system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does the gas pump automatically stop when its full?

Its been doing this for so long that no one even questions how. HOW?!
gpt
The pumping handle has a small sensor attached to the auto-clip that detects the air pressure inside the gas tank. When the tank hits about 90% full, the sensor disengages the auto-clip, and the pump turns off.