Gas Tank Expansion

[Roselaw1]

Just want to give a heads up to everyone regarding a potentially dangerous condition I just learned about. I sold my 2003 23' LSV this year and replaced with a 2010 23' LSV. Last week, I got a call from the purchaser of my old boat regarding a problem that had developed. The boat is stored at Lake Havasu, AZ, where the temperatures can get pretty extreme. After he had used the boat for the day, he filled the gas tank to the rim and parked the boat in his garage. He went to use the boat a few days later and discovered the floor board covering the gas tank had been dislodged and was sitting about an inch off the floor. Apparently, the temperature in his garage gets to about 140 degrees, which caused the gas in the tank to expand. Because he had topped off the tank, the vent line was covered and there was not place for the expanded gas and vapors to go and, as a consequence, the tank expanded. Apparently, he contacted Malibu and was told that this has happened many times and that Malibu is aware of the problem. Malibu would not fix the problem.

[wakeboy]

Is it sad that I am jealous of those temperatures? Also, that is good to know that. I will not ever be filling my gas tank more than 3/4 when I am done for any extended period of time.

[Bill_AirJunky]

This is not a problem isolated to Malibus, or even to boats. It's something that happens to any gas tank & is why it's not recommended to top off a tank.

http://www.epa.gov/donttopoff/

Edited July 1, 2010 by Bill_AirJunky

[wakeboy]

Damn, I always top off. I guess I will have to floor it leaving the gas station, just to be safe.

[CedarLakeSkier]

I also don't top off because when you pump gas it is cold from being in the ground. Just the gas warming up makes it expand. If you top off, just the trip home could be enough to send gas out the vent if it's warm enough.

[Bill_AirJunky]

Ever notice you can get more than 5 gallons of gas in a 5 gallon gas can? Now you know why.

[Roselaw1]

I also don't top off because when you pump gas it is cold from being in the ground. Just the gas warming up makes it expand. If you top off, just the trip home could be enough to send gas out the vent if it's warm enough.

Almost every time I filled the 03', it would spit gas out the vent as I towed to the lake - and I always stopped filling once the nozel clicked off. In that circumstance, the vent was working as designed. The problem arises when you top off completely and cover the vent opening.

[85 Barefoot]

In looking at this issue, I learned that gas actually expands...a lot, and that people in warmer states are getting ripped off because they get charged for gas volume at a standard temp and then when it is then dispensed at a warmer (and hence less gas) temp.

[BlastRlxi]

In looking at this issue, I learned that gas actually expands...a lot, and that people in warmer states are getting ripped off because they get charged for gas volume at a standard temp and then when it is then dispensed at a warmer (and hence less gas) temp.

There has to be some downside to living in warmer climes. It makes us northerners feel better...

[Ndawg12]

In looking at this issue, I learned that gas actually expands...a lot, and that people in warmer states are getting ripped off because they get charged for gas volume at a standard temp and then when it is then dispensed at a warmer (and hence less gas) temp.

That's why you should fill up in the morning as early as possible when it's still cool. However, keep in mind that the tanks are buried 4-6 feet in the ground to the top of the tank and the temperature change is far less drastic throughout the day.

[Bobby Light]

Maybe auto manufacturers should offer a refrigerated gas tank so consumers get their money's worth .

[RTS]

That's why you should fill up in the morning as early as possible when it's still cool. However, keep in mind that the tanks are buried 4-6 feet in the ground to the top of the tank and the temperature change is far less drastic throughout the day.

That's true...you're not getting ripped off as bad as you think. Fill up a 5 gallon can on a warm day and you will see that the fuel is cooler to the touch than the ambient air. But theoretically, yes, time your fill ups in the early mornng hours and you'll get a couple extra drops in the tank.

Also, some warmer climate states have mechanisms on the pumps to compensate for volumetric differences due to the fuels temperature. If I am not mistaken, there is a push to make those mechanisms mandatory here in Florida. I think I recall reading in in the local paper not too long ago.

[85 Barefoot]

Maybe auto manufacturers should offer a refrigerated gas tank so consumers get their money's worth .

Makes no diff what temp is once in the car, what matters is the temp when dispensed (in terms of cost savings)

[RTS]

Scratch what I said. Canada has temperature compensating pumps, the U.S. does not. From a website I found:

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.

And here's some more info on temperatures effects on gas:

The reference temperature for gasoline volume measurement is 60 °F (16 °C). Ten gallons of gasoline at that temperature expands to about 10.05 US gal (38.0 L; 8.4 imp gal) at 85 °F (29 °C) and contracts to about 9.83 US gal (37.2 L; 8.2 imp gal) at 30 °F (−1 °C). Each of the three volumes represents the same theoretical amount of energy. In one sense, ten gallons of gasoline purchased at 30° F is about 3.2% more potential energy than ten gallons purchased at 85° F. Most gasoline is stored in tanks underneath the filling station. Modern tanks are non-metallic and sealed to stop leaks. Some have double walls or other structures that provide inadvertent thermal insulation while pursuing the main goal of keeping gasoline out of the soil around the tank. The net result is that while the air temperature can easily vary between 30° F and 85° F, the gasoline in the insulated tank changes temperature much more slowly.

If you buy 85° gas instead of 30° gas (fahrenheit), you'd be out 3.2%.

Where's that guy that just let us know he was a petroleum engineer...maybe he could set us straight.

[skyskier]

If the promise of early morning butter can't shake me out of bed, I don't think free gas will do it either.

[LS-One]

That's why you should fill up in the morning as early as possible when it's still cool. However, keep in mind that the tanks are buried 4-6 feet in the ground to the top of the tank and the temperature change is far less drastic throughout the day.

[Bill_AirJunky]

If the promise of early morning butter can't shake me out of bed, I don't think free gas will do it either.

Hehe, damn foil riders....

Ever notice the footers getting ticked off whenever your out early in the morning?

[skyskier]

The only way I would ever see early morning is to stay up and wait for it.

[63Taylor]

I never top off because the pumps around the lake shut you off at 100 bucks, unfortunately 100 rarely fills the Bu

[Faceplant409]

I never top off because the pumps around the lake shut you off at 100 bucks, unfortunately 100 rarely fills the Bu

Here too...

[Pistol Pete]

Where's that guy that just let us know he was a petroleum engineer...maybe he could set us straight.

That's our friend ScooterM