Oh good....one I can answer since I work as a chemical engineer in a
refinery.
The grades of gasoline are based on octane only. Octane is merely a measure
of the resistance to knocking...it has nothing to do with "power" as
commercials might imply. Refineries make many different gasoline blend
stocks from various processes. These blend stocks are then blended into the
final grades of gasoline to meet the minimum requirements for octane, vapor
pressure, and other specifications.
Octane primarily does not come from an "additive." The octane of a gasoline
comes mainly from the inherent octane of the different blend stocks made by
refinery processes. The additive exception is MTBE. MTBE is added to
gasoline because the federal government requires that it be added in some
areas. MTBE has an oxygen atom in the molecule so it's called an oxygenate.
MTBE is added to gasoline to reduce emissions. It's true that MTBE has a
high octane, but it's also a very expensive way to get octane. One way
refiners make high octane blend stocks is by reforming. In this process
molecules that have a bunch of carbon atoms in a row are "reformed" so that
the carbon atoms form a ring thus turning a low octane molecule into a high
octane molecule. The cost of making this octane is less than making or
buying MTBE to add to the gasoline. Sometimes a refinery will add MTBE to
be able to make the amount of premium gasoline that it contractually
committed to making even if it isn't required to by law.
One question I hear a lot is "What grade of gasoline should I put in my
car?" The answer is the minimum octane that prevents your car from
knocking. If the engine doesn't knock on regular then you're wasting your
money putting premium in the tank.
Hope that helps.
Bob Bollinger
79 Spitfire
> -----Original Message-----
> From: Joe Curry [SMTP:spitlist@gte.net]
> Sent: Wednesday, January 27, 1999 3:56 PM
> To: fred thomas
> Cc: triumphs@autox.team.net; spitfires@autox.team.net
> Subject: Re: petrol
>
> Fred,
> Lets see if I can remember....
>
> The gasoline is pumped down a common pipeline from the refinery. It is
> pumped in batches that are separated by an air bubble between them.
> (Not sure of the dynamics of that process)
>
> The grades are more likely a result of additives which are mixed after
> the fuel is received.
>
> The different grades are then shipped in tank trucks to the station and
> into the holding tanks where they are distributed to the consumers
> through the pumps.
>
> Am I close? Or is it all done with smoke and mirrors?
>
> Joe
>
> fred thomas wrote:
> >
> > anybody have any idea how petrol gets from the refinery to your local
> > station, and then do they get the three different varieties, to your car
> > ??
> > How is reg., hi-test & premium manufactured, lets try this on for a few
> > days, should be interesting.
>
> --
> "If you can't excel with talent, triumph with effort."
> -- Dave Weinbaum in National Enquirer
>
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