There are 25 million cars running on LPG worldwide, including 13 million in Europe alone. The chances of one being involved in a road accident are no longer so small, that it can be disregarded. Unsafe practices in the past have led to a certain preconception about Autogas inducing a higher level of risk. So we ask ourselves the question: are Autogas cars safe? Are they bombs on wheels? How dangerous, really, is such an Autogas tank? How does the fuel system behave when your car is rear-ended? Will the tank take the stresses?
Test in Poland
In one of the top five of Autogas-countries, where this versatile fuel is used by many private individuals and almost 15% of all registered passenger cars, Polish Autogas magazine gazeo.pl felt it was time to once more run a test, to find out how well Autogas is holding up. Together with AC (manufacturer of STAG autogas systems), STAKO (manufacturer of autogas tanks), PARKER (producer of rubber autogas hoses) and the PIMOT (Automotive Industry Institute), gazeo’s partners of the Autogas-powered car crash test project tested the crash behaviour of two Autogas cars.
The scenario followed the assumption of a standard rear end collision. In fact as many as in four collisions and about one in eight road accidents involve one car being rear-ended by another.
Different than previous tests, the group chose to have the engines in both cars actually running on Autogas, in order to have most realistic conditions. While we wait for gazeo to publish the results of their tests, we can always look at how tanks are built, how the regulations describing the building process ensures a safe sturdy tank and how tanks have fared in tests previously conducted.
In 2009 the German automotive club (ADAC) had already performed a quite similar test in which an Opel Astra Caravan on Autogas was rear-ended by an Opel Kadett Caravan. The Astra had a toroidal LPG tank installed in the spare wheel well. The vehicles carried crash test dummies and were also outfitted wih sensors to measure the forces.
The Kadett impacted the Astra at a speed of 60 km/h in the rear with a 70 % overlap. The deformation was substantial and the LPG tank passed some of the crash energy on to the structure of the vehicle, partly bypassing the deformation zones. Nonetheless the tank and the LPG system remained intact and no leaks were found. The deformation of the passenger area was only marginal and did not influence survivability.
After the collision test, a fire test was performed in which liquid fuel in a pan under the vehicle was ignited. The flames engulfed the entire vehicle in only a few minutes. The heat from the ensuing fire raised the pressure of the LPG in the tank beyond the opening pressure of the pressure relief valve and the fuel was gradually released. At no time was there any danger, the fire remaining controllable at all time. The entire test was filmed and published on youtube, but is – unfortunately only available in German.
The dramatic footage shows, that the disturbances from airbags and tires exploding are far greater than the release from the PRV.
Autogas tanks are designed according to requirements laid down in specific regulations in which equipment, material properties, fabrication processes of the tank shell itself and testing procedures are defined. Although the regulation in your country might be different from another, the actual prescriptions are very similar, guaranteeing a high level of safety during normal operation and also in the case of accidents. Especially the latter enables rescue units to safely approach an Autogas car, even in case of fire. The choice of the correct tank and its equipment according to the regulation are very important element in maintaining the high level of safety associated with this fuel.