Water Flow Sensor – How to Use it?

Introduction:

Water Flow sensor is basically used to take a note of how much water has been transferred from one area to the other. Water flow sensor consists of a plastic valve body, a water rotor and a hall-effect sensor. When water flows through the rotor, the rotor start rolling after feeling the pressure. Its speed changes with different rate of flow. The hall-effect sensor outputs the corresponding pulse signal.

Usage:

Nowadays water flow sensor is used in wide variety of areas. Some common Examples are: Water Management, Mining and Extracting, Agriculture, etc.

Project for Reference:

Code:

byte statusLed    = 13;

byte sensorInterrupt = 0;

byte sensorPin       = 2;

float calibrationFactor = 4.5;

volatile byte pulseCount;

float flowRate;

unsigned int flowMilliLitres;

unsigned long totalMilliLitres;

unsigned long oldTime;

void setup()

{

  Serial.begin(9600);  // Initialize a serial connection for reporting values to the host

  pinMode(statusLed, OUTPUT);  // Set up the status LED line as an output

  digitalWrite(statusLed, HIGH);  // We have an active-low LED attached

  pinMode(sensorPin, INPUT);

  digitalWrite(sensorPin, HIGH);

  pulseCount        = 0;

  flowRate          = 0.0;

  flowMilliLitres   = 0;

  totalMilliLitres  = 0;

  oldTime           = 0;

  // The Hall-effect sensor is connected to pin 2 which uses interrupt 0.

  // Configured to trigger on a FALLING state change (transition from HIGH

  // state to LOW state)

  attachInterrupt(sensorInterrupt, pulseCounter, FALLING);

}

void loop()

{

  if ((millis() - oldTime) > 1000)   // Only process counters once per second

  {

    // Disable the interrupt while calculating flow rate and sending the value to

    // the host

    detachInterrupt(sensorInterrupt);

    // Because this loop may not complete in exactly 1 second intervals we calculate

    // the number of milliseconds that have passed since the last execution and use

    // that to scale the output. We also apply the calibrationFactor to scale the output

    // based on the number of pulses per second per units of measure (litres/minute in

    // this case) coming from the sensor.

    flowRate = ((1000.0 / (millis() - oldTime)) * pulseCount) / calibrationFactor;

    // Note the time this processing pass was executed. Note that because we've

    // disabled interrupts the millis() function won't actually be incrementing right

    // at this point, but it will still return the value it was set to just before

    // interrupts went away.

    oldTime = millis();

    // Divide the flow rate in litres/minute by 60 to determine how many litres have

    // passed through the sensor in this 1 second interval, then multiply by 1000 to

    // convert to millilitres.

    flowMilliLitres = (flowRate / 60) * 1000;

    // Add the millilitres passed in this second to the cumulative total

    totalMilliLitres += flowMilliLitres;

    unsigned int frac;

    // Print the flow rate for this second in litres / minute

    Serial.print("Flow rate: ");

    Serial.print(int(flowRate));  // Print the integer part of the variable

    Serial.print("L/min");

    Serial.print("\t");   // Print tab space

    // Print the cumulative total of litres flowed since starting

    Serial.print("Output Liquid Quantity: ");

    Serial.print(totalMilliLitres);

    Serial.println("mL");

    Serial.print("\t");   // Print tab space

    Serial.print(totalMilliLitres / 1000);

    Serial.print("L");

    // Reset the pulse counter so we can start incrementing again

    pulseCount = 0;

    // Enable the interrupt again now that we've finished sending output

    attachInterrupt(sensorInterrupt, pulseCounter, FALLING);

  }

}

void pulseCounter()

{

  // Increment the pulse counter

  pulseCount++;

}