How Gas Pumps Know When to Turn Themselves Off

Prolific science vlogger and author Steve Mould cut a gas nozzle in half in order to learn how it turns itself off automatically when the car’s gas tank is full. As it turns out, the process relies on a series of Venturi tubes, levers, and ball bearings that equalize internal pressure within the nozzle when the tank is full and prevent overflow.

Gas or petrol pump nozzles turn off automatically when your tank is full. The way it works is really clever and uses the venturi effect.