Tech Q: Electronically Regulating Water Flow

[OSUmaxx]

I'm hoping that some of you WC gurus will be able to lend a hand with a water project I'm working on.

I need a way to electronically throttle water flow in a system. The system will detect flow and increase it or decrease it as needed. The flow detection is taken care of, but I need to find a valve that will throttle based on an input voltage. As of now, the valve will need to have approx. 1" ID. I've found some various solenoid controlled valves, but they only go full closed to full open. Also, I would like this to cost under $100 if possible.

Any input you have on the topic would be great!

Thanks :)

[Mikeonatrike]

Im curious, why would u want to throttle the flow in the first place? I cant see any possible advantage to adding a flow restrictor to ur system.

[OSUmaxx]

Originally posted by Mikeonatrike
Im curious, why would u want to throttle the flow in the first place? I cant see any possible advantage to adding a flow restrictor to ur system.

Its not a project that will cool a CPU, but it involves water flow :) I should have mentioned that, sorry. I just figured that some of the people in here might be able to give me a hand.

[omaticrail]

Sounds like you need a servo and a driver circuit, and may I say, what a cool project!

How electronically inclined are you? Can you handle simple comparator IC's and basic TTL logic circuits?

[insnity]

well you could use a flow meter that generates an error voltage, and have a refrence with a comparator connected to a servo controlled valve heh could even make a display using sync/resolver setup could drive a led display or something could make it display gph/valve angle even rpm of pump

[NeoMoses]

A VFD would work if it's an AC pump.

[OSUmaxx]

Originally posted by omaticrail
Sounds like you need a servo and a driver circuit, and may I say, what a cool project!

How electronically inclined are you? Can you handle simple comparator IC's and basic TTL logic circuits?

Yes, I'm electronically inclined enough to handly those things. I'm basically just brainstorming right now. Thanks :)

[OSUmaxx]

Originally posted by insnity
well you could use a flow meter that generates an error voltage, and have a refrence with a comparator connected to a servo controlled valve heh could even make a display using sync/resolver setup could drive a led display or something could make it display gph/valve angle even rpm of pump

Seems like the comparator circuit with mechanical linkage will be the way to go overall. I'm not familiar with a sync/resolver setup, but I'll do some research tomorrow. Thanks!

[-J-]

im working on a pressure monitoring system with a friend.

that will check if the pressure of the water is higher or lower than the normal (preset).

if the pressure is lower, it would mean that the pump isnt pumping, so it would shut down the system.

if the pressure is higher, it would mean that something is limiting the flow, so it would also shut down the system.

only if the pressure is normal, then it would allow the system to run.

[insnity]

Originally posted by OSUmaxx


Seems like the comparator circuit with mechanical linkage will be the way to go overall. I'm not familiar with a sync/resolver setup, but I'll do some research tomorrow. Thanks!

sync/resolver is what aircraft/ships/tvweather radar use to show the line on the display showing the angle of the antenna
generally attached to a rotating device such as a valve or antena drive unit gives an error signal directly proportional to the angle of the rotor to the 3 stators


usually 3 rotors setup with 90degree phase angle to each other
ie 3phase 120 and stator has dc

well i was gona give a link to the navy neets module on synchros, resolvers
but cnet website is down, will update when i find it

[beepx1]

How about something like this:

http://www.measurementcomputing.com/cbicatalog/cbiproduct_new.asp?dept_id=238&pf_id=1103&mscssid=4M0QVV5UGABA8PN6TQTATA3JESCTBPND

You could hook up a pressure gauge and control the pump with a PC.

[Since87]

Might be easiest to get a DC pump like the Swiftech MCP-600 and just control the voltage to it.

Giving more specifics of what you are trying to do, might yield better suggestions.

Google "Proportional Valve" to find what you originally asked about.

[omaticrail]

Since87, he mentioned a 1" ID valve. Whatever the application, I kinda doubt the Swifty pump is going to produce the kind of volume he's looking for.

