Hi Everyone!
I wanted to poll everyone on opinions for the best option to check for the flow of water in an enclosed pipe. I have done some reading and found that I can put a Magnetic Wheel inside the Pipe, However there are issues with Sealing the pipe on which the wheel sits and is not very reliable. Also Ultrasonic giving an unstable reading when water is flowing. I have not yet tried the UltraSonic route but if anyone has any pointers on better options it would be greatly appreciated.

 

There literally hundreds of options from $3.00 to several hundred.
There are ready made hall effect wheel types that are really cheap and offer sealed fittings.
What type of interface and reading methods do you prefer?
Max.

 

I wanted to poll everyone on opinions for the best option ...

Define best. Cheapest, simplest, most accurate, least invasive, and on and on.

The industrial solution is generally a magmeter. The homeowner solution is the rotating wheel with a magnet in it. (That's how my water softener estimates flow.) Or there are all sort of see-through devices that indicate flow such as paddle wheels, weights falling in a conical tube with upflow.

Do you just want to detect water, or quantitate the flow?

 

Thank you for the speedy chime in. I think to be a bit more descriptive is to detect water moving at all, BUT if I can identify how much of a flow there is that would be even better.
I was looking around but I didn't find a solution that offered different size piping. It seemed they were all pretty much set to one specific size per product.

Best would be defined as reliable, I think that all that is really required. If a Pelton wheel is the way to go then is a Seal only required if the Rod that holds the wheel in place pierces the pipe? I'm thinking if I take a PVC and drill a hole through it. Run the rod inside and totally glue the holes shut while letting the rod inside freely rotate then that would work and wouldn't require any maintenance.. I'm sorry if that's what you already mean by Seal. When I initially thought Seal I was thinking the Rod would still be exposed to the outside of the pipe.

Am I going down the right road?

*Starts looking at magmeter's to get ideas*

 

A certain kind of fractional horsepower water circulating pump has magnets attached to a motor. On the other side of a plastic wall is the impeller...which is driven by the magnets! There is no hole.
Water flow detectors can also get a magnetic field to pass through a plastic wall. You just haven't found them yet.

Now, about this,

water moving at all,

That isn't going to work here. Any movement at all goes all the way down to osmosis through a membrane.
Try again.

 

What magnitude of flow are you anticipating?
The Venturi device here has no moving parts, but is likely suited to higher flow rates.
It looks something like this.:

... Where Q=A1*V1, and P1,P2 are in lbs/square inch, probably, need to confirm the dimensional correctness.
...might require some experimental verification.

 

More information...
Describe the application?
Whats moving the water in the pipe now? A stream? A pump?
Just household fresh water? DI water? Sour?
Water flow rate?
Pressure?
What size pipe?
What material?
Can you open the pipe?
Got a budget?
and more and more..

 

This kind is available at almost any scale, as are most of the other options. These are not great unless your fluid is clear and relatively clean. As noted, we need to know a lot more.

 

Describe the application? Generate a current to recharge a battery and detect water flow
Whats moving the water in the pipe now? A stream? A pump? The Water District pumping water into my house
Just household fresh water? DI water? Sour? Fresh
Water flow rate? If my numbers are right the Water district shows 100GPM max for inch and a half but I doubt its that high normally
Pressure?
What size pipe? 1 1/2"
What material? PVC
Can you open the pipe? Yes
Got a budget? <50 dollars if possible

 

The sightglass type I linked to (called a rotameter) would be ideal for this application, as long as piping in a vertical run is not too much trouble.

A magmeter would allow you to even totalize your flow, but these are in the thousands of dollars range.

Something like this would work, too, but is also out of your budget.

 

Forgive me if I mis-read something, but did you say you want to use it to generate power? Charge a battery was the term I think I read. Well, yeah, if you want to build a motor inside a pipe then sure you can. All you need is a pipe with a shaft mounted internally going the length of the pipe with an impeller that will spin with water flow. Spin magnets inside the pipe and on the outside you can have coils. But because of the wall thickness of the pipe, you're not going to have a very effective generator. POOR generator at best would be my guess.

At first you said you wanted to detect movement of water. To do that I'd go simple tech: a pipe with a TEE capped off. A flapper valve with a magnet hanging on it. When water flow is sufficient to push the flap up (in the direction of water flow) then the magnet can come close to a hall effect transistor OR just a simple reed switch. Of course a reed switch would be extremely low current, but you could use it to power a transistor to activate a relay to indicate water flow. But that's a static sensor. All it does is tells you when water is moving in sufficient volumes.

 

Here's what I'm gibbering about:

 

Ah Thank you Tonyr, Very interesting Idea! Seems Affordable too! =D

And Mayneh, I think your right.. This would be the ultimate solution to what I am looking for but too bad its like 500 bucks.. Crazy how something so simple is so expensive.

 

Back when I was foolish enough to see if I could make HHO work I needed a tank with a switch. I used a reed switch embedded into a 1 1/2 inch PVC pipe with a 3/4 inch pipe (capped on both ends) as a float with a magnet on it. When the magnet got near the switch it would activate a pump. When the magnet moved sufficiently away from the switch the pump would shut off. That was how I kept a specific level of water in my HHO system. The magnet floated inside the pipe (tank) while the reed switch (actually multiple switches in case the magnet floated around to the other side of the pipe) turned the pump on or off.

 

Check if any tickles you :

----> https://www.aliexpress.com/wholesal...0217155551&SearchText=hydroelectric+generator

 

I like that little generator for 16 bucks. The current would be a record of flow and one can charge a battery with it.

 

Describe the application? Generate a current to recharge a battery and detect water flow
Whats moving the water in the pipe now? A stream? A pump? The Water District pumping water into my house
Just household fresh water? DI water? Sour? Fresh
Water flow rate? If my numbers are right the Water district shows 100GPM max for inch and a half but I doubt its that high normally
Pressure?
What size pipe? 1 1/2"
What material? PVC
Can you open the pipe? Yes
Got a budget? <50 dollars if possible

Just winging it but you will be hard pressed to get any sort of inline flowmeter to produce enough signal to charge any form of battery. You would be looking at a turbine type flow meter which are expensive and only produce an unamplified signal of a few milli-volts. Most flow meters, aside from a roto-meter require external excitation to produce a signal proportional to flow. Without getting too technical industrial supply houses here in the US like McMaster Carr Supply offer a wide range of flow meters for all sorts of pipe diameters and line pressures. To really get any usable voltage or current you would need to push quite a bit of water through a turbine generator which is hardly a flowmeter or flow rate meter.

Ron

 

Whatis the goal?
- sensing flow
- creating a power source for wireless source of power
- ?

 

Hi Everyone!
I wanted to poll everyone on opinions for the best option to check for the flow of water in an enclosed pipe.

I'd use a couple of thermistors in a hot wire anemometer arrangement, with one ( Rth1) excited very little in order to measure the ambient temperature of the water, and one (Rth2) excited quite a bit in order for the water flowing past Rth2 to suck heat out of the thermistor, which would increase its resistance as the flow of water through the pipe increased.