Practical Engineering - 2016-07-26
What happens when a civil engineer mixes water and electricity? The results aren't always ideal, but you always learn something! A magnetic flow meter relies on Faraday's Law of Induction to measure the flow of a fluid. Magnets outside the pipe create a magnetic field. Electrodes are located perpendicular to the magnets. A conductive fluid moving through the pipe will generate a voltage (electromotive force) between the electrodes due to Faraday’s law. The faster the fluid moves through the pipe, the higher the voltage. Once you know the velocity of the fluid, you can calculate flow using the cross sectional area of the pipe. In this video, I walk through some of the details that electrical engineers have worked out so that this ingenious device can work properly. Unfortunately I couldn't get it working very well myself! Want to learn more? Wikipedia - https://en.wikipedia.org/wiki/Magnetic_flow_meter Neha Girme Blog - https://nehagirme.wordpress.com/2011/11/19/electromagnetic-flowmeter-design/ Arudino Code - https://github.com/gradyh/dc_pulse_gen Patreon: http://patreon.com/PracticalEngineering Website: http://practical.engineering Audible: http://www.audible.com/engineer 3D Model: Devin Sloan Music: Elexive - Tonic and Energy (https://www.youtube.com/watch?v=U6fBPdu8w9U) Errata: -At 4:36, the signal to noise ratio is low, not high.
Rotate the pipe into a vertical orientation. This ensures the pipe is full of liquid. This is a practice used in industry when installing mag flow meters.
the issue here may not be electronic. it might be more practical. your pipe setup allows for air in the pipe. this will show up as noise. raise the discharge so the pipe stays full. long straight runs get a more laminar flow which reduces noise (10*diameter at least before meter). also make sure your bucket is full so pump does not vortex and suck air. I troubleshoot these occasionally, air in pipe is one of the most common issues.
@Tim Kelton.. So then why there are min conductivity of the fluid is mentioned in the spec sheet of flow meters if it really doesn't matter?
@Tim Kelton would having 3 different grades of road use diesel fuel(summer, spring/fall, and winter) make one of theas obsolete for data logging fuel consumption? As well as having various rates of fuel contamination from different stations accrost the country require the 2 (pumped minus return differential = consumption ) sending units to be recalibrated with each fill-up?
@David Drescher From practical experience in the field, I would expect that different grades of diesel wouldn't have an effect. My experience has been with running water, sand, linear, and crosslinked polymers at high rates. I have a practical experience so technical answers are a little out of my reach.
Tim Kelton diesel does not coduct electricity , correct?
@Richard Price 😂😂
Here are a couple of tips from Deuteron Technologies Ltd, Jerusalem Israel. First, you can get at least an order of magnitude higher magnetic field if you close the magnetic circuit with a laminated iron or ferrite core. Secondly, use a lock-in amplifier, or equivalent to look for your signal. In other words you should process the signal by continuously multiplying it by a number proportional to the applied current, and then use a low-pass filter to extract the flow signal. It's easy to see nanovolts of signal that way. Your biphasic waveform is good, but better if that was the current waveform, not the voltage waveform, so you should make a controllable current source rather than applying a voltage directly to a coil. This becomes much more important as you increase the inductance of the coils and you increase the frequency.
Very helpful info. Thanks for sharing!
Wow, that's great info.
Uhmmm what? :p
All i heard was warp core, the borg, and engage.
If I ever get my hands on an oscilloscope, I'm totally putting googly eyes on it too.
KrazeeCain you can get basic scopes pretty cheaply, if you’re ok with connecting it to your computer. Let me know if you’re still interested in details.
@Moon Moon I'm interested.
I absolutely love the way you put googly eyes on everything. never stop.
top men are working on these artisan magnets
had he added a core to the magnets he would have had a much more powerful field :p
Who?
TOP. MEN.
But are they Antibiotic-Free²-Range Magnets?
R.I.P My sides.
Dear +Practical Engineering,
Please use the "math" function on your 'scope to multiply channels A and B, where A is the uV signal from the electrodes and the B is the current through the field-coils. Next, "measure" the average (mean) of the product-signal (i.e. the output of the 'math' channel), normalize for the excitation-amplitude and voila, you have filtered the needle out of the haystack :) The DC (average) level that you measure should be proportional to your flow. You can even measure bidirectional flow. For best results, put channels A and B on AC-coupling, HF-reject, heck you can even do triggered averaging if you trigger off of the current (channel B)! This is my favorite version of a low-budget-synchronous-detector :)
Yep, this is the reason for using the chopped Signal in the first place, so you can synchronously detect it in York noisy signal. This basically behaves like a really small bandwidth bandpass filter, thus reducing the noise voltage extremely.
same function as a Lock-in Amplifier....
A "synchronous detector" is a subset of a "lock-in amplifier" - this particular use-case doesn't warrant a (way more expensive) lock-in amplifier, i.m.o., especially since the reference excitation-signal is readily available.
Nice Video, but a small error 4:33 the SNR is low not high, no worries hope no one got confuesd
didn't sound right as SNR is in decibels and usually never see values <1 for commercial products
Man, I love this channel. Some of the highest quality content on YouTube!
Thanks. This is really encouraging to hear.
I concur! Excellent topic and treatment of the subject. Just to throw in my 2 cents: I'd love to see a followup if you do tweak the design.
I totally agree! Great video Grady!
