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I worked as a maintenance technician at a gas station for 6 years before I switched into software engineering. Some interesting things about gas dispensers/pum
by CoffeePython 6y ago
I worked as a maintenance technician at a gas station for 6 years before I switched into software engineering.
Some interesting things about gas dispensers/pumps:
- What most people call a gas pump is a dispenser. The actual pump is submersed inside the underground gas tank.
- mid grade gas is just premium and regular gas that is gets mixed at the dispenser before the fuel is dispensed.
- Holding the hose up high and pulling the trigger does not allow more fuel to drain from the hose after reaching your prepaid amount
- people drive off with the nozzle still in their car surprisingly often. There is a magnetic breakaway so the hose will disconnect and not pull the dispenser over.
I can probably think of some more of people are interested
- twosheep 6y agoHow often do people have gasoline fights?
- lenitabinol 6y agoI think Zoolander ended this practice from becoming common.
- PrinceKropotkin 6y agoOr started a hot new trend!
- darkerside 6y agoEarly candidate for most important documentary of the 21st century
- talmr 6y agoHaha thank you for this.
- treeman79 6y agoWorks RadioShack many many years ago. Customer came in soaked in gasoline. Into an electronic store... She got very fast service as we rushed to get her out the door. Apparently there was an “incident” at the pump. We suspected lack of brains
- Shared404 6y agoProblem exists between cognizance and cranium. (Anyone have a good word starting with K?)
- taneq 6y agoOnly on the way to get an orange mocha frappuccino.
- zygy 6y agointerested!
- tersers 6y agoSo if I want at least some of the benefits of the cleaning ingredients in the premium fuel, is the mid-grade an option?
- tw04 6y agoPriming has nothing to do with cleaning. It’s higher octane fuel. If your car Isn’t designed for higher octane fuel it will run like garbage. The whole point of high octane fuel is that it requires a higher temperature to ignite. If your car Isn’t designed for it it’s most likely only going to partially burn the fuel.
- kortilla 6y agoNo, the main point of high octane fuel is to be resistant to higher compression ratios so it doesn’t pre-detonate. Spark plugs have no issues igniting it. What op is referring to is additives that are added in by some gas dealers to the high octane fuel to upsell you. “Techron” is one I recall seeing at Chevron IIRC.
- herdrick 6y agoThe parent comment is right. It's not just the spark; heat and pressure are also part of what ignites your air/fuel mixture.
- kortilla 6y agoNot with gasoline. A gas engine can ignite at temps well below 0F and low compression. You might be thinking of diesel. Diesel depends on compression to combust and has heater coils to ensure minimum temps as well. This is more obvious when you read engine specs and they have minimum octane ratings, not specific ratings.
- pxx 6y agoYou can sometimes buy the additives separately. e.g. for Techron: https://amzn.to/33LH1RN https://amzn.to/33LH1RN
- zachrose 6y agoHow plausible is this scene from Rambo? https://www.youtube.com/watch?v=MgfoCa2-V3g https://www.youtube.com/watch?v=MgfoCa2-V3g
- bagels 6y agoCompletely plausible with enough movie pyrotechnics.
- dylan604 6y agoI worked with a guy that was a SFX guy for the old Walker TV series. Talking about some fun stories. He showed me a few "near misses" where the explosion was "slightly" larger than anticipated, and if you know where/when to look, you see the SFX team running for their lives in footage that made it into the edit. None of the guys I've worked with come close to the Danny McBride character in Tropic Thunder though.
- jMyles 6y ago> I can probably think of some more of people are interested Sure, I'll read a few more.
- mariusz331 6y agoYes me too
- laurent92 6y agoIs sand really efficient? If we overflow, should we put sand ourselves?
- Cerium 6y agoAccording to the story of Douglas Hegdahl it is [1]. [1] https://www.pownetwork.org/bios/h/h135.htm https://www.pownetwork.org/bios/h/h135.htm
- TedDoesntTalk 6y agoWhat does that have to do with sand?
- baby 6y agoI never understand what gas I'm supposed to get with my car. There's 87, 89, and 91 I believe? But I just don't understand why so many choices.
- User23 6y agoYour car’s manual will say.
- OkGoDoIt 6y agoSome states have different levels. In Colorado 85 is common. I assume it has something to do with the air pressure and oxygen content of the air perhaps?
- wiremaus 6y ago85 is functional at elevation, but definitely still not preferable at elevation. Works best with carbureted engines, which are obviously few and far between these days. You shouldn't put 85 octane in a modern fuel injected engine period.
- culopatin 6y agoThe method of fuel metering the car uses does not necessarily have any connection with what octane you should use. It's all about the engine design. If we are going after rules of thumb, I would say that if the car is turbocharged, it will most definitely run better with higher octane. Although my turbo VW can run with regular fuel, it will just change timing and make less power. I have a 78 Fiat with a carburetor however, that definitely needs 91 or higher.
