| Author | Message | ||
     86129squids |
OK folks, pardon me if this is a goofy question: When I fill up my "1.5 gallon" gas can, I routinely see the meter showing 1.7ish gallons. Yes, I fill it as full as I can, but I've not seen any particular level line denoting the 1.5 mark... I usually get the gas at the store down the street, know the manager and staff, mentioned this to them a few times, they've promised to check things out. I just got gas today from a different place, and the same thing happened. Of course I've always been accused of stuffing 10# of shiznit in a 5# sack, but I dunno about this. The state regulates these things, percentage wise if there's this much fudge going on, someone's being bent over a barrel. Bueller? | ||
| Froggy |
All gas cans have a little more than stated capacity to allow for gasoline expansion and the addition of oils for twosmokes. My portable can is a 2gal 4oz, and it is near full when at the 2gal 4oz line, but I may be able to squeeze another pint in it if I feel like living on the edge. (Source: My years as working as a full serve gas station attendant.) | ||
| 86129squids |
Thanks Frogs! I too worked once as assistant manager at the northernmost Tampa area fullservice station, but the question never crossed my mind back then... OK, guess I'll quit harshing my buddies downthe street. | ||
| Fast1075 |
When technically full (1.5 gallons), there should be enough room left in the container for expansion if the gas warms up...Assuming the gas comes from an underground storage tank, it will be considerably cooler than the air temperature outside....it could expand enough to occupy the entire space in the can, forcing a rupture or leak.. Kinda like filling a Buell up to the very top and watching fuel pee out of the vent hose after it sits a bit and engine heat warms up the fuel. Which reminds me of an interesting story...A while back, I was at the track and a friend stopped by my pit to mooch some nitrous oxide. He had forgotten to have his tanks filled at the local speed shop and didn't want to pay the $8.00 per pound they charged at the fuel shack at the strip. (I carried a 125 pound cylinder with me along with a cross-fill station to keep my bottles ready to go). I showed him how to use the gear and even weighed his bottles and wrote the full gross weight on them so he wouldn't over fill them, and then went back to what I was doing. Later, I walked over to his pit to chat...it was a cold day and when I walked up, I noticed he had one of his bottles sitting on the ground next to his running generator...I didn't even have time to say anything before there has a horrendous explosion...the 3 pound aluminum cylinder had exploded...I was standing on the other side of the generator and didn't get hit with debris. Part of the cylinder went thru the side of his neighbor's trailer and one piece went thru the tailgate of his truck....shouldn't have happened since there is a rupture disc designed to vent in the case of hydraulic overpressure right??? Fool had tapped and plugged the vent on the bottle. The bottle was rated for 1800 psi...with a failure rating of 3500 psi+..... I always kept spare rupture discs, and carefully weighed each bottle...every time... Then there are the stories of nitrous backfires....but that is for later  . (Message edited by fast1075 on July 29, 2011) | ||
| Mtjm2 |
Do you shake the nozel too ?  Watch the pump | ||
| Whatever |
There will almost always be a sticker on the gas pump from the State's Weights and Measures regulatory agency... otherwise they do not get the license to sell the gas. They have to get the inspection sticker every year to keep operating legally. Just as taxi companies like the one I worked for have to take some big old fat dude out for a spin so they can get all the taxi meters stamped with that Weights and Measures sticker or they face shutdown and fine too. | ||
| 01x1buell |
must always shake the nozzle | ||
| 86129squids |
"must always shake the nozzle"...  | ||
| Whatever |
sickos... | ||
| Birdy |
Shake it more than twice and you're playing with it! | ||
| 01x1buell |
you have to get every last drop that you pay for. that shits expensive | ||
| Pwnzor |
L x W x H (in inches) divide the result by 231. | ||
| U4euh |
I'd almost bet that if next time you watched the pump and stopped at 1.5 gallons the level will be at where the flat sides of the container stop and start to slant inward towards the nozel. I had the same question when it started costing me more than 20 bucks to fill up my 5 gal. jug, then realized i was putting in more than 5 gal! | ||
| Blake |
Liquid gasoline doesn't expand noticeably with increased temperature. It does vaporize and generate pressure which can force liquid fuel out the vent line. | ||
| 86129squids |
On the subject of temp expansion: Ethanol/gas will expand/contract more than 100% gas, I've been told- someone mentioned Ducati gas tanks are more susceptible to problems because of this. | ||
| Just_ziptab |
It's been my experience that an absolutely full gas can in the back of my truck will not leak from expansion.Give it a quart of air space and the pressure builds as well as sloshing..and the associated mess. | ||
| Froggy |
I would hope it wouldn't, there are safety features built into the jug to prevent it.
What mess? If it is leaking then you have a defective jug and it needs replacement. | ||
| Mr_grumpy |
The technical term is Ullage. That's the airspace left in a container or tank when full to recommended level. This is to allow for expansion/contraction of the liquid contained. If there is no ullage there's no margin for error as liquids are more or less non-compressible & expansion or contraction may rupture the vessel. Also, if the container receives a shock of any kind the ullage acts as a shock absorber allowing deformation rather than blowing the container at it's weakest point. I used to haul tankers of hot bitumen & you don't piss about with that stuff at 180°C / 350°F. | ||
| Kenm123t |
Blake it does expand and leak due to expansion! For a visual find the local flight school that uses C 152s and youll find a block wood under the left or pilots side main gear. Flight school top tanks to filler neck to prevent vaporization and then respiring moisture laden air back into the tanl when it cools The block of wood is to keep the end of the vent tube barely above the fuel in the Ullage area Grumpy refers to which on the c152 is pretty much the left fuel filler neck. When the plane heats up on the ramp it will purge lead laden 100LL on the ramp and the airport EPA tormenters will get upset. Want to see a guy scream so you can hear him 1/4 mile away dispurse you fuel sample out in the air. | ||
| 86129squids |
"ullage", hadn't heard that term in years... Gotta love all the gearhead nerds here- thanks! Now I can go around saying "I gotta check my ullage..." | ||
| Kenm123t |
Badweb is a den of gearghead geek engineer types. We need to do a survey and see how many of multiple Buell owners are engineers contractors and assorted gearheads as opposed to liberal arts majors  | ||
| Mr_grumpy |
I used to be a liberal arts major, but somebody stole my handbag. | ||
| Kenm123t |
 I see you have recovered! | ||
| Patrick2cents |
BTW... the pressure from the vaporization of the fuel does not change with the volume of air above the free surface (it's called the partial pressure). It is dependent only on the temperature and the material properties of the liquid. | ||
| Blake |
Ken, For every 10oF increase in temperature, gasoline volume increases less than 0.053%. It's pretty negligible. | ||
| 86129squids |
Geeks. | ||
| Mr_grumpy |
I know, sad innit? | ||
| Chauly |
.00055 per F deg, so 10 degrees is .0055 (.55%), 50 degrees is 2.5%. It adds up. I just went through this with 1200 ft. of 1" pipe. The temperature rise increased the volume by 4 gallons! | ||
| Blake |
Thanks for the math fix Chauly. Seems not so insignificant then. Ken was right! | ||
| Kenm123t |
I use the formula to calculate expansion tank volumes in closed loop systems. If the expansion isnt accounted for you will break pipes An example is better some times if you use the formula on a forum you can get called a Geek  | ||
| 86129squids |
You're smarter than you look. |
