Fluid flowmeter having a hall effect sensor with an internal magnet

Abstract From the Canadian patent

A flowmeter for sensing fluid flow. The flowmeter includes a housing including a first port a second port, a chamber in fluid communication with the first port and the second port and a fluid passageway extending from the first port to the second port. An impeller having a non-magnetized metal pole piece is located within the chamber of the housing and is rotatable about an axis in response to fluid flow through the fluid passageway. A Hall Effect sensor and a magnet are located outside of the fluid passageway. The magnetic field generated by the magnet enables the Hall Effect sensor to sense rotation of the impeller and thereby the rate of fluid flow through the fluid passageway.