Irrigation pipe advice

[TheLoneRanger]

I am looking at upgrading my well to a 5hp or 7.5hp pump so that I can irrigate 10 acres about 1000' from the well. Flood irrigation is not possible because the ground is not level enough to work so I am looking at impacts. Well is a 10"casing at 125' and the water supply is large enough to supply the rice farming north valley of California. I was looking at using 3" pvc as a backbone and splitting off to the spinklers but 3" is hard to come by affordably. Could I run 2-2" pvc and tie them together and get good results or is this just nuts?

 

[Pineland]

Here is a chart for friction loss on Schedule 40 pvc pipe. Assuming you are in the 50 gpm realm or less per pipe. With the assumption of using two- 2" pipes you would have ~ 25 gpm per pipe if your pumps put out 50 gpm. 50 gpm being max recommended flow rate for one 2" pipe. With a quick observation if you use two 2" pipes, you should have and additional ~ 3.5 lb pressure drop over 1000 feet compared to using a one 3 inch pipe. You should have approximately 11 percent less water carry before taking in friction loss. PS I reserve the right to be wrong, because calculating appropriate pump size, flow, and sizing of pipe is a simply complex process.

The other piece of the puzzle is having a pump curve for the two pumps that you are looking at using.

 

[Pineland]

Here is another chart to account for pressure drop.

 

[Pineland]

If the charts give you a problem you can look at the online calculator to do the work for you at:
Hazens-Williams Calculator I use the Imperial Units version of the model.

The design coefficient for PVC is 130. Plug and play and you can see what works for you. Enjoy.

http://www.engineeringtoolbox.com/hazen-williams-water-d_797.html

 

[1wlimo]

May be layflat is an answer from the well to your field.

 

[TheLoneRanger]

I do intend to lay flat if I understand your meaning. My intention is to use my trencher and dig it deep 3' plus with risers. I want to do this so I can renivate the pastures in the future and not worry about bringing up the pipe. The charts to help. I will have to work them out to figure out what is best.

 

[LRTX1]

I may be wrong but I think "lay flat" is refering to a fire hose type of hose/pipe.

 

[1wlimo]

Yes I was meaning "lay flat" as in like a fire hose. I was assuming that you were going over the ground. If you are burying it then for the extra expense going for a larger size may pay in the end. It is more important then to think where you will be in five, ten years time etc.

 

[Pineland]

Glad this info will help. I am in the process of designing an irrigation system myself. I looked for someone who could do a turnkey project but have been unsuccessful in finding one person with that ability in our area. We inherited a 8 inch water well from some drilling activity on our surface that goes down too 300+ feet. We had a water well specialist come and size out a pump for us after running a few tests on the well. We plan to put in a 3 phase pump and I am currently sizing up spray nozzles to match the system and areas we plan to irrigate.

Good luck.

 

[TheLoneRanger]

Ok here is a follow up question in regards to the pump for this set up. What is the difference in using a deep well pump verses an above ground pump? The above ground I am looking at has a head lift of 180ft, 55gpm, 250psi, 2".

 

[gimpyrancher]

One pushes and one sucks? <Smile>

 

[Anonymous]

The submersible pumps are usually more efficient. A 3/4 hp pump will push better than a 1hp will pull. And they usually last longer

 

[TheLoneRanger]

Thank You