Combustible Dust Explosion

Summer is the season for outdoor events where music festivals, fun runs, concerts, and outdoor street festivals are happening almost every day using displays of colorful explosions to excite the crowd. Participants at color festivals, color parties and color running events throw colored powder at one another or watch colorful powders launched into the air filling the sky with clouds of brilliance.

These colored powders usually consist of a plant-based, non-toxic material made from food-grade cornstarch with an approved Federal Food, Drug, and Cosmetic Act (FD&C) dye. Even though these materials are considered safe, when released into the air, they can form a combustible dust cloud that can ignite into a fireball if an ignition source is present.

What is Combustible Dust?

According to the Occupational Safety and Health Administration (OSHA) and National Fire Protection Association (NFPA), combustible dusts are any finely divided solid material that presents an explosion hazard when suspended in air under certain conditions. The types of materials below, when finely ground into very small particles and dispersed into the air, can burn very rapidly or explode in the form of a large fireball. If the particles are the right size, in the right concentration (called the Minimum Explosive Concentration or MEC) and expose to an ignition source, there is a high probability a dust explosion or deflagration could occur.

  • Wood
  • Plastic
  • Metals such as Aluminum
  • Flour
  • Rubber
  • Chemicals dusts such as Sulphur
  • Sugar
  • Coal
 

In 2015, an outdoor festival at the Formosa Water Park in Taiwan proved to be a dangerous exposition when colored combustible dust found its way to an ignition source and thus ignited into a powerful explosion that injured more than 500 people in the crowd. To ensure crowd safety, event promoters need to follow strict guidelines and standards when it comes to these types of displays.

The Dust Explosion Pentagon

When looking at the Dust Explosion Pentagon it takes all five components to come together in order for a dust explosion to be possible. If we remove confinement the possibility of an explosion is removed, however, there is still the possibility of a large rapidly expanding fireball. In order to eliminate the risk posed by a fireball one or more of the remaining four components must be removed as well. Typically, this means removing the dust or removing potential ignition sources. The dust is the easiest to control if it can be eliminated or significantly reduced. Ignition sources can be more challenging to eliminate depending on the environment the dust cloud is dispersed in.

Understanding and Removing Ignition Sources

To ignite a dust cloud, the spark or open flame must have enough energy to initiate the fireball or explosion. This is known as the Minimum Ignition Energy (MIE). Cornstarch powder has a relatively low MIE. Remember rubbing your feet on the carpet and touching someone with your finger? This is enough energy to ignite a cornstarch dust cloud under the right conditions. Potential ignition sources could include the following:

  • Open flame or sparks  
  • Static electricity
  • Lighting
  • Electrical systems
  • Smoking 
  • Sabotage

Safety Precautions for Cornstarch

  • Review the Safety Data sheet to better understand the properties of cornstarch, specific warnings can be found that include:
    • Special firefighting procedures Avoid procedures which could cause dust cloud formations
    • Unusual fire & explosion hazards Product dust may form an explosive mixture with air. Avoid conditions which produce dust clouds
    • Conditions to avoid Practices which produce dust
  • Understand how much cornstarch dust is needed to create the MEC when in the form of a combustible dust cloud 1/84th of an inch of cornstarch dust on the floor of a 100 square foot room would be enough to create a combustible cloud when dispersed within this room. It doesn't take much!
  • Control or eliminate the dust as much as possible
  • Ensure there is no smoking near the area of the dust
  • Ensure that there are no pyrotechnics near the dust
  • Ensure there is no electrical devices that could cause an ignition near the dust
  • If electrical devices are used while a dust cloud is present ensure they are properly rated for use in a known hazardous area
  • Ensure any dust producing machinery are bonded and grounded to minimize static electrical discharge

All live events where crowds of people will congregate should have an emergency action plan. From concerts to community art fairs, it is critical to know what to do when a crisis happens and to have had many “dress rehearsals” to execute when necessary.

HUB Entertainment risk management offers a wide range of specialty services to assist clients in identifying risks, reducing hazard exposures, and addressing claims issues. Our Risk Services professionals will meet with you to discuss goals and objectives, and develop customized programs to address your needs and exceed your expectations.

Download this PDF and contact a HUB Entertainment Risk Advisor today for more information.