YF-S401 Water Flow Sensor Hall Effect 0.1–5L/min Leakproof

$15.95 Inc. GST
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Description

🌊 YF-S401 Water Flow Sensor Hall Effect 0.1–5L/min Leakproof | AuscomTech

The YF-S401 Water Flow Sensor is a compact, high-precision hall-effect flow sensor designed for accurate low-flow water measurement in appliances and automation systems.

Built with a durable PVC body, stainless steel shaft, and high-quality hall sensor, the YF-S401 produces a stable pulse output proportional to flow rate. It is widely used in coffee machines, water dispensers, heaters, and embedded control systems where reliable, repeatable water flow detection is required.


⭐ Key Features

🧲 Hall Effect Flow Sensing
High-quality hall sensor delivers stable pulse output for accurate flow measurement.

📏 Low Flow Measurement Range
Designed for precise monitoring of small flows from 0.1 to 5 L/min.

🧱 Durable & Leakproof Construction
PVC housing with high-sealing performance and internal sealing ring for long-term reliability.

⚙️ Stainless Steel Shaft
Abrasion-resistant axis improves durability and extends service life.

🔌 Wide Operating Voltage
Operates from DC 5–24V, suitable for both low-voltage electronics and control systems.

🌱 RoHS Compliant Materials
Manufactured with environmentally friendly, compliant materials.


📊 Technical Specifications

Model: YF-S401
Sensor Type: Hall effect water flow sensor
Operating Voltage: DC 5–24V (min. 4.5V)
Max Current: ≤15mA @ DC 5V
Load Capacity: ≤10mA @ DC 5V
Flow Range: 0.1–5 L/min
Accuracy: ±2%
Pulse Output Duty Cycle: 50% ±10%
Pulse Output High Level: >4.7V (at 5V supply)
Flow Pulse Formula: F = (98 × Q) ±2% (Q = L/min)
Internal Diameter: 1.2 mm

Water Resistance (Static): 0.35 MPa
Max Water Pressure: ≤0.8 MPa
Operating Temperature: ≤80°C
Liquid Temperature: ≤120°C
Operating Humidity: 35%–90% RH
Storage Temperature: −25°C to +80°C
Storage Humidity: 25%–95% RH
Insulation Resistance: >100 MΩ

Dimensions: 58 × 35 × 27 mm
Weight: Approx. 25 g


⚠️ Important Notes

• Install vertically with an inclination ≤5°
• Ensure liquid temperature does not exceed 120°C
• Avoid strong vibration, shock, or corrosive chemicals
• Pulse output requires frequency measurement in software


🧩 Compatible With

• Arduino (Uno, Nano, Mega)
• ESP32 / ESP8266
• STM32 microcontrollers
• PLC digital input modules
• Coffee machines and water dispensers
• Embedded control systems


⚙️ Typical Applications

• Coffee machines
• Water dispensers
• Water heaters
• Low-flow water monitoring
• Automation and control systems
• Embedded electronics projects


🔌 Wiring Reference

• Red: VCC (Positive)
• Yellow: Pulse Signal Output
• Black: GND (Negative)


📦 Package Includes

• 1 × YF-S401 Water Flow Sensor

📌 Code Examples – SEA YF-S401 Hall Effect Flowmeter (0.3 – 6 L/min)

📋 Overview

This SEA YF-S401 liquid flow sensor outputs a pulse train whose frequency is proportional to the flow rate. It’s ideal for:

  • Small pumps & dispensing systems

  • Aquarium / hydroponics

  • Coffee machines & beverage dosing

  • Precision fluid measurement

  • IoT flow monitoring

Typical specs:

  • Flow range: 0.3–6 L/min

  • Hall effect pulse output (digital)

  • Works with 3.3 V – 24 V systems

  • Easy to interface with microcontrollers


⚠ Wiring Notes

Pin Function
Red Power supply (3.3–24 V DC)
Black Ground (common with MCU)
Yellow Pulse output (open-collector)

Important:

  • The yellow output is an open-collector / open-drain signal.

  • You must use a pull-up resistor (typically 4.7 kΩ to the MCU logic voltage) between the pulse pin and MCU Vcc.

  • Ensure common ground between sensor and MCU.


📈 Basic Flow Equation

The sensor produces pulses proportional to flow:

Flow (L/min) = Frequency (Hz) / K

Where K is the calibration constant. For the YF-S401, this is typically around:

K ≈ 97 (pulses per litre)

➡ A calibration value may vary slightly based on your sensor lot — best confirmed with a calibration run.


🧪 1️⃣ Arduino Example – Flow Rate & Total Volume

Use an interrupt pin for accurate pulse counting (e.g., pin 2 on UNO).

