Today's Message Index:
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1. 09:32 AM - Re: Flight to Lake Havasu (Brian Proett)
2. 04:48 PM - Re: Flight to Lake Havasu (GARY PENNINGTON)
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| Subject: | Flight to Lake Havasu |
A little gasoline trivia - Since I am in the industry I thought that I would
let you know what I know about crudes and gasolines. As a starter I am not
in the refining business. I am in the E&P (Exploration and Production) end
and I usually lose interest after the stuff comes out of the ground.
Firstly, crude varies dramatically from condensates that can be used
directly in your car to heavy oil that is the consistency of peanut butter.
As we are turning more to alternate crudes we are producing more peanut
butter and less light sweet stuff. Refineries must set up for the type of
crude being run and what product is being produced.
Two things that are not widely known: There are only a few places that oil
is refined and the product is transported across the country via pipelines.
Here is the thing, all companies use the same pipeline system. So at the
other end you don't really know who produced the product. The product must
be on spec before it enters the pipeline and the specs are very tightly
controlled. The difference between ExxonMobil and Chevron is not the base
product but the additives and blending at the terminals. Secondly, I can
count at least 18 formulations of gasoline that are used around the country.
Summer vs. winter, high density traffic areas (EPA reformulated e.g. Ca and
other major population centers) and high altitude areas. Each of these
carries three grades of fuels. Do the math.
The gasoline needs to have the proper octane, and it needs to have the
proper Reid vapor pressure, or RVP. Buz referred to the fuels vapor
pressure are an important factor. Fuels with a high RVP will begin to boil
if your tank is sitting there in 100+ F heat. Not Good. This is the
difference between summer and winter blends even when the octane remains the
same. As you all know atmospheric pressure is 14.7 pounds/in2 at sea level
and the pressure decreases with altitude. When the atmospheric pressure is
less than the RVP the fuel will begin to boil. This occurs in a carburetor
earlier with the lower pressure (Vapor Lock). The EPA has declared that
summer gasoline blends may not exceed 7.8 psi in some locations, and 9.0 psi
in others. I don't know how high the cheaper winter blends can go. Now
you know why the gasoline is more expensive in the summer.
The octane and RVP is controlled by the blend. Ok, back to the refineries.
Gasoline is composed of many different hydrocarbons. Crude oil enters a
refinery, and is processed through various units before being blended into
gasoline. A refinery may have a fluid catalytic cracker (FCC), an alkylate
unit, and a reformer, each of which produces gasoline blending components.
Alkylate gasoline, for example, is valuable because it has a very high
octane, and can be used to produce high-octane (and higher value) blends.
Light straight run gasoline is the least processed stream. It is cheap to
produce, but it has a low octane. The refinery mixes these components
together to meet the product specifications. The RVP is controlled by the
butane percentage. All the components vary but Butane has a RVP of 52.
This is much higher than the other components so the summer blends only
contain about 2% butane.
So what does this mean for aviation use of gasolines that are spec'ed for
use in ground based autos. Well it depends on the engine and fuel delivery
system. There is a constant balance between the auto manufactures,
environmental issues and commerciality. Engines have changed, these
changes have resulted in changes fuel specs. It has all gotten more complex
and the spec have gotten more stringent. There is an effort to create a new
fuel spec for Avgas with out lead. The primary issue is not the ability to
come up with a fuel but one that is compatible with the old engine designs
and installed base.
Personally, I would have more faith in a fuel that is specifically designed
for the engine that I intend to put it in. If you know the fuel specs and
the manufacture specs then you should be good to go.
Brian P.
_____
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of
N1BZRich@aol.com
Sent: Saturday, February 21, 2009 3:02 AM
Subject: Re: Lightning-List: Flight to Lake Havasu
In a message dated 2/5/2009 7:24:04 P.M. Eastern Standard Time,
pennington@q.com writes:
I don't know how to explain this, but as I noted before, my engine burns
less Premium Auto Fuel per hour than AvGas.
Gary,
I just re read your Lake Havasu flight report and this time actually
noticed your statement / question (above) about the difference of auto gas
verses AvGas fuel burns. And the fact that you got slightly better fuel
burns and thus used less fuel when you were using auto gas. The reason for
this is that auto gas is more volatile than avgas, and because of this you
may actually see slightly lower fuel usages. There can be some downsides,
such as higher vaporization, a higher potential for vapor lock, and perhaps
more carburetor icing. Another thing to remember is that auto gas has
looser manufacturing specifications and quality control is less stringent,
so actual quality and performance may vary widely from load to load. Hope
this helps.
Blue Skies,
Buz
_____
Need a job? Find
<http://yellowpages.aol.com/search?query=employment_agencies&ncid=emlcntusye
lp00000003> an employment agency near you.
Message 2
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| Subject: | Re: Flight to Lake Havasu |
Hello Brian
You obviously know your gas. Although, I wasn't able to determine any
significant difference between auto fuel and avgas from your response.
