Risk of fire and damage in connection with hot components

Transcription

1 Hot components Hot components WARNING! The exhaust system in a truck may, at high work load, reach temperatures in excess of 500 C. The fire hazard can be great if bodywork equipment is placed too close to the exhaust system or if inflammable materials make contact with the exhaust system or other 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, shielding or the correct protection. This applies to the following components in particular: Engine or parts of the engine Turbocharger Exhaust pipe Silencer Exhaust manifold Tailpipe Exhaust pipe for auxiliary heater IMPORTANT! Do not obstruct hot chassis components as good air circulation is important for cooling. Scania CV AB 2016, Sweden 1 (14)

2 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. Hot components Engine. 2. Exhaust pipe. 3. Silencer. 4. Turbocharger. 5. Exhaust manifold. Scania CV AB 2016, Sweden 2 (14)

3 Hot components Exhaust manifold. 2. Turbocharger. Exhaust manifold location under the compressor behind the cab. WARNING! The auxiliary cab heater has an exhaust pipe that emits exhausts gases behind the cab. Make sure that the exhaust pipe of the auxiliary heater is not placed close to any of the fuel tanks or other heat-sensitive equipment as this could pose a great risk for fire and explosion. Scania CV AB 2016, Sweden 3 (14)

4 Minimising the risk of fire next to retrofitted components To reduce the risk of fire when transporting flammable material, avoid installation of retrofitted components that transport exhaust gases, for example: Hot components 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. Scania CV AB 2016, Sweden 4 (14)

5 Flammable liquids Flammable liquids WARNING! Many liquids in the vehicle s containers 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 already when the hot surfaces are approx. 250 C. The risk increases further if the fluid is pressurised, as a flammable oil mist may form if there is a leak. Example of clamping with plastic blocks 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 Fasten and carefully connect the components or reservoir that contains inflammable liquid. Ensure that the hydraulic hoses are firmly secured and that the connections and attachments 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. Locate tanks and reservoirs on the opposite side to the silencer. If impossible, use a heat shield instead. Example of clamping with metal fastening Scania CV AB 2016, Sweden 5 (14)

6 Flammable liquids Scania generally recommends fastening using plastic blocks, but there are occasions when other clamping solutions are preferable. Metal fasteners are good from a temperature point of view, but are more sensitive to dirt and water. Take into consideration/account factors such as strength, temperature sensitivity, etc. Short distances between clamping points reduce the loading from: The hydraulic hoses own weight which otherwise may cause bending Movements and vibrations Snow and dirt Protect hoses with chafing covers if necessary. Avoid placing couplings above and close to hot components. Do not clamp hydraulic hoses together with compressed air lines or electrical cables. 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. Scania CV AB 2016, Sweden 6 (14)

7 Heat shields and safety clearance Heat shields and safety clearance WARNING! Even material with a high ignition temperature can give off flammable gases at a relatively low temperature. Risk assessment IMPORTANT! Make a detailed risk assessment using the following factors: Ambient temperature The vehicle s field of application 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. Scania CV AB 2016, Sweden 7 (14)

8 Heat shields Heat shields and safety clearance Use heat shields for the hot components of the vehicle for the following purposes: Protect heat-sensitive bodywork equipment Prevent flammable loads or liquid from coming into contact with hot components 2 The illustration shows examples of heat shields Hydraulic pump on power take-off When fitting a hydraulic pump on the engine power take-off a heat shield may be required to protect the hydraulic pump and it hoses. 1 Route the hydraulic hoses with stipulated safety clearances from the hot parts of the engine, see table under the heading Recommended safety clearance further on in this document. Ensure that the hydraulic hoses are firmly secured and that good quality connections and attachments are used. Fit a heat shield if necessary 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. Scania CV AB 2016, Sweden 8 (14)

9 Heat shields and safety clearance Heat-sensitive bodywork WARNING! The temperature around the engine behind the cab can exceed 100 C at high power outputs. Even temperatures up to 140 C are possible at extreme outer conditions, for example, high outdoor temperatures. This means, among other things, that the front end of box bodies or heat-sensitive equipment could be damaged. The auxiliary cab heater has an exhaust pipe that emits exhaust gases behind the cab. Do not obstruct hot chassis components as good air circulation is important for cooling The illustration shows the area on the bodywork that is affected and where heat-sensitive equipment should not be fitted. Fit heat shield in the exposed area. The most affected area and the heat shield s approximate location Box body The risk of heat damage applies particularly to box bodies with a sandwich construction. Fit a heat shield if there is any risk of damage. Use spacers of at least 15 mm. Box bodies 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 the box body on a vehicle that transports heat-sensitive goods. Heat-sensitive equipment Fit heat-sensitive equipment in other places than the most exposed areas, see the illustration. Examples of heat-sensitive equipment are electrical and hydraulic equipment. Scania CV AB 2016, Sweden 9 (14)

10 Heat shields and safety clearance 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 Grain Refuse Conditions There is a factory-installed catwalk that shields the silencer from inflammable material on all vehicles. IMPORTANT! Do not remove the factory-installed catwalk. If it has to be renewed, it is important that the new catwalk has similar construction and function as the factory-installed one. Scania CV AB 2016, Sweden 10 (14)

11 Safety clearance Heat shields and safety clearance Leave a safety clearance between the hot components and other equipment, or 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 components The heat sensitivity of surrounding components The ignition temperature of surrounding materials The turn-over of cooling air in the hot area Recommended safety clearance The 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 circulation Example of material Easy to ignite 300 mm 200 mm Wood and paper Difficult to ignite 200 mm 100 mm Polyamide Scania CV AB 2016, Sweden 11 (14)

12 Plastic or rubber hoses Heat shields and safety clearance IMPORTANT! Use steel pipes to convey flammable fluids, for example hydraulic oil, adjacent to hot components. Do not place rubber and plastic hoses closer than 250 mm to, for example, the turbocharger and the tipper body heating connection, as heat and exhaust gas leaks may occur. 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. Scania CV AB 2016, Sweden 12 (14)

13 Special conditions Special conditions Vehicles with an SCR system IMPORTANT! Engines fitted with SCR (Selective Catalytic Reduction) have sensitive components fitted on and in the vicinity of the exhaust system and silencer, for example reductant doser and NOx sensor. If they get overheated there is a great 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 the factory-installed catwalk, it is important that the new catwalk permits the same efficient air circulation around the silencer as the factory-installed one Scania CV AB 2016, Sweden 13 (14)

14 Stationary operation and high power output Stationary operation and high power output IMPORTANT! Stationary operation or high power output from the engines increases the temperature of the exhaust gases and the exhaust system. There is a great risk of damage to material in the vicinity of the exhaust pipe outlet. In unfavourable cases overheating can cause damage to asphalt, grass fires or other hazards depending on the direction of the exhaust, the location of the vehicle and the type of environment. Examples of vehicles affected are concrete mixer trucks and fire engines. The exhaust flow is often 5-15 m³/min and contains large amounts of energy. The temperatures can be in excess of 500ºC. Recommended action: Order the vehicle with a vertical exhaust pipe. Note: Always contact a Scania workshop before modifying the exhaust system. More information More detailed information with instructions and checklist for work carried out can be found in the following documents: Quality and safety checks before delivery to customer 1: Instructions Quality and safety checks before delivery to customer 2: Checklist Scania CV AB 2016, Sweden 14 (14)