Can a CNG cylinder explode

Car explodes at gas stationWhat about natural gas driverscan do now

It happened again. On Christmas Eve at 12.30 p.m., a huge bang shook the Euro Rastpark in Achern, Baden. When refueling an Audi A3 g-tron with natural gas, one of the two underfloor tanks suddenly bursts. The rear of the compact car is completely torn to pieces, the 34-year-old driver behind it is seriously injured.

The force of the detonation is enormous. "There could have been deaths," says Michael Wegel, commander of the local fire department, to AUTO BILD. "Even heavy debris flew 35 meters through the gas station." Several cars are damaged, including a Land Rover. Fortunately, its inmates, a family of five, had just gone to the petrol station shop.

“There could have been several deaths. Pure luck that nothing more happened here. ”Michael Wegel, Achern fire brigade

The accident is a shock for Audi and the entire VW group, as it is part of a series of explosions that were caused by defective pressure tanks (see below). Particularly explosive: For the first time, it does not tear apart rusted metal tanks, but a modern tank made of composite plastic!

The Kassel-based lightweight construction specialist Hexagon xperion has already delivered more than 100,000 such pressure vessels to Volkswagen. They weigh 70 percent less than conventional steel bottles and consist of three layers: Inside there is a layer of gas-tight polyamide, over which a layer of carbon fiber reinforced plastic (CFRP) ensures strength. A layer of glass fiber reinforced plastic (GRP) forms the end, which is supposed to protect against damage from the outside.

Save the containers Natural gas (CNG = Compressed Natural Gas) under 200 bar pressure, but according to the manufacturer can withstand up to 500 bar before they burst. Whether there was a construction, manufacturing or material defect in the tank during the accident in Achern is currently still open. Audi asserts that manufacturer fault can be ruled out based on initial findings. In addition, according to Audi, there is a possibility that there was serious previous damage to the vehicle.

Human error when refueling is also out of the question, say the police and fire brigade after evaluating the surveillance video. And the dispenser should also have been technically in order. According to vehicle owner, a construction company from Kehl, the rear bumper of the Audi was repaired after it rolled into an obstacle in the parking garage at walking pace. A Kuller crash that shouldn't actually cause the car to blow up.

The Federal Association for Gas System Technology (BFG) was able to inspect the destroyed Audi A3. “Questions about product safety came up, which the Federal Motor Transport Authority has to answer,” says BFG boss Peter Ziegler. He wrote a six-page report for the investigative authorities and filed a criminal complaint against unknown persons with the public prosecutor's office in Baden-Baden. The association also calls for the Federal Institute for Materials Testing to be involved in the investigation.

It can take weeks, if not months, to get a result. Should Audi, Seat, Skoda and VW owners, in whose cars lightweight gas tanks are installed, use CNG for so longrenounce and only use the existing petrol tank? Audi says no. The BFG thinks: It would be better. Site manager Nikolai C., who was injured in the forehead and leg in the explosion of the natural gas Audi, has since been released from the clinic. He is in severe shock and unable to work.

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That's what Audi says

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Is there any information about the possible cause of the gas tank bursting in the Achern accident? The process is currently being investigated by an expert. According to initial findings, a manufacturer's fault can be ruled out. We cannot make any further statements on this before the official investigations have been completed or the expert report is available. Should customers refrain from refueling with natural gas until the cause of the accident has been clarified? No, there is no need to do so. Will there be a recall? No.

Editor's comment

In the AUTO BILD endurance test over 100,000 kilometers, an Audi A3 g-tron achieved the dream rating of 1+. Would I get back into this model? Clearly: no. At least not before the disaster in Achern has been completely cleared up by an independent party. Federal Motor Transport Authority, Public Prosecutor's Office and Audi have to deliver now. Otherwise, natural gas is dead as a clean, inexpensive alternative.