How do the pumps at gas stations know when to stop filling the tank?


Kinda a dumb question, but I always wanted to know what causes pumps will automatically stop when you’re filling up your tank?

In: Technology

The next time you fill your tank, take a look in the gas nozzle, you will see an object, usually square, near the opening.

This object is a mechanical switch that works off of the vacuum created by your tank. When its low the fuel flows free, but as it fills the pressure changes enough to cause a back flow that triggers this switch, causing the pump to kick off.

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