Risk of fire, damage and injury from hot ... - Scania Group

Risk of fire, damage and injury from hot components
Hot components
Hot componentsWARNING!

At high workloads the exhaust system on a truck can reach temperatures of over 500°C. The exhaust gas temperature of a gas vehicle is hotter when idling and in op-eration compared with the exhaust gas temperature of a diesel vehicle. There may be a high risk of fire if bodywork equipment is placed too near the exhaust system or if flammable materials come into contact with the exhaust system or other hot compo-nents.

WARNING!Leaking oil coming into contact with hot components can cause fire. Make sure that hot components are protected in the event of an oil leak.

IMPORTANT!

Avoid building in the chassis' hot components as good air circulation is important for cooling.

Scania Truck Bodybuilder 22:10-633 Issue 2 2021-02-22© Scania CV AB 2021, Sweden 1 (17)

Hot components


On trucks there are hot components and parts that can cause fire or heat damage if they do not have a sufficient safety clearance from surrounding components, shield-ing or the correct protection. This affects the following components in particular:

• Engine or parts of the engine.• Turbocharger.• Exhaust pipe.• Silencer.• Exhaust manifold.• Tailpipe.• Exhaust pipe for auxiliary heater.


Hot components


Risk assessmentIMPORTANT!

Carry out a detailed risk assessment based on the following factors:• Ambient temperature.• The vehicle's area of use.• The appearance of the bodywork and the configuration of the hot components.• The probable course of action if a flammable load or leaking liquid comes into

contact with the hot components.• Conceivable breakdowns that may cause fire, for example, rupture in hydraulic

hoses or diesel leakage.


Hot components


4. Exhaust manifold.5. Turbocharger.

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Overview hot components The illustrations below show examples of components that can become so hot that they pose a risk of fire. The components may differ in appearance and be located in different places depending on the type of vehicle and specification.

1. Engine.2. Exhaust pipe.3. Silencer.

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Hot components


Exhaust manifold location under the compressor behind the cab.

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WARNING!Vehicles fitted with an auxiliary heater for the cab have an exhaust pipe that emits exhaust gases behind the cab. Make sure that the exhaust pipe of the auxiliary heater is not located close to any of the fuel tanks or other heat-sensitive equipment as this could pose a great risk for fire and explosion.

1. Turbocharger.2. Exhaust pipe.

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Hot components


Minimising the risk of fire next to retrofitted compo-nentsTo reduce the risk of fire when transporting flammable material, avoid installation of retrofitted components that transport exhaust gases. For example:

• Side-mounted exhaust pipe.• Vertical exhaust systems.• Components for tipper body heating.

If tipper body heating is installed, ensure that the safety clearance is sufficient. More information is found under the heading Recommended safety clearance.

Be aware that hot media can leak, especially at the transition between the chassis and the platform.

More information on how the exhaust system can be modified can be found in the document Modifying the exhaust system and Modifying tractor heat shields.


Flammable liquids


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Example of clamping with plastic blocks.

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Example of clamping with metal bracket.

Flammable liquids

WARNING!Many liquids in the vehicle’s resevoirs or hydraulic systems are flammable and are often the cause of fires, for example hydraulic fluid, diesel and oil.The risk of fire associated with leaking fluids occurs when hot surfaces reach approx. 250°C. The risk increases further if the fluid is pressurised, as a flammable oil mist may form if there is a leak.

IMPORTANT!

Plausible causes of leakage:• Poorly tightened couplings or inadequate maintenance of hoses and seals.• Insufficiently clamped hoses.• Chafing between hoses and other components.

Preventive measures:• Carefully fasten and connect the components or reservoir that contains inflamma-

ble liquid.• Ensure that hydraulic hoses are firmly secured and that connections and attach-

ments are of a good quality.• Use a heat shield that covers the whole area to prevent leaking fluids from coming

into contact with hot surfaces. More information on heat shields is available under the heading Heat shields and safety clearance.

• First, position tanks and reservoirs on the opposite side to the silencer. Then use a heat shield.

• Scania generally recommends fastening using plastic blocks, but there are occa-sions when other clamping solutions are preferable; see illustrations.


Flammable liquids


• Metal fasteners are good from a temperature point of view, but are more sensitive to dirt and water. Take into account factors such as strength, temperature sensitiv-ity, etc.

• Short distances between clamping points reduces the load from:– The hydraulic hoses’ dead weight, which otherwise may cause bending.– Movements and vibrations.– Snow and dirt.

• Protect hoses with chafing covers if necessary.• Avoid positioning couplings or valves above and near hot components.• Never clamp hydraulic hoses together with compressed air lines or electrical ca-

bles.• Make sure that the hydraulic hoses do not cross each another. If this cannot be

avoided, use double clamps to ensure that chafing does not occur.


Heat shields and safety clearance


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1. Heat shield above the exhaust pipe behind the cab.2. Heat shield between the exhaust pipe and hydraulic pump for power take-off with

hoses.3. Heat shield (also noise protection) between engine and bodywork.

Heat shields and safety clearanceWARNING!

Even material with a high ignition temperature can give off flammable gases at rela-tively low temperatures.

Heat shieldsUse heat shields for the hot components of the vehicle for the following purposes:

• Protect heat-sensitive bodywork equipment.• Prevent flammable loads or leaking liquid from coming into contact with hot

components.

See illustrations for examples of heat shields.




Hydraulic pump on power take-off

IMPORTANT!

