Powder and dust: a risky business

How to protect people and equipment from combustible dusts

By Claire Marchand

The dramatic incident at the Formosa Fun Coast, a water park in Taiwan, at the end of June was an extremely tragic but important reminder that dust explosions are real and that any activity that involves the use of powder or dust is potentially hazardous.

festival of colour in Taiwan During a "festival of colour" in Taiwan, coloured powder - corn starch - was sprayed over the party-goers, creating a very dense dust cloud

A thousand people gathered for a “festival of colour” – Colour Play Asia in Taiwan is said to be the largest in Asia – at the amusement park outside Taipei. As part of the entertainment during the event, coloured powder was sprayed over the party-goers, creating a very dense dust cloud over the stage and in the park area nearby. The powder was repeatedly blown into the air for beautiful special effects…until an explosion occurred. It is believed that the powder was ignited either by a cigarette or by the heat emanating from the powerful spotlights and an immense ball of fire very quickly engulfed the stage and ripped through the crowds, injuring more than 500 participants.

Why did it happen?

A publication by German-based company Stahl explains the mechanisms of a dust explosion:

“If a draft of air swirls up a layer of dust in a small area, the dust, along with oxygen, forms a combustible dust/air mix. If this mix is ignited by an ignition source, an explosion is triggered. The force of the resulting explosion swirls up more dust, which is in turn ignited. This process continues, and under some conditions chain reactions such as these sweep through entire buildings or facilities, destroying them.”

Many materials can become combustible under specific situations. Examples include:

  • agricultural products such as egg whites, powdered milk, corn starch, sugar, flour, grain, potato, rice, etc.
  • metals such as aluminium, bronze, magnesium, zinc, etc.
  • chemical dusts such as coal, sulphur, etc.
  • pharmaceuticals
  • pesticides
  • rubber
  • wood
  • textiles
  • plastics

In the Taiwan incident, the powder sprayed during the party was said to be corn starch.

A major risk factor

The large majority of industrial dusts are combustible, and dust explosions can occur in any enclosed area. Dust explosions are a frequent occurrence in underground coal mines, but they can happen in any location where powdered combustible material is present.

Even an extremely thin dust layer in a closed room is sufficient to trigger an explosion when the dust is swirled up and ignited.

Ignition sources for dusts include sparks from electrical or mechanical processes, arcs, open flames, ESD (electrostatic discharge), and electromagnetic waves among others.

Safe manufacturing processes

Because of the hazards associated with the presence of dusts, all equipment – electric cables and motors, enclosures, isolators and vents, lamps and switches, control systems and many, many more – used in manufacturing processes should have the relevant level of dust explosion protection. Failure to do so can result in major industrial accidents and have fatal consequences.

Through its standardization and conformity assessment work, the IEC has a solution for all sectors of industry that are operating in those hazardous environments. The Commission has been at the forefront of Ex standardization for many years, preparing International Standards and establishing a Conformity Assessment (CA) System that provides testing and certification for all types of Ex equipment and related services as well as personnel competence.

Specific requirements for explosive atmospheres

IEC Technical Committee (TC) 31: Equipment for explosive atmospheres, has a complete series of International Standards, IEC 60079, that cover all specific requirements for Ex equipment and systems, from general requirements to protection levels for apparatus used by all sectors that operate in hazardous environments, such as food processing, pharmaceuticals, sugar refineries, flour mills, grain silos as well as the paper and textile sectors.

TC 31 has also developed the IEC 61241 series of International Standards that focuses on electrical equipment in the presence of combustible dust.

How to ensure compliance and safety

To make sure that the equipment they purchase meets the very strict requirements specified in the IEC 60079 series of International Standards, as well as those put in place by national or regional regulations and legislation, the Ex industry can rely on IECEx, the IEC System for Certification to Standards Relating to Equipment for Use in Explosive Atmospheres for testing and certification.

An IECEx certificate provides clear proof of compliance with International Standards, an important assurance for anyone responsible for the safety of those working in such areas.

High level of safety for Ex workforce

To cover all safety aspects in Ex environments and to complement the Certified Equipment Scheme, IECEx has developed the IECEx Certification of Personnel Competence Scheme for assessing and certifying individuals working in potentially hazardous areas.

The IECEx Certificate of Personnel Competence (CoPC) provides independent proof that the certificate holder has the required qualifications and experience for working on electrical equipment located in hazardous areas and can implement IEC International Standards covering explosive atmospheres.

For the CoPC, competence is defined as "the ability to apply knowledge" rather than simply assessing knowledge. In this sense, the assessment of persons includes assessing their ability to perform certain Ex-related tasks.

A hard lesson to be learnt

Who would have thought that powder sprayed over a crowd in a water park could produce such an explosion and massive fire? It looks like that kind of entertainment had been performed many times before this fateful day in June that ended in tragedy. One can only hope that when planning future events, party organizers will remember what happened and won’t overlook the potential risks associated with the use of powder and dust.

festival of colour in Taiwan During a "festival of colour" in Taiwan, coloured powder - corn starch - was sprayed over the party-goers, creating a very dense dust cloud
The risk of dust explosion exists in the pharmaceutical industry The risk of explosion also exists in the pharmaceutical industry...
Grain storage silos ...and in silos for grain storage