Mechanical flow meters monitor the rotational speed of an impeller to interpolate the rate of fluid movement. When implemented with a magnet, the rotational speed of the impeller can be measured via changes in magnetic field through the use of Hall-effect sensors. This implementation has primary advantages of retaining the waterproof nature of the mechanical design, while also allowing for accurate measurements for rotational speed. The output of the Hall-effect device can then be connected to a microcontroller for frequency to flow rate conversion.

The flow meter design detailed in this document was created to offer an inexpensive test system capable of evaluating various magnet and Hall sensor configurations. In total, there are three primary configuration options for the 3D printed flow meter. Additionally, each configuration option is capable of evaluating various Hall sensors, including One-Dimensional (1D) and Two-Dimensional (2D ) SOT-23 devices. See Section 3.2 for the download link and for instructions for creating the 3D printable mechanical flow meter.