Hydraulic pumps connected to 16 litre engines must be covered with a thermal pro-tection casing. It is also recommended that hydraulic pumps connected to engine power take-offs on gas engines are covered with thermal protection casing.

Take the following safety precautions when fitting hydraulic pumps to engine power take-offs (ED power take-offs).

• Route the hydraulic hoses with stipulated safety clearances from the hot parts of the engine. More information can be found under the heading Recommended safe-ty clearance.

• Ensure that the hydraulic hoses are firmly clamped and that connections and at-tachments are of a good quality.

• A heat shield may be required to protect the hydraulic pump and its hoses.




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The most exposed area and the approximate location of the heat shield.

Heat-sensitive bodywork

WARNING!• The temperature around the engine behind the cab can exceed 100°C at high pow-

er outputs. Even temperatures up to 140°C are possible at extreme outer condi-tions, for example, high outdoor temperatures. This means, among other things, that the front end of truck box bodies and adjacent heat-sensitive equipment could be damaged; see illustration.

• Vehicles fitted with an auxiliary heater for the cab have an exhaust pipe that emits exhaust gases behind the cab.

• Do not build in the chassis' hot components as good air circulation is important for cooling.

The illustration shows an area on the bodywork that is exposed and where heat-sen-sitive equipment should be avoided. Fit heat shield in the exposed area.

Truck boxesThe risk of heat damage applies particularly to truck boxes with a sandwich construc-tion.

• Fit a heat shield if there is any risk of damage. Use spacers of at least 15 mm.

Truck boxes that are not insulated can get very hot at the front end and heat can pass into the cargo area.

• Fit a heat shield in front of uninsulated truck boxes on vehicles transporting heat-sensitive goods.

Heat-sensitive equipmentFit heat-sensitive equipment in other places than the most exposed areas; see illustra-tion.




Examples of heat-sensitive equipment are electrical and hydraulic components.




Vehicles that transport flammable material

WARNING!Loads with a low thermal ignition point can cause malfunctions or fire if they come into contact with hot components of the exhaust system.

Examples of loads with a low thermal ignition point:

• Wood chips and bark.• Timber.• Waste paper.• Cereals.• Refuse.

There is a factory-installed catwalk that shields the silencer from inflammable mate-rial on all vehicles.

IMPORTANT!

Do not remove or change the function of the factory-fitted catwalk. If it has to be re-newed or modified, it is important that the new catwalk has similar construction and function as the factory-installed one.




lation Example of materialWood and paperPolyamide

Safety clearanceLeave a safety clearance between the hot components and other equipment. Alterna-tively, shield the equipment with heat shields to reduce the risk of fire, overheating damage and operations disturbances.

The safety clearance size depends on the following factors:

• The temperature of the hot component.• The heat sensitivity of adjacent components.• The ignition temperature of adjacent materials.• Conversion of cooling air in the hot area.

Recommended safety clearanceThe following table shows the recommended minimum safety clearance between hot parts of the exhaust system and adjacent equipment.

Note:The recommended safety clearances apply to exhaust systems with completely sealed connections and no special heat shield.

Flammability Low air circulation Good air circuEasy to ignite 300 mm 200 mmDifficult to ignite 200 mm 100 mm




Plastic or rubber hoses

IMPORTANT!

Use steel pipes to convey flammable fluids, for example hydraulic oil, adjacent to hot components.The minimum permitted distance between plastic or rubber hoses and, for example, the turbocharger and the tipper body heating connection is 250 mm. This is because the turbocharger and the tipper body heating connection may leak heat and exhaust gases.Fit a heat shield to protect hoses from heat and exhaust gas leakage if it is not possible to leave the necessary clearance between hoses and hot components.


Special requirements


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1. Reductant doser.2. NOx sensor.

Special requirementsVehicles with SCR systems

IMPORTANT!

Engines with the exhaust emission control system SCR (Selective Catalytic Reduc-tion) have sensitive components positioned on and near the exhaust system and si-lencer. For example, reductant doser and NOx sensor; see illustration. If they get overheated there is a high risk of malfunction.Therefore, it is important that the air circulation around the silencer and SCR system components is sufficient for efficient cooling.When renewing or modifying a factory-installed catwalk, it is important that the new catwalk permits the same efficient air circulation around the silencer as the factory-installed one.


Stationary operation and high power output


Stationary operation and high power out-put

IMPORTANT!

Stationary operation or high power output from the engines increases the temperature of the exhaust gases and the exhaust system. There is a high risk of damage to mate-rial near the exhaust pipe outlet during stationary operation and high power output. In unfavourable cases, overheating may cause damage to asphalt, grass fires or other hazards depending on the direction of the exhaust, the location of the vehicle and the nature of the environment. Examples of vehicles affected are concrete mixer trucks and fire engines.The exhaust flow is often 5-15 m³/min and contains large quantities of energy. The exhaust gas temperatures can reach above 500°C. The exhaust gas temperature of a gas vehicle is hotter when idling and in operation compared with the exhaust gas tem-perature of a diesel vehicle.

Recommended action:

• Order the vehicle factory-fitted with a vertical exhaust pipe.

Note:Always contact a Scania workshop before modifying the exhaust system.

More informationMore detailed information with instructions and a checklist for work carried out can be found in the following documents:

• Pre-delivery inspection: Instructions.• Pre-delivery inspection: Checklist.


Documents

Risk of fire, damage and injury from hot ... - Scania Group