Using their vast and almost unparalleled experience in the rotational moulding industry, Corilla Plastics has been involved in the design, manufacture and testing of innovative plastic fuel tanks for more than three decades.
Although Corilla works with some of the best known and best respected names in the international off-road construction, commercial and automotive industry – including Ford New Holland, Massey Ferguson, Iveco Trucks, Landrover, Fiat and LDV – perhaps one of their most challenging projects is for a company which specialises in the conversion of vehicles into mobility vehicles.
A major part of the conversion includes lowering the vehicle floor to allow wheelchair access. This involves discarding and replacing the original fuel tank with what is known in the industry as a flat wafer tank. Although considerably thinner to create the extra space required, the replacement tank has to be created to contain the same amount of fuel as the original OEM fuel tank.
Corilla assists in the design process and works closely with an independent testing centre to ensure that the new tanks fully comply with the industry’s strict EC34 Annex5 regulations, specifically developed to test all vehicle fuel tanks manufactured from a plastic material.
To satisfy the rigorous regulations, the tanks are subjected to mechanical testing and fire testing at temperatures ranging from minus 40 degrees C and up to 96 degrees C. At the lower end, the tank must withstand cold impact tests without cracking, whilst at 98 degrees it must stand up to at least five hours of pressure testing whilst retaining liquid tight integrity.
For the cold impact test, the fuel tank is secured in a special framework and subjected to a swinging pendulum with a spherical end of a known weight. This strikes the fuel tank at a pre-determined force in six different nominated areas to test its strength against cracking.
The same tank is then filled with water at a temperature of 98 degrees C and pressurised to 0.3 bar continuously for five hours. The tank only passes the stringent test if it does not lose any of its contents, thus proving it is liquid-tight.
For the fire test, three separate tanks are subjected to intense flames and all must achieve exactly the same high level of pre-determined fire resistance to satisfy the test regulations.
There are more than a dozen different procedures involved in the testing of the replacement tanks, including a permeability test. For this, the tank is filled with diesel and elevated in temperature for a period of up to 12 weeks. After this time any resulting fuel loss is meticulously measured using laboratory instrumentation.
If a tank fails a particular test, then investigations are conducted to identify the cause and contingency plans are introduced to replace test tanks with improved specifications, particularly the wall thickness of the fuel tank.
Although time-consuming and expensive to conduct, the tests confirm conclusively that the ultimate design and specification of the tanks pass all EC34 Annex 5 regulations and are totally fit for purpose.
The company for which Corilla Plastics and its testing centre partner undertake this specialised work is a leading supplier of wheelchair accessible vehicles for the UK and Ireland markets, not only dealing in the conversion of cars but also MPVs and minibuses for private individuals and families. Their larger wheelchair access vehicles are also popular with social and community transport providers.
The company previously used a local manufacturer to supply fuel tanks, but as regulations and specifications became more stringent for the next generation of fuel tanks, they found that they needed stronger technical support. This is when South Wales-based Corilla Plastics was invited to become involved in the design and manufacture, using its many years of experience and expertise in the rotational moulding industry.
Between them, the two companies have created a team of appropriate skill sets which works in harmony to develop, design and manufacture the most cost-effective and rigorously tested solutions for high-quality fuel tanks for the mobility vehicle market.