The FS400A G1" DN25 Water Flow Sensor is a high-precision Hall-effect flow meter designed for measuring water flow rates accurately. It works by using a magnetic core and an internal impeller that generates pulses proportional to the flow rate. This makes it ideal for applications like water dispensers, coffee machines, irrigation systems, and industrial fluid monitoring.

Working Principle:

When water flows through the sensor, it rotates an internal impeller that contains a magnetic core. This movement is detected by the Hall-effect sensor, which then generates a pulse signal proportional to the flow rate. The flow rate can be calculated using the formula:

$$\text{Pulse Frequency}=\text{Flow Rate (L/min)}\times 4.8$$

For example, if the pulse frequency is 48Hz, then the water flow rate is:

$$48÷4.8=10\text{ L/min}$$

This data can be processed by a microcontroller (Arduino, ESP32, STM32, etc.) to measure real-time water flow.

Specifications:

Features:

• Hall-effect Sensor Output: Provides digital pulse output, making it easy to interface with microcontrollers like Arduino, ESP32, Raspberry Pi, and STM32.
• Wide Voltage Compatibility: Operates from 4.5V to 24V, making it suitable for various applications.
• High Durability: Designed to handle water temperatures up to 120°C and withstand pressures of up to 2.0 MPa.
• Accurate Measurement: Pulse frequency = Flow rate (L/min) × 4.8, allowing precise calculations.
• Easy to Interface: Works with both analog and digital input systems.

Applications:

• Water Flow Monitoring in dispensers, coffee machines, and vending machines.
• Industrial Fluid Control in irrigation systems, cooling systems, and water purification.
• Home Automation for smart water metering and leakage detection.
• HVAC Systems for monitoring liquid flow rates.
• DIY Electronics Projects using Arduino, ESP32, and Raspberry Pi.

The FS400A is a G1-inch DN25 water flow sensor that uses a Hall-effect sensor to measure the flow rate of water. It provides pulse signals that correspond to the flow rate in liters per minute (L/min). This sensor is ideal for applications like water metering, irrigation systems, and industrial flow monitoring.

Components Required:

• Arduino Uno (or compatible board)
• FS400A G1” DN25 Water Flow Sensor
• 10kΩ pull-up resistor (optional, for stable signal)
• Jumper wires
• 5V Power source (from Arduino’s 5V pin)

Wiring Diagram:

Notes:

• The signal wire (yellow) provides pulses proportional to the flow rate.
• A 10kΩ pull-up resistor can be connected between the signal (yellow) and VCC (5V) for noise reduction.
• Ensure the arrow on the sensor matches the water flow direction.

Arduino Code:

volatile int pulseCount = 0;
float flowRate = 0.0;
unsigned long oldTime = 0;

void IRAM_ATTR pulseCounter() {
    pulseCount++;
}

void setup() {
    Serial.begin(9600);
    pinMode(2, INPUT_PULLUP);
    attachInterrupt(digitalPinToInterrupt(2), pulseCounter, FALLING);
}

void loop() {
    if (millis() - oldTime > 1000) {  // Update every second
        oldTime = millis();

        // Flow rate formula: (Pulse Count / 4.8) = Flow Rate in L/min
        flowRate = (pulseCount / 4.8);  

        Serial.print("Flow Rate: ");
        Serial.print(flowRate);
        Serial.println(" L/min");

        pulseCount = 0;  // Reset pulse count
    }
}

How It Works:

1. The FS400A water flow sensor generates pulses as water flows.
2. The Arduino interrupt (pin 2) detects these pulses.
3. The pulse count is converted to L/min using the formula: Flow Rate (L/min)=Pulse Count4.8\text{Flow Rate (L/min)} = \frac{\text{Pulse Count}}{4.8} (4.8 is a manufacturer-provided calibration constant).
4. The flow rate is displayed on the Serial Monitor.