Trevor Sheppard wrote: > I'm still catching up on my emails .. lol > > Having bought some red diesel in 25ltr plastic drums recently I've > come to the conclusion that the problem had its roots in the fact > that the diesel frothed up in the tank whilst it was being pumped in > - this gave the impression that the tank was full of derv when, in > actual fact, the pump was cutting out because the nozzle sensor was > buried in froth rather than liquid; according to the garage (who sold > it at 67p/litre) the 'frothing' is caused by the dye :-( > > What I'm doing now is to let the tank settle for around an hour before > dipping it, which I failed to do initially! The good news is that this > has now 'proved' my original dipstick calculations, and stick > markings, as being accurate - much to my relief :-)) > > It does mean that 'fill 'er up' needs a tad more care, and time, than > previously - but I'm a little surprised that this frothing effect has > not been mentioned/noticed by others? > > Trevor
IIRC it's a function of the nozzle (and the make). At the end of the nozzle are 2 holes - a big one for the fuel and a small one (some nozzles have the small hole just back from the end). Anyway, as the fuel is delivered, it goes through a venturi and picks up air (sucked up from the small hole) - while air is being sucked up the cut-out is held off. When the fuel gets to the small hole, no more air can be sucked up the small tube and the auto cut-out comes in. So the faster the pump delivers, then the more air will be sucked with it - if the diesel is rather cold, then the resultant "foam" is likely to be more stable. In short the amount of foam made depends on the delivery rate and the diesel temperature. Ron Jones Process Safety & Development Specialist Don't repeat history, unreported chemical lab/plant near misses at http://www.crhf.org.uk Only two things are certain: The universe and human stupidity; and I'm not certain about the universe. ~ Albert Einstein
