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Thread: Plastic hose & Biodiesel

  1. #1
    Join Date
    Sep 2006
    Northern NSW

    Plastic hose & Biodiesel

    •I set up an experiment with 5 X300 mm lengths of 10mm clear plastic hose (the type you buy in any hardware store). I sealed one end & tied the unsealed end to a piece of wire. I then filled each 90% with a different dilution of diesel & biodiesel. B100/ B75/ B50/ B25 & Diesel.
    They were left hanging over the work bench.
    After 4 days there was evidence of the B100 osmosing through the plastic tube. I think osmosis is the correct term. It was oily to the touch on the outside. After a couple of weeks there was no difference, in that none of the other plastic tubes were osmosing. After a couple of months the diesel had gotten darker & all the dilutions of biodiesel had gotten lighter. There was a small amount of evaporation? & the B100 tube had a couple of mm less in it than the others. After 6 months the B100 was 10mm down on the rest all remained the same with minor evaporation?
    None of the hoses went hard. None of the hoses went soft. They all seemed about the same. The B100 tube was probably a little expanded but nothing I could measure accurately. It was not dripping or any worse than it was after a week.

    •After 2.5 years of B100 in the Hilux. None of the hoses or rubber fittings on the fuel delivery system from the filler cap to the return line on that vehicle show any signs of deterioration.
    •After the same time on B100 the Cumming return & feed lines show signs of osmosis. A bit gooey to the touch but nothing serious. The rubber seal on the filler cap has become malignant. I cut a new one out of 3mm neoprene sheet & it seems better.
    •The black rubber feed hose that came with the Alemite 5000 pump is un affected after 2 years of pumping.
    •After 18 months of B50 in the C4….It shows no signs of weeping or leaks or stickiness anywhere including the fuel filter
    •The 25mm clear plastic hose that I have rigged up as a sight glass on the B50 tank in the garage for the Citroen as shrunk considerably & has gone as hard as a rock but is still clear. This is the same cheap clear plastic from the hardware.
    You can draw from this what you will. But it would seem that if there is a little diesel in the mix it (somehow) seems to slow or stop the osmosis. The sight glass (plastic) has gone hard because (I’m guessing) it has the same fuel in it for months (eg there is no flow through it . just a slow drop as the drum is used. It is also exposed to direct sunlight.
    •This concludes item # 2876964730 in the trivea series.

  2. #2
    Join Date
    Sep 2005

    Re: Plastic hose & Biodiesel

    Well done!
    IS this tube the one commonly referred to as "Beverage tube"?



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