1/2 Inch Water Flow Sensor - YF-S201
📌 Overview
The YF-S201 Water Flow Sensor is a widely used module for measuring liquid flow rate and volume in pipes. It is commonly used in Arduino and IoT projects.
👉 It is designed for 1/2-inch pipes and works by generating pulses as water flows through it.
🧠 Working Principle
Inside the sensor → a rotating impeller (fan)
Water flow spins the impeller
A Hall Effect sensor detects each rotation
Each rotation → generates a pulse
👉 By counting pulses, you can calculate:
Flow rate (L/min)
Total volume (Liters)
✔ Example formula:
Flow rate (L/min) = Frequency / 7.5
📊 Infographic Summary
┌──────────────────────────────┐
│ 💧 YF-S201 FLOW SENSOR │
├──────────────────────────────┤
│ 🎯 Function: Measure water │
│ 📏 Flow Range: 1–30 L/min │
│ ⚡ Voltage: 5V – 18V │
│ 🔌 Output: Pulse Signal │
│ 🧠 Type: Hall Effect Sensor │
│ 📐 Size: 1/2 inch pipe │
│ 📊 Accuracy: ±10% │
└──────────────────────────────┘
🔌 Pin Configuration
┌──────────────┐
│ YF-S201 │
├──────────────┤
│ Red → VCC (5–18V)
│ Black → GND
│ Yellow→ Pulse Output
└──────────────┘
⚙️ Key Specifications
⚡ Operating Voltage: 5V – 18V DC
💧 Flow Range: 1 to 30 L/min
🔌 Output: Digital pulse (TTL)
📊 Pulses per Liter: ≈ 450 pulses
🎯 Accuracy: ±10%
🌡 Temperature: -25°C to 80°C
💥 Max Pressure: 2.0 MPa
🌟 Key Features
💧 Measures both flow rate & total water usage
⚡ Low power consumption (~15mA)
🔧 Easy to install inline with pipe
🔁 Stable pulse output for microcontrollers
💰 Low-cost and reliable
🧪 Applications
🚰 Smart water meters
🌱 Irrigation systems
🏠 Home automation (water monitoring)
☕ Beverage dispensing machines
🤖 Arduino/ESP32 projects
💡 Leak detection systems
🔗 Interfacing
Compatible with:
🔵 Arduino
📡 ESP32 / ESP8266
🍓 Raspberry Pi
👉 Connect pulse output to a digital interrupt pin to count pulses.
⚠️ Important Notes
🔄 Must follow flow direction arrow for accurate results
⏳ Needs calibration for precise measurement
❌ Not suitable for dirty or corrosive liquids
⚠️ Minimum flow required to rotate impeller
💬 From real user experience (Reddit insight):
Reverse flow may work but gives inaccurate readings
🆚 YF-S201 vs Other Flow Sensors
| Sensor | Pipe Size | Flow Range | Use Case |
|---|---|---|---|
| YF-S201 | 1/2 inch | 1–30 L/min | General projects |
| YF-S401 | Smaller | Low flow | Precision systems |
| YF-S402 | Larger | Higher flow | Industrial use |
💡 Pro Tip
To build a smart water meter:
YF-S201 + Arduino
LCD/OLED display
WiFi module (ESP8266/ESP32)
👉 Track real-time water usage and detect leaks!
