Water valve controller

I'd like to make controller for some water valves. This is to automatically change the water in my duck pond. Currently, the drain is a 1 1/4" line with a manual valve (the sort you buy cheap at Home Depot), and the filler is a garden hose attached to a float valve.

Sparkfun has a 3/4" 12v solenoid valve for $8, so easy peasy for the shutting the hose off while draining. Is there somethign that's not ridiculously expensive for the 1 1/4" valve? Rainbird has a 1 1/4" brass valve for $141, so forget that. They have a 1" plastic valve for around $20 so that's reasonable, but I I'm concerned if I stepped down it would cause it to clog up (feathers, leaves, feces, etc). A couple potential issues with the valves though: -Since this is a drain, it's gravity feed which means not much pressure. Are these irrigation valves like the Sparkfun 3/4" valve which only open if under pressure? -The irrigation valves are 24AC, but I read in one place that they work fine under 12v DC as long as you use a current limiting resistor. Can anybody confirm that 12VDC would actually work?

Anybody know what I could use for a 1 1/4" (or larger) valve that's not crazy expensive, and works under gravity?

-The irrigation valves are 24AC, but I read in one place that they work fine under 12v DC as long as you use a current limiting resistor. Can anybody confirm that 12VDC would actually work?

That sounds backwards... You might be able to run a 12V valve from a 24V source if you calculate the resistor properly. It really should be driven with the correct voltage.

Did you see the minimum pressure of 0.02MPa. AFAIK those valves rely on water pressure to actually open the valve. Leo..

For large bores i would suggest a motorised ball valve.

http://www.ebay.co.uk/itm/like/121714951930?lpid=122&chn=ps&adgroupid=27378760866&rlsatarget=pla-181484322306&adtype=pla&poi=&googleloc=1006494&device=c&campaignid=620865095&crdt=0

You could use 3 cheap 3/4" valves in parallel for a similar flow resistance (0.75 ^2) / (1,25 ^ 2) = 0.36

  • with a suitable coarse filter on each of course ...

regards

Allan.

Another thought, butterfly or gate valves are used for this applicaton commonly, manual ones can be had cheaply on ebay. Perhaps you could attatch a servo to one.

Consider that the time to drain will be a forumla that inculds pressure and orfice size as well as pipe diameters.

your water lever, or rather the height of the water above the valve the orifice size of the valve and the pipe diameter it is connected to

most solenoids require a pressure from the water to push them open, the solenoid only allows the unit to open. the water pressrue does the actual opening. you can get zero pressure solenoid valves, but the will be cosly.

the motorized valve will offer a lower cost, but they are reduced port. that means your 1 inch valve may have a ball from a 1/2inch valve. it is hard to get a full port motorized valve.

so, get many of them. get a pump, or get 1 and give it time to drain. add a screen to keep our leaves and such.

Boardburner2: For large bores i would suggest a motorised ball valve.

http://www.ebay.co.uk/itm/like/121714951930?lpid=122&chn=ps&adgroupid=27378760866&rlsatarget=pla-181484322306&adtype=pla&poi=&googleloc=1006494&device=c&campaignid=620865095&crdt=0

1" is the pipe thread connection size , port size is 20mm (3/4") two of these will offer 0.88 inches open diameter.

one will drain, two will drain faster.