How gas pumps know when to turn themselves off 

how did you do that? im in us and it says gas

It says petrol in the UK

American here, it does show as “gas” Thats really cool!

Gas for America

Petrol in uk. 🎉

Please make a video about that too :P It's quite difficult to understand how prepay is hit and what happens when a moron pulls out a flowing nozzle out of the car.

Cool story Mr "I am an Engineer"

I'm the bearing and I can confirm this is a lie

Anti-moron mechanism lol

Regarding the attitude device, what if I want to fill up a spare container of gasoline or something like that? Wouldn't the 'attitude' device prevent me from doing so?

Because many youtubers don't get millions of views like this channel, and it'll be a waste of effort

Every heard of practical engineering? He also loves making mini models

I know! I was thinking "wow, I actually understand this model that he made."😂 Give him much props for that 👌

I totally agree. I'm so impressed that he built the models & presented the effect so clearly. Very interesting - I'm a fan now.

Its very simple mechanically if you think of the two parts as a sensor and a signal not to mention whatever it takes to close the valve. These gas pumps basically take a three part problem and use two mechanisms to solve all three. The beauty of the design is that both operate with only fluid dynamics. Most other sensors require a bit of chemistry or some other physical property (to detect a chemical presence) and a bit of electricity (to transmit the signal) as well as moving parts to operate the valve.

@Glum Reaper If it was so simple, in the old days they would have used the system to fill up their horses.

It is simple. Basic pipe fitter knowledge

@Lord Zordid i tell ya son in the ol days we filled arr horses witha notha type of pipe and we damn well knew when to stop

Physics works.

I've found (accidentally) that it is possible to make the valve fail, at least on some pumps, if you are only partially pulling the trigger (so that the flow is reduced). Specifically, I was watching the meter (instead of the nozzle), trying to put in a "round number" amount of fuel, without realizing that it was just slowly overflowing onto the ground! I'd guess that the reduced flow-rate also reduces the "negative" pressure on the diaphragm, such that it can't overcome the spring force (to then shut off the fuel).

Oh it fails. Never fully trust it

I agree, Robert. It's a very clever bit of engineering going into those things.

Lucky you. It faild 4 times on me till now and I'm only 33. One time spilling all the gas and Three times stopping multiple times bevor the tank was full.

It has to be non electric. If there is anything electric in that nozzle, well, electricity+gas= trouble. 😅

right. to me, automatic watches still blow my mind. true engineering

someone was rewarded... by a paycheck... so dont worry!

Like what Edward R. Murrow said about television except put in the hands of people who care about such things- "This instrument can teach, it can illuminate; yes, and even it can inspire. But it can do so only to the extent that humans are determined to use it to those ends."

you must have been amazing teacher

@Adi i get the same energy

And the money he makes on youtube.

It's amazing how clever the guys were who invented these things. Wonder when a woman will ever invent something like this

Oh yeah! Good observation

Yea, and see the whole hose jump from that effect.

@Steve Mould From your demonstration, it also seems like when the gas valve gets closed, the fluid flow is now pushing the valve shut (it was held open by the lever action), which probably contributes to it slamming shut. Which I presume is also good at ensuring that the gas flow stops immediately. I bet if you had made your plastic cutaway demonstrator with a much larger diaphragm, it would have moved a lot further. Since there's no such thing as negative pressure as you said, the diaphragm moves because outside air pressure pushes on it since there is lower pressure pushing back on the other side. That's how the power brakes in a car work - they aren't being actively pressurized (except maybe when your ABS gets triggered), and instead a vacuum from the intake manifold of your car engine is formed on one side of diaphragm that can be up to 11" wide. That's 95 square inches, for a maximum sea level force of 1,425 pounds, and that is multiplied through the master cylinder like with the pedal leverage. Thus even a partial vacuum in your power brake booster has force comparable to how much you can press down on the brake pedal with all your might.

What is the mechanism that triggers the shut off when flow is stopped at the pump? I cannot see it clearly.

