Dependence of hall effect flow sensor frequency on the attached inlet and outlet pipe size

Hall Effect flow sensor YF-S201 is one of the most common, inexpensive, reliable and accurate flow sensor used in many applications for liquid flow rate measurement. The accuracy of the sensor is due to the linear relationship between the sensor pulse frequency and the flowrate. However, there are various factors that could affect the calibration model, one of them being the attached pipe size configuration. The present work investigates how the Hall Effect sensor calibration curve parameters are affected by the externally attached pipe diameters. The result shows that as the attached pipe size become smaller than the internal diameter of the sensor, the slope and intercept of the calibration curve is found to decrease and increase respectively. This means that the slope of 7.5 Hz per liter per minute (calibration factor) as specified by the by manufacturer of YF-S201 Hall Effect flow sensor cannot be used for higher accuracy requirement when the externally attached pipe size is smaller than the sensor internal diameter.