17 Apr 2023

Combustible dust: Everything you need to know

Combustible Dust Dangers

Combustible dust, also known as explosive dust, refers to tiny particles that pose a risk of explosions – particularly in the workplace. If dust levels aren’t maintained to prevent this, they can cause fatal injuries, damage equipment, and can completely destroy buildings. We’re not trying to scare you, but rather warn that combustible dust is a very real and problematic issue if the right systems aren’t implemented.

If combustible dust is a new concept to you, then this guide will cover everything you need to know – including the causes of a combustible dust explosion, how to tell if dust is combustible, why you need dust control, and preventative measures to reduce the risk of a combustible dust explosion.

What is combustible dust?

As we touched on before, combustible dust consists of small particles. They’re so small, that they’re almost invisible to the human eye. When they’re exposed to certain conditions, are dispersed into the air, and ignited in some way, they can present an explosion risk and endanger workers’ lives. The likelihood of coming across combustible dust is common in workplaces that handle food processing, chemical manufacturing, pharmaceuticals, and coal mining. Industrial ventilation systems, whilst imperative for the proper circulation of air, need to be combined with other safety measures to reduce the risk of combustible dust explosions.

What is a combustible dust explosion?

A combustible dust explosion happens when fine particles of combustible materials, such as dust or powder, are dispersed in the air and ignited in some way. The concentration of the combustible dust in the air needs to be relatively high for it to explode, however, this depends on the type of material and dust particles present.

So how does a combustible dust explosion happen in the first place? In the right conditions, this can cause a rapid release of energy in the form of an explosion. These explosions can vary in size and severity, but ultimately, they’re incredibly hazardous, which is why dust and fume extraction is incredibly important as a preventative measure. Fabrication services, which provide high-integrity ductwork, are paramount for reducing dust and other pollutants in the air which could be combustible in high quantities.

Why is combustible dust a hazard?

As you can probably tell, combustible dust is a hazard for several reasons. Ultimately, the hazards associated with combustible dust emphasise the importance of proper handling, storage, and control measures to prevent explosions and protect workers from harm. Let’s dive into the various ways combustible dust can be a hazard in the workplace.

1. Combustible dust can cause explosions

Firstly, when enough combustible dust is dispersed into the air, it creates the conditions necessary for it to explode. This is incredibly dangerous, as it can endanger the lives of workers, and destroy equipment and even whole buildings if the explosion is big enough.

2. It’s a fire hazard

Leading on from the first point – combustible dust also poses its own fire hazard. So even if you’re lucky enough to not witness an explosion as a result of combustible dust, it can still catch fire. These fires can start with even the smallest spark, an open flame, or a hot surface.

3. It can cause respiratory issues

Combustible dust is one of the causes of respiratory problems in an industrial workplace setting. This is because dust of any kind can cause health concerns when inhaled, even if they aren’t ignited in some shape or form (such as wood dust exposure). As a result, combustible dust can exacerbate existing asthma symptoms, cause bronchitis, and even increase the risk of various lung diseases.

What is deflagration?

You may have heard the term deflagration when reading up on combustible dust explosions. While the two terms are similar, there are some key differences to be aware of.

Deflagrations, much like combustible dust explosions, involves the rapid release of energy. However, deflagrations typically involve explosions caused by gas or vapour. Combustible dust explosions, on the other hand, involve the combustion of tiny particles like dust and powders. Whilst deflagrations can occur under low-pressure environments and velocity, they should not be seen as “less serious”, as they can still cause significant damage, injury, and in some cases – death.

If deflagration is a concern in your workplace, consider looking into fume extraction solutions that can remove harmful fumes from your working environment.

What are the five elements of a combustible dust explosion?

For a combustible dust explosion to occur, several things have to happen – more specifically, five steps. If one or more of these steps are missing, then typically an explosion won’t occur. Therefore it’s important that all aspects of your workplace are secure enough to prevent any of these five elements from causing a combustible dust explosion.

Without further ado, here are the five elements of a combustible dust explosion.

1. Combustible dust

A significant abundance of combustible dust needs to be present in the air for it to be at dangerous levels for an explosion to occur. As we’ve previously mentioned though, this is highly dependent on the material in question.

2. Oxygen

 Oxygen is a key element for any explosion to happen. Although the air we breathe is made up of various gases, there is enough oxygen for most combustible dust explosions to occur.

3. An ignition source

Think open flames, sparks, cleaning equipment with harsh chemicals, hot surfaces, and the like.

4. Dispersion

Enough combustible dust must be in the air, usually in the form of a “cloud” and within a confined area. This allows it to create an explosive atmosphere when there’s a reaction with oxygen. Speaking of confined areas…

5. Confinement

Small spaces and confined areas where enough pressure can be built up for the explosion. This is why ventilation is key if the workspace where there’s a higher risk of combustible dust is present.

What materials cause combustible dust?

There’s a surprising number of materials that can cause combustible dust, including some you may not have thought about. Let’s look into some of the materials that can cause combustible dust to release into the air.

1. Organic materials

Organic materials like coal, starch, pollen, sugar, grains, cotton and similar can be sources of combustion. Even flour dust is dangerous and can be combustible, too. This is why agricultural industries have to have proper ventilation and systems in place to reduce the risk of a combustible dust explosion. Even processes such as transporting grain silos, sawmills, and workplaces in the textiles industry can lead to combustion, which in turn harms the environment and workers in the immediate area. 

