1/8 Inch Water Flow Sensor YF-S401

Overview

The YF-S401 Water Flow Sensor is a compact sensor used to measure water flow rate in small pipes.

Ideal for:

• Water dispensing systems

• Irrigation systems

• Arduino & IoT projects

• Coffee machines & appliances

Working Principle

• Inside rotating turbine (rotor) + Hall Effect sensor

• Water flows rotor spins

• Speed of rotation flow rate

• Sensor outputs pulse signals

Based on Hall Effect

More flow more pulses

Infographic Summary

Measures: Water flow Range: 0.36 L/min Voltage: 5V24V Output: Pulse signal Size: 1/8 inch Tech: Hall Effect

Pin Configuration

YF-S401 Sensor Red VCC (524V) Black GND Yellow Signal

Key Specifications

• Operating Voltage: 5V 24V DC

• Flow Range: 0.3 6 L/min

• Output: Digital pulse signal

• Accuracy: 5%

• Current Consumption: ~15 mA

• Max Liquid Temp: up to 120C

• Pressure: up to ~0.82 MPa

Pulse Output Formula

Typical relation:

• 1 Liter 5880 pulses

So,

• Flow rate = pulses per second calibration factor

<" pipe size

Low power consumption

Easy to interface

Pulse output (easy to count)

Waterproof internal design

Applications

• Water flow monitoring

• Smart irrigation systems

• Coffee/tea machines

• Liquid dispensing systems

• IoT water management

• Cooling systems (CNC/laser)

Interfacing

Compatible with:

• Arduino

• ESP32 / ESP8266

• Raspberry Pi

Connect signal digital pin (interrupt recommended)

Working Example

Water Monitoring System:

• Water flows through sensor

• Rotor

Important Notes

• Must be installed vertically for accuracy

• Avoid air bubbles (affects readings)

• Not suitable for dirty/corrosive liquids

• Needs calibration for precise measurement

YF-S401 vs YF-S201

Pro Tip

• Use interrupt pin for accurate pulse counting

• Add filter or debounce logic in code

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