9 common truck fire risks and how to eliminate them
TO improve the safety of the heavy vehicle industry, the National Heavy Vehicle Regulator (NHVR) and industry experts have been working to review previous fire incidents to identify common causes and contributing factors.
The end result is the recently published Safety Bulletin targeting Reducing the risk of vehicle fires in the heavy vehicle industry.
"The intent of this Safety Bulletin is to remind industry of the common fire risks that have been identified and to outline some actions that can be taken to help mitigate the risks,” said Tony Martin, NHVR Safety Standards Director.
Here are the most common for truckies and what steps you can take to be safer.
Shorting of electrical cables and connections
Heavy motor vehicles include a number of electrical circuits that are either unfused or carry high currents, including starter motor, battery and alternator cables. The positive feed cable in the vehicle cabin or the trailer relay box are also common components identified as having the potential to cause heavy vehicle fires. Damage to, or faulty connections in, these cables or connections can lead to shorting, which can be the ignition source of a vehicle fire.
Inappropriately rated electrical components
Electrical components used in heavy vehicles, such as cables, terminals, fuses or fuse holders, are rated to ensure they are suitable for their intended use. In addition, the conduit that is used to protect electrical components in heavy vehicles should be made from fire retardant materials. Use of components, either during servicing or modification, that are inappropriately rated can lead to failure due to overloading. This situation often leads to shorting on nearby exposed components (chassis, wiring, etc.) resulting in an ignition source for a vehicle fire. Once a fire starts, non-fire retardant conduit can quickly spread the fire away from the original ignition source.
Fluid line failures
Damage can occur to fuel lines when they are not properly supported, when they rub on other components or their connections are not secure. Lines that carry lubricant or hydraulic oils can also be subject to deterioration, damage or poor connections. Leaking fuel, lubricant, oil or other flammable liquids which comes into contact with hot engine bay components, such as turbocharger or exhaust components is highly likely to result in a vehicle fire.
Turbochargers generate significant heat and it is important to ensure that combustible materials are placed a safe distance away from the turbochargers (approx. 200mm). Alternatively, if it is not possible to provide this space, a shroud made of a suitable non-combustible material (i.e. metal) should be used to deflect the heat away from the combustible material. In cases where a turbocharger oil seal fails and feeds oil directly into the exhaust system, the oil can ignite resulting in excessively high temperatures. These higher temperatures increase the risk of nearby components igniting. Lines that carry lubricant to turbochargers can also be subject to deterioration, damage or poor connections. The proximity of these lines to the turbocharger significantly increases the risk of ignition.
Engine bay maintenance
Maintaining a clean engine bay can reduce fire risk and help to ensure contaminants that could act as a fuel for a fire are removed. Routine cleaning also ensures other components within the engine bay, such as insulation, do not deteriorate and fall onto hot engine bay components. A clean engine and surrounds allows maintenance personnel to conduct thorough inspections of high risk components where deterioration and damage may not have been evident otherwise.
There are multiple reasons why a wheel bearing can fail, including:
- poor maintenance regimes
- water submersion
- incorrect pre-loading.
When a wheel bearing fails, its temperature increases significantly, which can result in the bearing lubricant or tyres (via heat transfer from the wheel rim) catching fire.
Brakes generate extremely high temperatures that can increase further in certain situations, including:
- brakes not adjusted correctly resulting in dragging of the brake linings
- reduced air supply at the rear trailer(s) in longer vehicle combinations resulting in slow brake disengagement
- poor brake imbalance.
Increased temperatures from defective brakes are transferred to the wheel bearings and tyres (via wheel rims), which can lead to a vehicle fire.
In general operation, tyres do not generate high temperatures. However, in some situations tyre temperatures can increase significantly to a point that can lead to a vehicle fire. Common situations where this temperature increase occurs include:
- tyres rubbing on vehicle components (suspension, guards, adjacent tyres, etc.)
- partially deflated tyres
- fully deflated tyres.
The type of loads a vehicle carries can also increase the risk and/or severity of a vehicle fire. For example, mixed commodity loading where one part of the load contains a potential ignition source (batteries) while another part of the load is a potential fire fuel source/accelerant (cardboard).
1. Heavy vehicle operators should:
- review the common causes of fires and identify those that may be most present in their fleet
- review their maintenance management systems to remove or reduce any risk factors, and improve the safety of their transport activities
- ensure those who carry out servicing or modification on higher-risk components or systems on their vehicles, such as electrical systems, have measures in place to verify that fire risks are not introduced (i.e. persons appropriately qualified, work performed to relevant standards, work procedures or checklists completed etc).
2. Where an operator experiences a heavy vehicle fire incident, or a near-miss event, they should report the incident to the NHVR to improve our understanding of this safety-critical issue. Reports can be made to the Heavy Vehicle Confidential Reporting Line or to the NHVR's Vehicle Standards team. For operators accredited in the National Heavy Vehicle Accreditation Scheme (NHVAS), reports can also be submitted to the NHVR's Accreditation team.
- Heavy Vehicle Confidential Reporting Line - 1800 931 785
- NHVR's Vehicle Standards team - firstname.lastname@example.org
- NHVR's Accreditation team - email@example.com