- aquaticsunset 6y agoVW is seemingly, in my experience, an outlier. Their small displacement turbocharged engines will run fine on 87, but really like 91 (or E-15 88). My '14 Jetta with the 1.8T got better power and fuel economy on "the good stuff."
- 6y ago
- autarch 6y ago> - people drive off with the nozzle still in their car surprisingly often. There is a magnetic breakaway so the hose will disconnect and not pull the dispenser over. I've done this at least once that I can remember, and maybe twice or more. Yep, the handle just popped right off. Embarrassing but fortunately not dangerous.
- xellisx 6y agoFrom what I heard, pretty much all gasoline starts off the same in the US, the brands will add a tiny amount of their own detergent on top of what's already in the base. Seems plausible.
- bluGill 6y agoThere are many different blends of gas, and refineries change with the weather (winter fuel mix evaporates faster than summer mix, and will not need summer emissions). Gas stations often choose their own mix of detergents/additives, but otherwise all fuel in a town comes from the same refinery with the same contents. Most stations just go with the refinery default additive mix, which is typically pretty good. Some national brands go with a slightly better additive mix. Some national brands go with a cheaper additive package. You need to be a large chain to afford to pay a chemist to design an additive mix though, so the majority of stations don't.
- deleted 6y ago[deleted]
- uptown 6y agoAny truth to the rumor that you should avoid filling your car when the main station tank is getting refilled? Think the logic was that their refilling would stir up sediment and potentially damage your car’s engine.
- Nextgrid 6y agoAren't the fuel filters in cars good enough to prevent engine damage even if foreign objects or residue were to end up in the tank?
- vel0city 6y agoFuel filters should prevent damage to the engine, but if you got a ton of gunk in the filter you might suddenly find yourself with a dead car on the side of the highway because your fuel line is clogged.
- prussian 6y agoThe fuel flows through a filter in the dispenser, so it shouldn't be problematic.
- EvanAnderson 6y agoIf you're using a dispenser that's particularly slow it's likely that the filter in the dispenser is clogged, too. At the station where I worked we stopped buying from a distributor who continually delivered "dirty" diesel fuel. Right after we took a load from them we'd see our dispensers flow rates decrease dramatically.
- dwd 6y agoI was once told by an electrical engineer that the whole ban on using a cell phone near a pump was due to potential interference with how the dispenser tracks how much you have pumped. Is there any truth this?
- dsshanley 6y agoI don’t think that’s the main concern. I worked on offshore platforms and the devices needed to be class 1 div 2 compliant. Meaning they need to be sealed completely to avoid vapors being sparked by electrical devices. It’s a small risk, but gasoline vapor is very combustible.
- anon_cow1111 6y agoThis might have been true historically, but samsung has since released the Galaxy Note 7.
- PrinceKropotkin 6y agoSorry? What do you mean? What's the relevance of the galaxy note 7?
- ClumsyPilot 6y agoOnce in a blue moon even a dog shoots his owner, or a person is born with two genitals.
- taneq 6y agoThey seem pretty capable of exploding in your pocket and starting a fire at the petrol station. No need to be talking on it at the time.
- santraginean 6y agoWhat I read back when the bans were lifted around here was that cell phone use correlated with people opening the car door and rummaging around, which created a static electricity buildup, and that that was the real fire risk.
- tomger 6y agoMore please :)
- keithnz 6y agoMy first job I worked doing software for petrol pumps and underground tank monitoring systems. One of the main guys who worked on the pump software, in forth, actually wrote a book where the petrol pump is his main example https://www.manning.com/books/functional-reactive-programming https://www.manning.com/books/functional-reactive-programmin...
- anon_cow1111 6y agoDoes anyone still use above-ground tanks? Just wondering if there's any truth to buying gas in bulk during cold weather for density reasons. (though I'd imagine the price/barrel has been fluctuating more than the temperature would cause lately)
- brendoelfrendo 6y agoAs I understand it, petroleum companies provide "winter mixes" of fuel that accommodate for the difference in density, so there isn't a real advantage to this.
- maxerickson 6y agoSummer fuel blends are an emissions control. https://www.caranddriver.com/news/a15339380/the-vapor-rub-summer-versus-winter-gasoline-explained/ https://www.caranddriver.com/news/a15339380/the-vapor-rub-su...
- fotbr 6y agoThere's a station local to me with above ground tanks. They're in an area that flood regularly, which is why the tanks aren't buried. I've never noticed a measurable difference when filling up the 20 gallon tank in the truck. I suspect you'd have to buy a LOT to make a meaningful difference.
- KiDD 6y agoDepartment of weights and measures calibrate and confirm the amount pumped twice a year. The amount dispensed should be compensated for temperature.
