Are you kidding? The volumetric expansion of metal is something like 30x that of gasoline. It's probably still not a significant factor when it comes to volumetric accuracy, but my point was that of all things the liquid expanding and contracting probably has less of an effect than many other things. I think my point was valid and in the context of my question the expansion is significant.
I made that calculation based on the first reply that stated the average temp of tanked gas in the US was 64.xx degrees. That translates to a 2.6 degree Celsius difference assuming that number is accurate. Volumetric expansion is 3*a with a being the coefficient of thermal expansion. So that would be 3 * 950 * 10^-6 or.00285. 3.00 *.00285 is.00855 or roughly 9/10 of a cent. So I guess my initial calcs were off by a bit although the temperature difference I initially sated was larger as well. Ironic that they tack that 9/10 on the price board. I guess that if you filled up right after a truck delivered more fuel the temp would be higher, but even then the fuel already underground would prevent the temperature from rising up to the full surface temperature.
What about the fact that the pump components are also expanding? It seems like that would be more significant than the gas its self expanding. The most accurate solution, as mentioned on car talk, would be to sell gasoline by weight as the weight does not change with temperature.
It's more like 2 cents because it's only a about a 3.2 degree celsius increase, not 20C. That is listing the expansion for a rise of one degree with the liquid being at a temperature of 20C
Slashdot Mirror
Fuck, got my numbers swapped. Gas expansion is 30x that of steel. Ignore my previous conclusion.
Are you kidding? The volumetric expansion of metal is something like 30x that of gasoline. It's probably still not a significant factor when it comes to volumetric accuracy, but my point was that of all things the liquid expanding and contracting probably has less of an effect than many other things. I think my point was valid and in the context of my question the expansion is significant.
I made that calculation based on the first reply that stated the average temp of tanked gas in the US was 64.xx degrees. That translates to a 2.6 degree Celsius difference assuming that number is accurate. Volumetric expansion is 3*a with a being the coefficient of thermal expansion. So that would be 3 * 950 * 10^-6 or .00285. 3.00 * .00285 is .00855 or roughly 9/10 of a cent. So I guess my initial calcs were off by a bit although the temperature difference I initially sated was larger as well. Ironic that they tack that 9/10 on the price board. I guess that if you filled up right after a truck delivered more fuel the temp would be higher, but even then the fuel already underground would prevent the temperature from rising up to the full surface temperature.
Touche
What about the fact that the pump components are also expanding? It seems like that would be more significant than the gas its self expanding. The most accurate solution, as mentioned on car talk, would be to sell gasoline by weight as the weight does not change with temperature.
It's more like 2 cents because it's only a about a 3.2 degree celsius increase, not 20C. That is listing the expansion for a rise of one degree with the liquid being at a temperature of 20C