# How to measure water flowing from a washing machine pump?

Hi all
Am trying to find a way to measure the vol/time flow of water from the washing machine. Is there an electronic component that can be used like a coil of copper wire over the tube and the do something with a microcontroller perhaps and it figures out much flow? by electromagnetic measurement?

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#### davenn

Gold Member
Hi there
Welcome to PF

Is there an electronic component that can be used like a coil of copper wire over the tube and the do something with a microcontroller perhaps and it figures out much flow? by electromagnetic measurement?

water is neither magnetic nor electromagnetic

there's zillions of flowmeters available .....

Dave

#### Bystander

Homework Helper
Gold Member
there's zillions of flowmeters available .....
Dynamic range is another matter; admittedly I've not been all that active recently, but "flow-rates" have, in my past experience, seldom exceeded 10 percent accuracy outside a very limited dynamic range, single O(m).

#### PeterDonis

Mentor
Moderator's note: Thread level changed to "I".

#### Nugatory

Mentor
Am trying to find a way to measure the vol/time flow of water from the washing machine.
You will likely get better answers if you tell us more about what problem you're actually trying to solve. By far the most cost-effective and practical way of measuring the flow from a washing machine is a bucket and a stopwatch.... but if that answer isn't what you looking for, then there must be other constraint as well.

Are you by any chance trying to adapt a washing machine motor for some purpose other than washing clothes? If so, tell us what you're trying to do and see what the collective experience of this group can contribute.

There are several ways to measure your water flow. These include:

a 'Mag Meter' (requires that the water be slightly conductive) -these are commercially available - I've never 'rolled my own.'

A dP device - insert an orifice and measure the flow-related pressure drop - this is a pretty standard approach.

A thermal device - measure the water temp and measure the power required to maintain a heated probe at a slightly higher temp. This is a common way to precisely measure gas flow - it will work with water.

I don't think you'll get near $25 with any of them, unless you have a pretty good junk box and mad skills. Well the dp device sensing pressure drop may be the best to start with. problem is that in the washer, water flow is say 100% then it drops and tapers off so thermal may not work on the partial flow. Used to have alot in the junk boxes. people called me a hoarder? I just needed a larger shop. Sadly I have next to no junk now. #### Brad_805 You will likely get better answers if you tell us more about what problem you're actually trying to solve. By far the most cost-effective and practical way of measuring the flow from a washing machine is a bucket and a stopwatch.... but if that answer isn't what you looking for, then there must be other constraint as well. Are you by any chance trying to adapt a washing machine motor for some purpose other than washing clothes? If so, tell us what you're trying to do and see what the collective experience of this group can contribute. Well... I dont know how to explain it better, If I said what its for? then the discussion would move away from trying to measure water flow, it is not some hack of the washing machine, its a standard washer. having an electronic sensor thing that sends digitized flow info 24/7 I think the bucket idea may not be ideal. to calibrate it perhaps? sure. I wanted to know the mechanisms for sensing water flow thru a pipe, what reacts with the water? if a coil was placed over the pipe and the coil was part of a tank circuit with some freq range, and water passes in the pipe would the freq change? #### jbriggs444 Science Advisor Homework Helper If I said what its for? then the discussion would move away from trying to measure water flow The problem is that unless we know what it is for, we do not know what cost/benefit tradeoffs are relevant. One cannot choose a good design unless one knows the constraints under which one is operating and the design goals one is working to optimize. Just to add another possibility... flexible tubing and a spring scale to measure centrifugal force around a curve in the tube. Of course, good calibration would probably need to compensate for pressure in the line as well. #### Bystander Science Advisor Homework Helper Gold Member #### Brad_805 Well I mean its a microcontroller and then some wires going to some kind of sensor, or some kind of sensor unit thats powered and all it does is quantify flow. Is there nothing water reacts to? magnetic field zero, charge zero are there no fundamental forces known that water reacts to? yes the spring idea is perhaps very workable, how much deflection happens to some plate as the hose comes up and bends down into the drain pipe, add a device the water hose plugs into, water hits a plastic flap held shut by a spring. water dripping onto the flap would push it some amount, then the trick is to find the conversion sensor to measure that flap #### davenn Science Advisor Gold Member Is there nothing water reacts to? magnetic field zero, charge zero are there no fundamental forces known that water reacts to? as far as I'm aware, nothing in a way that would help you measure the flow building your own for$25 probably isn't going to happen

What is your electronics experience ( be honest, don't exaggerate) ?
You will have to buy the flow sensor and that could easily cost more than $25 on its own ( I haven't specifically priced them, have you ??) let alone the rest of the electronics, the time programming your micro to work with the data from the sensor I gave you a whole page of links #### Asymptotic Another consideration is you propose to measure gray water flow rate from the washer whih will be loaded with dirt, fibers and other debris, and tend to clog certain types of flow meters. #### russ_watters Mentor So the requirement here is to have an electronic sensor and microcontroller that measures the instantaneous d/dt flow, sending out flow measurements with a time stamp. How often? And are you sure you mean instantaneous and not cumulative? #### Brad_805 What is your electronics experience ( be honest, don't exaggerate) ? extensive. about 45 years, alot of school, alot of design, test. Worked with and owned tv repair shops, fixed tube-transistor and newer, alot of electronics work on alot of things for many companies over the decades. still learning, always new things I didnt know. You will have to buy the flow sensor and that could easily cost more than$25 on its own

--No, I want to make the flow sensor, there has to be some way.

( I haven't specifically priced them, have you ??) let alone the rest of the electronics, the
time programming your micro to work with the data from the sensor

--I also do programming, RT embedded is fun.

let me look for that list. One of my problems today is that I had to give up just about ALL of my junk, things, tools, spools of wire large/small, connectors, circuits, chips, passives.... a small fortune in parts. dont have access to my stereo scope nor hot air soldering tool, or all the automotive tools. most of those are gone. so instead of just try something? I dont have anything to work with, its a very depressing feeling, literally. Then being employed part time, there isnt a budget to buy anything

How often? And are you sure you mean instantaneous and not cumulative?
Need both but need to rate d/dt and then the total, but would summarize

Another consideration is you propose to measure gray water flow rate from the washer whih will be loaded with dirt, fibers and other debris, and tend to clog certain types of flow meters.
Thats a great point, its gray water. so a plastic flap being deflected over a spring and then a 3 axis resolver chip glued to the flap, they cost about $1 glued to the hinge. then map out xyz and make a correction factor chart, and the microcontroller would calculate based on what it gets from that resolver chip. probably a good way to go #### russ_watters Mentor Need both but need to rate d/dt and then the total, but would summarize How often? #### Brad_805 How often? I think a plastic flap with a 3d resolver chip on the hinge fed to the microcontroller would work, 100 samples/sec should work? then calibrate with known volumes of water, etc #### JT Smith You can buy a flow meter for$10 or less that will work for you, provided you're not looking for high accuracy. But since you don't want to buy one you could copy that design. If you do an internet search you'll find an example of someone who did that. I turned up two different inexpensive build-your-own-flowmeter designs in five minutes of googling.

You can buy a flow meter for \$10 or less that will work for you, provided you're not looking for high accuracy. But since you don't want to buy one you could copy that design. If you do an internet search you'll find an example of someone who did that. I turned up two different inexpensive build-your-own-flowmeter designs in five minutes of googling.
Ok I found some ideas but one of the purposes of asking here was to ask about the fundamental physical properties of water flow measurement; what reacts with water, or actually gray water. Maybe gray water is more reactive? will gray soap rinse water store an electric charge? but that may not be good,

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