Flashover

As a follow-up to yesterdays post, today I wanted to discuss what flame retardants do, and why they are beneficial and controversial. Before you read this post, it might be helpful to watch the movie Backdraft, or the first season of Rescue Me, as they each do a great job of depicting what it is like inside a fire, and highlight the very real danger they present (in a pinch you could watch Ladder 49, or Third Watch, I just don’t find them to be as good). As mentioned yesterday, flame retardants act to slow the spread of fire, mainly they increase the time to flashover. Flashover is the point at which temperatures get so hot that everything in the room bursts into flames. The incorporation of flame retardants increases the time to flashover, by some estimates up to 8 minutes.

Progression of a fire without flame retardants (red) and with flame retardants (blue).

While that may not seem like a lot of time, in a fire every second counts, and those extra minutes might be the difference between life and death. In fact after the August 2nd, 2005 plane crash at Toronto’s Pearson Airport, where an AirFrance airbus carrying 309 passengers, burst into flames, yet everyone managed to escape, flame retardants were credited with giving the flight crew the few extra minutes needed to ensure everyone got off the plane safely.

In addition to their use in the transportation sector, flame retardants are also heavily used in the household. In the United States, a total of 3 010 civilian fire related deaths occurred in 2009, 85% of which were in the home. The major causes of home fires include cooking equipment (40%), heating equipment (18%), electrical distribution and lighting equipment (6%), intentional (5%), candles (4%), smoking materials (4%) and playing with heat source (2%). The risk of dying in a fire increases with certain factors, both modifiable and non-modifiable. Modifiable risk factors include place of residence, type of residence, smoking, alcohol use, and lack of safety measures (smoke detectors, telephones and adequate number of exits). Non-modifiable risk factors that increase the likelihood of injury or death in a fire include young age, old age, male gender, non-white race, low income, and disability. Great efforts have been undertaken to improve the fire safety of homes in light of the number of injuries and deaths that result in the home each year. Public awareness campaigns to reduce smoking, and increase use of smoke detectors have contributed greatly to reducing the number of fire related deaths. Flammability standards and regulations for household products have also been successful in reducing the number of fire related deaths. The practice of incorporating flame retardants into materials is one method that has been employed to improve public safety. Flame retardants are incorporated into ignition-prone parts of electrical equipment and appliances, especially wiring; circuit boards and plastic cabinets; synthetic textiles like nylon and polyester used in upholstery and curtains; and cushioning, like polyurethane. These products have a  relatively high probability of accidental ignition, which left unchecked could result in flashover. So you would think that the incorporation of flame retardants would be universally hailed as a great improvement to human life, but that is not the case. The ubiquitous use of flame retardants has led to them being detected in almost every compartment of the environment, and indeed in humans as well. And there will be more on that later.

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2 thoughts on “Flashover

  1. Pingback: Retarding Flame Retardants | On a Quasi-Related Note

  2. Pingback: Reflections on the 6th International Symposium on Flame Retardants | On a Quasi-Related Note

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