05-29-12, 10:35 PM | #1 |
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irrigation options (low pressure)
I'd like to start installing irrigation lines/emitters to water our fruit and vegetable garden. The pressure will be low (~ 1 to 4 psi depending on the water level in the dedicated cistern) and I'd prefer not to run electrical power to the site. Have I got any options?
Thanks, Greg Vancouver Island, Canada |
05-30-12, 08:36 AM | #2 |
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I'd just use a drip irrigation type setup. Pretty simple really. It won't dump a ton of water fast but I doubt you care about that.
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05-30-12, 09:32 AM | #3 |
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I have used a regular soaker hose connected to a rain barrel with a 2ft drop. It works tolerably well, but as the pressure drops the amount of water coming out drops. With such a low head, the last couple of feet of water was left standing in the rain barrel. From a quick calculation of .43 psi/vertical foot, that means that at about 2 psi my system started to fail. I ended up poking holes in the soaker hose to increase flow rate and get the last bit of water our.
A better choice would be a pre-drilled irrigation line. These have holes that get larger as you get farther from the source, so they have the same flow rate the entire way. I think the emitter holes are spaced at 18 inches. The openings are larger than the pore spaces on my soaker hose, so the low pressure should be able to overcome the water's surface tension. Turn it on overnight and you should have a well watered garden by morning. |
05-30-12, 01:17 PM | #4 |
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I'm not sure that you'll get much out of a drip system at 4 psi. you'll definitely need to balance it to make sure the end of the line isn't dry.
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05-30-12, 07:27 PM | #5 |
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Is there any sort of mechanical timer available so I could increase the size of the holes in the line and shorten the duration of the watering cycle to make better use of the low pressure?
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05-30-12, 10:49 PM | #6 |
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I have soaker hose on my rain barrels as well with a 2 foot drop giving a fraction of a PSI of pressure and it works great! I use the soaker hose that is a course rubber instead of having holes in it so the water seeps out.
I also have a mechanical timer that works well, but I tend to leave the soaker hose on over night, a single stretch of it empties out 100 gallons over the course of 6-8 hours, so not very fast but enough to keep the soil moist. If you have a lot of trees, then the heads that you install in a larger soaker hose seems like the way to go, that way you get a head or two next to each tree. Bottom line is, what you are wanting to do has been done and it works well with off the shelf stuff. |
06-10-12, 10:30 PM | #7 |
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Thanks everyone. I've settled on standard 1/2" distribution line with 1/4" going to the individual plants. I've ordered a selection of non pressure compensated drippers and will experiment to see which ones work best with the low pressure supply. I'll set up a soaker hose to water the raspberries. Multiple valves connected to a sprinkler controller would likely work best for us. So... is anyone happy enough with their controller to recommend it? I'm going to be powering the unit with a solar panel so 24 vdc would be perfect but a small inverter is no problem either if the controller is 115 vac.
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