- jcrawfordor 6y agoAbove-ground tanks can be appreciably cheaper, mostly due to increased inspection and maintenance requirements for underground tanks due to a history of leakage problems. That said, the price difference isn't big enough to justify the use of space (especially considering setback requirements) in urban environments. You will still find above ground tanks in newer gas stations in rural environments, though.
- TedDoesntTalk 6y ago> people drive off with the nozzle still in their car surprisingly often I did this in the late 80s. The handle ripped off and was not magnetically attached. However, gas did not spill from the hose. I drove back to the station and handed it to the attendant sheepishly. He said thanks.
- rjmorris 6y agoHow far did you get from the station before you realized it and turned back?
- lostlogin 6y agoNot the OP but the cashier at the Wendy’s drive-through pointed it out to the driver when I was a passenger. I think the passengers laughter could be measured in litre of tears.
- TedDoesntTalk 6y agoAbout 1/2 a kilometer. I stopped the car, removed the handle, and drove back to the gas station. The attendant had been outside, so he saw it happen. In fact he had pumped the gas (this was not self-serve). And when I came back, holding the nozzle in my hand, he was dumbfounded.
- EvanAnderson 6y agoThe breakaways on the dispensers I worked with in the early 90's had shear pins and were mechanical. We lost 1 or 2 a year at our station in rural Ohio.
- darkerside 6y agoThanks is an amazing response to this
- TwoBit 6y agoI drove off with nozzle once because it was my first time filling my new German car, which has the port on the right, which I wasn't used to.
- 6y ago
- jfb 6y agoThis is awesome, thank you!
- EvanAnderson 6y agoI worked as a cashier in my family's gas station for a few years. I ended up doing contract development work for a retail petroleum distributor about 15 years later. A couple of these that I can think of: - The temperatures in our underground storage tanks were very stable, varying only by a couple of degrees F irrespective of the air temperature. - Fuel almost always arrives warmer than the underground temperature, so you see contraction of volume on your tank monitor as newly-dropped fuel cools. - Gross volume is the amount dispensed into the distributor's transport trucks. Net volume is the amount dropped into the Customer's tank. Gross vs. Net and temperature adjustment factors are a place where distributors play around to eke out some margin. I wrote some code that took into account air temperature at the terminal (the "rack") where trucks were filled, along with historical rack temperatures, to produce temperature-adjusted normalized costs. When you're making fractions of a cent per gallon margin every little bit helps.
- refurb 6y agoAdding to this, at least the station I worked at used the tank temperature to adjust for density changes. You were buying 1L at 20C, so in the middle of winter when the fuel was 10C, you'd get a slightly smaller volume since the density increased. And slightly more volume during summer.
- Scoundreller 6y agoSo uhhh, I guess I should insulate my home natural gas pipe at the outdoor above-ground portion before it hits the meter? (The gas would be warmer coming from the ground than atmospheric temperature during the heating season) Wait: wouldn’t I want it to be cooler when it’s measured so it’s denser and I get more moles per volume measured?
- m463 6y agorefrigerated meter? I've also heard you could probably do something with magnets near your electric meter. (I read this from some "get even with someone" book where it said to prominently put magnets on the target's electric meter for the utility guy to find)
- lostlogin 6y agoWas water in the fuel ever a thing? I had a car run really badly after filling up and had a poke about. I noticed a fluid level in the fuel pipe (it had a glass site bowl thing in the fuel line). It turned out the tank of ‘petrol’ was mostly water.
- kaikai 6y agoWater in the gasoline is an issue in stations that have above ground tanks. When the tanks are mostly empty they’re filled with air, and the changing temperature means water condenses out of the air and ends up in the gas. I used to live in a rural area with a gas station known for watery gas; if we wanted to run a chainsaw we’d get gas from farther away to avoid damage.
- fensterblick 6y agoMy father sold gas back in the day. He told me a story of an incident where he accidentally sold water instead of gas. When the supply tanker was filling up the underground reserves, someone forgot to close up the underground reserve. A heavy rain came overnight and water infiltrated the tank. It was an accident. Repair costs for customers were handled through the gas station's insurance.
- EvanAnderson 6y agoTypically the submersible tank pumps pull fuel a few inches off the bottom of the underground storage tank. You'd have to have a very high water-level for the pump to pull water.
- perl4ever 6y agoPeople take the possibility very seriously with aircraft, so I inferred that it's a real, but rare, problem.
- maxerickson 6y agoIt's pretty much gone away as a problem for cars, there's been design changes to vehicle fuel tanks, and the use of ethanol as an oxygenate means that water doesn't really build up over time (the ethanol allows the water to mix into the fuel; 'dry gas' is often just a jug of alcohol)
- chmod600 6y agoWhat fraction of gas sold is mid-grade? I have never purchased it.
