Need Help with Getting Decimal Pulses for Flow Meter Readings

Hello everyone,

I am working on an in-line flow meter project and am having difficulty with the data readings since I am measuring the flow rate based on pulses. Is there a way to read pulses as decimals instead of integers? The flow rate data from my testing was 1.6 L/hr and 3.21 L/hr. The 1.6 L/hr corresponds to 1 pulse, and the 3.21 L/hr corresponds to 2 pulses when checked using the pulse counter. The flow rate obtained from another flow meter is within this range, so it is correct. However, I need an approximate and consistent value for the flow rate to create a calibration curve when doing manual testing. Does anyone have an idea of how I can achieve this? I used an Arduino UNO. Here is my code.

#include <max6675.h>
#include <LiquidCrystal_I2C.h>
#include <SD.h>
#include <RTClib.h>

byte sensorInterrupt = 0;  // 0 = digital pin 2
byte sensorPin       = 2;
// initialize the library with the numbers of the interface pins
LiquidCrystal_I2C lcd(0x27, 20, 4);
RTC_PCF8523 rtc;

// for the data logging shield,I use digital pin 10 for the SD cs line
const int chipSelect = 10;

// The hall-effect flow sensor outputs 
// litre/minute of flow.

volatile float pulseCount;  


float flowRate;
float totalLiters;
float density;

unsigned long oldTime;


int thermoDO = 4;
int thermoCS = 5;
int thermoCLK = 6;
MAX6675 thermocouple (thermoCLK, thermoCS, thermoDO);


// File object for data logging
File dataFile;

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

    // Set up the LCD's number of columns and rows:
  lcd.init(); //initialize the lcd
  lcd.backlight(); //open the backlight

    //Initialize SD card
  if (!SD.begin(chipSelect)) {
    Serial.println("SD initialization failed!");
    return;
  }
    Serial.println("SD initialization done.");



      dataFile = SD.open("MANUAL", FILE_WRITE); 
    if (!dataFile) {
    Serial.println("Error opening data file.");
    return;

  }
  // Write header to file
  dataFile.println("Time, Flowrate (L/min), Volume (L), Temperature (°C), Density (kg/m3");
  dataFile.flush();
  
  pinMode(sensorPin, INPUT);
  digitalWrite(sensorPin, HIGH);
  

  pulseCount        = 0;
  flowRate          = 0.0;
  totalLiters       = 0;
  oldTime           = 0;

  // The Hall-effect sensor is connected to pin 2 which uses interrupt 0.
  // Configured to trigger on a HIGH state change (transition from LOW
  // state to HIGH state)
  attachInterrupt(sensorInterrupt, pulseCounter, HIGH);
}

/**
 * Main program loop
 */
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 / 37.40;
// flowRate = ((1000.0 / (millis() - oldTime)) * pulseCount / 2244.19)*3600;
    
    // 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.
    totalLiters += flowRate / 60 * 1000;
    
    // Add the millilitres passed in this second to the cumulative total
    //totalLiters += flowRate;
    thermocouple.readCelsius(); //Data for temperature sensor.

    if(28 > thermocouple.readCelsius() >= 27);
     density = 840*(.9898 - (((27-thermocouple.readCelsius())*(0.9898-0.9890))/(27-28)));
    if(thermocouple.readCelsius() >= 30);
    if(29 > thermocouple.readCelsius() >= 28);
    density = 840*(.9890 - (((28-thermocouple.readCelsius())*(0.9890-0.9881))/(28-29)));
    if(thermocouple.readCelsius() >= 30);
    density = 840*(.9873 - (((30-thermocouple.readCelsius())*(0.9873-0.9847))/(30-33)));
    if(thermocouple.readCelsius() > 33);
    density = 840*(.9847 - (((33-thermocouple.readCelsius())*(0.9847-0.9839))/(33-34)));
    if(thermocouple.readCelsius() > 34);
    density = 840*(.9839 -(((34-thermocouple.readCelsius())*(0.9839-0.9830))/(34-35)));
    if(thermocouple.readCelsius() > 35);
    density = 840*(.9830 -(((34-thermocouple.readCelsius())*(0.9830-0.9822))/(35-36)));
    if(thermocouple.readCelsius() > 36);
    density = 840*(.9822 -(((34-thermocouple.readCelsius())*(0.9822-0.9813))/(36-37)));
    
          
    // Print the flow rate for this second in litres / minute
    Serial.print("Flow rate: ");
    Serial.print(flowRate, 5);  // 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("Volume: ");        
    Serial.print(totalLiters);
    Serial.print("mL"); 
    Serial.print("\t");       // Print tab space

    Serial.print("PULSE: ");        
    Serial.print(pulseCount);
    Serial.print("p/s"); 
    Serial.print("\t");       // Print tab space

    // Print temperature
    
    Serial.print("Temp: ");
    Serial.print(thermocouple.readCelsius());
    Serial.print("°C  ");
    Serial.print("\t");
    //Print Density

    Serial.print("Density: ");
    Serial.print(density);
    Serial.print("kg/m3");
    Serial.println("\t");
        
    // Write data to CSV file
    dataFile.print(millis() / 1000); // Time in seconds
    dataFile.print(",");
    dataFile.print(flowRate); // Flow rate
    dataFile.print(",");
    dataFile.print(totalLiters); // Volume
    dataFile.print(",");
    dataFile.print(thermocouple.readCelsius()); // Temperature
    dataFile.print(",");
    dataFile.println(density);
    dataFile.flush(); // Flush data to SD card
    dataFile.close();
    
    // LCD
    lcd.setCursor( 0, 0); // set the cursor to column 0, line 0
    lcd.print("Flow: ");
    lcd.print(flowRate);
    lcd.print(" L/min");   // Print the volumetric flow rate in Liters per minute:
    lcd.setCursor( 0, 1); // set the cursor to column 0, line 1
    lcd.print("Volume: ");        
    lcd.print(totalLiters);
    lcd.print(" mL");
    lcd.setCursor(0, 2); // Set the cursor to column 0, line 2
    lcd.print("Temp: ");
    lcd.print(thermocouple.readCelsius());
    lcd.print(" °C");
    lcd.setCursor (0,3);
    lcd.print("Density: ");
    lcd.print(density);
    lcd.print("kg/m3");
    
    // 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, HIGH);
  }
}
/*
Insterrupt Service Routine
 */
void pulseCounter()
{
  // Increment the pulse counter
  pulseCount++;}

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