[UnLoadeD]

I agree with Neo, look into Frequency Drives.

peace.
unloaded

[OSUmaxx]

Wow, thanks for all of the great advice. Gives me a lot to research.

Looks like there will be one complication to this. It needs to be scalable to flow 5 gal/s IRL, but the model will only need about 1" ID tubes. That means that though my implementation will remain the same, it has to be feasible to scale up.

Let me shed some more light on this project. It will be a power generation unit (well this part will be). There will be a large reservoir elevated off the ground and water will flow from that, controlled by my valve, and then to a generator (not sure if it will be AC/DC yet) that will power a device.

beepx1, a computer won't be able to be used to control this unfortunately.

Neo, UnLoadeD, I'll look into frequency drives, as I'm not familiar with them at this time.

-J-, that is an interesting concept, but since this will be a free fall waterfall type setup, the tube won't always be full of water. I believe this would complicate the matter.

insnity, sounds interesting. I'll look into that also.

Thanks again guys!

[brucoman]

the place I work at does industrial chemical pumping systems

we use AC as well as DC variable speed motors on positive displacement pumps contolled by a drive board/magnetic flowmeter/loop contoller using 4-20ma signals... costs thousands...

also can use a proportional valve, mostly 4-20ma as well, with a pressure transducer/loop controller

can't see how in your price bracket

[Planus]

Just adjust the voltage to the pump with a avarible voltage regulator, dont mucj aroudn with flow restrictors

[OSUmaxx]

Originally posted by Planus
Just adjust the voltage to the pump with a avarible voltage regulator, dont mucj aroudn with flow restrictors

The water will already be in a reservoir, dropping down through the valve and then the generator. How would I adjust the speed? I'm open to suggestions!

[OSUmaxx]

Originally posted by brucoman
the place I work at does industrial chemical pumping systems

we use AC as well as DC variable speed motors on positive displacement pumps contolled by a drive board/magnetic flowmeter/loop contoller using 4-20ma signals... costs thousands...

also can use a proportional valve, mostly 4-20ma as well, with a pressure transducer/loop controller

can't see how in your price bracket

The full scale system can cost thousands, but I need it to be possible to scale down to a model.

Wow, I sure have lots of research to do!

Thanks

[insnity]

you could use the freq or voltage thru a comparator would give a diff between refrence and output, could ue sig from comparator to drive servo and you would have autoflowcontrol

[omaticrail]

insnity is basically thinking along the same lines I was.

What is the method and output of the flow measuring? Is it a voltage output? Frequency? Digital? Whatever it is, you'll need some adjustable reference, a comparator of the appropriate type, a motor driver circuit, and of course the motor and gears to move the valve itself.

[OSUmaxx]

Originally posted by omaticrail
insnity is basically thinking along the same lines I was.

What is the method and output of the flow measuring? Is it a voltage output? Frequency? Digital? Whatever it is, you'll need some adjustable reference, a comparator of the appropriate type, a motor driver circuit, and of course the motor and gears to move the valve itself.

The actual flow isn't directly measured. The power that the generator generates will be measured. If we need more power, the valve will open more, less power, it will close a little more.

The circuit design for that aspect is still up in the air.

[UberBlue]

Originally posted by OSUmaxx


The actual flow isn't directly measured. The power that the generator generates will be measured. If we need more power, the valve will open more, less power, it will close a little more.

The circuit design for that aspect is still up in the air.

Why don't you do what's been done for a couple of hundred years and use a simple flywheel governor and gate valve? Water mills and older hydro-plants have used this system for years as a throttling system. Simple, reliable, and effective.

[OSUmaxx]

Originally posted by UberBlue


Why don't you do what's been done for a couple of hundred years and use a simple flywheel governor and gate valve? Water mills and older hydro-plants have used this system for years as a throttling system. Simple, reliable, and effective.

Yet another thing to research :) Thank you for the suggestion. This project should be electronically completed if possible FYI.