Combustible Dust 101: Understanding the Hazard

_{This blog provides an outline of the dangers associated with Combustible dust and ways to reduce the risk.}

Industrial dust, or process dust, is pollution generated during the manufacturing and production process. These pollutants come in the form of gas, smoke and/or particular matter, and can harm both the environment and workers who come into contact with them.

Among the most dangerous types of dust is combustible dust, which can cause explosions and may result in employee injuries, deaths, and the destruction of entire buildings. More recently, on September 1, 2022, NBN News reported a massive grain terminal fire at an agribusiness in Carrington, Australia. The incident caught the attention of the public and the media as it posed a potential risk to both the workers and the residents in the area. According to reports, firefighters were on-site fighting the dust collector fire for almost 24 hours.

Prior to that, another incident recorded in May of 2018 was an explosion at a flour mill in Manildra, New South Wales where combustible dust played a role in the incident that injured one employee and forced 40 others to be evacuated.

What is Combustible Dust?

Combustible dust refers to particles of material that can readily ignite and explode while suspended in the air. Industrial processes like grinding, cutting, sanding or pulverizing materials can cause the formation of combustible dust in a variety of industries, including but not limited to: agriculture production, food processing, chemical production and mineral extraction.  

In order to combat the risk of combustible dust explosions, customers turn to companies like Airtight to provide well-engineered solutions. These solutions often come in the form of dust & fume control systems that work to ensure the safe removal of dust, mist, fumes, excess heat and other harmful particles/contaminants, to provide clean and safe working environments.

The Combustible Dust Culprit

Although many industrial processes can generate dust that has the potential to produce combustible fumes, two major factors to consider are the material itself and the size of the particulates (any dust less than 420 microns is considered combustible).

A general rule of thumb is that “if it grows, it blows”. In other words, if the material utilized in a particular manufacturing process comes from a natural or organic source, it is highly likely to be combustible. This applies to industries such as sawmills and timber processing, paper and textiles, agriculture, seed and grain, and food and beverage manufacturing, where particularly combustible ingredients include sugar, baking flour, spices, and flavoring materials. However, this rule of thumb is not exclusive, as fine particles of explosive material (such as aluminum, titanium, and chromium) are also produced in metalworking and welding.

Airtight’s Approach to Combustible Dust 

Airtight’s approach to combating combustible dust involves a methodology termed the hierarchy of controls. In the hierarchy, the most effective control is to eliminate the problem altogether. If possible, manufacturers are encouraged to substitute combustible materials with non-combustible ones. If elimination is not possible, as is often the case, Airtight engineers turn to isolating the problem and dealing with it mechanically via dust control and disposal systems that are uniquely tailored to the customer’s needs, both from a suitability and compliance perspective. 

Conditions For a Dust Explosion

Preventing combustible dust incidents requires manufacturers to identify and control the sources of combustible dust in their operations. In the identification process, five conditions must generally exist for an explosion to occur:

1. Combustible dust is present.
2. A sufficient concentration of combustible dust is suspended in a cloud. A sufficient concentration will depend on what the material is and/or how fine it is. In woodworking, for example, 50 grams of dust (about ½ a coffee cup) suspended in 1 cubic meter of air is considered sufficiently concentrated for an explosion.
3. There is a containment zone around the combustible dust. This “container” could be a machine, dust collector, room or even a building.
4. Oxygen is present (in factory environments, this is almost always the case).
5. A source of ignition is present. Typical ignition sources include electrical sparks, arc flames, hot surfaces (mechanical sparks), lightning, and electrostatic electricity & discharges (not visible to the human eye).

Key Questions to Understand and Address Combustible Dust Risks

When it comes to combustible dust, it may be difficult for the average customer to sort through technical data and resources. However, one simple question to ask is, “Could my dust be combustible?” Signs that indicate the need to contact a professional at Airtight include visible or noticeable dust, dust buildup on machinery, and the use of organic materials in manufacturing processes.

Explosion Venting Strategies

• Explosion Panels: When tailoring a dust extraction system to mitigate the risk of combustible dust explosions, Airtight engineers often utilize explosion panels – safety devices designed to protect personnel and equipment in the event of an explosion. The panels, made from a variety of materials (both metal and composite), are designed for different levels of pressure and temperature and are installed in particularly hazardous locations in order to mitigate the pressure and heat generated during combustion.
• Exclusion Zones: Also used are exclusion zones – restricted areas within industrial facilities where access is limited or prohibited to ensure the safety of personnel and equipment in the event of an explosion. These zones are typically established around particularly hazardous areas, like those with high voltage equipment, heavy machinery and/or hazardous materials.
• Flameless Venting: A third method of risk mitigation suggested to customers is flameless venting – a safety mechanism designed to prevent explosions that may occur due to the accumulation of flammable gasses or vapors in factory settings. These systems release the pressure and heat generated in an explosion in a controlled manner, preventing damage from spreading to other areas of the facility.
• Preventative Maintenance: To further reduce the chance of dust explosions, companies should regularly inspect and maintain their equipment and manufacturing facilities to ensure that they are free from accumulations of dust that could ignite or explode. 

Every facility has unique demands that may require customized solutions, such as establishing effective exclusion zones in limited spaces. The Airtight team collaborates to develop suitable, long-term advantageous solutions.

For assistance with combustible dust, reach out to one of our experienced team members at 1800 424 784 or visit airtight.com.au.