system
Given the following post, respond as if you're commenting on Reddit:
human
How does the gas pump know when to stop pumping the gas? Does it use certain sensors or just stop at a certain amount of gallons?
gpt
Next time you get gas look closer at the nozzle, you'll notice it has two holes. One where the gas comes out and one were air is allowed to flow back in. When the gas fills your tank eventually it covers this hole, and a pressure valve releases closing the valve to the pump inside the handle. It's quite a neat design.