Flour is a complex carbohydrate; it retains the flammable properties of the sugar in the glucose molecules found within. When flour is tightly crammed together, it won't explode. However; when a lot of air surrounds unpacked flour, such as in a flour mill, explosion is possible. Add this to my Recipe Box.
Dust
Explosion occurs when dispersed dust forms. If fire is introduced to flour dust, the flour pieces will burn. If a cloud of dust occurs and is big enough, a flash fire can occur inside the cloud of dust. This can cause an explosion. Explosions are more apt to occur in environments with large amounts of flour, such as in a flour mill or grain elevator, where significant clouds of grain dust or flour dust are present.
Combustible
Combustible dust is a particulate solid that presents a deflagration or fire hazard when suspended in the air, or in some other kind of oxidizing medium over a range of concentration, explains National Fire Protection Association. Materials that can form combustible dusts include food products like flour, grain, cocoa, maltodextrin, powdered milk, cellulose, starch and sugar.
Lower Explosive Limit
Grain dust is produced when grain, such as rice or flour, is moved. The more the grain is handled, the more dust that results. Every type of grain, and the dust it produces, has its own specific lower explosive limit. When this limit is exceeded, an explosion can occur. Rice has a lower explosive limit of 50, whereas soy flour's limit is 60, and wheat flour's limit is 50. The symbol for the lower explosive limit per specific dust is written as (g/m3).
Processing Grains
The processing of grains creates dust explosion hazards because the grain is ground into fine particles, which results in a flammable concentration that can't be avoided when large amounts of fine dust particles occur. Explosions happen when stones or metal produce sparks that can ignite material during the grinding part of the process. Fire is also possible when the moving parts of machinery break and result in sparks. When the flour is moved to another area, this can cause explosion because the materials that break free from the processing machinery, which settle on the floors beams and walls, can dry and form a dangerous layer of dust and potentially an explosion hazard.
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