1/2 Inch Water Flow Sensor – YF-S201

The 1/2 Inch Water Flow Sensor – YF-S201 is a compact and reliable flow measurement device designed to measure the rate of water flow in pipes. It is widely used in automation systems, irrigation setups, water dispensing systems, and IoT-based monitoring projects. The sensor works on the Hall-effect principle, making it accurate, durable, and easy to interface with microcontrollers.

This sensor is installed inline within a 1/2 inch water pipe, where water flow causes an internal rotor (pinwheel) to spin. As the rotor turns, a built-in magnetic mechanism triggers a Hall-effect sensor, generating electrical pulses proportional to the flow rate. These pulses can be read by microcontrollers such as Arduino, ESP8266, ESP32, and Raspberry Pi to calculate both real-time flow rate and total water volume.

The output signal is a digital pulse, which makes it simple to process using basic timing or interrupt-based programming. By measuring the frequency of pulses, the system can determine the amount of water passing through the sensor with good accuracy.

The YF-S201 is designed for long-term use and can handle continuous water flow with a strong internal structure. Its sealed housing helps protect internal components from water damage, ensuring stable and reliable performance in different environments.

Working Principle

The YF-S201 works using a Hall-effect sensing mechanism combined with a rotating turbine.

• Water enters the sensor and spins the internal rotor.

• A magnet attached to the rotor rotates with the flow.

• Each rotation triggers the Hall-effect sensor.

• The sensor outputs electrical pulses corresponding to rotation speed.

• The microcontroller reads these pulses and calculates flow rate using calibration formulas.

The standard formula used is:
Flow Rate (L/min) = Pulse Frequency ÷ 7.5

Key Features

• Measures water flow rate from 1 to 30 L/min

• Built-in Hall-effect sensor

• Digital pulse output (TTL compatible)

• Operating voltage: 5V to 18V DC

• High accuracy measurement (±10%)

• Easy microcontroller interface

• Durable internal rotor mechanism

• Long operational life (up to ~300,000 cycles)

• Suitable for continuous water flow monitoring

• Compact and lightweight design

Applications

The YF-S201 Water Flow Sensor is widely used in:

• Water flow monitoring systems

• Smart irrigation systems

• IoT-based water meters

• Automatic water dispensers

• Industrial fluid control systems

• Home automation projects

• Arduino-based measurement systems

• ESP32/ESP8266 IoT projects

• Laboratory liquid flow experiments

• Smart agriculture systems

• Tank filling control systems

Specifications

• Product Type: Water Flow Sensor

• Model: YF-S201

• Pipe Size: 1/2 inch

• Flow Range: 1 – 30 L/min

• Operating Voltage: 5V – 18V DC

• Output Type: Digital pulse signal

• Sensor Type: Hall-effect sensor

• Accuracy: ±10%

• Max Pressure: 2.0 MPa

• Connection Type: Inline pipe fitting

Package Includes

• 1 × YF-S201 Water Flow Sensor (1/2 Inch)

Safety Precautions

• Use only with clean or filtered water.

• Avoid exposing the sensor to corrosive liquids.

• Do not exceed maximum pressure rating.

• Ensure correct flow direction during installation.

• Keep electrical connections dry and insulated.

• Disconnect power before installation or maintenance.