Risk Of Explosion Due To Escaping Combustible Gas Or Overheating Of Gas Cylinders - AS00.00-Z-0018-01A
Model all (4xWD, busses, cars, heavy vans, light vans, trucks, Unimog)
Risk of injury caused by burns to skin and eyes. Risk of frostbite to body parts caused by escaping gas and by touching components near the valves when empty
Remove any sources of ignition.
Protective clothing, safety gloves and safety glasses must always be worn.
Ensure that the work area is adequately ventilated.
When working on vehicles at ambient temperatures over 60 °C, all gas cylinders must be removed.
Potential risks
Risk of explosion
There is a risk of explosion when gas escapes (e.g. due to a leakage) or in case of overheating of the gas cylinders.
Risk of injury
Accidental ignition of the escaping gas may pose the risk of burns to skin and eyes.
Risk of frostbite
When filled gas cylinders are emptied, the expanding gas cools down to such an extent that there is a risk of frostbite when coming into contact with components close to the valves.
Risk of poisoning and asphyxiation
There is a risk of poisoning and asphyxiation if gas is inhaled when high gas concentrations are present in the surrounding air. Particular attention must be paid in this respect to the potential accumulation of gas in closed environments.
Safety precautions/instructions
No smoking, fire, open flames or mobile phones:
- in the vicinity of the refueling point,
- in the vicinity of the engine compartment,
- in the vicinity of the gas cylinders,
- in the vehicle parking hall or the workshop.
In workshops, adequate ventilation openings must be provided in the roofs of the shops to ensure that any escaping gas is able to rise up and escape into the atmosphere without risk.
Before commencing work, ensure that all sources of ignition have been removed. Ensure adequate ventilation of the immediate area around the vehicle.
Adequate ventilation means an exchange of air at least 3 times an hour at a distance of 3 meters from the gas shutoff valve.
Close the gas shutoff valves on the gas cylinders before commencing repair work.
After closing the gas shutoff valves, empty the gas lines by running the engine.
The gas lines are sufficiently emptied when the engine switches to gasoline operation or stops by itself after running at idle speed for several minutes.
Model 956, 963 with two pressure unloading valves at gas cylinder It must be taken into account that the line to the pressure unloading valve remains pressurized at the gas pressure of the associated gas cylinder, even with a closed gas shutoff valve.
Vehicles fitted with gas systems on which the gas shutoff valves remain closed and the gas lines have been emptied can be handled in the same way as vehicles that operate with spark-ignition engine fuel, provided that
- the gas shutoff valves remain closed,
- the gas lines have been emptied and
- the gas cylinder is not allowed to reach a temperature in excess of 60 °C.
Work that involves any risk of ignition is only permissible on vehicles with natural gas systems after special safety precautions, e.g. closing gas shutoff valves, have been taken to prevent gas from escaping and to prevent the heat from increasing the pressure in the gas cylinder or in the gas lines. If applicable, the gas lines must be emptied and the gas cylinders removed.
Maintenance and repair work may only be carried out by specially trained personnel.
Any vehicle fitted with a natural gas system and present on the premises of the workshop must be provided with an easily visible warning of the presence of a natural gas system.
Natural gas is lighter than air and may under certain conditions accumulate in the air. For this reason, vehicles fitted with a natural gas system on which the gas shutoff valves are not closed and the gas lines are not emptied may only be parked at places
- at which an exchange of air takes place at least 3 times an hour.
If there is a risk that gas cylinders filled with natural gas may reach a temperature of more than 60 °C when placed in driers for coating material (e.g. when painting), they must be removed prior to drying. After performing work on the components or gas lines of the natural gas system, a leak test must be carried out. The specifications regarding the leak test vary between countries. Please refer to the national legislation for the specific regulations.
The procedure for detecting leaks in a natural gas system must avoid any risk of igniting gas that may escape.
Leak detectors that can also perform gas measurements far below the explosion threshold are especially suited as gas measurement and warning devices. A leak detecting spray is used for precise location of leaks.
Natural gas can cause frostbite injuries. Protective leather gloves should be used if necessary.
Discharge area:
You should avoid discharging the gas of the gas system to the atmosphere - if possible - because natural gas is a greenhouse gas. Furthermore, discharging may also disturb the neighborhood. If discharging cannot be avoided, the specifications from the vehicle or system manufacturer must always be observed.
Pressure relief of gas systems by means of discharging may only be performed outside. A marked area of approx. 10X 10 m is required for pressure relief of the gas system. No other vehicles may be located in this area during the pressure relief process and no other work may be performed.
The discharge area should preferably be equipped with a lightning protection system (lightning rod). Alternatively, it can be stated in the service instructions that pressure relief of the gas system is not to be carried out when there is the risk of a thunderstorm. The discharge area should have a way to ground the vehicle, e.g. by using a steel rod hammered into the ground.
Special considerations for CNG:
If the discharge area is partially or completely roofed over, you must ensure that the escaping gas can flow freely upwards.
Storage area for removed and non-inerted gas cylinders:
Removed and non-inerted gas cylinders should not be stored in the general maintenance and repair area. The storage area can also be located outside. The storage area must be marked and access to the cylinders can be restricted, e.g. by means of a tightly-worked chain link fence. In any event, make sure that the gas can mix freely with the ambient air.