fuel tubes / hoses exposed to ethanol / methanol fuel  

Posting by Didier Tabor on 07 Jul 2008 at 21:27:51.

Hi all,

I just heard on the news that ethanol containing fuel is being promoted for use in every car (thus also cars manufactured before 2005). This ethanol fuel contains 15 mole % of ethanol, which is a significant increases compared to the 2 mole% fuel already contained in the past.

I was wondering whether polyvinlydene fluoride (pvdf), polyoxymethylene (pom, acetal resin), polybutlylene terephthalate (pbt) or polyamide based fuel line, tube, hose and containment systems can deal with this increasing concentration of ethanol in fuel. Not only from the viewpoint of gas emissions but also from view on the material's long term service life. Secondly, how is permeation rate of the other gasoline components influenced by ethanol or methanol permeation these plastic based lines, hoses, tubes and tanks?

I read that especially polyamide based system perform worse with this regard. Is this the case and what sort of fuel hoses are applied in a normal family car?

Thanks to all for your possible comments!


          follow up posts
    On 08 Jul 2008 at 18:52:01 Tom Christiansen posts:
    For 50 micron films, using test fuel CE 10 (90% fuel C, 10% ethanol), a temperature of 60 degrees Celsius, atmospheric pressure, we acquired:

    PVDF: 2E-8 gram / m s {gram per (meter times second}
    PBT: 1E-7 gram / m s
    POM: 1E-7 gram / m s
    PA6: 2E-7 gram / m s
    PA12: 6E-7 gram / m s

    Seemingly fluoro based polymer are superior concerning permeation resistance, especially when compared to polyamide 6 and 12. Very probably there are even better performing fluoro polymers, like ETFE and CTFE. On the other hand, polyamide has a better mechanical performance, especially for flexible tube applications. Hence, a multilayer structure is often used.

    Concerning the second part of your question: I do not exactly know since when these multilayer hoses are applied... I think a lot of fuel systems are indeed not resistant against bio fuel. I am very curious to further responses on this thread!

    [responses: 1]

      On 16 Jul 2008 at 19:08:53 Didier posts:
      Thanks for your support so far. Your information is a handy CE10 bio ethanol fuel reference for diffusion and permeation in polymer hose and containment materials. For comparison with normal gasoline, do you also have the permeability figures for indolene in plastic tube and hose materials?
      [responses: 0]

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