Gas station pumps rely on a clever mechanical device called a venturi tube to know when to stop pumping fuel. Here's how it works:
1) The venturi tube: This is a small tube located inside the nozzle and handle. It narrows in the middle, creating a region of lower pressure as fuel flows through it.
2) Vacuum creation: This lower pressure acts like a vacuum, sucking air from your car's gas tank through another small opening in the nozzle.
3) Fuel fills the tank: As the tank fills with fuel, there's less and less air space remaining. This means there's less air for the venturi tube to suck in.
4) Triggering the shutoff: When the fuel level reaches the venturi tube, it blocks the air intake. This sudden loss of air disrupts the vacuum, triggering a mechanism that shuts off the fuel flow.
5) No electronics involved: Interestingly, this process doesn't rely on any electronics, it's purely based on the principles of fluid dynamics and pressure changes.
