This article looks at the combustible nature of powdered food substances and how to prevent explosions.
The Danger of Ingredient Dust and Powder
One of the most overlooked aspects of working with ingredients in a food production facility, is the fact that some ingredients have the propensity to cause explosions. These substances include, for example, flour, sugar, dried milk, custard powder, instant coffee and soup powder. Common processes that can create explosive dust in the food industry are flour and provender milling, sugar grinding, spray drying of milk and storage of whole grains. Other processes include using finely sprayed oils, mixing with potable flammable solvents and certain sterilization techniques.
According to the Health and Safety Executive,
“If any combustible substance is mixed or suspended in air at the correct concentrations and contained in a vessel or building when ignition occurs, then a violent explosion can result. If it is uncontained then a fireball may occur.”
On 14th August 2015, a worker at Adams Foods in Leek, Staffordshire, suffered facial burns after a powder explosion. A spokesman for Adams Foods, which supplies ingredients to retailers, said,
“A member of staff working on the production line received minor injuries. Emergency services were called and the incident is now fully under control with all other production lines operating as normal.”
Fortunately, the injured worker was discharged after being treated at the Royal Stoke University Hospital. However, another similar incident could result in far more serious, and even life-threatening injuries. For more information on this story, click here.
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What Causes Powder Explosions
Powder explosions are caused by combustible powdered substances in the air, coming into contact with a source of heat.
The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) are concerned with preventing or limiting the instance and harmful effects of such explosions.
According to HSE,
“In DSEAR, an explosive atmosphere is defined as a mixture of dangerous substances with air, under atmospheric conditions, in the form of gases, vapours, mist or dust in which, after ignition has occurred, combustion spreads to the entire unburned mixture.”
Considerations When Working with Combustible Powders
In order to operate your process plant safely and to meet DSEAR requirements, you must take the appropriate precautions. These precautions relate to storage and handling, pneumatic conveying systems, chokes etc. To read the recommended precautions, please click here.
Another issue to consider is your ductwork, which can get clogged with extracted dust particles. As well as presenting a significant fire risk, a massive build-up of can dust can even cause ducting to rupture, as a manufacturer of morning foods found recently. Please see our case study for further details.
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