ROTAREX Compact Line and ABC Powder systems

Engine Fire Suppression Systems in Commercial Vehicles

Vehicle engine fire suppression systems have been available in the UAE for more than a decade but have not seen widespread adoption due to lack of regulations.

Statistics indicate that 60–70% of vehicle fires originate in the engine compartment and surrounding areas where temperatures are high and combustible materials are installed. Engine fires can cause extensive damage to vehicles, and in many cases, claim lives. The first line of response in case of such fire incidents is a vehicle suppression system working in combination with a fire detection system. A reliable fire suppression system could extinguish a fire in the engine compartment within 4–5 seconds.

Currently, all public transport buses in the UAE have fire suppression systems installed in their engine compartments. The Roads and Transport Authority (RTA) in Dubai and Department of Transport (DOT) in Abu Dhabi have their own specifications for procurement of public transport buses with engine fire suppression systems.

The first time a regulation was introduced in the UAE for private transport fire suppression systems was for school buses in 2009, when the RTA specified in its School Transport Manual that all 2009 school bus models operating in Dubai were required to have fire suppression systems. Within the next two years, the DOT (Department of Transportation) introduced a similar regulation for school buses operating in Abu Dhabi. The other Emirates have adopted fire suppression systems as part of their safety guidelines and best practices but have not yet enforced regulations.

Swaidan Trading Company, one of the largest distributors of buses in the UAE representing brands such as Ashok Leyland, Sunwin, Optare and VDL, was among the first companies to supply school buses with inbuilt fire suppression systems. Since 2009, the distributor has delivered over 6,000 Ashok Leyland and Sunwin school buses with fire suppression systems in the UAE, mainly to large fleet operators such as Emirates Transport and School Transport Services. The school buses have both front-engine and rear-engine configurations; while Sunwin supplies rear-engine buses, Ashok Leyland supplies front-engine buses in the UAE.

Harris Kaladi, general manager, commercial vehicles and heavy equipment division, Swaidan Trading Company, says: “Fire suppression systems are crucial for passenger safety. In the case mild fires, it’s possible to evacuate passengers and minimize vehicle damage. When fires occur due to collisions making it difficult or impossible for passengers to evacuate from the vehicle, a fire suppression system could be the life saver.”  

Harris Kaladi, general manager, commercial vehicles and heavy equipment division, Swaidan Trading Company.

Several factors are responsible for significant temperatures increase in engine compartments. Many engine fires occur due to poor maintenance of vehicles and driver errors, according to Harris.

“We’ve not seen cases of fire suppression system activation in vehicles that are well maintained are operated by well-trained drivers. However, a few cases have been reported where drivers have pressed the manual emergency button accidently and activated the fire suppression system. One of our school bus customers faced such a situation when a bus driver stuck in traffic switched on the exhaust brake accidently, partially closing the exhaust path and slowing down the vehicle. The driver ignored the warning signal and continued driving in the same manner. This caused pressure to build up in the exhaust manifold and increased the engine temperature rapidly, which activated the fire suppression system. In another case, a foreign object, an aluminum foil, entered the exhaust manifold and increased the engine compartment temperature, leading to activation of the fire suppression system,” says Harris.

Harris warns that once a fire suppression system is activated, the vehicle must be inspected and serviced in a workshop.

“The driver should move the vehicle to the side of the road and take it to the nearest workshop. The vehicle can be driven provided the inspection is done because there’s a chance of re-ignition due to fuel leakage. We’ve supplied an additional safety feature for Sunwin buses, based on a customer requirement. A fuel cut-off system that activates along with the fire suppression system was installed in the Sunwin buses to prevent additional fuel leakage into the engine. After the fuel suppression system is triggered, the safety mechanism does not allow the driver to start the vehicle; instead, a bypass switch is installed, which can be operated only by an authorized person,” says Harris.

Swaidan Trading also offers the Maxus, a 16-seater minibus retrofitted with fire suppression systems for school transport.

“Maxus is the only minibus brand that has approval from the RTA and DOT to be registered and operated as a school bus. We have won a contract to supply 160 Maxus minibuses with retrofitted fire suppression systems to Emirates Transport,” says Harris.