I really like the fact you still shared the results even with failed practical part. Failure IS an option, if you have data as a result. <- Someone said? ;-)
I was having a problem sourcing magnet wire locally due to a lack of the requisite copper mine. Then I remembered my house was just full of copper pipes. Problem solved!
On a side note, do you have a line on a good plumber?
+LeiserGeist Bruh get out of my life
@Spoder Man oh hell you're everywhere D:
the copper inside the power transformer is a better source, the power company will replace it. Or you can use pre '82 pennies.
@LeiserGeist Thankfully, the gluten-free water thing (or at least Clara) was a mickey-take. https://www.newscientist.com/article/2100550-gluten-free-water-surely-thats-not-a-real-thing-is-it/
If it's inside the house, it has to be glutten-free CPVC piping.
What is this, the 80's though??
It's all about grade-A, free-range, cage-free, glutten-free, non-gmo, organic, free-trade, lead-free, NSF approved, ASTM-listed, UPC approved PEX piping.
@4:35 -- the signal to noise ratio would be low. The noise to signal ratio would be high.
I thought so too, I'm glad to see another comment about that discrepancy.
Yeah, that bugged me to.
Man! I'll add an annotation about this mistake. Good catch.
Correct.
You should make a video with Destin (SmarterEveryDay)!
I like your mindflow. You are exceptionally consistent in your narration.
The cat just chillin there at the end tho <3
I really love this video, really shows how electrical engineering and engineering in general is riddled with difficulties and some times failure opposed to just the façade of perfection some people imagine.
Thanks!
Would love to see a redesign video of this. Success videos make failure videos all the more relevant.
Agreed. Failure videos are great and I'm happy to have watched this, but as a fellow engineer who knows all too well that the devil is in the details, I can't help but wonder what details are missing from this setup to make it work.
+Ben Burns Yes!
Add an active low pass filter, if it still noisy, make a simple lock in amplifier
The production quality on these videos are going up every time great work keep it up and you will blow up!!!
I love it... “EE is hard.” But, that was still a GREAT tutorial.
4:35 "we would say signal to noise ratio is high" could be corrected. Thank you for the video!
Next, try to make a massflow meter using the coriolis principle.
I really love this channel! Maybe someday I'll even have the opportunity to contribute to the nerd-sphere myself; 'till then, keep up the great work!
Good video, glad it got posted. This is a super-tough problem and a much better showing than I would have made. I like the demonstration of how to solve the problem.
Love this channel!
8:31 Hell yeah it is! Amen!
3:04 ahhh why are you threading the thread tape on backwards
always go cw
He is an engineer, no practical knowledge.
ah good there are some people here that noticed
Thank you, I was reading the comments to see if anyone else caught that. I stopped the vid at that point, now I can go watch the vid in peace without that nagging at me. lol
Scabbage 😂😂😂 I caught this too damn plumber in me
"It seems very straight forward"
Appreciate you posting the "failure"
"Electrical engineering is hard"
said every civil engineer ever.
I've worked 10 years as a fracker and we use 3" and 4" mag meeters in some of our rate monitoring. It's neat to see the theory on how some of the stuff around you works
Shame you couldn't get it to work, but interesting concept
I love the point you made about documenting failure. We don't get nearly enough of that in STEM education.
Practical (real) Engineering is just like that. Best luck next time! Love your videos!
Such an underrated channel, the quality of these videos is phenomenal
3:04 Wrapping it the other way will cause the loose end to stay in line rather than cause it to roll up onto itself.
"Artisan electromagnet coils...hand spun..." XD
Love this guy!
"Documenting your failure is just as important as documenting your success" -true
I've been interested in this before, Really glad to see it explained so well. thank you!
Love how you are always on the edge on your comfort-zone!
Rats... was hoping for a actual working diy flow meter :'(
Thanks Practical Engineering i learn how to use the word Artisan in a new way, instead of saying a contraction that i made now i will say is an Artisan project.
You could get a much stronger magnetic field by using an iron core in your electromagnet. In fact, your best bet might be to use a pre-made electromagnet: tear the rotor out of a small AC motor and run your pipe through the stator. A small C-frame shaded pole motor might be perfect for this (cut the shading coil.)
https://en.wikipedia.org/wiki/Shaded-pole_motor
great idea
jason
i was thinking the exact same thing.
"Of course I'm using artisan electromagnet coils hand wound in small batches with locally sourced magnet wire"....Haha...best line in the whole video!
how about making a video on how hydraulic press works :)?
"and viewers like you" GAH CHILDHOOD MEMORIES ARE FLOODING IN(PBS anyone?)
Thanks for posting the failure. IMO, it's important to show both success and failure.
Thank you for this video! It was very interesting to watch. And the visualisation of information is really great.
Thank you for this video! It was very interesting to watch. And the visualisation of information is really great.
beautiful simple solution. love such things.
Thanks for putting it up, even with the experiment failing. If we only used our successes, we'd be centuries behind
Jim Fortune - 2016-11-10
Noise to signal is high, not signal to noise.
Tyler Patterson - 2020-03-02
its signal to noise ratio in electrical engineering like he said actually ie SNR = 10log(Vsig/Vnoise), as Resistance cancel we can use log properties and the fact that P = V^2/R, to make it SNR = 20log(Psig/Pnoise) in dB. Look up signal process engineering or an embedded systems textbook for a better definition :)