2. Wood

Though technically an organic material, there are many ways to process and handle wood, some of which can cause combustible dust. These processes include sawing, planing, sanding, routing, and more. In terms of the potential for combustible dust caused by wood, it depends on the type of wood that is being processed. For example, hardwoods like oak, beech, and maple are generally more prone to producing combustible dust than softwoods like pine.

3. Metals

Various types of metals are potential sources of combustible dust. The metal has to be ground up into a powder-like form, in order for it to be fine enough to mix in with the air. Some of the more common combustible dust particles from metals include aluminium, magnesium, and zinc.

4. Chemicals

Commonly found in places where various types of chemicals are processed – it’s possible to see the likes of sulphur, coal, and plastics create combustible dust.

5. Textiles

Textiles like cotton, wool, acrylic, silk, and other synthetic fibres can cause combustible dust, as they’re known to be flammable. Some textile processes that can create combustible dust include weaving, spinning, cutting, sanding, polishing, and more.

6. Pharmaceuticals

Pharmaceutical manufacturing facilities can create combustible dust from medications and dust. This is done through a variety of processes such as dispensing, batching, blending, milling, and sampling.

7. Fossil fuels

Whilst mined to be combusted and create energy – coal and oils are also capable of producing combustible dust during the mining process which can be a danger to the employees, the workplace, and surrounding areas.

How do I know if dust is combustible?

Dust can be combustible if it is made up of flammable materials and is present in sufficient quantities and concentration. According to the Health and Safety Executive (HSE), “anything which can burn, and which exists in a fine powdered form, unless tests show that particular hazards are not present. In some cases, a very simple knowledge of chemistry can rule out the explosion risk, e.g. in the case of sand, cement, and sodium carbonate (soda ash).”

Even if your place of work provides clear guidelines on what does and doesn’t cause combustible dust – it can still pose a risk if it accumulates in large quantities. No matter what materials you’re handling, be sure to wear the appropriate protective equipment and have proper ventilation and dust control measures in place.

How to identify combustible dust in the workplace

By identifying what materials produce combustible dust (and dust in general), you can heavily reduce the risk of combustible dust explosions, health risks, and many other factors associated with it. 

Here are just a few ways to identify combustible dust.

1. Look for materials that produce dust

Identify combustible materials used in your workplace that are capable of producing combustible dust (and dust in general), such as wood, metals, plastics, and chemicals.

2. Check whether the dust is combustible

HSE UK guidelines surrounding the safe handling of combustible dust are free to download and highlight all the possible combustible materials.  It also provides advice for employers on where combustible dust may be present in the workplace too. 

3. Conduct an air sampling analysis

Conduct air sampling to measure the concentration of dust in the air within your place of work. Air sampling can help identify potential dust explosion hazards and determine if control measures are effective in reducing dust concentrations. With the results, you can determine where ductwork and industrial ventilation may be required.

4. Watch for warning signs

If dust is accumulating in a specific area, particularly from materials that produce combustible dust, you’ll need to report this and get the issue rectified. Look for further signs like fires, charred surfaces, and discolouration.

5. Perform these inspections regularly

By keeping a record of your dust inspections, you can gather data on how well your future preventative measures work (or don’t). This way you can make any changes necessary to create a safe and healthy environment free of combustible dust.

6. Consult with an expert

At Airmatic, we’re experts in all things extraction and ventilation. Our air extraction case studies speak for themselves, but we always recommend reaching out to the Airmatic team for further information and support on combustible dust solutions.

How to prevent a combustible dust explosion

To prevent combustible dust explosions, you need to identify and review sources of combustible dust to effectively implement control measures. This will ultimately reduce the risks of combustible dust explosions, as well as exposure to dust in the workplace. Here are some ways to prevent combustible dust explosions, with help from HSE guidelines.

1. Implement combustible dust control

Once you’ve followed the steps on how to identify combustible dust, you’ll need to implement proper dust collection systems. One of these ways is through dust extraction. Our industrial dust extraction system works by collecting dust particles from the air through a filter, and circulating purified air back into the immediate environment it’s placed in. This promotes a safer place to work and reduces dust particles in the air too. 

2. Provide combustible dust control training 

Employers should regularly provide training on dust and combustible dust control. This is especially important in environments where the risk of dust accumulation is higher. Be sure to document instructions on handling combustible materials, how to safely eradicate dust, potential hazards, places where dust is likely to accumulate, and how to handle combustible dust fires and explosions.

3. Use and maintain the right equipment

It’s advisable to use equipment and clothing that is designed to minimise the generation of dust and prevent ignition sources, such as spark-resistant tools and equipment. It’s also important to regularly review equipment and make changes where necessary to promote a safe working environment.

4. Monitor air quality in the workplace

We touched on conducting an air sampling analysis regularly – but what does this entail? To monitor air quality for combustible dust regularly, tests may include dust collection, lab analysis of samples, and visual inspections. Employers should conduct the most appropriate tests for air quality for their specific place of work to ensure they’re adhering to combustible dust maintenance guidelines. Besides implementing ventilation and extraction systems, you may want to explore on-site or off-site fabrication systems, that can also help ensure a safe working environment for those in manufacturing-based positions. 

5. Always follow safety regulations

All of the tips above should be followed on a regular basis, alongside additional safety regulations set by the workplace. This is to ensure your safety, as well as others, from combustible dust evolving into a combustible dust explosion. While there may be many steps, it could make all the difference in saving a life.

Looking for a dust extraction system that’s durable and built to last? Airmatic provides a host of solutions for a variety of sectors. Plus, if you need any maintenance, our team of highly trained extraction specialists are always ready to help. Contact Airmatic for air and dust extraction solutions today.

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