Abstract
Keywords: secondary safety, rear-end crash test, CNG retrofitted vehicle
Rising fuel prices and a changed attitude towards environmental concerns have resulted in an increasing demand for alternative forms of fuel for vehicle propulsion. In particular, the registration figures of vehicles powered with compressed natural gas (CNG) and liquefied petroleum gas (LPG) show strong growth rates in Germany. Customers are interested in both, vehicles originally equipped by the manufacturer and vehicles which are retrofitted. To find out more about the crash performance of retrofitted cars regarding the integrity of the tank system and the secondary safety of the occupants, DEKRA Accident Research carried out two rear-end crash tests in accordance with the standard FMVSS 301.
A CNG retrofitted estate car was used for these tests together with a conventional reference vehicle of the same make and model. The integrity of the tank and fuel system as well as the function of its valves and the influence of the retrofitted installations to the secondary safety of the occupants have been tested in comparison to the reference vehicle.
As a result of the tests, both the conventional and the alternative fuel installations were not leaking and the safety valves of the CNG system shut down as intended. All the components necessary to turn the gas flow off manually remained accessible and capable of working. However, the gas bottle mounted behind the rear seat was pushed forward during the collision and resulted in a clearly increased loading of the chest of the dummies sitting on the rear seats.
The crash test showed that the fire-risk of a CNG converted car does not exceed the firerisk of the conventional car. However, to minimise the risk of rear-seat passengers some optimisations concerning the position of the built-in gas bottle and an additional cushioning may be options for further improvements.