How Does A Gas Nozzle Know When To Shut Off?

If you've ever put gas in a car, you've probably noticed how the gas pump shuts off when your tank is full. But how does it know to do that? Learn more about the clever mechanism that keeps your gas tank from overflowing in this episode of BrainStuff.

Whether the topic is popcorn or particle physics, you can count on the HowStuffWorks team to explore - and explain - the everyday science in the world around us on BrainStuff.

[QuaabQueb]

If this guy was anymore laid back he'd fall over

[EqualsThreeable]

As a Gas Station owner I already knew this, but not in this much detail or a diagram, I didn't know what the effect was called but I certainly knew it was mechanical. Here's something you may not know, the pump nozzle( the handle and everything besides the hose) is surprisingly cheap, while some models may run a little better or be built better they can be purchased for under $14. The safety mechanism does fail, but there aren't many ways to test pumps to see when they are going to fail, some may work for years or fail a week out of the box. This is why it is still a law for you to be attending the pump so it is not to overfill and not the owners fault that you were irresponsible. Here's a tip if you ever notice this mechanism going off when you know your tank is not full this is because the pump isn't all the way in your tank or something is blocking it causing gas to flow up the tube, you see their is often a metal flap in your newer cars between the outside air and the tank, so if this happens just take the pump out and reinsert it into the tank. Finally a safety tip, if under any circumstance a fire occurs at the pump don't remove the nozzle from your cars tank, your car will not explode, there isn't enough oxygen in the tank for the fuel to burn so just the fuel and gas on the outside catch fire leading you to believe the flame will reach the tank and blow up. It would eventually happen but not if you rush to the attendant and have them press the emergency stop button to prevent anymore gas from flowing and to activate the on site fire suppression system or any near by fire extinguisher. 

[markchavez]

I didn’t ’t even know it would shut off. I never have enough money to fill it up all the way. 🤦🏽‍♂️

[fatheramerica]

I just had an experience at the gas station where the gas didn't shut off. It kept pouring and I didn't notice till there was already a pool of gas on the ground. My tank was full, but the nozzle didn't shut off. Prior to watching this video, I assumed there was a bad sensor, or issue, with my vehicle. After watching this video, I realized the issue was with the gas nozzle. Thank you for the knowledge.

[poederruiker]

Man, I love Josh. The dry humor really fits him

[kohlmjj]

I'm a Weights and Measures inspector here in WI and I get the opportunity to inspect TONS of gas pumps and field TONS of consumer complaints, many of which, stem from malfunctions of check valves and automatic shut offs. Thanks for this wonderful explanation. It should prove to be a great resource when explaining to consumers what is happening at the pump.

[ApplegrApe]

I'm overwhelmed with your enthusiasm

[Boryspitzanzx]

If you play the videos at 1.25 it actually makes up for his lack of well i would say enthusiasm but mostly any part of GIVING A SHIT about the topic.

[AdultsSwim]

I had actually been wondering about that. Thanks!

[Groaznic]

Next, please explain the same thing on Don't Be Dumb! :)

[ESPPsycho]

I'm sorry, but this was not explained well.

[DIZAZZO]

The answer to something that I never asked, or thought about...

But I'm glad to know now.

Cheers.

[rados]

You’re explaining this little bit poorly. If I hadn’t  been studding mechanics for last two years I probably wouldn’t understand your video. It seems like you barely know what you are talking about.

[geetarwanabe]

In the UK you simply let go of the handle and it turns off...

[eckosboy]

i was curious about this, thank you

[goling]

Excellent, ir really like you videos guys. Best regards

[joaqchannel]

That solved one thing i never knew kudos!!!!

[ItsonlyaJimmy]

I will think about this my whole life. Thanks man it did actually help me out. My only words of advise. A couple of more takes and this video would have been perfect. Thanks for posting it also.

[torpa]

wow, i've been listening to Stuff You Should Know podcast for years, and i've never seen this guys face. My ears and eyes are freaking out because i've had this imaginary image of this guy in my head for so long that i can't comprehend seeing someone different

[hanukirandavuluri]

The way the logic was narrated was good.