Measure Water Flow in literes using Arduino Mega 2560 Board and Water Flow Sensor

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prakash_prasad

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Posted by prakash_prasad: Fri. Nov 14, 2014 - 06:33 AM

I have a water flow sensor with Arduino Megs 2560 board. I am trying to conceptualize the concept to calculate amount of water getting dispensed esp. in 1,2,3,4 and 5 liters quantity.

The Water flow sensors generate pulses/sec when water is flowing through it. In my case it is 4.5 pluses per sec as per specification. I would connect the sensor input to any pin from 22-53 pin.

Suppose I connect to ping 23 so in my setup() function I would add:

    attachInterrupt(23, pulseCounter, FALLING);

where pulseCounter is an interrupt function triggered on each signal generated from sensor and increments a variable

   void pulseCounter()
    {
      // Increment the pulse counter
      pulseCount++;
    }

Now how do I calculate the flowrate and water dispensed in milliliters using this information? I am not sure but I understand that I first need to calculate flowrate first, if so is the below formula correct:

    flowrate = pulseCount / 4.5;

and to measure amount of litres have dispensed is

    flowMilliLitres = (flowRate / 60) * 1000;

as we keep adding flowMilliLitres oto a global variable:

totalMilliLitres += flowMilliLitres;

Please correct my understanding if I am proceeding in wright direction.

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Last Edited: Fri. Nov 14, 2014 - 06:36 AM

valusoft

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Posted by valusoft: Fri. Nov 14, 2014 - 06:42 AM

Can you provide a link to your flow sensor please? Pulses per second make no sense alone... you need to know the relationship between the volume of water passed and the pulses. That relationship should be stated in the sensor datasheet.

Ross McKenzie ValuSoft Melbourne Australia

prakash_prasad

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Posted by prakash_prasad: Fri. Nov 14, 2014 - 08:15 AM

I may be wrong - it would be pulses per volume:

http://www.seeedstudio.com/wiki/images/b/b7/Water_flow_sensor_datasheet.pdf

But then it varies from freqz of the MCU unit. How do I know the freqz of the MCU and I would assume that counting that much pulses then would mean that a liter of water has been dispensed?

valusoft

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Posted by valusoft: Fri. Nov 14, 2014 - 08:43 AM

OK Prakash. The datasheet says in two places that it produces approximately 8 pulses for each litre of water that flows through it. The graph is wrong (compare the figure for 480 litres per hour with the printed values. Someone plotted the wrong values).

So your MCU must simply measure the number of pulses received in a known period of time, eg how many pulses are counted in one second. If you count 8 pulses in one second (8Hz), that means that 1 litre of water has flowed through in that one second. The frequency of your MCU (eg 16MHz) is not important except for being able to measure 1 second.

So...

Volume in litres = 0.125 * (number of pulses)/(number of seconds of counting)

... therefore 16 pulses counted during 2 seconds is 1 litre of water measured.

Hope that helps you.

Cheers,

Ross

Ross McKenzie ValuSoft Melbourne Australia

awneil

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Posted by awneil: Fri. Nov 14, 2014 - 08:58 AM (Reply to #4)

valusoft wrote:

The datasheet says in two places that it produces approximately 8 pulses for each litre of water that flows through it.

So time is irrelevant?

Quote:

therefore 16 pulses counted during 2 seconds is 1 litre of water measured.

Surely, 16 pulses counted in any period of time is two litres of water?

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valusoft

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This reply has been marked as the solution. #6

Posted by valusoft: Fri. Nov 14, 2014 - 09:21 AM

Yeah OK... just count pulses and divide by 8 and call the result litres. I'll go back to sleep now...

Ross McKenzie ValuSoft Melbourne Australia

wagnerlip

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Posted by wagnerlip: Fri. Mar 11, 2016 - 06:40 PM (Reply to #6)

No no no, wrong, sorry.

8 Hz means one liter per minute... doesn't mean that each 8 pulses one liter went through.

If ONE LITER per MINUTE creates 8Hz, than each 60 seconds of 8Hz, 480 pulses, means one liter.

In other words, each 8 pulses means 16.6ml, or each pulse means 2.08ml (2.08 cubic centimeter of water).

So, you can yes, multiply pulses times 0.00208 and obtain "liters".

