Bob Wise wrote:
>But this raises a couple of questions. How many steel underground gas
>storage tanks are left? My impression is that in Wisconsin, at least, they
>have all been replaced with fiberglass units because 100% of steel tanks
>eventually leak. So what could have been the source of the rust? Also,
>too, don't the gas stations filter the gas before they run it through their
>very expensive pumps? Ever see the inside of a gas pump? These babies are
>pretty compliated and can't be cheap. If the amount of (presumably dirty)
>gas I run through my truck's fuel pump (~10 gallons a week) is enough to
>ruin it, then how long can a gas station fuel pump last if it is pumping
>>>1000's of gallons a week of dirty gas? Wouldn't the gas stations need to
>filter their own fuel just to protect their pumps?
Having worked for a gas pump manufacturer for 15 years I may be somewhat
qualified to answer this one.
I think you're right; I believe 22 December, 1995 was the date for all tanks to
be EPA approved, either by fiberglas replacement tanks or having the steel
tanks sprayed with a resin to prevent leakage. However, this applied *only* to
underground storage tanks. The bulk tanks where fuel drops are picked up are
above ground and the same rules do not apply. These tanks are also steel and
the sedimentation and rust therein are carried by the tanker trucks (along with
the fuel) to your friendly neighborhood convenience store/fueling station. It
is stirred up by the fuel drop and floats around in the fuel for awhile. We
have found that the temperature stabilizes, after a drop, top to bottom in the
UST in about eight hours. I would think the sedimentation would settle in
about the same time. If it's any consolation, tanks are installed with a
deliberate tilt to them to allow the water and trash to flow to the lowest
point in the tank. The submersible pump is at the high end of the tank which
minimizes the p
ick-up of trash/water.
As for dispensers/pumps filtration....we use 10 and 30 micron filters in our
units. For really trashy fuel (usually in International markets) a 100 mesh
strainer, or about 300 microns, is used. Though this is what we recommend and
install, a station owner, in a sense of false economy, can remove the strainer
to the detriment of the components downline from the filter and, ultimately,
your lbc. Our pumps will better handle the particulates than will your car.
The advice to not get gas if a tanker is making a fuel drop holds true.
The above views are my own and do not necessarily reflect those.....blah, blah,
blah.
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