I'm new here and just wanted to share this information with you all.
I got it as an email........


Subject: [sffi] Pumping gas.... good things to know

This is from my FRIEND and he knows !!!!

I've been in petroleum pipeline business for about 31 years, currently
working for the Kinder-Morgan Pipeline here in San Jose, CA. We
deliver about 4 million gallons in a 24-hour period from the pipe
line; one day it's diesel, the next day it's jet fuel and gasoline. We
have 34 storage tanks here with a total capacity of 16,800,000 gallons.
Here are some tricks to help you get your money's worth:

1. Fill up your car or truck in the morning when the temperature is
still cool. Remember that all service stations have their storage
tanks buried below ground; and the colder the ground, the denser the
gasoline. When it gets warmer gasoline expands, so if you're filling up
in the afternoon or in the evening, what should be a gallon is not
exactly a gallon. In the petroleum business, the specific gravity and
temperature of the fuel (gasoline, diesel, jet fuel, ethanol and other
petroleum products) are significant. Every truckload that we load is
temperature- compensated so that the indicated gallonage is actually
the amount pumped. A one-degree rise in temperature is a big deal for
businesses, but service stations don't have temperature compensation at
their pumps.

2. If a tanker truck is filling the station's tank at the time you
want to buy gas, do not fill up; most likely dirt and sludge in the
tank is being stirred up when gas is being delivered, and you might be
transferring that dirt from the bottom of their tank into your car's
tank.

3. Fill up when your gas tank is half-full (or half-empty), because
the more gas you have in your tank the less air there is and gasoline
evaporates rapidly, especially when it's warm. (Gasoline storage
tanks have an internal floating 'roof' membrane to act as a barrier
between the gas and the atmosphere, thereby minimizing evaporation. )

4. If you look at the trigger you'll see that it has three delivery
settings: slow, medium and high. When you're filling up do not
squeeze the trigger of the nozzle to the high setting. You should be
pumping at the slow setting, thereby minimizing vapors created while
you are pumping. Hoses at the pump are corrugated; the corrugations act
as a return path for vapor recovery from gas that already has been
metered. If you are pumping at the high setting, the agitated gasoline contains
more vapor, which is being sucked back into the underground tank, so
you're getting less gas for your money.

Hope this will help ease your pain at the pump.

 

Very interesting!
Thanks, will keep this in mind when I fill up.

 

If the tanks are underground, shouldn't the temperature of the gasoline remain relatively stable during the day, since ground temperature remanis relatively stable? Just asking.

 

I've never bought this argument. The temperature at 20+ feet below ground is essentially constant even though the air temperature fluctuates. So the temperature of the gas being pumped from the storage tank should change very little based on time of day.

Even if you ignore the fact above, daytime high and low air temperatures rarely differ by more than 40 degrees F. Gasoline changes volume at ~0.058% per degree F. So worst case scenario that's a 2.3% difference. While not negligible, 2% pales in comparison to how driving style affects fuel consumption.

 

Thanks for the tip!

 

I'm in O&G as well, but on the production side.

I agree with the first theory, however, like spreadhead said, ground temperatures remain relatively stable. The tanks are usually buried a few meters below the surface of the ground and is subsequently covered by concrete. The compacted dirt and concrete act as a barrier and insulate the tank preventing drastic temperature changes that could affect the gasoline/diesel. Over time, however, the ground temperature will change a few degrees (i.e. over a period of hot days or cold days out of season) and could affect the density (sg as mentioned in the blurb). He is right though, small temperature changes can have an adverse affect on fuels such as gasoline.

I'm not too sure about the second statement. I don't know exactly how those pumpers extract the gas from the tank, but the simplest method is to withdraw the gas from the bottom of the tank and use the weight of the gas itself to help the pumpers generate enough pressure to force the gas up from the tank to your car. This withdrawl from the tank will constantly create some sort of motion inside of the tank and will displace any sediment at the bottom of the tank. One thing that we do in the business is to have our tanks cleaned out every month and circulate to inhibit corrosion and other damaging effects from particulates. But we deal with crude oil, not gasoline. Gasoline that has been refined should be very clean and should have very small amounts of particulates. A good gas station would have their tanks cleaned every so often as well.

