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Flour Explosions in the Processing Industry: Understanding the Risks and Preventing Disaster

Although flour is a staple ingredient in the kitchen, it is a significant danger to the processing industry.

Companies can take several measures to prevent flour dust accumulation and explosions.

This can include proper maintenance and regular equipment inspection, the use of explosion-proof ATEX-rated equipment and proper employee training.

In this article, we’ll provide a brief overview of the dangers of flour explosions in the processing industry, their causes, and what you can do to prevent them.

Understanding Flour Explosions in the Processing Industry

Flour, when in dust form, can be a highly combustible material.

A flour explosion occurs when a cloud of flour dust particles in the air is ignited by a spark, flame, or another ignition source.

In the processing industry, where flour is often handled in large quantities, it’s common to see large clouds of flour dust in the open air.

This often makes it particularly susceptible to dust explosions and flash fires.

Why Materials in the Food Industry are Susceptible

Most ingredients that are used throughout the food industry including grain, sugar, artificial sweeteners, spices, and most powdered flavours, burn with difficulty as a powdered layer.

When formed as a dust cloud, however, these ingredients have the potential to ignite and cause an explosion when there is a sufficient ignition source present.

Although there are multiple factors that may affect explosion size or sensitivity (moisture content, cloud density and particle size), foodstuff dust explosions have the potential to be the most susceptible to catastrophic incidents.

In 2008, for example, a sugar refinery (USA) was evacuated, and production was suspended when a build-up of combustible dust caught fire.

This resulted in 14 fatalities, multiple injuries and major facility destruction.

In 2015, three explosions destroyed a flour mill killing four of its workers.

The Causes of a Flour/Dust Explosion

Several factors can contribute to the risk of flour/dust explosions.

Below are a few common causes that may result in the creation of an explosion:

  • Inadequate ventilation: flour dust accumulation will gather and form an explosive atmosphere.

  • Equipment that generates heat, static electricity or friction: this can create sparks that can ignite flour dust.

  • Human error: improper maintenance or failure to follow safety procedures can also increase the risk of flour explosions.

  • Poor housekeeping leading to high levels of dust deposits.

The Importance of Conducting Risk Assessments

During a risk assessment, there are multiple factors to consider.

This can include the flammable nature of the flour, the quantity of flour being handled, the ventilation system, the type of intrinsically safe equipment being used in potentially hazardous zones and the presence of ignition or heat sources used.

Based on the results of the process risk assessment, companies can implement appropriate control measures, such as improving ventilation, installing explosion-proof equipment extraction systems, and developing emergency response plans.

Understanding the explosive properties of different flour types

To prevent flour explosions in industrial settings, several process safety dust and powder tests can be carried out.

These tests help identify potential sources of ignition and determine the appropriate measures to prevent them, determine the explosive properties of flour dust and help to evaluate the risk of a potential explosion and understand the behaviour of flour dust under different conditions.

By conducting the below tests and implementing appropriate safety measures, the risk of flour explosions can be significantly reduced.

MEC - Minimum Explosive Concentration (MEC)

– Determines the minimum quantity of dust required, when dispersed, to form a flammable atmosphere.

MIE - Minimum Ignition Energy (MIE) (Capacitive & Inductive)

MIT - Minimum Ignition Temperature (MIT)

– Determines the sensitivity of a dispersed dust to ignition by hot surfaces.

Layer Ignition Temperature (LIT)

– Determines the sensitivity of a layered dust deposit to ignition by hot surfaces.

Pmax & Kst - 20L Explosion Severity

– Determines the resultant over pressure, rate of pressure rise and dust constant on ignition of a confined dispersed dust.

Learn more about Pmax & Kst here. 

Proper Ventilation in Preventing Flour Explosions

One of the most effective ways to prevent flour dust explosions in the processing industry is through proper ventilation.

Proper ventilation should be a priority in any processing plant that handles flour or other combustible materials.

There must be enough air exchange systems, such as fans, air ducts or local exhaust ventilation systems (LEVs) to keep air circulating and prevent the build-up of fine dust or powders.

In addition, it’s important to install air filters that can capture any other flour particles or combustible dusts.

Using Intrinsically Safe Equipment to Prevent Flour Explosions

Another component of preventing flour dust cloud explosions in industrial environments is the use of intrinsically safe equipment.

This equipment is designed for hazardous zones and will prevent sparks and other ignition sources from coming into contact with flour dust clouds.

ATEX-rated equipment with a suitable temperature class, for example, is specially designed to prevent the ignition of combustible dust or materials.

As an example, explosion-proof motors are designed with sealed housings to prevent sparks from escaping, while explosion-proof lighting fixtures are designed to prevent hot bulbs from coming into contact with flour dust particles.

Regular Maintenance to Prevent Flour Explosions

Regular maintenance is also critical in preventing flour explosions.

All equipment should be regularly inspected and serviced to ensure that it’s functioning correctly and not generating excessive heat or friction.

Equipment like mixers, conveyors bucket elevators, and elevators must be regularly inspected and maintained for any signs of wear or damage.

Bearings and seals should also be maintained to ensure that they are lubricated correctly.

By conducting regular maintenance, companies can identify and address any potential issues before they lead to a flour or explosion hazard.

Training Employees on Proper Safety Procedures

Employees must have full training on proper safety procedures to prevent flour explosions.

They should know how to identify potential hazards.

By providing proper training and training resources, companies can empower their employees to identify and mitigate potential risks and prevent any flour dust explosions from occurring.

It’s also important to train employees on emergency response procedures.

All employees should know how to evacuate the processing plant safely and should receive training on basic first aid procedures in case of injury.


Flour explosions are a serious risk in the processing industry, but they can be prevented with proper safety procedures.

Companies that work with flour should take the necessary measures to prevent flour explosions, including maintaining a clean and well-ventilated processing plant, using the correct explosion-proof equipment in potentially hazardous areas, conducting regular maintenance, and training employees on proper safety procedures.

By doing so, companies can reduce the risk of flour explosions and protect business, people, workplace and the environment.

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