Drip system timer/valve for low pressure?

[sendero]

This is a long shot, but I'm running out of ideas.

I've recently set up a water tank to provide irrigation for our garden plants (blackberries, blueberries a few grapes). The water tank is about 400 feet from our pond. I put in a 1.5" pvc line from the pond edge to the (1500 gal) tank. We fill the tank and then let it gravity feed our drip system. The tank is about 3 feet higher than our garden, and water flows freely through the 3/4" pvc output side and through the drippers.

After all the work of trenching, gluing and covering, I was happy to see it all work. I got out a timer that attaches to a water faucet and lets you water when on a schedule. But I wasn't prepared for the fact that the timers apparently depend on having water pressure to operate. One I tried never opens, the other never closes.

I've poked around the web and one company makes one of these hose timer gadgets that will operate on 5 PSI, but I'm' probably working with more like 2-3. I'd have to raise the tank 6 feet or so to get 5 PSI, and given what 1500 gallons of water weighs, that's not really an option.

I'm wondering if all electric valves, such as the ones used in sprinlker systems, require pressure to work. I'm trying to find some way to water on a schedule, since I'm not there most of the time.

Anyone have any ideas?????

 

[gsganzer]

I've bought from these folks before.

Drip Store

 

[CATMAN]

I have no experience with this, but I will throw out some thoughts. I assume 120 AC is not available. Have you considered something like a 12 volt DC deep-cycle car/motorcycle battery to run a solenoid valve(on/off) or even a 12 volt DC water pump(Harbor Freight) that would increase the pressure so your timers would work. Maybe a solar charger to keep that battery charged up. Theses ideas are probably not that easy, but I was just trying to "think outside the box" a little.

 

[jinman]

The water tank is about 400 feet from our pond. I put in a 1.5" pvc line from the pond edge to the (1500 gal) tank. We fill the tank and then let it gravity feed our drip system.

You didn't say how you fill your 1500 gallon tank through the 1.5" line. Is it pumped? Gravity? Is there any chance you can control the filling side instead of the drain side? ...something like letting the tank fill up as a sump and drain out through your distribution 3/4" system at the same time the sump is filling.

Perhaps you just want to fill the sump and then drain out 300 gallons or so each day thereafter when you aren't there with no power applied. I think that or something similar is what you are saying and that won't work by controlling the input as I am suggesting.

 

[LoneCowboy]

I thought it was 2.2psi per foot of head?
Am I wrong?
at 5', you should be at 10psi or so, and relaly it's to the top of the tank
Most irrigation/sprinkler valves need 30 to 40psi to run right.

Try a plumbing supply store, there have to be timed valves that open more like a ball valve, than a sprinkler valve.

 

[_RaT_]

I thought it was 2.2psi per foot of head?
Am I wrong?
at 5', you should be at 10psi or so, and relaly it's to the top of the tank
Most irrigation/sprinkler valves need 30 to 40psi to run right.

Try a plumbing supply store, there have to be timed valves that open more like a ball valve, than a sprinkler valve.

2.33 feet gives 1 psi. I have yet to see a solenoid valve that does not operate on some water pressure. I have a faucet connection type that uses 4 C cells and actually rotates a ball valve which would work. I forgot the name brand, but look for something like that.

 

[RavensRoost]

I have had good luck using Melnor timers, believe it is model 3060, uses two AA batteries that last all summer, motor-driven valve vs. water pressure/pilot control, so no minimum water pressure issues. Bought at Home Depot....but can't remember price.

RavensRoost

 

[shaley]

You need a MOV (motor operated valve) or a AOV (air operated). Just a cheap pvc ball valve and mount a 12V window motor or this windshield wiper motor over it. I'd buy a 1" ball for stoutness and sleeve it down to the pipe size you need.
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That's pretty much how we control RCW (reactor coolant water) at the nuke plant cept we use a bigger window motor.

 

[RavensRoost]

Forgot to mention that the Melnor time (3060?) uses standard hose connectors, so you may have to use adapters.

 

[shaley]

Here is a nice 1" ball that you could add a air cylinder to real easy and just have it spring return.
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