Carl Denk wrote:
> The pumps are all submersible, and have a check valve after the pump
> turbines (very close, the entire pump including motor, turbine and check
> valve, probably less than 2 feet long). The entire system is liquid(and
> for all practical purposes air too) tight, When the pump is turned on
> for the first time (new, after maintenance or running the tank dry)
> after being immersed in fuel, it will  self prime very quickly and the
> air will get compressed in the piping, dispenser, and hose to the
> nozzle. Opening the nozzle valve will allow the air to be expelled from
> the system. Once this is done (should be done by the system operator,
> and not customer) there should not be any air in the system, though it
> would be possible to drain the liquid in the hose by turning off the
> pump (read as including a manifold valve if multi dispenser system) and
> opening the nozzle valve with the nozzle lower than it's attachment to
> the dispenser. Most meters I have seen only measure liquid, and not air,
> but this may not be always true.

This is generally how all pumps work I've seen in recent decades, but things
were not always so.  Back when I was in grade school we were driving thru
northern Arizona and New Mexico, and happened to need gas in the Hopi indian
reservation.  We had ask around a bit for where there was a gas station, but
eventually we were directed to a town on the top of a hill a few miles from
the main road.  The gas pump had a big upside down jar on top, looking
sortof like one of those replacable water jugs of office water coolers.
Except this jar was a bit bigger, glass, and on top of the pump at eye
level.  The gas station attendent asked how much gas we wanted, then worked
a mechanical pump by hand that caused the big glass jar to fill up.  It was
marked off in gallons.  Once he got to the gallons we requested, he stopped
pumping and the car was filled by gravity from the big jar.  Pretty cool.  I
vaguely remember gas cost in the low 30 cents per gallon range.

The cheapest gas I remember was in the middle of noplace Nevada (maybe Utah
or Arizona).  It was at a crossroads of two paved roads with a gas station
on 3 of the 4 corners with pretty much nothing else around for 10s of miles.
The gas price was 18 cents/gallon, which was a great deal even then.


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