OT: Sprinkler valves (how do they work)

[sfsuphysics]

Ok, it's somewhat off topic, but it got my mind spinning when I saw them in the hardware store the other day.

basically underground (or above) sprinkler valves work with a solenoid or something, they seem to need 24VAC supplied to it. But how do they work? They don't flip on instantly I'm guessing, something pushes them open slowly? The current that's applied to them I'm guessing they're default closed, and with 24volts applied they open up and stay open until the power is shut off?

Just trying to wrap my mind around how these work before buying one, finding a transformer to get 24volts, and then finding out that they work completely differently from how I intended.

[troutonmyline]

Solenoid irrigation valves have an internal diaphragm. There is a port from the bottom half of the valve that supplies pressure to the top half of the valve. They are designed so that there is more surface area on the top half of the diaphragm compared to the bottom half. This port always supplies pressure to the top of the diaphragm. There is a second port that is usually kept closed by a spring loaded plunger inside the solenoid. When the port is closed by the plunger, pressure is maintained on the top of the diaphragm, keeping it closed. When 24 volts is applied to the solenoid, a magnetic field is created that pulls up the plunger, opening the port, releasing the pressure on the top of the diaphragm, allowing the line pressure from below to open the valve and water to flow. I hope that's clear. If a knew how to draw on the computer, I'd make a drawing, but......

[Engine 7]

Originally posted by troutonmyline
Solenoid irrigation valves have an internal diaphragm. There is a port from the bottom half of the valve that supplies pressure to the top half of the valve. They are designed so that there is more surface area on the top half of the diaphragm compared to the bottom half. This port always supplies pressure to the top of the diaphragm. There is a second port that is usually kept closed by a spring loaded plunger inside the solenoid. When the port is closed by the plunger, pressure is maintained on the top of the diaphragm, keeping it closed. When 24 volts is applied to the solenoid, a magnetic field is created that pulls up the plunger, opening the port, releasing the pressure on the top of the diaphragm, allowing the line pressure from below to open the valve and water to flow. I hope that's clear. If a knew how to draw on the computer, I'd make a drawing, but......

WOW!
If they sell the valves they may sell controllers. basically a sprinkler controller is a fancy timer that you can set to open close valves as often as you want and as long as you want. With water pressure behind the valves, opening and closing the valves supplies water to different parts of the lawn simulating rainfall.
I own a sprinkler company that keeps me busy 8 months a year.

[sfsuphysics]

Trout: Thank you that's absolutely clear. Basic bones of the matter is by default a closed port, which I thought. The diaphragm part got me though, but eh, it's a part that moves an actuator/ball valve I get it

Engine: Well instead of a controller I was thinking of a float switch, I already have one sitting around hooked to a relay (although I'm pretty electronic stupid once you get beyond resistors and capacitors ). Thought this would be a perfect way to keep my freshwater reservoir topped off. Maybe even throw in one of those float valves as a last bit of security from an "infinite supply of water", even though it's all down stairs next to a drain so no biggy if it does spill over (which it has MANY times before when I forgot I was making fresh water). But what I'm really looking for is something before the RO unit, first because of nature of purified water being able to strip stuff from metals, second my low water pressure usually means my membrane tries to flush itself almost constantly sometimes.

Now if I can just figure out a way to get 24v from a float switch...

[troutonmyline]

The valves can also be throttled down to limit the water flow. Mike, are you considering using them for you tanks?? Yes, controllers are available rather cheaply. The controllers convert the AC to 24 volt DC.

[sfsuphysics]

Well not so much for my tanks as for the RO unit to make freshwater so I don't forget about them. As for the controllers, do they come just with an on/off version? Or do they only have the timer versions.

Edit; Just found a site that sells 24v AC transformers for cheap, I wonder how much power they actually take though, I looked at the instructions and it only says 24V required, doesn't give a power requirement.

[troutonmyline]

I'm not sure what you mean by "on/off version". Most controllers are turn on at a set time for a set period of time. There may still be types that turn on and discharge a programmable amount of water. They also have battery operated controllers that screw onto a hose bib and are programmable for different periods of time(might fit your situation if I understand what you're trying to do). These are very simple, no need for solenoid valve, etc

[sfsuphysics]

On/Off meaning you manually have to flip it on or off. I don't need a controller, you're probably not grasping what I'm trying to accomplish, which is simply when my garbage can full of freshwater for top offs reaches a certain level a float switch activates the sprinkler valve allowing water to go to the RO/DI unit which produces water until it raises the float switch to turn off the sprinkler valve.

[Matt_Wandell]

Originally posted by sfsuphysics
On/Off meaning you manually have to flip it on or off. I don't need a controller, you're probably not grasping what I'm trying to accomplish, which is simply when my garbage can full of freshwater for top offs reaches a certain level a float switch activates the sprinkler valve allowing water to go to the RO/DI unit which produces water until it raises the float switch to turn off the sprinkler valve.

Mike, how exactly is the water from your RO/DI reservoir entering your tank? Float switch? Dosing pump? Manually?