12v control valve

[outback]

I know this is getting out there, but nothing ventured nothing gained.

I'm after a 12v valve for controlling the flow of a liquid. I need to be able to control the flow rate going through the valve. I've looked at irrigation places, pump places, pool places etc. All I can find is a solenoid type valve which is no good as its only on or off.

Any ideas, options, thoughts all gratefully received.

[echnidna]

Coupla ideas
1. You could use several solenoid type one, each fitted with a different size jet or restrictor.
2. Use a step motor with the shaft connected to a tap.

[himzol]

Outback,

This is even more out there ... Check the RS electronics catalogue (or online), I think they may have something like what your after. Look in the pnuematic/fluid control area.

Himzo.

[rick_rine]

its a long shot but maybe a hydroponics company as they have controlled amounts of fertilizers in a liquid form added to the tanks automatically .

[echnidna]

What about a model aircraft RC unit hooked up to a valve

[DavidG]

outback
Can you control the pump rate rather than using a valve.

[outback]

OK,
Different solenoids with different valves sounds messy.

Stepper motor I had thought of, and was looking the answer.

RS Australia may well have what I want, they must have a brazillian different bits and pieces, I can't find it tonight, so I'll ring tomorrow/next week.

Can't control the pump speed, it has to remain constant.

I looked at RC stuff, couldn't really hit upon anything which got me excited.

Tried Hydroponics, couldn't see anything there either.

The problem is I need to vary the valve on the run so to speak. I can find stuff to vary pressure but not flow.

[Ashore]

Outback what volume of fluid are you talking about
What size pipe , flow and output of the pump
How accurate does it have to be


Russell

[gazaly]

From a hydraulic perspective WRT a variable DC linear solenoid, there are basiclly 2 types. One is force controlled and one stroke controlled. Both are driven by a controling DC amplifier.

A force controlled solenoid is used to output an change in output force for a set output stroke. For example, for a given input signal, the output force of the solenoid will be X neutons over a stroke of approx. 1.5mm. If the input signal is doubled, the output force will double, but the stroke length will remain constant.

A stroke controlled solenoid is basiclly the opposite. For a given input, the variable is the length of stroke. From what you have said, I think this is the type you are after.

Now, in the fluid power world, these are bloody expensive ($thousands), mainly due to the closed loop signal amplifier needed to drive the solenoid, but also becuase of the extreme accuacy. Bosch are one of the big manufacturers. They bought the German company Rexroth a few years ago, who where the big producer.

Hope this helps :)

[gazaly]

Just read your last post. Are you where the valve is when you want to vary its output? If so, you just need a simple flow control valve. This may need to be pressure compensated though.

[Ashore]

Gazaly
but can the pump handle the restriction on its output pressure , thus should it be a feed foward control system .
I was thinking as you however on a stroke type valve, but with control from a second hand car electric window winder with reduction via a belt pully as a cost effective alternative


Russell

[Cliff Rogers]

Hmmm... you need a proportionally controlled valve, most of them are current loop & need a controller to go with them.


Try the control shop at Honeywell. AC Controls for big AC installations. Mining control suppliers, Best, Leeds & Northrup.

[Munga]

We use bypass valves on boom sprays to vary the flow rate but only if the fluid can be recirculated back to the tank but in your case this may not be possible.

Cheers Arch.

[DavidG]

Outback
How about a full description of the proposed system please.
It is a bit hard trying to advise what is possible when we do not know the what or why of the question. :confused: :confused:

[echnidna]

Yeah - watcha makin"

[outback]

And I thought if I got one reply to this I'd be happy. :cool:


Scenario is this.

I am operating a machine whilst travelling, don't panic I'm
only going 15km/Hr. The fluid I wish to control the flow of is basically water with some dye and a few other non dangerous bits in it.

At present if I need to vary the flow, I gotta stop, get off machine adjust get back on start off, all a pain in the bum. So of course what happens is I put up with non-ideal amounts, not the end of the world but too little means I'm sorta wasting my time, too much and I'm wasting $$$$. What I want is a toggle to go up a bit down a bit back a bit etc.

The volume we're talking is mind blowing, probably 15 L/min. max :D As for pressure, I dunno, bugger all I guess. The current setup is just a 1/4" or 3/8 " manual valve. I had thought of whacking a stepper motor on it. Also I can get really slow 12v motors, but attaching to the current valve has me stuffed.

As you can see, anything industrial is overkill. Simple cheap and effective, that's what we're after.

[Dan]

If the valve is a ball type (1/4 turn open/close) then a windscreen wiper motor and gearbox would drive it (with a linkage).

[himzol]

The fluid I wish to control the flow of is basically water with some dye and a few other non dangerous bits in it. :confused:

OK,

If you don't want to tell us, ;)

Try these guys, http://www.oceancontrols.com.au/motor_controller/motor_controllers.htm

As for how you atach it depends on the valve assembly,.

Himzo.

[doug1]

If you use the previously mentioned quarter turn valve you could rig a brake cable arrangement to it and set it with a handle from a set of bike gears all able to be scrounged from junk bikes

[RETIRED]

Why not just position the quarter turn valve where a solid rod can be fitted and operated from the drivers seat like on the old road water sprayers?

Or move the tap inside like fire trucks have for their front spray bars?

[outback]

Can't use the rod Idea, too far, and I'm in an enclsed cab.

I have thought about putting the valve in the cab. It is certanly the easy option. I am just worried if it ever leaks I'll end up with bright red everything, and this stuff doesn't wash out too easy.

[Cliff Rogers]

OK, what about using a DC bilge pump to deliver the graffitti & control the flow by varying speed of the pump motor?You'll get something like that from caravan &/or boating supply places.

[outback]

The pump does two operations so I can't vary its rate.


I have it worked out, I can get a slow 12v dc motor, gear it down a bit if I need. A mate has just offered to make a coupling from a 4mm motor shaft to a 6mm valve shaft, way beyond me, but he says no worries.

Thanks for all the help, I was worried I had mised an obvious cheap and easy and cheap fix.

You guys are so clever. :rolleyes: :cool: