Equipment Compliance & Combustible Dust Explosions

Published 05 Apr 2022

Combustible Dust Explosions | Reducing Risk & Managing Workplace

Reducing Risk

& Managing Workplace Safety 

Do you work with industrial processes or manufacturing applications where there is a risk of explosion due to the presence of combustible dusts?

If so, you should be aware of the legal requirement to use correctly certified Hazardous Area Electrical & Lighting Equipment which is appropriate for use in these potentially explosive dust atmospheres and environments.

Dust explosions can have catastrophic consequences as the initial shock wave resulting from the explosion kicks up more dust triggering a chain reaction throughout the plant, often resulting in mass destruction to buildings and possible death or injury to employees.

A dust explosion requires 3 basic inputs: air, combustible dust and an ignition source such as an electrical spark or a hot surface – other factors that determine explosion intensity include particle size, cloud density or moisture content.

Both worker and workplace are at risk – specific legal requirements, namely Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR), stipulate the obligation for systematic identification and control of ignition sources. DSEAR requires all workplaces where substances that could give rise to fire or explosion are handled or stored must be fully assessed and protected.

Here are some ignition risk processes:

  • Most solid organic materials (such as wood, flour, grass, paper and cereals)
  •  Many powdered metals (such as aluminium, magnesium and titanium)
  •  Certain non-metallic inorganic materials (although less common)

Selection of Equipment

Thorne & Derrick, Experts in Equipment for Explosive Atmospheres, specify, design and supply safe products to guarantee Light, Heat, Power & Ventilation in potentially combustible dust atmospheres. Combustible dust atmospheres are classified into hazardous area zones with associated equipment categories determined on the basis of the frequency and duration of the occurrence of an explosive atmosphere.

Zone 20 A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, or for long periods or frequently.

Zone 21 A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally.

Zone 22 A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

We supply an extensive range of ATEX Dust Atmosphere Equipment:

Panels | Plugs | Isolators | Enclosures | Lighting | Control Stations | Motor Starters | Heat Trace | Gas Detection | Flame Detection | Process Instrumentation | Process Heating | Fans | Security Locking & Access Control 


Thorne & Derrick can overcome process and space heating challenges to achieve consistent, optimised and reliable production both in safe/industrial and hazardous area zoned locations.

The EXHEAT FWD flameproof air warmer provides worker comfort heating for use in work or storage areas with versatile horizontal floor or wall mounting options – the ATEX Certification is inclusive of Zone 21 or 22 (IIIA, IIIB, IIIC) Dust Group and the electric heater range emits powerful airflow and output 500W to 2kW. The EXHEAT FWD-T features an integral easy to adjust external thermostat Zone 21 or 22 (IIIA, IIIB, IIIC) dust group.







The EXHEAT FLR range of liquid filled electrically heated radiators are floor mounted and complete with an externally adjustable room control thermostat (0 to 25°C).

The radiators are certified for use in hazardous areas where the explosive atmosphere is classified as Zone 21 or 22 (IIIA, IIIB, IIIC) Dust Group – the standard heater ratings are 1kW, 2kW and 3kW.

Customisation as Standard 

Dust-like and powdered substances are either processed or a by-product of the production processes frequently found in the food and beverage industry. pose an ignition source or explosion hazard

Whether your plant and equipment requires defence against cold-weather impacts as part of a Winterisation System or general all-year-round process temperature or space heating requirements, we can help.

For instance in the food and beverage sector we can provide products to deliver assured and consistent heating for bulk stored products that can be at risk of crystallisation when subject to low ambient temperatures – viscosity maintenance, mixing separation of sensitive fluids, extraction and refining to provide accelerated heat-up. Recent applications include drums storing honey, corn sugar, palm oil and molasses.

Thorne & Derrick can innovate and custom-design flexible silicone heaters that can be applied to heat the most complex shapes, geometries, curves and pipes.


Portable & Temporary Heating

MFH ‘The Bulldog’

Designed for compactness and portability, the EXHEAT MFH Bulldog electric heater, provides localised and targeted heating where combustible dust explosion hazards stipulate the requirement for correctly ATEX certified heaters to meet the requirements of DSEAR: typical explosion hazard applications could include agricultural, carbonaceous, plastic, chemical and metal dusts.


The Bulldog combines efficient design with simple functionality to provide a portable heating solution for use in hazardous environments where the atmosphere is classified as Zone 1/2 (IIB+H2) or Zone 21/22 (IIIC) – Bulldog comes ready to ‘plug and play’ with the option of fitting a plug, or hard wiring to an isolator unit. The Bulldog heater can be used with or without ducting to provide a warm stream of air that can be felt metres away, even in ambient temperatures as low as -40°C and up to +40°C.

