Listening to a ticking water meter to measure flow - Page 1
Forum section: electronics / projects

author: e100
author_rank: Frequent Contributor
timestamp: December 27, 2017, 05:00:13 am
content: Under high flow conditions, my mechanical household water meter makes a ticking sound that travels through the pipework and can be heard inside the house. The frequency range is approx 5 to 15 Hz.I'm guessing that it's a nutating disk or similar type of meter that introduces a pressure pulse every time it rotates. I guess you could describe it as a low level water hammer that gently shakes the pipes.The meter is owned by the water company and is used for billing purposes so obviously I cannot attach anything to it, but attaching something to the pipework inside the house would be OK.I use the sound to check that my garden watering system is working ok. As the different watering zones activate the flow changes and the ticking sound speeds up or slows down. If a pipe springs a leak then the flow increases dramatically and I can hear that something is not right and needs investigating.Has anyone done a project that listens acoustically using a microphone or strain gauge for this subtle type of water hammer and is able to pick out the pulse frequency. Ideally I would like something that is non-invasive and cheaper than cutting the pipework and installing a mains pressure rated (100 psi+) professional level electronic flow meter.https://youtu.be/Gg0frjrqHJk?t=51

author: danadak
author_rank: Super Contributor
timestamp: December 27, 2017, 01:39:27 pm
content: Even an mechanically attached accelerometer might be a way to go.Use ESP8266 or ESP32 to condition and serve it up wireless to web page.Or PSOC over Bluetooth, all the signal conditioning you need should beable to accomplish with on chip resources.Regards, Dana.

author: Richard Crowley
author_rank: Super Contributor
timestamp: December 27, 2017, 01:54:03 pm
content: But what is the effect under low (or VERY low) flow conditions? It seems to me that you would lose track of the total flow under low-flow rates. My meter has a little triangle indicator that turns even when there is just a slow drip somewhere. (Which is why it is there.) The scheme might work as a warning of high rates, but maybe not as a reliable long-term metering technique.

author: e100
author_rank: Frequent Contributor
timestamp: December 27, 2017, 03:25:40 pm
content: Quote from: Richard Crowley on December 27, 2017, 01:54:03 pmTotal flow would be useful but my initial goal is just to detect abnormally high flow rates associated with burst pipes. This can cost hundreds of dollars per year if unnoticed. The system is run at night when the evaporation rate is lowest so I rarely get to see it in operation.

author: jonovid
author_rank: Super Contributor
timestamp: December 27, 2017, 03:45:55 pm
content: a piezoelectric disc clamped on to the pipework may just work use a op amp like a 741 then feed to your data logerI have used piezoelectric discs as thay pick up vibrations in solid objects, but not sound in the air like a mic.

author: rhb
author_rank: Super Contributor
timestamp: December 27, 2017, 06:44:04 pm
content: A friend of mine designed a retrofit remote reading kit for a water meter maker in the US. He used an MSP430 and used either an optical or Hall effect sensor to count the turns of the little triangle indicator on the face of the meter. Design life for the battery is 15 years! It's been a few years since he showed it to me, but as I recall it simply attached in place of the standard dial cover. It was short range, so you had to drive by to query the meters.

author: coppice
author_rank: Super Contributor
timestamp: December 27, 2017, 06:59:24 pm
content: Quote from: rhb on December 27, 2017, 06:44:04 pmThere are a number of electronic add-ons for mechanical water meters which work in that way. Around the world most mechanical meters have a triangle or a pointer that turns in a distinct enough manner to count revolutions from it.

author: e100
author_rank: Frequent Contributor
timestamp: December 28, 2017, 08:46:20 am
content: Quote from: jonovid on December 27, 2017, 03:45:55 pmI've placed an order for a $10 piezo pickup with amplifier and 5 band eq intended for acoustic guitars.Hopefully this will give me a signal big enough for a microcontroller to digest.I also saw some James Bond style "through the wall" room listening devices for $100 but I'm guessing that these are basically the same thing, but with a higher gain amplifier. I'll see how the guitar piezo goes.

author: amyk
author_rank: Super Contributor
timestamp: December 28, 2017, 06:34:33 pm
content: Something like this might work well for your application:http://www.aliexpress.com/store/product/TUF-2000M-TM-1-DN50-700mm-Ultrasonic-Flow-Meter/506853_32498573561.html

author: fourtytwo42
author_rank: Super Contributor
timestamp: December 29, 2017, 10:56:39 am
content: Quote from: e100 on December 27, 2017, 05:00:13 amMy water company has never had an issue with the reed switch I have attached to the face with Bluetack to sense the magnet they have kindly fitted to the dial that rotates like a watch second hand. I was very careful not to obscure the digits used for reading the meter. Guess I am lucky having a friendly water companyIn the same vein I also have a photo-diode attached to the front of my electric meter again with Bluetack and the electric company have never complained either