Reducing the Risk of Explosions in Flour Mills

Flour mills are the backbone of the American economy and an essential part of the agricultural industry.

These mills are responsible for breaking down the cereal grain obtained from wheat into flour quickly and at a low cost — but this poses a serious threat to labor and flour mills which we will discuss in this article.

Ever since the flour explosion of Washburn mill in 1878 that claimed 18 lives, the milling industry has worked tirelessly to develop preventative reforms. However, problems are still prevalent. For instance, despite numerous technological advancements, a recent grain mill explosion in South Sioux City, Nebraska claimed a life and decimated the structure.

What Causes Flour Mill Explosions?

Flour dust combined with factors like an ignition source, confined space, dispersion and oxygen are the main culprits behind flour dust explosions.

The process of flour production can create an environment where all these elements unite. As such, flour dust acts as a fuel source when mixed with oxygen which can result in a fire when confined in a limited space.

Is Flour Combustible?

So, can flour explode? As astonishing as it may sound, the fact is that flour dust is more explosive than gunpowder and 35 times more combustible than coal dust.

However, it is not explosive in small, non-dispersed quantities. For example, if you burn a small pile of flour sitting on top of your kitchen counter, it won't explode since it's not dispersed in a cloud-like form.

The case is different when dealing with airborne flour particles, as they have ample oxygen to fuel combustion. Combine that formula with multiple secondary dust sources in a confined space, add an ignition source, and you have a recipe for a chain reaction that could lead to an explosion.

Poor Operations at Flour Mills

Eliminating one of the five elements responsible for a flour dust explosion (dust, ignition source, confined space, dispersion and oxygen) will prevent this problem, but due to the operating environment in flour mills, eliminating any of these elements can be difficult.

Several ignition sources are at play in flour mills such as rubbing pulleys, static electricity and sparks from friction.

Plus, almost all flour mills have flour handling systems like transfer bins, bucket elevators, hammermills, headhouses and baghouses. These provide the required confinement and pressure, and ultimately, increase the risk of an explosion.

Risks Associated With Flour Dust

U.S. flour mills generated a revenue of $22.8 billion in 2019 and currently employ more than 22,532 people. With so much at stake, it's crucial to identify potential risks and hazards involved for the safety of both workers and the mill.

Following are some risks associated with flour mills:

Respiratory System Damage

Dust from flour mills can cause serious damage to the respiratory system as it contains various contaminants such as fungi, silica, bacterial endotoxins, mammalian debris and pesticides.

Flour processing produces airborne dust that is regularly inhaled by mill workers. This causes serious respiratory ailments like irritated rhinitis, wheezing, coughing, lung fibrosis and even asthma.

Suffocation is also a major issue that many workers experience; it is a major cause of death in storage bins. According to a report issued by Purdue University, 51 workers were buried under grain stored in bins, out of which only 25 survived, the most catastrophic incident on record in terms of the number of deaths. In other words, these bins act like quicksand for workers trying to walk in them.

Dust Explosions

Many people believe that since a mill has been running for years without an explosion or fire, it must be safe. Sadly, this is simply not true as combustible dust particles can accumulate anywhere and at any time.

Flour explosions are known to cause serious damage from worker casualties to the destruction of the facility. The explosions typically start in equipment like dryers, classifiers, mixers, conveyors and hoppers.

During the past 35 years, more than 500 incidents have been reported in flour mills across the U.S., which have caused more than 180 deaths and 675 injuries. This represents an accurate picture of how destructive exploding flour can be.

How to Mitigate Risks Related to Flour Dust

One key factor to prevent these risks is to stop the accumulation of dust in different areas of the mill(s). This is easier said than done; this process requires serious maintenance and dedication from everyone involved in the facility.

Here are some tips to reduce the risk of flour dust explosions and other health issues:

Preventative Maintenance – Ongoing Education and Training

Lack of preventative maintenance, poorly managed grain handling and conveyance equipment can cause an increased buildup of flour dust. Hence, one primary responsibility of safety supervisors is to educate all workers about the serious consequences of dust buildup and to ensure they are doing everything possible to mitigate these risks.

Elimination or Substitution of Hazards

This step involves the elimination or substitution of hazardous materials where possible. In other words, owners of flour mills and factories must decide if they can implement a process that uses or generates less flour dust.

Changing Work Policies

A major aspect of creating a safe and healthy work environment is changing the work policies to limit the risk of flour dust exposure or explosions.

For this, managers must create a written plan for controlling exposure, posting warning signs in and around the factory and improving the overall cleaning practices.

Building a Safer System – Physical Modifications

To further reduce the risk of flour dust explosions, it is important to make physical modifications to the equipment and factory.

For instance, factories are encouraged to improve their ventilation and install a dust extraction system. A major part of this is using a HEPA vacuum to efficiently clean up 99.8% of the combustible dust. In fact, as per safety code NFPA 654, factories should only use vacuums that are properly approved and certified for dust collection.

Using Vacuums to Eliminate Dust

An industrial vacuum is an ideal solution for cleaning out flour storage facilities and getting rid of accumulated dust. They are highly capable of minimizing the risk of flour mill fires while eliminating the hazards related to food safety.

Popular Types of Vacuums Used in Flour Mills

Specially designed for flour mills, these vacuums come in different sizes and are used for different applications.

Dust, Fumes Extractors

These are designed to eliminate dust, fumes and mist from different areas of flour mills.

Certified Explosion-Proof Industrial Vacuum Cleaners

They are built to work in hazardous zones and designed to prevent sparks, charge or any type of electric tension through special technical features.

Industrial Air Powered Vacuum Cleaners

With no moving mechanical parts, these are extremely durable and are used in flour mills to extract dust without providing an ignition source. Instead, they use compressed air to run, a power source easily found in flour facilities.

HafcoVac Vacuum Explosion-Proof Vacuums

Explosion-proof vacuums, like the HafcoVac Vacuum, that run on compressed air rather than a motor are necessary to eliminate the risk of static charge that can ignite a fire.

HafcoVac's intrinsically safe vacuums are ATEX Certified and are cleared for use in locations with excess dust or other combustible materials by the National Fire Protection Association (NFPA). They also meet OSHA's housekeeping standards.

These cost-effective vacuums are capable of running for an extended amount of time (with no motor to burn out) while maintaining high levels of suction. They are available in stainless steel, so they match the rest of your equipment.

If you need an industrial vacuum, contact us today. Our representatives can answer all of your questions and provide recommendations based on your specific requirements. You can even get same-day delivery, so you can get started right away protecting both your workers and your business.