----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----
Hi Alan,
Thanks for all this information. It's one of the few 'long' messages
that held my interest right to
the end.
Bob Saville
[EMAIL PROTECTED] wrote:
> ----[Please read http://ercoupers.com/disclaimer.htm before following
any advice in this forum.]----
>
> WHY I have more faith in MoGas than AVgas:
>
> For over a decade I have worked with a company that makes
instrumentation
> that meters and monitors watercuts in hydrocarbons.
> The main purpose of the instruments when used with finished fuels is to
> monitor and not pay for water delivered, sold, transported through
pipelines,
> tanks, trucks, etc.
> Water is a funny thing when mixed with fuels.
> Diesel fuel can hold over 1 1/2% of water and remain homogeneously
mixed. It
> will not separate with residence time. It is normally burnt with the
fuel.
> Gasolines work differently, They can also scavenge humidity out of the
air
> but in smaller proportions and it does separate. The only way to keep
water
> homogeneously mixed with gasoline is by mechanical mixing / agitation.
> Gasolines, diesel, avgas and all other fuels are transported from the
> refineries by truck or a combination of pipeline and truck. The further
you
> are from a refinery, the higher chance of a pipeline being involved. It
does
> not matter who owns the refinery or the pipeline. If you believe that
TEXACO
> gas stations only sell TEXACO gasoline with TECHRON and all that
advertising,
> you are very wrong. One pipeline across Texas is shared by three
refineries
> and the distribution centers trade, exchange and sell gasoline to each
other
> as convenience and cost dictates.
> Pipelines range anywhere between 6 inch diamter to 28 inch lines with
12" to
> 18" being the most common sizes.
> The pipeline is always flowing. If a distribution center, lets say like
the
> one in Hearne, TX owned by Texaco buys a shipment of unleaded gasoline,
a
> refinery like the Citco refinery in Lake Charles takes the order because
that
> day they had the best price. They wire SHELL refinery in Pasadena who
owes
> them more money than anyone else. This refinery pumps 800,000 gallons of
> regular unleaded gasoline at a specified time into the pipeline with
nothing
> to separate it from the products that are already in the line. The
> combination of the product ahead and behind of the slug with the fuel
> injected is called "interface". This means that after a certain amount
of
> time the large slug of regular fuel reaches Hearne and they detect the
shift
> in product. The interface ahead of their order. They send it into a tank
> until they detect the next interface. Here they shut off the line and
pay for
> what they received after calculating volume and water content. They have
also
> received a relatively small quantity of interface which is a mixture of
other
> fuels at the beginning and end of the delivery. Inb a large shipment,
this
> interface is not significant and they do try to make sure that the
shipment
> ahead and after the delivery is as similar as possible. (They TRY, or so
they
> say).
> When Hearne orders a small batch of Avgas, lets say 50,000 gallons,
because
> they don't sell it as fast as regular unleaded, it is also received with
> interface. Sometimes they divert the interface into another tank and
sell it
> as whatever octane range it is closest to, but with a significant
difference
> in price, they would lose money if they sold their AVgas interface as
regular
> unleaded. Secondly, the volume of the interface remains constant and in
a
> small batch such as AVgas, it is a noticeable proportion of fuel that
may or
> may not meet specifications. Compliance to specifications is done at the
> refinery and not at the point of final delivery.
> Sorry to disappoint all those of you who are faithful to one brand and
> quality, but I feel much more confident of a stable product buying
regular
> unleaded fuel than AVgas, mostly because of the volumes handled.
> Both can have water in them, very low residence time will allow all of
the
> water to separate and it is drained off the bottoms of tanks at every
point
> in the road.
> Any pilot worth his salt should drain the sumps of his tanks regardless
of
> the fuel used. It is best to keep tanks as full as possible. Air in the
tanks
> can hold moisture which will condense and sink through the fuel. The
less air
> in your tanks, the less moisture. Keeping a plane out in the rain with
almost
> empty tanks is going to collect water. Coupes will burn anything
octanewise
> between 80 and 110 octane safely. Aditives are another story and we will
save
> that for a rainy day.
> I also buy fuel for our local airport and I make darned sure the fuel
comes
> from the Phillips refinery in Pasadena, 30 miles by truck. No pipeline.
I
> drain the tank 30 minutes after delivery and weekly in between. I have
no
> control over where Phillips gets their Avgas though, They may have
refined it
> or they may have traded with another refinery for all I know.
> I get my unleaded at the cheapest gas station, the one that handles the
> largest volumes.
> I keep the tanks as full as possible, drain my sumps before pulling the
plane
> out of the hangar and have yet to find any water.
> AF
>
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