Re: pressureless drip irrigation?

Diana
Pressureless drip irrigation is not possible. Every emitter or small hole
takes a pressuredrop to allow water to go through. Also the hoses take
pressuredrop, but if you take the diameter big enough this is very small.
But please realize that if you water down from a slope you do have pressure.
This is the static pressure due to the higth. 10 meter water column is 1Bar
pressure. Your system is called a gravity flow system. Most irrigation
systems are designed with pumps which give 2 Bar. The main problem with
gravity flow is that it is very hard to distrubute the water properly. At
the top the emitters get only a very smal pressure, due to the lack of higth
and at the bottem there is the maximum pressure resulting in more water. So
you need bigger emitter at the top and smaller at the bottom. This needs
very carefull design and might need some small valves halveway to trottle
the pressure at the bottom to reduce the waterflow. The best is to use the
bottumpump to irrgate everthing  our to build a basin at the top and install
a small irrigation pump at the top.

Wim van Putten
Algarve
Portugal
----- Original Message ----- 
From: "Diane Whitehead" <voltaire@islandnet.com>
To: <medit-plants@ucdavis.edu>
Sent: Saturday, July 26, 2003 2:06 AM
Subject: pressureless drip irrigation?


> I rent a slope on which I grow plants from my hybridization of
> several kinds of plants. Watering is a big effort, except for winter
> when it rains. There is a pond at the bottom of the slope, and I use
> a gasoline-fueled pump to fill various containers at the top
> (bathtubs, garbage cans and such.)  I tried siphoning water in a
> hose, and it does flow, slowly.  This only waters one spot. When I
> used one of those cheap plastic hoses with holes all along, it filled
> up with water but there was not enough pressure for the water to come
> out.  The occasional drop of water did appear in the holes, but they
> dried up before they managed to drop onto the soil. So I water my
> plants by dipping buckets into the containers and carrying them to
> the plants. There is a slight improvement from before I had the pump
> - now I don't have to carry the water uphill.
>
> I've searched on Google for information on low pressure irrigation,
> but all I get is information about how to reduce my water pressure so
> I don't blow out the drippers.  I need to know how to operate with
> what is essentially NO pressure.
> Everything I've read tells about pumping water from a well into a drip
system.
> I don't want to keep the pump going that length of time.  Also, I
> can't start the pump myself (it has a cord to pull) - my husband has
> to drive to the farm every time I need to run it. I hope to put in a
> large water tank if I can manage a siphoning-drip system.
>
> -- 
> Diane Whitehead  Victoria, British Columbia, Canada
> maritime zone 8
> cool mediterranean climate (dry summer, rainy winter - 68 cm annually)
> sandy soil
>
>
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index