I ran across an interesting bit of advice today: Pumping gas.... good things to know. 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'
<div class='quotetop'>QUOTE(LYLUVLY @ Sep 8 2007, 12:19 AM) [snapback]508943[/snapback]</div> Thanks, LYLUVLY. What is the source of this advice (it sounds like someone in your industry provided it to you)? A question for you: Because the Prius has a bladder within the gas tank, does that take away from the concerns noted in "trick" 3, above? I could always see #1. In fact, we had a neighbor who filled up on a very cold evening and then parked his car in a warm garage. The gas expanded so much it popped his gas-cap and the garage quickly filled with vapors. We all found out about it during the middle of the night when the local fire department showed up for a hazmat response! I hadn't thought much about #2, but it does make a bit of sense. I thought the pumps had in-line filters to protect us! Again, thanks for the helpful info. a priori
Yeah, #3 is a moot point for Prius owners because of the bladder that helps minimise vapour. However, you should still pump a bit slower because the bladder will not fully collapse when the tank is empty (like.. say a balloon without air) so pumping at high in an empty tank will still have vapour from the fuel. Here's a few more tips I can pass on: 5. Have the nozzle at an angle (usually with the handle lower than the nozzle) so that when the fuel is dispensed, it flows down the side of the fuel filler pipe, rather than cascading straight to the bottom of the tank. Again, it minimises vapour 6. After you're done pumping, partially pull out the nozzle and tilt the handle upwards. You can get quite a bit more from the droplets (and it's not just a few drops.. there can be quite a bit)
Thanks for the tips! I wonder if they take the density thing into account in the winter time at places such as Ontario, where the temperature difference between summer/winter can be 50oC or more!
<div class='quotetop'>QUOTE(LYLUVLY @ Sep 7 2007, 10:19 PM) [snapback]508943[/snapback]</div> In spite of the bladder design, this is still a great idea for Prius drivers, given the number of "I ran out of gas in my Prius" posts...
<div class='quotetop'>QUOTE(arolf @ Sep 8 2007, 07:09 AM) [snapback]509034[/snapback]</div> the gas pumps say the volume is corrected at 15°C. So.. I do not know about -20°C lol. But then again, it is winter fuel with more additives so the volume of fuel is less anyway so it might balance out.
<div class='quotetop'>QUOTE(LYLUVLY @ Sep 7 2007, 11:19 PM) [snapback]508943[/snapback]</div> <snip> I guess you verified what somebody else in the gas business told me... that all gas is the same until it gets into the Shell or Chevron or whatever tanker truck. All the gas is the same in the pipeline, separated from diesel etc by a water "pig", and is the same in the common distribution center storage tanks. So the only difference between Shell and 7-11 and Bell and the rest is an additive that is put into the Brand's (like Chevron) tanker truck. How many gallons of those additives go into the tanker?? Do the unbranded stations ever put additives if they are not selling excess Chevron or Shell? Out here Costco sells whatever branded or unbranded gas is excess and cheapest, so you might get Shell one time and no-name the next.
<div class='quotetop'>QUOTE(LYLUVLY @ Sep 7 2007, 11:19 PM) [snapback]508943[/snapback]</div> <snip> I guess you verified what somebody else in the gas business told me... that all gas is the same until it gets into the Shell or Chevron or whatever tanker truck. All the gas is the same in the pipeline, separated from diesel etc by a water "pig", and is the same in the common distribution center storage tanks. So the only difference between Shell and 7-11 and Bell and the rest is an additive that is put into the Brand's (like Chevron) tanker truck. How many gallons of those additives go into the tanker?? Do the unbranded stations ever put additives if they are not selling excess Chevron or Shell? Out here Costco sells whatever branded or unbranded gas is excess and cheapest, so you might get Shell one time and no-name the next.
Very informative. I will now be trying to minimize vapors by pumping at a slow speed, never really thought of this in the past, thanks.
Very informative. I will now be trying to minimize vapors by pumping at a slow speed, never really thought of this in the past, thanks.
I don't understand. What is the relationship between the density/volume and the amount of energy stored in the petrol?