In this link below, you can read 7.5Hz per liter/minute, or, 450 pulses per liter, same as my calculations above.

http://www.hobbytronics.co.uk/yf-s201-water-flow-meter

Wagner Lipnharski
Orlando Florida USA

Last Edited: Fri. Mar 11, 2016 - 07:54 PM

wagnerlip

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Posted by wagnerlip: Fri. Mar 11, 2016 - 07:41 PM (Reply to #7)

So, your program should be;

 void pulseCounter()
    {
      // Increment the pulse counter
      pulseCount++;
      if(pulseCount > 47)
         {
         pulseCount -= 48;
         totalMilliLitres += 100;
         }
      end if

Wagner Lipnharski
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Posted by js: Fri. Mar 11, 2016 - 09:05 PM

Nice to see you around Wagner but the thread is 1.5 years old.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

wagnerlip

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#10

Posted by wagnerlip: Fri. Mar 11, 2016 - 10:13 PM (Reply to #9)

js wrote:

Nice to see you around Wagner but the thread is 1.5 years old.

Hey John, I still orbiting...

I like to dig and fix old wrong information... looks like ourselves... old and wiser...

Wagner Lipnharski
Orlando Florida USA

veno

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#11

Posted by veno: Thu. May 17, 2018 - 10:32 AM

wagnerlip wrote:

No no no, wrong, sorry.

8 Hz means one liter per minute... doesn't mean that each 8 pulses one liter went through.

If ONE LITER per MINUTE creates 8Hz, than each 60 seconds of 8Hz, 480 pulses, means one liter.

In other words, each 8 pulses means 16.6ml, or each pulse means 2.08ml (2.08 cubic centimeter of water).

So, you can yes, multiply pulses times 0.00208 and obtain "liters".

In this link below, you can read 7.5Hz per liter/minute, or, 450 pulses per liter, same as my calculations above.

http://www.hobbytronics.co.uk/yf-s201-water-flow-meter

How can i measure volume when pulse is not stable?

(when see actual water flow its not stable flow rate or stable pulse. in that case how can i calculate liquid volume that flows through the sensor during specific time period(eg:1hour))

valusoft

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#12

Posted by valusoft: Thu. May 17, 2018 - 12:43 PM

As I said in post #6... count the number of pulses and when you reach 8 that means 1 litre has passed. How many times have you counted to 8 in your one hour... irrespective of stability or not.

Ross McKenzie ValuSoft Melbourne Australia

awneil

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#13

Posted by awneil: Thu. May 17, 2018 - 12:50 PM (Reply to #12)

but that's not what wagnerlip said in #7 - which veno quoted to re-resurrect this old thread again in #11.

Top Tips:

How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
"Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
Difference between a crystal, and a crystal oscillator: https://www.avrfreaks.net/comment...
When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...

valusoft

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#14

Posted by valusoft: Thu. May 17, 2018 - 01:42 PM

Yep. Correction. Count 480 pulses equals 1 litre.

Ross McKenzie ValuSoft Melbourne Australia

wagnerlip

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#15

Posted by wagnerlip: Thu. May 17, 2018 - 05:52 PM

The OP seems to produce some confusion when use the expression "flowrate" but not correlated to time, and also, did not used the concept of "volume" when time is not involved.

We need to be careful, since it can leads to wrong assumptions.

Flowrate is always "some volume" by "some time".

In this specific case, the weblink states approximately 2.25mL per pulse, so, 8 pulses means only volume of liquid (18mL), but 8Hz means frequency in time, and it means 18mL per second, it can not be translated to 1.08 liter per minute, since you can not ensure stability of such reading during the next 59 seconds. As an instantaneous sample of just one second, you can say that 8Hz could represent an assumption of 1.08 liter per minute.

One should never confuse things. The uC calculation should multiply pulses per second (Hz) by 135 in order to obtain milliLiters per minute, but again, that is an assumption. If the liquid flow was zero during 900ms and produced 8 pulses in the last 100ms, it would means absolutely bullsh*t, and the assumption of 1.08 LPM would be wrong.

The only valid information would be accumulating pulses to represent volume in multiples of 2.25mL. Based on that accumulated pulses and the time, one could assume a more reliable LPM.

Wagner Lipnharski
Orlando Florida USA

prakash_prasad

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#16

Posted by prakash_prasad: Fri. May 18, 2018 - 01:30 AM (Reply to #15)

Thanks for all the details - I remember being able to resolve the issue close to your approach.

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Measure Water Flow in literes using Arduino Mega 2560 Board and Water Flow Sensor

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