Petrol Nozzle

[Bonzo 2000]

How does the mechanism work in the handle of a petrol pump to make the trigger cut off when your tank is full?

[finex]

At the end of the delivery nozzle there is a a small air return tube. It has a specific name but I can't remember it at the moment! A small amount of air whilst is drawn up the tube while you are pumping fuel. Whilst the tank is not full, air can tavel up this tube, but when the fuel level reaches the end of the nozzle, the air is cut off, which causes the trigger lock to open and the fuel is cut off.

[Mortartube]

Would the name of the tube be a Venturi perchance?

[finex]

That's the one!