Thanks for your help.
Gary Pennington
----- Original Message -----
From: Brian Proett<mailto:baproe@online.no>
To: lightning-list@matronics.com<mailto:lightning-list@matronics.com>
Sent: Sunday, February 22, 2009 10:31 AM
Subject: RE: Lightning-List: Flight to Lake Havasu
A little gasoline trivia - Since I am in the industry I thought that I
would let you know what I know about crudes and gasolines. As a starter
I am not in the refining business. I am in the E&P (Exploration and
Production) end and I usually lose interest after the stuff comes out of
the ground.
Firstly, crude varies dramatically from condensates that can be used
directly in your car to heavy oil that is the consistency of peanut
butter. As we are turning more to alternate crudes we are producing
more peanut butter and less light sweet stuff. Refineries must set up
for the type of crude being run and what product is being produced.
Two things that are not widely known: There are only a few places
that oil is refined and the product is transported across the country
via pipelines. Here is the thing, all companies use the same pipeline
system. So at the other end you don't really know who produced the
product. The product must be on spec before it enters the pipeline and
the specs are very tightly controlled. The difference between
ExxonMobil and Chevron is not the base product but the additives and
blending at the terminals. Secondly, I can count at least 18
formulations of gasoline that are used around the country. Summer vs.
winter, high density traffic areas (EPA reformulated e.g. Ca and other
major population centers) and high altitude areas. Each of these
carries three grades of fuels. Do the math.
The gasoline needs to have the proper octane, and it needs to have the
proper Reid vapor pressure, or RVP. Buz referred to the fuels vapor
pressure are an important factor. Fuels with a high RVP will begin to
boil if your tank is sitting there in 100+ F heat. Not Good. This is
the difference between summer and winter blends even when the octane
remains the same. As you all know atmospheric pressure is 14.7
pounds/in2 at sea level and the pressure decreases with altitude. When
the atmospheric pressure is less than the RVP the fuel will begin to
boil. This occurs in a carburetor earlier with the lower pressure
(Vapor Lock). The EPA has declared that summer gasoline blends may not
exceed 7.8 psi in some locations, and 9.0 psi in others. I don't know
how high the cheaper winter blends can go. Now you know why the
gasoline is more expensive in the summer.
The octane and RVP is controlled by the blend. Ok, back to the
refineries. Gasoline is composed of many different hydrocarbons. Crude
oil enters a refinery, and is processed through various units before
being blended into gasoline. A refinery may have a fluid catalytic
cracker (FCC), an alkylate unit, and a reformer, each of which produces
gasoline blending components. Alkylate gasoline, for example, is
valuable because it has a very high octane, and can be used to produce
high-octane (and higher value) blends. Light straight run gasoline is
the least processed stream. It is cheap to produce, but it has a low
octane. The refinery mixes these components together to meet the product
specifications. The RVP is controlled by the butane percentage. All
the components vary but Butane has a RVP of 52. This is much higher
than the other components so the summer blends only contain about 2%
butane.
So what does this mean for aviation use of gasolines that are spec'ed
for use in ground based autos. Well it depends on the engine and fuel
delivery system. There is a constant balance between the auto
manufactures, environmental issues and commerciality. Engines have
changed, these changes have resulted in changes fuel specs. It has all
gotten more complex and the spec have gotten more stringent. There is
an effort to create a new fuel spec for Avgas with out lead. The
primary issue is not the ability to come up with a fuel but one that is
compatible with the old engine designs and installed base.
Personally, I would have more faith in a fuel that is specifically
designed for the engine that I intend to put it in. If you know the
fuel specs and the manufacture specs then you should be good to go.
Brian P.
-------------------------------------------------------------------------
-----
From: owner-lightning-list-server@matronics.com
[mailto:owner-lightning-list-server@matronics.com] On Behalf Of
N1BZRich@aol.com
Sent: Saturday, February 21, 2009 3:02 AM
To: lightning-list@matronics.com
Subject: Re: Lightning-List: Flight to Lake Havasu
In a message dated 2/5/2009 7:24:04 P.M. Eastern Standard Time,
pennington@q.com writes:
I don't know how to explain this, but as I noted before, my engine
burns less Premium Auto Fuel per hour than AvGas.
Gary,
I just re read your Lake Havasu flight report and this time
actually noticed your statement / question (above) about the difference
of auto gas verses AvGas fuel burns. And the fact that you got slightly
better fuel burns and thus used less fuel when you were using auto gas.
The reason for this is that auto gas is more volatile than avgas, and
because of this you may actually see slightly lower fuel usages. There
can be some downsides, such as higher vaporization, a higher potential
for vapor lock, and perhaps more carburetor icing. Another thing to
remember is that auto gas has looser manufacturing specifications and
quality control is less stringent, so actual quality and performance may
vary widely from load to load. Hope this helps.
Blue Skies,
Buz
-------------------------------------------------------------------------
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