Francesca Knowles
Port Hadlock, Washington
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Gas temperatures and thus volumes do fluctuate with the heat of the day, though more often at the pump.
It expands when warm, as anybody that has ever owned a gas can well knows.
Gas is sold by volume and not weight. On a hot day gas expands though of course its energy content doesn't.
A pound of feathers and a pound of gold occupy much different space, right?
The expansion of gas can result in a significant reduction in ACTUAL ENERGY purchased.
If you don't believe this, just ask Costco about the settlement agreement they reached in 2009 in a class action suit brought by consumers.
Costco Settlement agreement
" Not every mind that wanders is lost. " With apologies to J.R.R. Tolkien
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tatest
Oklahoma Green Country
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Measuring miles per gallon, you get more miles with colder, denser fuel. But the time when the temperature matters is when it flows to the injectors.
If you could buy the fuel colder, you would get more pounds per dollar, because it is being metered by the gallon. But for 10% shrinkage in volume, it would have to be a whole lot colder, because the expansion coefficient is relatively small (0.00095 /C). For 10% change in volume we need a temperature increase of 100 C. We don't usually see that much change in temperature morning to the daily high, not on clear nights out here on the plains or even in the desert. About 30 C is a more typical swing where temperature swings are extreme.
How many BTUs you get in your gallon, when you buy it, varies little because underground storage for retail is typical in the U.S.
The place where density change matters is when loading above-ground tanks and tankers, and for commercial transfers (and fueling aircraft) the fuels is sold by weight and the temperature is factored in when converting gallons to pounds, if measured by volume. Many times loading tankers, weight is measured directly by scales at the fill point.
Whether or not the actual volume changes during handling (up to 3%) are "significant" depends on how you view that difference. For wholesale transfers, the buyers and sellers consider it significant.
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timwood
Oxford, Michigan
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Francesca Knowles wrote:....If you don't believe this, just ask Costco about the settlement agreement they reached in 2009 in a class action suit brought by consumers.
Costco Settlement agreement
Oh, get the lawyers involved, that's a sure fire way to get to the truth! Lets not forget cell phones cause cancer, people can't possibly be expected to realize mowers can cut their feet off, and no one ever expects their coffee to be served hot...lol!
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Harvey51
Alberta
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Quote:Temperature compensation is common at the wholesale transaction level in the United States and most other countries. At the retail consumer level, Canada has converted to automatic temperature compensation and the United States has not. Where automatic temperature compensation is used, it can add up to 0.2% of uncertainty for mechanical-based compensation and 0.1% for electronic compensation, per Handbook 44.
There are many fewer retail outlets for gasoline in the United States today than there were in 1980. Larger outlets sell gasoline rapidly, as much as 30,000 US gal (110,000 L; 25,000 imp gal) in a single day, even in remote places. Most finished product gasoline is delivered in 8 to 16 thousand gallon tank trucks so two deliveries in a 24 hour period is common. The belief is that the gasoline spends so little time in the retail sales system that its temperature at the point of sale does not vary significantly from winter to summer or by region. Canada has lower overall population densities and geographically larger gasoline distribution systems, compared to the United States. Temperature compensation at the retail level improves the fairness under those conditions.
http://en.wikipedia.org/wiki/Fuel_dispenser
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Gene in NE
Omaha
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LARRYAG wrote:I think the theory is based on the differences in temperature of the fuel. Gas is stored in underground tanks that maintain a constant temperature of lets say 60 degrees. That is true providing the fuel is in the tank long enough to equalize to the ground temperature. You might consider that the entire underground tank may be emptied daily. <--as alluded to by "Harvey51" in his posting. Depending on when the tanker makes the delivery, the fuel early in the morning might have the best chance to be at the ground temperature of 60*F. ...Sorry, I am a diesel owner and still can't understand why diesel fuel is priced higher than regular fuel, when it costs less to manufacture diesel than gasoline. This whole fuel situation just doesn't pass the smell test. Sorry, just my 2-cents. I have heard it said that the reason the price of diesel is higher is because the demand does not change because of price. The railroad engines and semi-tractor/trailers run daily regardless of the cost of diesel. My comments in RED above.
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Gene
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Dakzuki
Carnation, Wa, USA
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It's a load of bollocks. The only thing that affects the volume of the fuel is temperature and that is nil day vs. night as the fuel we usually buy is kept underground.
On aircraft we use pounds of fuel because that is how one can equate the amount of energy you are going to get for a given amount of fuel. Gas is the same. What changes the weight is temperature. That will change in a plane (or any vehicle) depending on where you get fuel and what is came from (tanker sitting in desert sun all day for instance). The fuel tank indicators in an airliner are in lbs (or Kilos), and not gallons for that reason.
Now I did hear on the radio today there are some gasoline manufacturers than promised to make fuel to a spec that several manufacturers liked (for their fuel economy numbers) and one can get significant increases in economy by using these....especially in those vehicles. Of course I can't find the story on the web. A group did do a study and found merit in it.
* This post was
edited 02/04/12 10:15pm by Dakzuki *
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Francesca Knowles
Port Hadlock, Washington
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Dakzuki wrote:It's a load of bollocks.
No.
It's not.
Since words aren't getting the science across to some, here's a nice simple picture:
Hope that's not over any heads...
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timwood
Oxford, Michigan
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Francesca Knowles wrote:....
Hope that's not over any heads...
What seems to have gone over YOUR head is that the fuel is stored UNDER GROUND! The arguement is whether the gas gets warmer in the afternoon, not whether it loses energy with warming.
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mgirardo
Brunswick, GA
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Here's a link to some Myth debunking that Ford did a few years ago. The myth in question is the last one in the list.
Even if it were true that you would get more gas by filling up in the morning, it couldn't possibly improve gas mileage. You would just have more gas in your gas tank once the gas comes to ambient temperature.
-Michael
Michael Girardo :: michael@ecxc.com
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oldtrucker63
Harlan Kentucky
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One thing that most people do not know, When you buy gas And the sign says it cost $3.35.9 That means your paying $3.35 For 9/10th of a gallon It's not $3.35.9 per gallon your only getting 9/10 of one gallon for that $3.35 And at the pump it measures the gallons by volume and not by presser or weight, I know everyone has seen a clear plastic jug with gas in it expand and push the jug out, OK turn the lid and the air comes out, Although the level of liquid will not change inside the jug, The temp of the gas makes no differences, Now with this being said, The cooler the gas and air that go's into an engine the more efficient it will run, So with cold air in early morning will produce better MPG Not 10% but better, If you have ever been to a drag strip and go to the pits you will see the race guy's putting dry ice onto the intake of the engine to get them as cold as possible just before there run, This is them trying to make the Gas and air cold as they can to get all the HP out of there engine. So Hot outside air with warmer gas will get less MPG than cooler air and cooler gas.
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