// SEA YF-S401 Flow Meter Arduino Example
const int flowPin = 2; // Flow pulse pin to interrupt pin
volatile unsigned long pulseCount = 0;
unsigned long lastTime = 0;
float flowRate = 0.0;
float totalLitres = 0.0;

// Calibration: pulses per litre (use your sensor’s datasheet value)
const float Kfactor = 97.0;

void IRAM_ATTR pulseISR() {
pulseCount++;
}

void setup() {
Serial.begin(9600);

pinMode(flowPin, INPUT_PULLUP);
attachInterrupt(digitalPinToInterrupt(flowPin), pulseISR, FALLING);

Serial.println(“SEA YF-S401 Flowmeter Test”);
}

void loop() {
if (millis() – lastTime >= 1000) {
detachInterrupt(digitalPinToInterrupt(flowPin));

unsigned long count = pulseCount;
pulseCount = 0;
lastTime = millis();

// Convert to frequency (Hz)
float frequency = (float)count;

// Flow rate (L/min) = (Freq / K) * 60
flowRate = (frequency / Kfactor) * 60.0;

// Litres in the last 1 second
float litres = flowRate / 60.0;
totalLitres += litres;

Serial.print(“Flow (L/min): “);
Serial.print(flowRate, 3);
Serial.print(” | Total (L): “);
Serial.println(totalLitres, 3);

attachInterrupt(digitalPinToInterrupt(flowPin), pulseISR, FALLING);
}
}


⚡ 2️⃣ ESP32 Example – Low Flow Precision

ESP32 often uses custom pins — choose ANY interrupt-capable GPIO.

const int flowPin = 15;
volatile unsigned long pulseCount = 0;
unsigned long lastTime = 0;
float flowRate = 0.0;
float totalLitres = 0.0;

// Calibration constant (approx)
const float Kfactor = 97.0;

void IRAM_ATTR pulseISR() {
pulseCount++;
}

void setup() {
Serial.begin(115200);

pinMode(flowPin, INPUT_PULLUP);
attachInterrupt(digitalPinToInterrupt(flowPin),
pulseISR, FALLING);

Serial.println(“ESP32 YF-S401 Flowmeter”);
}

void loop() {
if (millis() – lastTime >= 1000) {
detachInterrupt(digitalPinToInterrupt(flowPin));

unsigned long count = pulseCount;
pulseCount = 0;
lastTime = millis();

float frequency = (float)count;
flowRate = (frequency / Kfactor) * 60.0;
totalLitres += flowRate / 60.0;

Serial.print(“Flow (L/min): “);
Serial.print(flowRate, 3);
Serial.print(” | Total (L): “);
Serial.println(totalLitres, 3);

attachInterrupt(digitalPinToInterrupt(flowPin),
pulseISR, FALLING);
}
}


🧠 Notes & Calibration

✔ Choosing a precise Kfactor is critical for accurate measurement — use calibration with a known volume for best results.
✔ For low flow rates (<1 L/min), sample over longer intervals (e.g., 2–5 seconds) to smooth noise.
✔ Use INPUT_PULLUP or an external pull-up resistor between the pulse pin and the MCU Vcc.


📊 Flow Smoothing & Filtering

You can improve measurement stability by averaging over multiple intervals:

float avgRate = 0;
const int sampleCount = 5;
float rateBuffer[sampleCount];
int index = 0;
void loop() {
// (capture frequency like above)
rateBuffer[index++] = flowRate;
if (index >= sampleCount) index = 0;

// Compute average
float sum = 0;
for (int i = 0; i < sampleCount; i++) sum += rateBuffer[i];
avgRate = sum / sampleCount;

Serial.print(“Avg Flow (L/min): “);
Serial.println(avgRate, 3);
}


🔌 Pump / Control Example (Optional)

Use the flow meter as a closed-loop control:

const float targetLitres = 2.0; // 2 L goal
const int pumpPin = 8;
void setup() {
pinMode(pumpPin, OUTPUT);
digitalWrite(pumpPin, HIGH); // turn pump ON
}

// in loop(): after calculating totalLitres
if (totalLitres >= targetLitres) {
digitalWrite(pumpPin, LOW); // turn pump OFF
}

Make sure your pump is driven properly (use a relay/driver) — do not drive it directly from an MCU pin.


💡 Tips & Troubleshooting

✔ Add a small capacitor (100 nF) across sensor power for noise suppression.
✔ Shielded cable improves signal in industrial environments.
✔ Verify the pulse shape with an oscilloscope if readings jump around.
✔ Long wiring runs may require a pull-up of lower resistance (e.g., 2.2 kΩ) for cleaner edges.

Additional information

Weight 100 g
Dimensions 260 × 160 × 20 mm

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