Backyard Aquaponics
A place to discuss aquaponics

Part of my musings about doing some simple datalogging and experimenting was flow rates. I wanted a simple sensor that i could make at home that was kinda sorta accurate and found this.






It looks like it should be fairly simple to make. Just a H-Bridge for the pulsing dc driven by a micro, an opamp and an adc. Im thinking simple like picaxe, mosfets, opamp, cable. Done. I think you should be able to calibrate it easily enough by taking a measurement and holding a bucket under the end so you can calculate the flow rate and relate it to the reading. Thoughts?

Interesting.
I know mechanical flow meters are notoriously inaccurate (unless you get really expensive ones)
This approach should eliminate that.
Nice idea.

It should also be very solids friendly. The biggest hurdle will be the op-amp for me. Me and analog do not mix well.

I have also found that alot of companies that manufacture them are very open about how to calculate flow rates etc and how to build one.

Hehe yeah, I don't have a very good history with them either.
I usually get there in the end though.

Looks like the meters used to calculate chill water usage downtown from the com ed ice building plant. I know my dad used to go calibrate their gear with his meter and it worked really well. The meter he had was 20k though. I might be going to his house soon and I will try to get pics and the name of it of it. I need to swipe the MMI cable out of the same box for another control panel.

It works really well and I used to to measure a pump once I suspected of getting near failure or clogging and it was. You program in the pipe type and liquid then its transducers will measure flow. I do think solids might throw it off but who knows.(maybe dad?)

They mention their version works with solids in the video. Although I get the feeling that the way they describe how it works isn't the way they have made theirs.

or perhaps I have no idea what I'm talking about

http://www.google.com/patents/US7716995 ... &q&f=false

It was just the way they said "[one way to do this]" in the video made me think it wasn't the way they are doing it.

Perhaps they have something new in the works. The company has plenty of patents..

We have Coriolis flow meters at work. The principal on how they work is very easy to demonstrate. Search youtube, there are heaps of vids. But i think they would be harder to make and calibrate. Especially at low flow levels.

Sorry but I cannot resist.



NEEEEEEEERRRRRRRRRRRRRDS


No offence ment.

I got all excited about a comment only to be teased!



Ok so here is phase one of my plan:

Step 1: Collect underpants.
Step 2:
Step 3: Profit.

The second phase is:
Step 1: Make a pole shoe like this.
Step 2: Make a Helmholtz Coil like this.
Step 3: Insert the probes into the pipe.
Step 4: Make a magical black box that makes it all work.
Step 5: Profit.

Phase 2 does have more steps is far more likely to be the weak point int he whole plan. But we will see how i go.

If she could find her Star Trek uniform, my mum would give you a piece of her mind.

I am assuming thisis some sort of ultrasonic flow meter? I have used similar ones in hydraulics that measure the flowrate based upon the temperature,viscosity etc. You just clamp them onto the pipe, and they spit out the numbers for you

The actually works a little bit like an alternator. The idea being that you need three things to generate an EMF. Movement, a conductor and a magnetic field. The coils generate a magnetic field, the water is your conductor and as it moves from being pumped it generates a weak voltage. The probes pick up the voltage and you can calculate the speed of the water. Knowing the speed of the water and the volume of the pipe you can calculate flow.

Wonder if capacitance changes with flow.....
CMTU's can detect tiny changes in capacitance.