@Agustin Campeny It could be a simple pressure sensor somewhere in the whole tube system. It also depends on the pump used - it can be simply running all the time you take the nozzle assembly out of the main body till you return it - some pumps have no problem to pump the liquid against the closed system - in that case you need no sensor just the one that checks if the nozzle assembly was returned back

I've been going through an engineering course over the last couple years, and I've learned a ton about fluid physics and dynamics. This video covered so much of those classes all at once and explained it all so clearly and succinctly, such in-depth topics so concisely, he makes it look easy! This video is incredibly well done!

I read a youtube comment about it a couple days ago and didnt really understand it. The visual explanations really helped it click all together!

@Micah Philson because "highly" educated people think to complex, i follow a professor here on tube, it's pretty much theory, but no practical experience and rather clumpy. they have a star mind, not really open for new things and ideas, than someone without a university degree comes along and leaves the professor stunned and in the dust. you shouldn't really admire these people, they aren't really smart al better at numbers because of routine. they can't solve simple things.

@Analog Dude I'm in a military training program, we're only learning about the systems and the theory behind the systems we use, and working practically with those systems. We're taught by people with like at least 6+ years of experience, not professors. But to do it, we have to learn all the theory and physics, chemistry, materials science, fluid dynamics, engineering etc. behind it all because it's literally nuclear physics and nuclear power.

@Micah Philson waste of time, people that see ghost where there aren't, better the invent something on your own and hope that it sells. they asked me as well when i was 18 and i told them you must be joking, you must be out of your mind and they left me alone, recently i got to speak to one of these people, lol.

That's how our system works. If You have a really good idea that will generate millions or maybe billions a small group takes basically all the money at the same time you receive almost nothing. Even more, some of them will say that if you are not rich it's because you are not trying enough (when in the first place all of your work is their source of richness).

fascinating to find those with near 0-degree connections to things like this. Have you any stories from the 2 engineers you're keen to share?

Why not mention their names?

@João Gabriel Paina that's because the world is far more complicated than just having a really good idea. Marketing, logistics, accounting, managerial skills are all critical to turning a good idea into a gold standard. I'm not saying we can't make improvements, but the skills to take a product to market are just as important as having the idea for the product to begin with.

@Mister E Well, you are completely right. Even blue-collar workers play an essential part in that system. Without the guy soldering, machining and so on your idea is just an idea. My point on that is to have everyone that works to run the business then share the profits. The billionaire who runs the business is nothing without the marketing, engineering, logistics, e so-on team. If the class of workers (and by worker I mean those who depend on salary) begins to understand that everything that exists around it depends on them, the few billionaires that explore their workforce are done.

Cause theoretically they’re not simple, the fluid mechanics behind them is quite fascinating

Interact*

Some people can explain in 2 minutes what others take 2 hours to do.

Well, it is multiple simple devices put together to make a somewhat complex device.

Steve always makes see-through 2D versions!

Luckily this is not Matt Parkers channel. His stuff is great too, but he would make a 4D version that clarifies nothing.

@Andreas Gurdel haha, excellent comment!

That might be a mechanism with the modern electronics of prepay pumps. The gas station assumes you turning off the flow means you've finished your purchase, so their pumps probably have an electronic override when the flow stops. It's likely electronic since that override only gets disabled by the computer sending a signal to the pump to turn on after you've paid. If you've used a very old not prepaid pump, they don't have to be reset to continue the flow after being tripped (but they will still stop if they're experiencing a venturi siphon against a full tank).

And so robust , too!

Welcome to the channel!

A M A Z I N G

If somebody could understand and explain quantum physics, it’s this man. Thanks, Steve, amazing, as always.

@GuyJustCool For those topics, I think ScienceClic does the best job one could possibly do.

Many principles that would function forever with repair that a craftsman can do will be replaced by digital stuff that needs from now on monetarized upgrades from above. That's cool for the big players.

can it make the fuel free?

Want your mind blown? Look for videos on mechanical targeting computers.

