Explosion Protection & Process Safety

Combustible dust explosions

Dust can be created when materials are handled, transported, processed, ground, shaped, and polished. They can arise through crushing, mixing, sifting, or screening dry bulk materials. 

Combustible dusts are fine particles that present an explosion hazard when suspended in air under certain conditions.

Combustible dust explosions can cause tragic loss of life, injuries, and destruction of industrial buildings and occur within milliseconds.

In many incidents, workers and managers are unaware of the potential for dust explosions or fail to recognize the severe nature of dust explosion hazards.

Five elements to initiate a dust explosion

Five elements are necessary for a combustible dust explosion to occur: fuel (combustible dust), ignition source (heat), oxygen, dispersion, and confinement of the dust cloud.

Different approaches to protecting against the ravages of the explosion are regularly used to limit this damage.

Safety measures

Good housekeeping is an essential first step toward mitigating dust explosion hazards.

Other safety measures include:

• The use of proper dust collection systems and filters,
• The use of vacuum cleaners specifically approved (ATEX) for dust collection,
• Implementation of a hazardous dust control program that includes dust inspection, testing, and housekeeping,
• Regular review of both open and hidden areas for dust residue,
• Ensuring that employees are trained on the hazards of combustible dust.

Using proper electrical equipment in hazardous locations is crucial to eliminating familiar ignition sources. Other ways of controlling ignition sources include:

• Ensuring the use of appropriate electrical equipment and wiring methods,
• Keeping heated systems and surfaces away from combustible dust,
• Governing the use of open flames and static electricity,
• Having an ignition control program, such as grounding and bonding, and other methods dissipate any electrostatic charge that could be generated when transporting and handling dust.

Combustible dust explosion protection

The complexity of the processes that can lead to a dust explosion makes it challenging to assess the actual risks in dealing with combustible dust/air mixes. This makes flammable dust explosion protection very important. These are generally considered to mean avoiding or limiting the build-up of a hazardous explosive atmosphere. 

Dust explosion testing

Results of dust explosion testing can be used to determine the appropriate solutions to protect potential dust explosion hazard areas within facilities.

Dust explosion mitigation

Dust explosion mitigation systems can be categorized into two main types of technologies, being:

Passive safeguards: passive safeguards react to an event

Active safeguards: detect and respond before or during an event

By using passive, active, or a combination of both safeguards, a custom explosion protection solution can be designed to mitigate or prevent dust explosion hazards specific to particular process needs.

Explosion Protection Standards

Companies that manufacture explosion-proof equipment and systems for the global market must conform to applicable explosion protection standards.

ATEX

ATEX (ATmosphere EXplosibles – French for Explosive Atmospheres) is the formal name given to the two European Directives for controlling explosive atmospheres.

There are two European Directives in place for the control of explosive atmospheres: Directive 1999/92/EC (also known as 'ATEX 153' or the 'ATEX Workplace Directive')

Directive 2014/34/EU (also known as 'ATEX 114' or 'the ATEX Equipment Directive')

ATEX Certification

ATEX is the European certification given to equipment tested and approved to be intrinsically safe in potentially explosive atmospheres.

Equipment and protective systems intended for use in potentially explosive atmospheres (ATEX) cover a range of products, including those used in chemical plants, food manufacturing plants, flour mills, pharmaceutical production, and other areas where a potentially explosive atmosphere may be present.

ATEX is not harmonized with NFPA combustible dust standards and is not considered by OSHA an acceptable certification for electrical equipment used in hazardous locations.

Click here for more information about equipment for potentially explosive atmospheres (ATEX)

NFPA 652 - Standard on the Fundamentals of Combustible Dust

The National Fire Protection Association (NFPA) 652, Standard on the Fundamentals of Combustible Dusts, provides requirements for the management of combustible dust fire and explosion hazards and directs the user to appropriate NFPA industry or commodity-specific standards. The standard also ensures that crucial needs are addressed consistently across industries, processes, and dust types.

Click here for more information about NFPA 652 - Standard on the Fundamentals of Combustible Dust.

IECEx

IECEx is a global standard to ensure that explosion-proof equipment and systems are safe for use in countries participating in the IECEx system. To be validated against the IECEx Certified Equipment Scheme, manufacturers need to obtain the Certificate of Conformity (CoC), validation of the technical report (ExTR), and the quality assurance report (QAR).

Click here for more information about the IECEx system

Because combustible dust issues are complex and incidents can be devastating, it's essential to use experienced, independent, and professional engineers to help design and install powder handling systems.