction such as welding, grinding, electrostatic discharge, smoking, sparks, lighting and electrical equipment. Staff training and information and instruction for all staff should also be implemented. Vigilance and good housekeeping are of course always required in any setting, but especially where combustible dust is present.