Ethanol-petrol compatibility study

The Vincent Owners Club, which accommodates enthusiasts for these excellent motorcycles has published an article in their magazine about the long-term effects of combinations of various proportions of ethanol and petrol on fuel system materials. The Vincent Owners Club article features work carried out in Germany, and published in the German magazine Oldtimer Markt. While the tests reported in these articles do not necessarily correspond to normal usage patterns, they do provide some useful information, whilst paradoxically giving rise to various questions. The tests consisted of immersion of fuel hoses and complete carburettors into blends of 5%, 10% and 85% ethanol, and petrol for a 12 month period. At the end of the 12 months, the items immersed in the fuels were examined, when it was found that the carburettor immersed in 85% ethanol was only fit for scrap, while fuel hoses in the same blend were untouched. Conversely, the hoses immersed in both 5% and 10% ethanol-fuel blends had disintegrated. There were differences between the effects on carburettors immersed in the 5% and 10% ethanol-fuel blends; in the 5% blend there was marked corrosion, whereas in the 10% blend, there was very little deterioration. This apparent anomaly was explained by the greater water absorbing capability of 10% ethanol blended in petrol.
The results raise questions about the materials employed, which are not disclosed. Elastomeric materials, such as those used in fuel hoses clearly can suffer as much or possibly more from hydrocarbon exposure as from contact with ethanol, and the combination of varying amounts of ethanol with petrol provides a further variable, so the issue is complex. However, there are materials which will resist both hydrocarbons as found in petrol, and ethanol separately, or in combination, which is really what is needed. The CONCAWE list of materials which the Federation published several years ago when concerns about the use of ethanol in petrol started to emerge, provides some assistance in this respect, since the oil companies appear to have checked this specific aspect in their studies. There is unfortunately no ‘magic bullet’ to protect against deterioration of fuel hoses etc., but replacement of unsuitable products with materials fully resistant to the effects of both hydrocarbon fuels, ethanol, and the combination will solve the problem. Information on compatible materials originally provided by CONCAWE appears on the Federation website, http://fbhvc.co.uk/


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