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Richard Casady

On Fri, 03 Apr 2009 09:37:39 -0400, wrote:

On Fri, 03 Apr 2009 07:22:26 -0500, Richard Casady
wrote:

On Thu, 02 Apr 2009 12:36:01 -0400, wrote:

Storing gasoline above ground in a small tank (car, lawnmower,
outboard motor tank, etc) greatly increases the rate at which
moisture is absorbed. The underground tanks maintain a pretty constant
temperature.

Moisture has no particular effect on the formation of gum, which is
the issue under discussion.

Casady

The subject, stated on the subject line, is bad fuel. When talking
about problems with storing gas for long periods, water is a bigger
problem than formation of gum. You can retard or prevent the foramtion
of gum. You can't do much about phase separation of water in fuel.

Good fuel that happens to be in the same container as water is still
good fuel, you can start a new thread about separating water from fuel
if you like, but good fuel floating on water is still good fuel. This
is normally found in all tankers and most storage tanks. They strain
out the dead shrimp before it gets to you tank.

As for preventing gum, they mostly do all that needs doing at the
refinery. We have been leaving gas over the winter in the same
runabout for fifty years without a trace of gum. No problems with
water either. The only gum I have ever seen was in a lawn mower from a
thrift shop, and for all I know the varnish and gas were thirty years
old. The mower was that old.

You might not want drain valves for gasoline possibly dripping into
the bilge, but Diesel tanks should have quick drains, same as all the
light airplanes. [I presume heavy planes have them as well.]

The references to phase separation that I have found refer to water
washing the ethanol from fuel. When you then remove the water layer,
in numerous ways the boating community seems not to use,
the gasoline will be a point or so lower in octane since ethanol rates
100+ octane, [as do methanol, propane, toluene, acetone, 2,2,5
trimethyl pentane]. That last I threw in because it is the reference
fuel for the octane scale.

Casady