Measuring either pressure or liquid flow--appropriate part?

I'm not sure whether this should be here or in Project Guidance . . .

I have my sprinkler/garden controller largely successful.

I resorted to making my own after frustration when my $100 Orbit controller partially failed after two years. Seeing sprinklers go off, it never occurred to me that it had lost most, but not all, which cost me two lawns and several trees. :stuck_out_tongue_closed_eyes:

Being the paranoid that I am, I would like to monitor the flow to make sure it's actually happening.

I'm not worried about the amount of flow (although, come to think of it, that could be used as an indicator that a head has blown off or a garden line opened), but just determining that the valve is open.

On the sprinkler lines, it simply needs to be able to distinguish between over 100psi (line pressure) and under two feet of water pressure (the back yard rises something over a foot above the valve, I think), which is about 1psi. For the garden circuits, I could modify my rig to test before the pressure reducers, or check after it drops to about 40 psi.

Or, rather than the pressure, some device that can go inline with 1" or 3/4" pvc pipe that could measure the flow (about 1 gallon/sec on the sprinklers, less on the garden/berry/tree circuits.

Do parts like this even exist?



Turbine sensor...

Hall sensor...

Thanks. Those are nifty little devices, but:

Durability: minimum 300,000 cycles

And they cycle every 2.25 mL or 2mL, respectively!

That would give a life of about 600L, or 150 gallons!

They're for a couple dozen liters/hour top rate, while I'm dealing with a gallon a second, roughly, on the sprinklers, and probably around a hundred gallons/hour on the garden circuits.

But knowing the name for such a device is valuable in and of itself . . .

1/2" isn't wide enough for the sprinklers, but I suppose such a thing could go in parallel, thus taking only a fraction of the flow, and I could calibrate.

For flow, it wouldn't even be the actual flow that matters, but deviation from "typical" for that circuit, with two much suggesting a burst somewhere, and too little suggesting clogged, and none suggesting the valve didn't open.

Other possibilities drifting to mind:

  • a rubber membrane, perhaps fitted to the leg of a pvc T, which would flex outward a bit and operate a switch when the line was pressurized (on).

  • somehow mounts pivot point inside, and measure how far up a flap was pushed with a magnet.

High volume flow meters can be expensive. Getting a pressure sensor teed into the piping seems appropriate to detect on/off.

Perhaps something like this which can detect 0 -232 psi. (0-1.6MPa)

Hmm, that's a definite possibility.

Given what the plants cost (or, for that matter, the water I give them), five to twenty bucks a line is kind of small. I lost over $100 of trees lat year, another couple hundred dollars of gape plants, at least two of the four fruits on my fruit cocktail tree, and two lawns that I have to reseed, all because we didn't realize that only some of the circuits were actually firing . . .