By Matt Shimansky
The most important thing to remember about firefighting is that extinguishing is the operative term. If you apply enough heat to any vehicle or fuel, it will burn regardless of fire extinguisher or fire extinguishing system. No fire-fighting system on board will be 100 percent effective at extinguishing fires 100 percent of the time – but the goal is to buy the bus driver or bus more time to evacuate passengers from the bus during an emergency evacuation.
There is a lot of work for drivers who evacuate riders after an accident, especially following an active fire. Driver is not expected to put out the fire himself – their priority is the riders. Firefighting works to give the driver as long as possible to evacuate the vehicle safely.
Advanced detection in technology
We advocate a nuanced approach to fire detection and extinguishing, mainly due to the status of the thermal protection service as the sole licensed distributor of Kidde Technologies fire extinguishing systems.
For dry ingredients, we suggest using the BC-grade Purple-K formula – a compound specific for Kidde – which completely coats a cell, and greatly reduces the chance of regeneration. The use of standard ABC dry chemical is also an industry-best practice.
What really sets one fire extinguishing system apart is the detection technology. Furthermore, identification technology can be rated according to the budget and needs of a transit agency or a road operator.
At the top end of detection technology is a dual-band infrared optical sensor. Developed for the United States Army, this “smart eye” sensor has an average detection rate of less than one second. The eye is a reset sensor with an LED display for easy confirmation of system operation. We have seen more and more commercial land vehicles opt for this level of fire detection in recent years.
Another available sensor is called an armored linear thermal detector (LTD). It is a wire covered in a stainless steel casing, with a built-in melting point. When it detects a certain level of heat, the wire melts and activates the fire extinguishing system.
Below these, operators can also opt for a standard LTD at a lower price due to the lack of a steel casing – or even more affordable spot thermal detectors, which focus entirely on spot heat detection.
In many cases, an effective fire extinguishing system may put out a fire before it actually begins. If the infrared sensor detects the fire in less than one second, there is a chance that the operator will have no idea that even a fire has occurred. But even if you have a slower detector in the vehicle, and the fire does cause damage to the propulsion system, then we are still buying the operator time to stop the bus and evacuate passengers.
Dealing with new electrical systems
The advent of electric vehicles (EVs) is so new that data is still being collected on the best methods to combat lithium-ion battery fires. The most important component in these fires is the monitoring of the cells and their temperature.
Ideally, the best way to detect a battery fire is to monitor the inside of the battery box. However, due to proprietary information, battery manufacturers do not currently allow this level of detection. The next best way to detect these fires is to monitor the outside of the cell and provide extinguishing material to that outside and all remaining systems. For now, this is the best method we have found for detecting and suppressing these fires.
A preferred system should include 24/7 self-monitoring capabilities. Therefore, if there is ever a problem with the system, there will be an audible and visual alarm. In these cases, the system should require zero output from the driver.
In other cases, some agencies or operators may prefer a manual unload button. For such systems, the agent will disassemble automatically as well after the driver presses a button.
Initiated fire safety is key
In an ideal world, buses do not just catch fire – fires arise due to other mitigating problems. Therefore, preventative maintenance (PM) is first and foremost in initiated fire safety. Oil leaks, exhaust leaks or loose belts and hoses can all contribute to a car fire. If you stay in PM tracking, then you can feel confident in the remote monitoring and detection that are in your fire extinguishing system – which usually only requires a six-month visual inspection and a six-year bottle service.
Matt Shimansky He is the Chief Operating Officer of the Thermal Protection Services (TPS). TPS is the only licensed distributor of Kidde Technologies commercial off-road vehicle parts, off-road service, technical support and warranty, and customer training in North America. visit www.thermalprotectionservices.com Learn more.