system
Given the following post, respond as if you're commenting on Reddit:
human
How does the nozzle know to shut off when my gas tank is full?

I imagine it would have a sensor that would know when liquid touched it, but how would that work? Whenever I go to the gas station, it’s usually just a metal nozzle attached to a hose...
gpt
Suction is applied to this pipe using a venturi. When the tank is not full, air is being drawn through the hole by the vacuum, and the air flows easily. When gasoline in the tank rises high enough to block the hole, a mechanical linkage in the handle senses the change in suction and flips the nozzle off.