Water Flow Sensor YF-S201 (OT2104-D114)

Water flow sensor to measure the flow rate of water or other liquids. This sensor connects to a water pipe or hose and uses a pinwheel sensor to measure how much liquid is passing through it. The pinwheel has a small magnet attached and a Hall effect magnetic sensor on the other end of the plastic tube that can measure how many spins the pinwheel has made through the plastic wall.
The water flow sensor comes with three wires: red (5-18VDC), black (ground) and yellow (Hall effect pulse output). By counting the pulses from the sensor output, you can keep track of the liquid flow: each pulse is approximately 2.25 milliliters. Please note that this is not a precise sensor and the pulse may vary depending on the flow rate, liquid pressure and sensor alignment. Careful calibration is required if more than 10% precision is required.
Water flow sensor specifications:

Type: YF-S201
Max 30 liters per minute
Operates on: 5 to 18VDC
Max current draw: 15mA @ 5V
Flow Rate: 1 to 30 Liters/Minute
Temperature range: -25 to 80°C
Humidity Range: 35%-80% RH
Max water pressure: 1.75Mpa
Pipe / connection diameter: 1/2″ / 20mm
Color: white

DimensionsLength: 6.2cmWidth: 3.5cmHeight: 3.6cm