I wouldn't be surprised if there are electronic components to some these days or in the near future. But these automatic shutoffs long predate the cheap and widely available integrated circuits we have today to enable us to computerize everything. These cutoffs were used before electronic displays became common. /I had always assumed it was based on a float, though

yes, when most of the technology is becoming less mechanical more electrical, this piece of tech remains the same;)

where is the wire hidden/

Sensors need to be replaced once they break. Thats why stuff like this should always be achieved mechanically if possible. Practical application for stuff like this is always mechanical.

I’m so confused how would you do that😂🧐

Part of the fun? I never open anything up to figure out how they work because of the anxiety it causes me knowing that I am invariably going to break something or not be able to figure out how to put it back together.

nozzle, venturi. and yes, it does matter.

@Danny Archer That is why you only do that with stuff you don't really care about or that is already broken. I never throw any device away before performing an "autopsy" on it. Though, I would still advise doing some research before dismantling something. Knowing about compressed springs, dangerous capacitors or possible toxic substances in certain components can save you a lot of pain. Besides, this is YT and it has its own version of Rule 34. If it exists, there is a video YT video of someone dismantling it.

@Corintur Back when I was a kid in the 50's and 60's I used to drive my parents nuts because I took just about everything apart and tried to but it back together. I succeeded most of the time, but there were a couple of times I made things a lot worse. We didnt have youtube back then and the stuff in the libraries was vague at best. I grew up trying to fix everything I owned and never threw anything away. As to compressed springs and stuff like that, I had a couple go flying across the room, but you learn to be careful over time. And yeah, I now have a ton of junk stacked in my garage from all the fixin, but now, I can call them all antiques and sell em on ebay!

@Danny Archer That's why you're not an engineer

Did u put them back together afterwards?

@Max A he didn't say he was a puter back togetherer.

I like to take things apart. But, when i try to put it back together, i always get some extra screws.

i recently started driving,infact got my license on 14th of this month,and wondered about this question only a few days back.

I thought the European model would be much smaller considering they are pumping Liters and not Gallons.

@TIMEtoRIDE900 Maybe the pressure (flow) is just much higher in the USA? So that it takes the same time for a European to fill up the 40 liters tank of a shoe-sized Fiat Punto and for an American to fill up the 40 gallons tank of a Ram TRX monster.

Haha! Me too! And my work mate also. We discussed this just the other week. So now, rest at last.

@Herra Käärme It varies between gas stations (USA) sometimes you get a slow pump, very rarely you get a REALLY fast pump, and if you pay inside the last gallon delivered goes SOOOO slow! like they don't want to give you an extra penny's worth. When I fill my boat it doesn't "trip" the shut-off so I have to listen for a slight gurgling and shut off myself or it spills several OZ on the swim deck. It's because the filler tube is 2 1/2" (60mm).

Yes, the principles discussed here affect the functioning of wings, pitot tubes, traditional "six pack" instruments, etc

@Julian Brelsford yep, and the applications only scale up the bigger the plane gets! I have disassembled something so many times and found a venturi of some flavor or another so many times!

My fluid mechanics professor would kill me though if I were to tell that Bernoulli principle can be explained by conservation of energy (such explanation is limited and works only in some specific cases)

Venturi effect is how carburettors work, too.

@Julian Brelsford Unfortunately wings do not fly because of bernoulli's principle (and as such the venturi effect), its a misconception.

I wouldn't worry too much, he's getting paid hundreds of thousands from JPvid for all the views he's getting from these videos. It's a full time job that pays very well.

@Brian Merritt It might be lucrative, but that doesn't negate the amount of the effort that went into the video. Sometimes the ability for a JPvidr to turn their videos into a career is at the whim of the mysterious algorithm.

@Brian Merritt No, he's really not getting nearly as much money from JPvid as you think he is. He's almost certainly getting most of the money for this video through Patreon. Most JPvid users don't realize this, but JPvidrs need to have several sources of income (JPvid, Patreon, sponsors, merch, etc) because no one single source will provide enough money on its own.

If you really want to do more to support the channel, consider contributing as a patron on Patreon.