- harlanji 6y agoSlightly higher compression engines, perhaps <2L high RPM, like sub-compacts or maybe motorcycles. I’ve had rentals, don’t recall. Hyundai?
- kube-system 6y agoSome 90s german cars call for mid-grade
- RedShift1 6y agoLong time ago I read somewhere you shouldn't hold the lever all the way because it could potentially allow more oxygen through and thus have to pay just a little bit more for the same amount of fuel. Is that really true or was I being gaslighted?
- userbinator 6y agoThe metering is done in the dispenser, not the nozzle.
- RedShift1 6y agoYes, but can having the nozzle not 100% open influence the metering?
- userbinator 6y agoNo, because that would become widely known and people would take advantage of it. I believe they use a https://en.wikipedia.org/wiki/Positive_displacement_meter https://en.wikipedia.org/wiki/Positive_displacement_meter
- swivelmaster 6y agoI was filling up one time when the person on the opposite side of the pump drove off with the nozzle still attached. Once the end broke away, the rest of it snapped back and slammed into the other side of the pump enclosure so loudly and violently that it set off my adrenaline and I was freaked out for a good few minutes. Quite an experience!
- richev 6y ago> I can probably think of some more of people are interested Yes please!
- BayesStreet 6y agoDo you happen to know the ratio of regular to premium in mid grade?
- function_seven 6y agoI think it's the same as the relationships between the octane numbers you see. So if the pump as 87, 89, and 91 grades, then the mid-grade will be a 50/50 mix (ratio 1:1) of the 87- and 91-octane fuel. If the grades are, say, 87, 89, and 93; then the ratio would be closer to 2:1 of regular:premium to get to that mid-grade. Only reason I know this is because premium gas in California used to be 92 octane. So the three choices were 87, 89, and 92. When we dropped to 91 octane, a lot of the stations near me had to swap out the yellow sticker on their mid-grades to read "88.5". That was my clue that the ratio had not been adjusted yet.
- hackmiester 6y ago> Holding the hose up high and pulling the trigger does not allow more fuel to drain from the hose after reaching your prepaid amount Doesn't it though? I feel like I know this because if I don't do it, gas pours out onto the side of my car and/or the ground, when I pull the hose out.
- taneq 6y agoIt doesn't push any more out past the meter but it certainly clears the last few cc from the line.
- hoschicz 6y agoDoes it make sense to buy premium gas?
- perl4ever 6y agoWith turbos and computer adjustment of timing and everything, it's more plausible than it used to be that premium will give you more power. On the other hand, it's also more likely that a lower grade will not damage your engine even if premium is recommended.
- PowerBar 6y agoOnly if your vehicle requires hit. Premium gas is rated for higher compression (generally turbo or supercharged engines). If your owner's manual doesn't recommend a particular octane, just get regular.
- Daviey 6y agoIn the UK, you can't "latch" it on - for flow, you need to hold the handle down constantly. This means that you are unlikely to drive off with the dispenser still in the car as there is no benefit to the driver to leave it in when they have finished. It is interesting that it is the same dispenser design used around the world, but the latch is removed in the UK. However, As a teenager I discovered the wonders of the latch on fuel dispensers on airfields. Then on the road I started using the removable fuel-cap as a wedge to the dispenser. eeeeek! (Now I use an electric car)
- sjwright 6y agoSame in Australia—no latch.
- chris1993 6y agoExcept some independents still have the latch which means you can fill and wash your windows at the same time.
- implements 6y agoYou're not the only one - though I completely forgot I used to do that until I read your comment!
- juahan 6y agoNo latch in Finland either.
- nojokes 6y agoInteresting. Similarly in some countries the ATM will return the money first and then the card and in other countries the order is reversed.
- Daviey 6y agoYeees. I used to work for Diebold on ATM's, and we had some research that proved that: - people want to take out money from the machine - once they have their money, the activity is complete We found that if we provided the card back before the money, they stopped leaving their card in the machine. This is because the 'activity' was taking out money.
- CamperBob2 6y agoAt what point in the distribution chain is ethanol added? I prefer to run ethanol-free fuel when possible, but would also prefer to use fuel with good detergent additives. I've always wondered if the gas at the local ethanol-free station is missing the additive package as well.
- sampo 6y ago> mid grade gas is just premium and regular gas that is gets mixed There is nothing else "premium" about premium gas, than that it can be compressed more in the engine. Compressibility is measured by the octane rating, so it makes sense than mixing 87 octane gas and 91 octane gas, gives you 89 octane gas (using the American octane scale, Europe uses a different scale).
- parliament32 6y agoDepends on your country and gas station. Here in Canada, "premium" fuels often have different additive packages and different amounts of ethanol added. For example, https://www.shell.ca/en_ca/motorists/my-fuels/shell-v-power-nitro-plus-premium-gasoline.html https://www.shell.ca/en_ca/motorists/my-fuels/shell-v-power-...