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Water flow meter with RS485

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UroBoros

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I need to design a system to measure the water consumption of separate apartments in a building.
I have to install a flow sensor in different pipes with say 1.5" dia. I will get the data from sensor, transmit through RS485, CAN or MiWi and consolidate in a central unit for billing.

The networking and reporting part I have an idea how to do. But I have no experience with sensors/meters suitable for this purpose.
What are the options available to me in this case?
The sensor/Meter will be placed in a duct or somewhere. So no display needed there. I need only data out from the meter to be recorded and displayed by my main unit.

Ultrasound, hall effect or any other; which will serve my purpose.
Thanks
 

srizbf

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Water flow sensors are available in different flow rate spec.
based on the flow in the pipeline(lit/sec) , suitable sensor can be selected.
bare sensors give o/p in pulses. a separate controller to count the pulse and interpretation is necessary.
then finally rs485 conversion.

sensor+controller+rs485 interface ---the reqd units.

dia of pipe to be connected and flow rate range are to be known for the selection.
 

horace1

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if you do a forum search for water sensor you will find a number of posts on this topic
also a general web search will give plenty of links
have you thought of using a wireless network? e.g. Zigbee or similar
 

FvM

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Using the flow sensor for billing restricts the sensor choice to types suitable for certification, at least if the project application is more than fictive academical. For smaller pipes, regular residental water meters supplemented with a pulse output seem to be the first choice.

In Europe, you would most likely refer to M-BUS enabled water meters, either wired or wireless, an existing standard for electronic meter readout.
 

UroBoros

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I was able to find posts, but no vendor details. The only one I got was German.
Wired or wireless is not the issue - A suitable sensor is the issue for me.
 

SunnySkyguy

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Pulse counter method is cheapest then use signal conditioning to filter out noise into parallel ports or latch the pulse and clear it when selected by MUX for as many as you need as fast as required.
In short form> characterise pulse width> design matched filter for best EMI impulse rejection with Transient suppression.> drive edge sensitive FF or dual NAND gates on each pulse and clear when pulse is read in to PISO register. (parallel in , serial out) then Mux data. Use a check pulse on last channel that toggles or has some Serial data for MUX integrity check.

$20 each http://www.ebay.com/itm/1-5-Water-F...-Sensor-Switch-Meter-1-120L-min-/111316005163 ( dont know about reliability vs contamination level) these are very cheap.
these too http://www.ebay.com/itm/Self-clean-...005&rk=5&rkt=6&mehot=pp&sd=151314136035&rt=nc

LAtching the rising edge of pulse ensures you dont miss it when sampling the meter as long as you scan faster than fastest pulse rate. THis can be done centrally with edge sensitive port with PISO register.


Keep in mind accuracy, reliability is not a given and UPS and backup data collection is a must, daily!


For more general concepts, http://www.omega.ca/literature/transactions/volume4/images/06_Table.I_l.GIF
 

UroBoros

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Pulse counter method is cheapest then use signal conditioning to filter out noise into parallel ports or latch the pulse and clear it when selected by MUX for as many as you need as fast as required.
In short form> characterise pulse width> design matched filter for best EMI impulse rejection with Transient suppression.> drive edge sensitive FF or dual NAND gates on each pulse and clear when pulse is read in to PISO register. (parallel in , serial out) then Mux data. Use a check pulse on last channel that toggles or has some Serial data for MUX integrity check.
I am planning to use a Micro controller locally for handling the sensor and then will upload via MiWi or RS485. I think in that case the above mentioned processing can be avoided.

Thank you
 

milan.rajik

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Why not use Ultrasonic sensors like US-020 which can detect 700 cm (7 meters) and nRF24L01 and make the system witeless.
 

milan.rajik

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In the 1st post he mentioned Ultrasonice so I thought he is ready to use ultrasonic and I assumed that if he uses ultrasonic then he will be measuring the height of water in a tank and then use dimension of tank in calculation and based on these find out how much water was used.
 

FvM

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I presume, an ultrasonic flowmeter has been considered as possible option in post #1. But US flowemeters are rather expensive compared to regular displacement water meters and are more interesting for large pipes. For large water tubes, one would probably prefer magnetic inductive (MID) sensors.
 

UroBoros

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Thanks for the responses.
Actually on googling I found ultrasound or ultrasonic flow meters. So mentioned it as a possibility. I have no idea weather it is suitable for my purpose or not. So far what I understood from reading the web is that I can use water meters with pulse output and the count should be converted to volume of water.

http://www.chetascontrol.com/product26.html
http://www.ebay.in/itm/Water-Flow-S...5?pt=LH_DefaultDomain_203&hash=item2a4e3ed16d

These are some options I have located. They look like modifications on a normal one. was not yet able to find a good quality water meter which is supposed to be interfaced to a digital system. Even the dial is not needed. this will be placed in a duct or somewhere, so no use for a dial, instead cost should be reduced.
Search still on for a flow meter with 1.5" dia coupling with around 50L/min flow rate. I believe that will be more than adequate for a apartment. Correct me if I am wrong.

@FvM
In Europe, you would most likely refer to M-BUS enabled water meters, either wired or wireless, an existing standard for electronic meter readout.
can you refer some links for this M Bus Enabled options?
Thanks
 
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FvM

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Ask for the prices of ultrasonic water meters at chetacontrol and you'll see why the mechanical meters are preferred for your project. But mechanical meters have a calibration validity period of e.g. 5 years, ultrasonic flowmeters don't suffer from mechanical wear and may achieve a higher lifetime.

May be that ultrasonic water meters will supersede classical mechanical water meters one day, as digital electric meters are presently on the way. But not immediately.

Water meters with mechanical dial are made in millions quantity and rather cheap, thus it's a good idea to supplement the basic instrument with an electronical pulse output. You also have a backup sum counter if the electronic fails.

Notice that the flow meter in the second link isn't qualified for billing purposes.

Regarding M-BUS devices, just google for "M-BUS water meter".
 

paulfjujo

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UroBoros

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A litle MCU (PIC12F1840) interface the sensor and send the info via bluetooth
Thanks , but not English.
The Ebay item is no longer available.
Anyway I got an idea about the situation.
Now let me compare the pulse output models and M Bus enabled models.

Thanks for the inputs
 
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