In-depth
Unqualified gasoline the culprit of vehicle fires: experts
  • | Tuoi tre | May 16, 2012 02:30 PM

After months of research into the cause of numerous vehicle fires, mainly motorbikes, that have occurred nationwide since late 2010, scientists have concluded that poor quality gasoline was the main cause of the fires.

 
 The SH motorbike with number plate 30X9-9479 suddenly exploded into flames in Hanoi on December 12, 2011 - Photo: Tuoi Tre
The research was conducted by the Refinery and Petrochemical Technology Research Center and the Ho Chi Minh City University of Technology, under the direction of the City Department of Science and Technology.

After conducting various tests and analyzing statistical figures the researchers, who are from many scientific organizations based in HCMC, have come to the conclusion that the fires were caused by three factors.


The first is the use of poor quality gasoline, like gasoline mixed with methanol or ethanol of low standards. This type of gasoline can cause damage to the gasoline pipe, leading to a fuel leak, which will catch fire if contacted by sparks caused by a short circuit, heat from friction in the brake system, or a source of continuous heat from the engine or other parts of the vehicle.


A short circuit can occur when a fuse falters or is of poor quality.


Secondly, a fire on a motorbike could be caused by a short circuit, which generates sparks that then set fire to the leaked gasoline or inflammable items like plastic parts of the vehicle.


Thirdly, a fire could be caused by inflammable items, like gas lighters or perfume, which were left in the boot of the vehicle and caught fire when the boot, along with other parts of the vehicle, was heated up by a source of heat from the engine caused by gasoline with low octane indexes, like A83 gasoline or gasoline mixed with methanol or ethanol.

In brief, mixed gasoline of poor quality was the leading cause of most cases of fire, researchers said.

They said they have conducted many tests of samples of A83, A92 and A95 fuel, gasoline mixed with methanol and ethanol, and gasoline injected with a kind of energy-saving additive made in China.


The test results showed that mixed gasoline itself could not explode into flames without coming into contact with a source of fire or extreme heat.


However mixed gasoline, depending on the quality of methanol or ethanol added to it, may damage the gasoline pipe of a vehicle, thus causing a leak of fuel from the damaged pipe.

When added to gasoline, methanol or ethanol helps increase the octane value of the fuel, and a higher octane value means less gasoline is burned by the ignition of the spark plug.

However, depending on the volume of additive added to the gasoline, engines using such a mixture need to have their fuel operating system, sparking system, and compression rate, as well as a few other components, improved in order to enable them to use such a fuel.

If such improvements are not implemented, the gasoline pipe may crack and the carburetor float needle may be damaged, leading to a fuel leak in the carburetor and a flooded engine, especially in engines using an electronic fuel injection (EFI) system.

In such a case the leaked gasoline will catch fire if it is exposed to a spark coming from the vehicle’s electrical system, as mentioned above.

On the other hand, in vehicles run with gasoline mixed with poor quality methanol and ethanol, the temperature of its engine and many other components is often 10-20 degree Celsius higher than in vehicles fueled with standard gasoline.

Meanwhile, methanol and ethanol are usually chosen to be added to gasoline since they are much less expensive than other kinds of additives that have the same effect, researchers said.


The use of gasoline with methanol or ethanol as a replacement for conventional gasoline produced from crude oil has become common in many countries, since oil is becoming scarcer.


In Vietnam, the volumes of methanol imported in 2010 and 2011 were 90,000 tons and 80,000 tonnes respectively, while the figures in 2008 and 2009 were much lower, just 52,000 tonnes and 66,000 tonnes, respectively.

Recent investigations showed that gasoline containing a high content of methanol accounted for a not small proportion of the fuel in use.

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