For further information see portable ATEX heater, or to discuss a specific application please do not hesitate to contact us.

Customer Service Excellence

Thorne & Derrick International, based in the UK, were voted Winners of the Award for ‘Best Customer Service’ at the annual HazardEx Gala Dinner on 6th October 2021. The competitive Award category at the prestigious event was for providing excellent customer service over the last two years.

Terry McDonald said, “It was an honour to collect the award for Excellence in Customer Service on behalf of Thorne & Derrick – we have a robust reputation for supporting our customers with the replacement and upgrade of end-of-life equipment to deliver significant operational safety and process improvements to their project or plant.

Customer Service | Hazardous Area Electrical Equipment


Switching-off & Switching-out

The SPARTAN range of LED Technology lighting for hazardous areas manufactured in the UK by Raytec and stocked by Thorne & Derrick provided sustainable, energy efficient lighting with carbon footprint reductions – upgrading from conventional SON to modern LED technology will significantly reduce annual energy consumption and lower carbon emissions. The LED lights will also lower light pollution and reduce maintenance costs – talk to us about your requirements for Zone 21/22 explosive atmosphere lighting.

Specifically, the SPARTAN range of lighting is designed to be mounted at height in applications such as grain, flour and sugar storage warehouses, as well as processing facilities or any other location where a combustible dust hazard is present. Using Raytec’s field-proven, long-life LED technology SPARTAN luminaires are ATEX and IEC Ex approved for all Zone 21 applications with a Food Safe option.

Read our Case Study to learn how Thorne & Derrick working with the Electrical Design & DSEAR Consultant specified and supplied a Zone 21 lighting system to a UK university.

Floodlights | ATEX Certified Zone 1 & 2 | Zone 21 & 22


The SPARTAN range of ATEX Certified lighting manufactured by Raytec is designed for lighting hazardous areas which require high performance, high reliability, energy-efficient brilliant “White-Light” illumination using latest LED technology.

Linear Light Fittings | Floodlights | ATEX Certified Zone 1 & 2 | Zone 21 & 22

Linear Light Fittings

Hazardous Area Lighting Design

Biomass Focus

Biomass power is electricity generated using plant-based fuels – this can include wood pellets and wood chips, bioenergy crops or even agricultural and domestic waste. As a result, biomass is Britain’s second biggest source of renewable electricity. The Climate Change Committee believes sustainably sourced bioenergy could provide up to 15% of the UK’s primary energy by 2050, and has said that “sustainable bioenergy is essential for reaching Net Zero”. However, biomass is an inherently dangerous material possessing significant fire and explosion hazards. The increasing scale of biomass use brings several challenges, especially where the scale of installations significantly exceeds the scope of any previous installation in terms of size.

Compliance with current standards does not necessarily mean that the installation is “safe” and a risk based approach is required to ensure that the level of risk to personnel is reduced to a level that is As Low As Reasonably Practicable. Further detailed information about Fire and Explosion Hazards in the Biomass Industries can be found by downloading the Hazards 26 IchemE 2016 article here.

Thorne & Derrick can support, specify and supply Hazardous Area Electrical & Process Instrumentation Equipment to ensure process plant safety in the biomass sector of the electricity generation industry where Zone 21/22 potentially explosive atmospheres are present. 

Kent Renewable Energy Biomass Plant  | the power plant generates 27MW of renewable electricity using locally sourced wood as fuel, which is the equivalent of supplying 50,000 homes and saving over 100,000 tons of CO2 every year. 

Hazardous Area Electrical Heating

Image: Estover Energy Ltd

Learn More | CSB Safety Video: Anatomy of a Disaster

On February 7, 2008, a huge explosion and fire occurred at the Imperial Sugar refinery northwest of Savannah, Georgia, causing 14 deaths and injuring 38 others, including 14 with serious and life-threatening burns – the dust explosion was fuelled by massive accumulations of combustible sugar dust throughout the packaging building. Should you require assistance with the correctly certified products to provide safe working operation at your plant please do not hesitate to contact us.



Thorne & Derrick are leaders in the development and distribution of Product Innovations that deliver significant improvements to clients plant, people and operational safety in the explosive atmosphere industries.

Your proactive problem solvers experienced in succession planning for the replacement of obsolete, non-conformant and legacy equipment in hazardous areas.

Your first-choice provider of innovative and competitive solutions to ensure ATEX & IECEx Compliance for Hazardous Area Electrical & Process Instrumentation Equipment to UK and international projects.

Hazardous Area Electrical Equipment


Further Reading