I don't understand. What is the relationship between the density/volume and the amount of energy stored in the petrol?
<div class='quotetop'>QUOTE(zenMachine @ Sep 12 2007, 12:24 PM) [snapback]511471[/snapback]</div> The more dense the fuel, the more energy there is per gallon. Worst case scenario is that you pay about 3c per gallon more during the hottest season as compared to the coldest. but since you'll buy gas all year long, it evens out, so who really cares? And that's only in states that don't compensate for temp yet (like CA). Some states already do that, as I understand it. My tip for saving money at the pump? Don't buy gasoline.
<div class='quotetop'>QUOTE(zenMachine @ Sep 12 2007, 12:24 PM) [snapback]511471[/snapback]</div> The more dense the fuel, the more energy there is per gallon. Worst case scenario is that you pay about 3c per gallon more during the hottest season as compared to the coldest. but since you'll buy gas all year long, it evens out, so who really cares? And that's only in states that don't compensate for temp yet (like CA). Some states already do that, as I understand it. My tip for saving money at the pump? Don't buy gasoline.
1. The temperature of the gas in the underground tanks is fairly stable throughout the day. The depth at which the tanks are buried and the significant thermal mass of the tanks and fuel precludes much temperature variation on a daily cycle. Temperature will vary by season, but there's not much you can do about that, unless you want to wait until Christmas to fill your tank. 2. All fuel pumps contain filters which keep contaminates from getting into your car, so mixing from the tanker will have no effect. If the tanker is hot, it could reduce the specific gravity of the fuel and cause you to get slightly less bang for your buck (#1 above). 3. The fuel tanks in all modern cars are sealed, which prevents gasoline vapor from escaping and water vapor from entering. If you are driving a boat, then this is a valid issue, since boat tanks are vented to the atmosphere. 4. The Prius has a sealed fuel filler system that prevent fuel vapor from escaping even while pumping, regardless of the pump setting. Hope this helps. If you flip this list over, you can still use the paper for a grocery list. Tom
1. The temperature of the gas in the underground tanks is fairly stable throughout the day. The depth at which the tanks are buried and the significant thermal mass of the tanks and fuel precludes much temperature variation on a daily cycle. Temperature will vary by season, but there's not much you can do about that, unless you want to wait until Christmas to fill your tank. 2. All fuel pumps contain filters which keep contaminates from getting into your car, so mixing from the tanker will have no effect. If the tanker is hot, it could reduce the specific gravity of the fuel and cause you to get slightly less bang for your buck (#1 above). 3. The fuel tanks in all modern cars are sealed, which prevents gasoline vapor from escaping and water vapor from entering. If you are driving a boat, then this is a valid issue, since boat tanks are vented to the atmosphere. 4. The Prius has a sealed fuel filler system that prevent fuel vapor from escaping even while pumping, regardless of the pump setting. Hope this helps. If you flip this list over, you can still use the paper for a grocery list. Tom
#1 is the only semi valid reason on the list. I know that the temp for the gas tanks at a gas station are pretty much a solid temp all year round. That doesn't excuse the fact that it's gonna heat up a little when it comes out. I can say that if you do have a choice on filling up during the day or at night that you should choose at night. It doesn't matter that much though. Maybe 1 cent a gallon difference, tops.
#1 is the only semi valid reason on the list. I know that the temp for the gas tanks at a gas station are pretty much a solid temp all year round. That doesn't excuse the fact that it's gonna heat up a little when it comes out. I can say that if you do have a choice on filling up during the day or at night that you should choose at night. It doesn't matter that much though. Maybe 1 cent a gallon difference, tops.
<div class='quotetop'>QUOTE(qbee42 @ Sep 12 2007, 02:42 PM) [snapback]511482[/snapback]</div> Yes and No. Filters on fuel pumps are fairly coarse and will stop some contaminates getting into the tank. That said car manufacturers still fit fuel filters and fuel pumps still fail due to being damaged by a build up of contaminates being sucked up from the bottom of the tank in the car. Pete.
