fuel density

1. ## fuel density

Need to see if there is some formula for figuring expansion rates for gasoline. For instance, if you put 20 gallons in a tank at 80 degrees F, what will that gasoline expand to at 115 degree F (like PARKER).

The 7.46gallons/ft3 is at what temp and then what is it at 115?

Say Johnny has a 20 gallon tank and Jimmy puts.....you know.

2.

3. Originally Posted by franky
Need to see if there is some formula for figuring expansion rates for gasoline. For instance, if you put 20 gallons in a tank at 80 degrees F, what will that gasoline expand to at 115 degree F (like PARKER).

The 7.46gallons/ft3 is at what temp and then what is it at 115?

Say Johnny has a 20 gallon tank and Jimmy puts.....you know.
i dont know anything about a formula to figure that, but, i do suspect expansion might have to do with where ur tanks are mounted & how much sun/temp hits them...i have 2 12.5gal side tanks & i never fill them over 10gal each...i have never had any probs with temps...i try to fill my tanks when its not blazeing out (early am) when the gas is colder from sitting in the ground!...the colder the gas...the less expansion...just my .02 cents

FastRat

4. i think this is what you're looking for.

5.

6. Originally Posted by FastRat
i dont know anything about a formula to figure that, but, i do suspect expansion might have to do with where ur tanks are mounted & how much sun/temp hits them...i have 2 12.5gal side tanks & i never fill them over 10gal each...i have never had any probs with temps...i try to fill my tanks when its not blazeing out (early am) when the gas is colder from sitting in the ground!...the colder the gas...the less expansion...just my .02 cents

FastRat
excact oposite. the colder the gas is to begin with, the bigger the delta when it heats up.

7. Originally Posted by RvRrat
i think this is what you're looking for.
nice!!

now if that is for real, what is the symbal in front of the second V (volume) mean?

but if that is not for real, still nice!!

8. Originally Posted by RvRrat
i think this is what you're looking for.

β(=3α) in 10-6/K at 20 °C

9. Originally Posted by franky
Need to see if there is some formula for figuring expansion rates for gasoline. For instance, if you put 20 gallons in a tank at 80 degrees F, what will that gasoline expand to at 115 degree F (like PARKER).

The 7.46gallons/ft3 is at what temp and then what is it at 115?

Say Johnny has a 20 gallon tank and Jimmy puts.....you know.
Since the formulas are a nightmare to the non-physicist, sufice to say, the expansion of gasoline (looked this up long ago on another board when someone claimed a major truck stop was selling fuel that lost 20% of it's volume to cooling, bull-crap) is roughly 1.5% per 100 degrees.

Thus gasoline, at a set volume at zero*F, is 1.5% bigger, at 100*F, and about 3.1% bigger at 200*F, about 4.2/4.3% bigger at 300*F, and self-ignites before 400*F.

Fuel filled into your boat @ 50*F, is about 0.75% greater at 100*F

Your 40* increase above, is only worth about 0.5% or so increase.

Only worth bothering about if you brim fill them and don't drive any out before letting it sit in the sun.

10. Originally Posted by franky
Need to see if there is some formula for figuring expansion rates for gasoline. For instance, if you put 20 gallons in a tank at 80 degrees F, what will that gasoline expand to at 115 degree F (like PARKER).

The 7.46gallons/ft3 is at what temp and then what is it at 115?

Say Johnny has a 20 gallon tank and Jimmy puts.....you know.
Curious why do you ask, just general knowledge or what ?

My boat has 12.5 gallon tanks at 11.5 in San Diego is fine in Yuma if 12 gallons here in Yuma it's overflow time at 100-105*.

Sleeper CP

11. Originally Posted by Sleeper CP
Curious why do you ask, just general knowledge or what ?

My boat has 12.5 gallon tanks at 11.5 in San Diego is fine in Yuma if 12 gallons here in Yuma it's overflow time at 100-105*.

Sleeper CP
Building a tank for my boat for the Parker 300. I know how much fuel I want to carry, just need to adjust size for expansion, plus general knowledge. BTW, the outside info I am getting says 10%.

12. The 1.5% per every 100° is pretty close. There are some variables (type of fuel, absolute pressure, etc,) but this is close enough for most. Also keep in mind that your venting is the main concern, too many people when building a fuel tank do not install a large enough vent.

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