Home SCIENCE Automatic Bell Siphon Explained – How It Works

Automatic Bell Siphon Explained – How It Works

This is a demo of a bell siphon I built in collaboration with a couple of engineering professors. There are certain cases where it would be nice to be able to create a siphon without any intervention, a self-priming or automatic siphon: the next level of siphonry.

source/image(PrtSc): Practical Engineering

It’s built out of an acrylic sheet and a piece of clear pipe. Thanks to Rolf Hut and Pete Marchetto for inviting me to collaborate on their project.

A bell siphon works solely on the physics principles of atmospheric pressure and vacuums! At the highest point in a siphon, the pressure is actually lower than atmospheric pressure, also known as a vacuum.


This allows the atmospheric pressure to push water up over the peak of the siphon so gravity can carry it the rest of the way. For most situations, that’s enough theory to describe your typical siphon. It’s a very convenient way to drain a reservoir or transfer a liquid without a pump.