The demand for retrofitted fire suppression systems in the UAE increased sharply a few years after 2009 when the RTA and DOT extended their regulations to bus models manufactured before 2009. Swaidan Trading entered the retrofit business in 2017 as the UAE distributor for Rotarex vehicle engine suppression systems.

“We entered the retrofit business because of the market opportunity and to counter the entry of inferior, unreliable systems that had no international certifications. We opted for Rotarex because it is among the few companies that is certified according to the UNECE R107 standard by Sweden-based research institute RISE, although compliance with the standard is not mandatory in the UAE. Nevertheless, we wanted the most reliable system in line with the safety assurance we provide for our buses,” says Harris.

So far, the company has retrofitted more than 3,000 buses in the UAE.

“The UAE has a significant number of pre-2009 buses that do not have retrofit systems. Considering the maximum lifespan of a school bus in the UAE is 15 years, the phase out of the older buses will happen within the next three years,” says Harris.

Rotarex Compact Line and ABC Powder systems

Swaidan Trading offers two types of Rotarex fire suppression systems for commercial vehicles: the FireDetec Compact Line system and ABC Powder system.

The FireDetec Compact Line system is designed for small and large engines compartments (below and above 4m3) in all kinds of motor-driven vehicles, ships and generators.

The Compact Line system has two kinds of activation: the FireDetec sensor tubing and electromagnetic (EM) actuation. The system can use either FireDetec TS55, a liquid-based agent (water mist) with glycol-free antifreeze, or Berki Cold, a biological foam concentrate, as the extinguishing agent.

An external power source is not required for fire detection or suppression, except for the EM version which is actuated electrically. The combination of the extinguishing agent FireDetec TS55 or Berki Cold and nitrogen is suitable for suppressing fires which are triggered by oils, gasoline, diesels, lubricants or other combustible liquids.

The Compact Line system is made from extruded aluminum alloy and it is resistant to corrosion. The Compact Line has a dual-chamber, coaxial cylinder system, with a high-pressure inner cylinder filled with nitrogen gas and low-pressure outer cylinder with the extinguishing agent.

The nitrogen cylinder has a filling pressure of 200 bar at 20°C. During normal operation, the outer cylinder serves as additional protection for the inner high-pressure nitrogen cylinder. The cylinder is available in three capacities – 4L, 7L and 12L. Rear-engine buses require higher volumes of extinguishing agent than front-engine buses.

The heat-sensitive FireDetec sensor tubing is connected to the Compact Line and pressurized with 16-bar nitrogen gas. The tubing bursts at approximately 110°C and triggers the fire suppression process. If an electronic fire detection system is used or if the FireDetec sensor tubing is not desired, the EM actuator can be used, which upon reception of an external signal, will trigger the release of extinguishing agent.

Rotarex Compact Line system installed in an Ashok Leyland school bus.

When the FireDetec sensor tubing bursts or when the system is actuated by the electromagnetic actuator, a pressure builds up behind the annular piston inside the Compact Line. The annular piston moves and releases the extinguishing agent. The extinguishing agent flows through the discharge line to the nozzles, which distributes the extinguishing agent on the protected area. The number of and distance between nozzles can be adjusted according to the size and geometry of the protected area. While the Compact Line is releasing the extinguishing agent, the pressure and the flow rate remain constant.

The second type of fire suppression system for commercial vehicles is the ABC Powder system, which uses the ABC 90 dry chemical as the extinguishing agent. When in service, the sensor tubing is pressurized with dry nitrogen to 15 bar. If a flame-up occurs, the heat of the fire causes the pressurized sensor tube to burst at the hottest spot. The sudden tube depressurization actuates the special pressure differential valve and discharges the ABC 90 dry chemical agent. Swaidan Trading supplies the agent in 6kg cylinders.

Rotarex ABC Powder system installed in a bus.

“Both the systems are effective for fire suppression. ABC Powder is not compliant with the UNECE standard, which makes it a cheaper alternative to the Compact Line system. Because UNECE compliance is not mandatory in the UAE, price-conscious customer opt for ABC Powder. If safety is the top priority, then Compact Line is the superior system,” says Harris.

“PLANT MACHINERY VEHICLES”  Article.