[MUSIC PLAYING] Hey, there. I’m Josh Clark. This is Brain Stuff. Have you ever been
pumping gas in your car, and all of a sudden, pssh, it
just shuts off in your hand. Bam. Maybe it takes a finger off. That kind of thing. How does the gas nozzle
know when to shut off? Well, I’m here to explain. It’s actually
surprisingly complicated. You ever heard of
the Venturi effect? If you take a tube and you pitch
it in the middle, then fluid– and remember, fluid can be gas. It can be liquid. It doesn’t just have to
be water or something. After the pinch, after it
goes through the pinch, it becomes compressed. And as its velocity
speeds up, the pressure on the other side of the
tube actually decreases. Keep that in mind. That’s the Venturi Effect. If you look at a
gas nozzle, you’ll see a little hole
toward the end. And that hole actually
leads to a tube. And that tube runs all
the way up the length of the gas nozzle. And it usually tees off. On one side, you’ve
got a Venturi tube. On the other side,
you’ve got a tube leading to a diaphragm of air. Now that diaphragm of air is
all blown up nice and big, while there’s air running
through the nozzle sensor. So while you’re pumping
gas, and gas is in the tank, and you’re still
filling it up, air is moving through this little
sensor pipe quite nicely. The pressure on one end
of the Venturi tube, which is on this
side, is nice and low. And on the other
side, the diaphragm is nice and puffed up. Air pressure, no problem. But as the gas starts to
rise, maybe it starts to foam, or it starts to just
simply fill up the tank. That sensor, that pipe,
starts to suck up gas. And when the gas is sucked
up, the density of gas is a lot heavier than
the density of just air. The Venturi tube all of a
sudden changes in pressure, which creates suction on
the other end of this pipe, which sucks the diaphragm,
which collapses a little bit, triggering an
automatic shut off. Seriously, that’s what’s
going on in your gas nozzle when you’re pumping
gas and it fills up. That’s how it knows
your tank is full. So I guess maybe
ruminate on this. Chew on it. Think about it for possibly
the rest of your life. It is really complex,
but pretty cool. It’s not magic, I guess
is what I’m trying to say. I’m sure you like this video. There are tons of other ones. If you have a question that
you wanted us to answer, you can leave it in the comments
section below on YouTube. Like us. Subscribe to us. Just be all things Brain Stuff. It’ll make you smarter.

## 100 thoughts on “How Does A Gas Nozzle Know When To Shut Off?”

1. mosouss says:

So it means that from 1:42 until 2:00 I am paying my own gass that has already been sucked?

Didn't get anything

3. Amaan Baig says:

Is it just me or this guy looks like Christian Bale

4. SaucyDanny says:

So it sucks the gas out a little, meaning they take gas from us everytime??

5. matt w says:

Awesome visual

6. Elite Falcon legacy says:

In other words it’s a vacuum mechanism

7. AyabaraGaming says:

Ok, you didn't actually say how it triggers or how it happens, you left out the actual part you called out in the title

8. Anty Holm says:

I never that gas could also be liquid. You learn something New everyday 😒

9. serious Dopamine says:

Played at x0.75

10. Sumudu Sankalpa says:

This guy has the mouth of Messi

Cuz when because the lady she put in when it's done with the leaders it shuts off the

12. Anonymous ? says:

Are you Josh Clark form how stuff work?

13. MK says:

So don't pump after the bump

14. Sachin mae says:

Its a dumb thing to call liquid fuel 'Gas',, what do you call gaseous fuel? 'solid'?

15. Kevin Flores says:

Stuff You Should Know!!!

16. Federico Cresci says:

"magic"

Wendy's chili CAN be served with cheese. A useless comment; kinda like this vid

18. jamesthemaniac says:

This is a terrible video. Desperately hope they didn’t PAY this guy…

19. Zarith Azmir says:

Holy.. ive been thinking & womderimg about it everytime i pump gas.. thnks..

20. Daniel Chavez says:

How tf am I supposed to explain all this shit to my friends?

21. Chevifier says:

Jesus my life is complete. Ive always been wondering for years. And finally decided to look it up now🤣

22. Chevifier says:

Fluid can BE gas. The same way fluid can be Water. both can become vapor. I guess he shouldve said petrol(which is still british for gas. Cant win lol)

23. Mario M says:

great info

24. mirus says:

most confusing explanation ever

25. Jord B says:

When he said "remember gas is a liquid" … Smh stupid americans

26. Johnathan Escobar says:

It tells you when your tank is full?! When I put 25\$ and it doesn’t fill so why’s it stoping! FILL ME UP! WOOOOOOOOO!

27. Sam Eppink says:

Damn that is clever

28. Nenad ИС XC Shuput says:

It doesn't.

29. Endangered White Male says:

It's not gas, it's simply petrol or diesel. Gas isn't liquid LOL.

30. RAVI TEJA says:

31. Hanukiran Davuluri says:

The way the logic was narrated was good.

32. Arianm09 says:

Christian Bale?

33. Blam-o says:

Can "topping off" damage your vehicle or the pulp? Why is it discouraged?

34. Lonewolf 18 says:

Watch this video in 0.25x playback speed

35. Huttbole says:

Cut the hate, he’s a nice man

36. Jonathan Lin says:

He seems high

37. Dylan Breznay says:

This guy sounds like he’s on rick and Mortys inter dimensional cable

38. CozmicK G says:

I feel like you're not very good at making things easy to understand.

39. Steev Be Loved says:

Hahaha thank you 🙏 for that 😂🐸

40. Wahid Rahman says:

Use it upside down

41. Walmart Fanatic says:

Boring. I wish I never knew this.

