[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]
Jim Adney wrote: >Unless there's some defect in your system, the tank is completely vented and no >pressure buildup is possible. > > Well, if the liquid is vaporizing at a higher rate than the vent will allow, then the pressure would be higher than atmospheric- even if marginally so. Also, keep in mind that 1 mole of gasoline vapor takes up a significantly higher volume than 1M of liquid. So, if you have a cubic foot of fuel vapor, that might actually only be a few drops of fluid. >OTOH, the bottom of >the tank, which the fuel is actually in contact with, is probably cooler. > > Right, and this would explain why your fuel isn't boiling off like a teakettle- it's going to be cooler in the bottom of your fuel tank. If your fuel tank were 100 deg F and were wide open, you would see significant vaporization, though not necessarily the visual of "boiling water". > To my knowledge, being polar or non-polar does not have anything to do > with the > >how violent the boiling might be. That would only have to do with how fast you >are putting heat into the liquid. > > > I may have misunderstood my friend the MatSci guy, or he might have oversimplified this for me. >Absolutely correct. The vapor pressure of any material increases up to the >point where it boils, which is the temp where its vapor pressure equals >atmospheric pressure. > > > Right, and in a fuel tank there might be a pressure greater than atmospheric if its warm. I'm not sure how radically the boiling point changes over pressure. Perhaps +1 PSI over 1 atmosphere is enough to raise the boiling point 20 degrees. I don't know what the exact numbers are. What's the boiling point of water in Denver, and what's the atmospheric pressure? >I'm just skeptical about this 77F figure, especially since none of the typical >chemicals that I expected to see in gasoline had boiling points anywhere close >to that low. OTOH, you're the only one who has come up with a reference, and >that reference looks authoritative. > > And other similar products have similar statistics, too. It seems a bit counterintuitive given our collective experience, but I'll buy it. Any chemists out there wanna settle this once and for all? :) ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~