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Auto shutoff watermain project

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ed12309

New Member
i want to make a automatic pipe shutoff that will turn off your main when a pipe is leaking, i was thinking a gauge in the beginning of the pipes, that would measure how much water is being put into the pipes, then a gauge at all the exit points, it would add all the exits together and compare it to the mains value, and if they didnt match up then it automatically shut off the pipes and alert you so, i have no idea where to start or if this is even plausible, any help would be great.
thanks ED
 

tcmtech

Banned
Most Helpful Member
A leak can be as slow as a few drops a minute. I seriously doubt you can build something with that level of precision measuring.

Your best bet would be some sort of thermal sensor system that can sense the actual pipe temperatures at many points and react from there.

Unless of course you just have bad plumbing. Then your money and time would be best spent on replacing stuff before it breaks!
 

MikeMl

Well-Known Member
Most Helpful Member
Our water meters use a pulse counter where there is a small turbine in the flow. In my house, the usage pattern would have periods of time when the flow completely stops. Only if there was a leak someplace, would there be continuous flow. Leak detection could be as simple as alarming if the flow never stops (cessation of pulses from the meter) within a several hour detection window.
 
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Mr RB

Well-Known Member
I'm not sure those turbine sensors work very well for extremely small flow rates. I would imagine they are optimised for decent accuracy at "typical" flow rates and the rotor probably has some amount of friction and some amount of load where very small flow rates might not turn it or might not turn it reliably.

Some type of positive displacment flow sensor might pick it up, or even a no moving parts solution like an orifice flow sensor (orifice with a sensitive differential pressure sensor across it).
 

3v0

Coop Build Coordinator
Forum Supporter
More information would be useful. Like how much are willing to spend. Is it for a dream house where anything goes, or do you want to retrofit it to existing homes. etc

But I can speculate....

I favor the idea of using a solenoid valve to turn off the main and measure pressure drop per unit time. The drawback here is that you either need to make sure no water is being used or force a short none use period. Another is that testing is not continuous.

As an extreme example, if you equip all water control points with sensors you could easily know when the system should not be using water. With solenoid controlled water flow you could force short periodic non-use times to do the testing.

3v0
 
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MikeMl

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Most Helpful Member
The turbine sensor seems to be accurate to very small (faucet drip) flow rates. If you are able to insert an electric solenoid valve in-line after the meter, then periodically shut off the valve, and measure the rate of pressure leak down once per hour or so. If there is no leak, then there should be a few times per day when the leak-down rate is very slow. If you always get a leak-down rate that exceeds a certain rate, you have a fixable leak.
 

tcmtech

Banned
Most Helpful Member
As said earlier your going to need a very sensitive device to do it but that also means your going to have another problem as well. Line expansion.

The actual volume of your water lines changes as the pressure changes. All plastic line has a fair amount of give and so does metal line to a lesser extent. From low to high pressure you may see as much as a quart or more of volume change (hot water heater included) despite no actual leaks having been formed.
 

rjp

New Member
A normal water meter can detect very small leaks over time. As Mike said above, a water meter monitor only needs to look for a period of continued water use (eg no period with zero flow say for an hour). This would indicate a leak of very small degree which could then trigger an alarm or text message for further investigation. As a test, simply read your water meter before you leave for a couple of hours and then read it when you return. If you have no leaks, the reading will be the same. This test, automated, will provide leak detection from one meter or a meter you add to the main incoming line.
 
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