Solenoid valves - picaxe controlling fluids

[defuzz]

Hello, I did a search on this but didn't find what I needed.

I'm looking for low voltage CHEAP solenoid valves to control water, anyone know of a good source for them, ideally UK based? Of the ones I've seen, most are either 240v or 12v, I'd like to find something to run from the same 5volts as the picaxe, the lowest I've been able to find is 6volts

 

[moxhamj]

Nothing beats mass production for value. Thus, 24VAC is the standard for water solenoids. There are some good parts on ebay, particularly from the US (even with shipping to Australia and thus the UK also) and they all run on 110VAC but close ok with 40VDC. However the US uses NPT pipe thread (though by a fortunate coincidence 1/2" NPT = 1/2" BSP). You might need a few 1/8 to 1/2" NPT adaptors.

Ideally use 1" garden watering system solenoids sourced locally. Switch with 24VAC using a 547 and a relay. If you don't have 24VAC, try maybe 20VDC dumped from a cap charged up via a resistor. With DC volts you will find they need lots of volts to close but only a few volts to hold.

What is the project in question?

 

[Rickharris]

Depend on the pressure involved but you could try this DIY option:

Run water through a rubber tube - the old red stuff you used to connect the Bunsen burner to the gas tap is ideal.

Make a V shape cut in a section of suitable wood and place Pipe across the open side of the V. Take a loop of cord round the pipe and attach to a suitable motor and or pully so that when the motor turns it pulls the cord tight - pulls the rubber pipe back into the V cutting off the water. The natural spring in the pipe will restore flow when the motor releases its pressure.

Advantage: Very cheap - operate on whatever voltage you like to arrange - Simple to construct - fairly foolproof - when current is off motor retains position with zero power.

Disadvantages: Water pressure may overcome the squeeze (although with a steep V it needs a LOT to blow past. - Rubber pipe must be fairly soft so again pressure may be limited - Needs making.

 

[leftyretro]

If you do utilize a solenoid, be aware that you need to find out it's spec for max working pressure (so it can shut off flow) and it's flow (or Cv) rating as some have very small passages that don't allow alot of quanity to flow.

Lefty

 

[Dippy]

This depends on application so much. As said pressure rating and flow required is quite importance. As is significance if it fails.
To water your pot plants outdoors Ricks Rubber Hose may be fine, but for flushing your bog or controlling your shower then proper stuff is needed and rubber hosing is out of the question.

And quality will vary with price tag.

Could you use a washing machine water inlet valve? (Or diswasher or similar?)
CPC used to do them very cheap (in current paper catalogue) but couldn't see them on website.

 

[defuzz]

I'm working ona couple of ideas, both low pressure though.


My main plan is to do with photography of water drips, I'm looking to have a camera, flash and "water dripper" connected to a picaxe, the chip controls the drip and then sets the camera off at the appropriate time.

I've seen similar projects such as the awesome "Time Fountain" :

http://cre.ations.net/creation/the-time-fountain


use pumps rather than solenoids, so maybe I'll go with that.

It won't kill me to use 6v or even 12 volts so I'll look to them instead.

Edited by - defuzz on 16/04/2007 15:50:00

 

[hippy]

If the unit is to be mains powered then you could use a mains powered solenoid and find a 5V/6V/12V relay which can handle switching that on and off.

The usual caveats to mains working apply, but it's probably easier and cheaper to take whatever solenoid would normally be used and control that than trying to find a solenoid you can work directly with. You can do nearly all the development and testing disconnected from the solenoid using batteries with the relay switching a LED so the risk is minimised.

 

[BeanieBots]

Obviously this will depend on whatever solenoid you can obtain, eg old washing machine or irrigation controller, but sometimes it is possible to rewind the actuator coil yourself to convert from 240v AC to 5v DC. I have done this myself on several different valves both for air and for water. It really depends on if you can easily get to the coil.
You seem to be dealing with very small flw rate so also consider using valves normally used for air. I've used 'swagelok' air valves for both water and oil with no problems. (butane dissolves the seals so don't try that one!).

 

[KMoffett]

Not sure what your price range is, but these companies have 5v miniature valves:

<A href='http://www.theleeco.com/LEEWEB2.NSF/424c53712be7278e852567b400719c9f/f3f63ce869753c96852568c5006e50d4!OpenDocument' Target=_Blank>External Web Link</a>
<A href='http://www.hargravesfluidics.com/magnum.php' Target=_Blank>External Web Link</a>
<A href='http://www.ascovalve.com/Applications/Products/MicroGeneralServicesData.aspx' Target=_Blank>External Web Link</a>

 

[premelec]

With the key word 'cheap' in mind there are usually free valves on scrapped washing machines and from hydronic heating zone valve replacement [these are not fast but motor driven]. Check your local plumber / appliance store / dump or recycle yard.

 

[Denzel]

I only know of 12v valves in nz, I used one to control ballast in my submarine with a picaxe. these valves are easily controlled via picaxe.
Have fun

 

[ljg]

If you are near High tech manufacturing operations, they often surplus entire air powered solenoid valve setups for almost nothing when they are done with a production run. The local surplus houses grab them and resell them for just a little more.

The ones I have in my hand are very nice Dynamco units (retail for $60+ US) I got a whole rack of 'em at a surplus place near me for $20--- for 20 valves. They ran air in the chip plant they came out of, but they are rated for oil or water, also. They are manufactured for 500 million cycles, so they probably will never wear out in most applications.

It's often cheaper to buy a whole rack of them still on the manifold, because it saves labor on the reseller's part.

The standard for these industrial units is 24v DC at a bit over a watt, so they aren't the power hogs that cheaper units are. They have a nice little LED on them to let you know when they are running, and they still have lots of life left in them. all it takes is a TIP120 and a 1 k resistor and a diode to run them. You might get lucky and find some 5 or 12 volt units, But 24v is the standard in the plants around here.


They don't have the volume of the sprinkler system kind-- they would be more for fine control of fluids or gasses at up to 150 PSI. Mine use a 2mm i.d. hose.

 

[jamesbruton]

You could try one of these cheap manual valves:

http://www.mutr.co.uk/catalog/product_info.php?cPath=17&amp;products_id=351

...and turn the lever with an R/C servo controlled by a Picaxe. Then you could open it a little bit, a bit more, or completely etc.

You'd need to make up a custom bracket of some sort, maybe out of Polymorph?:

http://www.mutr.co.uk/catalog/product_info.php?products_id=550

 

[defuzz]

my first picaxe kit arrived this morning so I'm not in any rush to find a solution, need to learn how to use them first!!

In the mean time I'll take a look around the local DIY store for washing machine valves. I also thought of using a servo (of which I already have a few) to just open and close a small plug in order to control the fluid, I'll try it at some point and let you know.