Third point, he is right that gasoline evaporates quite quickly. If I remember correctly, the liquid point of sales gasoline is quite low, which is why tanks are kept under pressure. Increase in pressure = higher liquid point (via PV=nRT). When you withdraw gas from the pump, similar conditions exist as the gas is under pressure when it is withdrawn from the tank. The big difference is when it goes into your tank where the pressure is at 1 atm. Vapor point decreases and gasoline fumes are generated. What you are losing at that period of time I would believe is minuscule enough to not be of concern as the difference in diameter between the nozzle and the filler neck is small and most nozzles I find have those rubber flap things to prevent any over spill onto you. That acts as a barrier for the vapors as well. Good theory, but I doubt there is much savings, if any there.

The fourth point I definitely agree with. Slow setting is best.

 

Not trying to troll....but...

1) the amount of expansion of a liquid would be barely noticeable. You'd probably save less than .0001 cents by filling a 40 liter tank.

2) most gas pumps have filters (they look like oil filters) to filter out particles from entering the gas tank.

3) most, if not all, cars have sealed systems to prevent gasoline fumes from the gas tank to escape into the atmosphere. The evaporative canister in cars is used too capture these fumes and feed them back to the engine.

4) the fumes from the already metered gas would save you .000001 cents...but for the environment, it's worth it.

 

Thanks for the tips!

 

As I said before......I got this as an email. And that it would be nice to share this information with you all. I was happy to hear what other ppl thought of this. And it's also good to hear that some of this information maybe be true and can be useful.

thank you.

 

awesome info, gonna do it all except the half full thing i run that bitch dry lmao

 

you know in some provinces in canada they have legislation for all gas stations to have gauges that measure the tempurture in gasoline so that consumers dont get the shaft... in CA they tried to pass similar legislation to make gas stations have those guages and the gas companies fought it and won.

 

wow.....now I'm wondering why they fought it and won.......(hmmm)
what does that tell you.......(hint, hint)

 

Some folks (including myself) believe that this is hard on fuel pumps. Let us know if yours fails. I have never had a fuel pump failure (rarely go below 1/2 tank). My wife runs hers dry and had to replace the fuel pump on her Camry a few years ago.

 

Ummm, I have to disagree with you here. I had a Dodge Neon for about 12 years, I almost ran it out of gas twice and would always run it down to almost nothing. I never had any problem with the fuel pump, injectors, or filters on it. I had 182,900 miles on it when I sold it too.

I'm not sure but perhaps my habit of running Premium in it may have had something to do with it, I'm not sure.

Besides which, fuel pumps work by keeping a constant pressure in the fuel line so they work pretty much all the time the car is running so there will be no difference in whether or not the fuel tank is full, half empty, or empty.

 

Running it dry can be hard on the fuel pump, because if the pump ever runs dry, it overrevs, and can wreck itslef. I'm not saying it WILL, but it does increase the wear on the pump to run your tank down to nothing. I likewise have run my tank down to empty and haven't seen any consequences, but I worked at an auto shop and we replaced more than a few fuel pumps for similar reasons. I run mine till I get the light, but I try and make sure not to be completely out of gas.

 

My understanding of the fuel-pump issue is that the liquid gas in the tank actually serves to cool the fuel-pump. By running your tank on empty all the time, the fuel-pump tends to run hotter and fail sooner.

 

Correct, the pump is cooled by the fuel being pumped, some of which is returned to the tank. The less fuel there is in the tank to take this heat, the higher the tank temperature gets. The hotter fuel cannot cool the pump as well.

 

Thanks for the info...the best way to see if it makes a difference is to try em out.. won't hurt

 

Currently under investigation at snopes.com
Urban Legends Reference Pages: Refueling Tips

Also I think this thread should be posted under the ECO-FIT section.

 

good tip now I know not to pump if trucker is filling up the stations. and go slower when pumping gas. I was kinda wondering why gas go so quick... heheh and sometimes it go so slow.... thanks for posting.