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MaynardKrebs
Heave Steve, for the good of the country
Premium
join:2009-06-17
kudos:4
reply to talz13

Re: Weights and measures

said by talz13:

said by IowaCowboy:

When you pay for a gallon of gas, it should be a true gallon of gas.

It is always a gallon of gas, but due to temperature fluctuations, it may not be the same mass due to higher densities in cold temperatures, and lower densities in warmer temperatures.

In Canada, the gas is sold volumetric corrected to a temperature of 15C, which is the typical temperature of the gasoline in the underground tanks at the depth they are buried. Since the path of the gasoline in the above-ground portion of the pump is short there is no appreciable need to correct for the ambient atmospheric temperature.

You *might* gain some energy content advantage is you filled up in the winter just after the underground tanks were replenished, if the tanker had traveled 200 miles in -20F weather and chilled the gasoline.


cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
said by MaynardKrebs:

You *might* gain some energy content advantage is you filled up in the winter just after the underground tanks were replenished, if the tanker had traveled 200 miles in -20F weather and chilled the gasoline.

To quantify that amount...

Gasoline expands about 1.2ml per liter per 1 degree C increase in temperature. The variation between -20F and the baseline 15C is approximately 44C. That gives you the equivalent additional energy as an extra 52.8mL at the baseline temp, or a 5.28% advantage. Putting that in terms of units Americans would understand, that's like getting an extra 7/8ths of a cup of gas per gallon.

It usually averages out though for non-ATC pumps. Because for tanks that you might get at -20F, you may also get gas at 80 or 90 degrees and you lose the advantage.

MaynardKrebs
Heave Steve, for the good of the country
Premium
join:2009-06-17
kudos:4
said by cdru:

.......That gives you the equivalent additional energy as an extra 52.8mL at the baseline temp, or a 5.28% advantage. Putting that in terms of units Americans would understand, that's like getting an extra 7/8ths of a cup of gas per gallon.

52ml is roughly 20% of a standard 8oz./250ml 'cup', or approximately 2 ounces or 1/4 cup.

Anyone have any idea what the typical temperature of gasoline is when it's held in above ground tanks at the refiners terminal, and how much hat temperature varies though the year in different climatic zones?