How it works:
The flow switch consists of a paddle system, at the top a permanent magnet. Above this magnet a reed contact is placed outside the current.
A second magnet serves to generate a restoring force for the paddle. When the current to be monitored meets the paddle, it is deflected. This causes the magnet to change position in the reed contact, which is thus controlled. Once the current is interrupted, the paddle moves back to its original position and thus reactivates the reed contact. The necessary restoring force is generated by the two repelling magnets.
The utilization of magnetic force compared to a conventional leaf spring results in much better long-term stability and much higher insensitivity to pressure spikes.