Buses Fires - why suppression duration is critical
Kristian Bischoff
CEO & Director at United Safety & Survivability Corporation Australia
The attached video shows a DCP Powder system failure on a single decker bus that then engulfs the bus with panic of passengers attempting to evacuate the bus. How would this bus fire go in a tunnel?
Worldwide there have been dozens of deaths on bus fires, especially double deckers with passengers trapped upstairs.
With up to 100 passengers onboard double decker buses and up to 70 passengers on single decker buses, when selecting a fire system to suppress a fire, duration is one of the most critical items under AS5062-2016 for risk assessment. Whilst many systems may pass P Mark certification, in assessing risk of evacuation of occupants, buses have the highest risk to loss of life and therefore extended duration is critical. The Fogmaker watermist system is therefore the primary choice Firestorm assessed the risk on allowing 40 to 90 seconds discharge duration to safely evacuate passengers as studies have shown 25 - 90 seconds to evacuate buses and this is without duress, elderly passengers, disabled or children potentially impacting evacuation.
Other items for consideration does the fire product remove oxygen, provide cooling and cover material? DCP Powder disrupts this but is prone to reflash, cause corrosion and also create messy cleanups whilst possibly restricting vision and impairing other vehicles. Watermist attacks all 3 side of the fire triangle.
Firestorm installs DCP Powder on many mobile machines across Australia, however always recommends a foam cooling agent or water mist as DCP offers no cooling properties
Finally electric buses are on their way, Fogmaker provides cooling of batteries and suppression that no other product can reach to allow safe evacuation.
District Life Safety Support Leader at CertaSite
5 年That’s what I was thinking and I’m glad to hear you’re already doing something about it with such a great result. Life safety improved immensely once integrated. Thanks for the dedication and raising the bar.
With respect, while duration may be a critical component, fast effective detection and suppression play at least an equal role. While dry chemical powders may not provide the same cooling mechanism as a water mist, they have been shown to prevent reflash for a minimum of 45 seconds per the standard, and moreover many have continued to prevent it past the 2 minute mark that concludes the test. Moreover, they have been demonstrated to be effective against hidden fires where the fire location was not in direct line of a suppression nozzle, and in high load high airflow scenarios, again a task no water mist was able to complete. When evaluating performance all factors should be considered when evaluating the overall performance. With DCP achieving perfect scores of 10:10 point for most manufacturers, and water mist at best achieving 7 across the many systems evaluated, I’d humbly suggest that simply basing a decision on discharge time may be shortsighted. As part of a system evaluation, a prudent step is to ask for the certification, which will include the test results. While passing is a 6/10, that means simply the system was not demonstrated to be effective against 40 percent of the fire scenarios. Is that enough?