WEBVTT - How gas pumps work

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<v Speaker 1>Welcome to brain Stuff from how stuff works dot com,

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<v Speaker 1>where smart happens High Marshall Brain. Next time you're filling

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<v Speaker 1>up your tank at a gas station, ask yourself this,

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<v Speaker 1>How does the nozzle know when the tank is full? No,

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<v Speaker 1>there's not a miniature camera inside the nozzle hooked to

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<v Speaker 1>a microprocessor. This mechanism has been around for decades. It's

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<v Speaker 1>purely mechanical and ingenious. Near the tip of the nozzle

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<v Speaker 1>is a small hole and a small pipe leads back

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<v Speaker 1>from the hole into the handle. Suction is applied to

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<v Speaker 1>this pipe using a ventur e. When the tank is

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<v Speaker 1>not full, air is being drawn through the hole by

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<v Speaker 1>the vacuum, and the air flows easily. When gasoline in

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<v Speaker 1>the tank rises high enough to block the hole, a

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<v Speaker 1>mechanical linkage in the handle senses the change in section

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<v Speaker 1>and flips the nozzle off. Here's a way to think

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<v Speaker 1>about it. You've got a small pipe with suction being

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<v Speaker 1>applied at one end and air flowing through the pipe easily.

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<v Speaker 1>If you dick the free end of the pipe and

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<v Speaker 1>a glass of water, much more section is needed, so

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<v Speaker 1>a vacuum develops in the middle of the pipe. That

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<v Speaker 1>vacuum can be used to flip a lever that cuts

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<v Speaker 1>off the nozzle. The next time you fill up your tank,

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<v Speaker 1>look for this hole, either on the inside or the

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<v Speaker 1>outside of the tip of the handle. Do you have

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<v Speaker 1>any ideas or suggestions for this podcast? If so, please

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<v Speaker 1>send me an email at podcast at how stuff works

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<v Speaker 1>dot com. For more on this and thousands of other topics,

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<v Speaker 1>go to how stuff works dot com.