42. Dul Johnny says:

It tries its best

43. davefilms345 says:

I've never used a gas pump that took my finger off

44. Bill Malec says:

That would be a diesel nozzle in the pic 😊

45. Bill Malec says:

Gas is short for gasoline in the USA. Don't like it? Stay where it's called petrol… Short for… Petroleum… An oil. 😂
But but but…

46. Toasted Fan Art says:

Maybe next time don't blaze up before you go on camera bro haha

47. Lytheus says:

if this is how it works, why does the gas nozzle cut off when my tank is empty in older cars? I have to take the nozzle half out in order for it to stop cutting off in my 20 year old car

48. Colin MacVicar says:

As I was filling up earlier today I was wondering how this was done and thought I should look it up on YouTube but then completely forgot about it. Now I’m browsing recommendations and see this. I knew my phone was always listening but didn’t know it could read my mind as well.

49. Jonathan Lee says:

Still dont get it

50. Dan Rudder says:

You sound like a guy from a podcast I listen to.

51. Majestic Hotwings says:

I think this guy has been spending too much time hanging around the gas pumps huffing those fumes, definitely missing a few brain cells

52. Dairys Moreta says:

Today I purchased 17.5 Gallons of gas for only \$5.99!

53. Mr. Nuance says:

I'm stoned af so this video was perfect. Thank you.

54. IgnitionDJ says:

This literally sounds like a rick and morty script lol

55. Chinmay Nani says:

56. GoPro478/Howling Dawn says:

It doesnt

57. BITE THE BILLET says:

Play at 1.25x speed for normal listening

58. C.I.A. says:

Play at 0.25

Thank me later

59. Akash Ramesh says:

What is the way to prevent spillage of petrol when the nozzle is taken out from the vehicle?

60. Delenis R says:

What if the gas pump fails to do that…and you end up spilling gas …asking for a friend…

61. Apollo says:

What the fuck, this showed up in my recommendations and I was thinking about it yesterday

62. Johannes D Leveler_93 says:

Why is the air leaving the diafram when gasoline is suck up the smaller internal pipe?

63. Paul Shankland says:

This thing was described in way too complicated fashion, there are 1 million basic physics and mechanics basics misrepresented, Including fluid incompressibility, The Venturi effect, on and on. Need to go back to High school physics class, and pay attention next time 🙂

64. Munsur Ahmed says:

Fluid can’t be gas

65. Jorge Peralta says:

How to fill up a car tank without guessing the amount you have to pay?

66. Timothy Hatton says:

Does this happen with trucks as well

67. JM Veda says:

Awesome mayn

68. Benjamin Barenblat says:

This video shows the diaphragm connected to the thick part of the Venturi tube, not the thin part. This would cause gasoline to flow into the diaphragm. To maintain suction on the diaphragm and pull air in through the hole in the spout, the diaphragm needs to be connected to the thin part of the Venturi, as shown in https://i.imgur.com/F6RvAXs.jpg and https://www.youtube.com/watch?v=afKwoc5DG9Y.

69. Ken Sendelofski says:

70. CardinalKaos says:

Holy shit real life Morty

71. Hsin-Chih Chang says:

maybe you also know why would a gas pump not shut off while fueling and overfill? I've had that happen after replacing fuel pump on a 2008 hyundai santa fe.

72. Johnny Wilds says:

Thank you so much. I am forever in debt to you.

73. ziggamon says:

In your fuel pump there's two tubes inside, an air tube that leads to a sack up top and a tube for outgoing fuel. When you pump your tank, air comes in and inflates the sack, fuel goes out. As the fuel level increases and less air coming in, which causes the sack to lose integrity until there is no more air to keep it inflated and it collapses. Once that happens, it triggers a shut off valve and then click, no more fuel.

74. EdEdd Edgar says:

Nice video i appreciate the time

75. Saliba T says:

I love this. But you are awkward

76. Delfino Garza says:

This guy is totally wrong !!! It is magic !!!

77. Mike Lacroix says:

Thanks, Josh!

78. SVETOGOR says:

It’s for sure a magic for me!

79. Kyle Juggalo Newton says:

Ok that's full tank what about you fill tank from empty to half tank struggle gas won't get sucked up into the nozzle

80. J B says:

Where do they go for research? They must be the only ones that read and actually understand owners manuals.

81. Shawn Spencer says:

This is what happens when you snort Xanax before work.

82. Unnat Baja says:

Finally now i am satisfied

Playback speed 1.75x works best

84. Jorvas25 says:

Very laidback guy. Thanks for the knowledge imparted.

85. Andrew Persing says:

Why does my car a (2006 mustang) have a "hard fill" as described from Ford? It only lets the gas tank to fill up half way or a little more before it clicks off. I know I can fill it a few gallons past when it stops and its really irritating because if you don't know exactly how much is in the car when you start filling it then you don't know how far to push it.

86. Jose Luis Cano says:

I need help with something idk if you can e-mail me or massage on on here it's a long story so I rather wait for your answer… I did subscribe and like 😉

87. Rens de Lange says:

I don't understand that suction part. If the gas fills up the venturi pipe, why does that create suction so that the air pushes the gas out of the pipe again?

88. Rick Pearce says:

I love the info, but it’s so painful to watch these guys

89. N gate says:

doe this work on motorcycles? I dont think its ever stopped for me.

90. Marks Alot says:

I’m sure to many of us, it is magic.
🤔💕🤣

91. racefan32 says:

And what does the little nub at the end of the nozzle have to do with this?

92. arsenijcz says:

i love you josh!

93. Orrin Jones says:

thats not complex g

94. Donald Tramp says:

This video sucks!

95. Erandaka thushara says:

You can't explain how stuff work

Thx u soo much

I didnt even know that was happening to me in the gas station

Btw my lvl of gas dosnt work

97. вσrutσ uzαmαkí says:

You let the grip go.