Never heard that brake fluid is the majority cause of vehicle fires before, care to back that up somehow? I know that they can be started by fuel, oil, exhaust heat and brake fluid but the majority being caused by brake fluid doesn't seem to be mentioned anywhere other than your posts.
Secondly of course, a vehicle with no fuel in it is far less dangerous than a vehicle with fuel in it but no brake fluid, so your point is stupidly made anyway.
hrmm - yes a big problem for the O/P, it also becomes a problem of credibility for the motor trade. Most (lots? many?) motorists do not have the skills/experience/knowledge to know when they are being duped.
If 'Hugh' had read my original message in full rather than just replying to a bit he can argue with he would know that John is taking the warranty issue to court so isn't exactly being "fobbed off"...
Greg
On or around Fri, 13 Oct 2006 13:19:31 +0100, "Greg" enlightened us thusly:
indeed:
"Then he managed to find a pump that apparently wasn't set right and over filled his tank, at least that's what the dealer claims, it was ok until next day when it was warmer and he got a flashing message on the dash telling him to evacuate the car immediately, which he did even though he was on a motorway, only to see clouds of gas escaping from somewhere under the car."
see, I don't understand that bit, unless there was something wrong with the system. To get from the garage to wherever he was sleeping and then onto the motorway he must have driven at least 10 miles, which, even if the tank was full to capacity with liquid (fairly unlikely but possible) would have used some gas and created a vapour space. OK, not as big a vapour space as required by the regulations (20% of tank capacity) but it should have been enough - notwithstanding the comments about temperature, you have to expand the liquid in the tank by enough to use all the vapour space to make it over-pressurise and vent.
Unless, of course, the people fitting it didn't purge the tank properly, which I suppose is quite possible. In that case, the tank would have air in it as well, which will compress, but will occupy part of the vapour space and that part will be unavailable for the LPG vapour. (assuming I remember my partial pressures thing correctly) [1]
either way, the system *has* to have malfunctioned for this to occur. The most likely is a fault in the 80% fill device,
[1] Consider a 60l tank. If the tank has air in it at atmospheric pressure, which is not purged, then once liquid LPG is present (in significant amount) the tank pressure will go up to 7-8 bar, or about 100psi or so. let's use 8 bar cos the maths is easier. The 60l of air, compressed, will now occupy 60/8 or 7.5l. The vapour space, provided by the 80% fill device, will be 20% of 60l, or 12l, when the tank is nominally "full" of LPG, so there's now only 4.5l available for the LPG vapour, which is still plenty. The 48l of liquid gas in the tank has to expand by almost 10% to cause any notable increase in pressure - all the time there's some vapour space available the tank pressure should stay more or less constant. I've just been googling and for no obviously good reason it's not easy to find actual figures for the CoE of liquid propane, other than one site which describes it as "relatively high".Even if the liquid gas does expand by more than 4.5l, thereby using up all the available space, you still have the air in the tank. To double the tank pressure, for example, it's got to expand a further 3.75l to halve the remaining space full of air. I'm not sure what pressure the PRV is supposed to operate at, but it's liable to be significantly higher than normal working pressure or they'd be going off all the time. I found one mention of 375 psi, which is more like 3 times normal working pressure.
So although a tank full of air which is not purged is an installation fault, it's not a major safety issue. The problems come with tanks which have air at higher pressure still present following, for example, a safety test. If the air was at 2 bar, say, then the compressed air at 8 bar will now occupy
1/4 of its original volume, or 15l. If the tank is filled to 80% with liquid gas, then the tank pressure will be above 8 bar, since the aforementioned air will now have been compressed to 1/5 it's original volume: it'll now be at 10 bar. This will preclude vapour-phase propane (I think). It won't necessarily be dangerous - if the PRV operates at 25 bar, there's still plenty of margin.BTW, for would-be installers... you purge the tank by putting a small amount of LPG in it, inverting it, and opening the outlet valve. In a well-ventilated area... This is not needed for vapour delivery tanks, as any air will be at the top of the tank, and the outlet is also at the top. Vehicle tanks have a dip tube and deliver liquid LPG from (near) the bottom of the tank.
I think that was the most likely scenario, but of course the dealer tried to blame the pump. Greg
Why should I bother to try to educate someone who is so offensive.
Why bother posting to this group at all?
SE Wales or Bournemouth. Depending on the time of the week.
Thanks Dave
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