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View Full Version : Design/gpm Help!!


offshore1234
07-11-2008, 08:08 PM
I am starting a homeowner system and need some help getting started. I was told to cut into the 1 inch copper line just ahead of my 3/4 meter. I put a "T" in the line. From that I ran a psi gauge and down from that a stop valve. Then another right angle down to drain into a 5 gal bucket. I ran 3 tests. The static pressure is 56 psi. I tested the flow at 50 psi = 12.5 gpm, 45 psi = 16.5 gpm, and 40 psi = 21.4 gpm. QUESTIONS: First was I correct to do this, if so, now what do I do. Which of these numbers do I use to configure the system. I was going to run the system main with 1 inch copper and the laterals with 3/4 poly. Is that correct? What should I use? I read that the gpm should be around 18. I have glanced at the irrigation tutorial and it is alittle confusing. Any advice to get me in the right direction would be greatly appreciated.

I tried to attach a drawing of what I did.

AI Inc
07-11-2008, 08:32 PM
Have you considered hiring soimeone for this?

Mike Leary
07-11-2008, 08:57 PM
Have you considered hiring soimeone

I thought she was busy with with the SHESHOVEL project.

offshore1234
07-11-2008, 09:28 PM
Yes I have considered it, however I would like to try this on my own. Thanks for the comments, however any comments that might help out would be greatly appreciated. Thanks in advance.

Mike Leary
07-11-2008, 09:47 PM
Yes I have considered it, however I would like to try this on my own. Thanks for the comments, however any comments that might help out would be greatly appreciated. Thanks in advance.

You might understand that the guys that really know their stuff are in the
middle of the season & don't have time to spit. The only comments you're
going to get are from we hacks.

Dirty Water
07-11-2008, 09:50 PM
I'm assuming you got the lowest PSI (40 psi) with the stop valve wide open, so I'd design the system around 14 GPM, because you will have friction loss from the pipe runs. You want to keep your running pressure above 40 psi if at all possible.

Mike Leary
07-11-2008, 09:59 PM
I'm assuming you got the lowest PSI (40 psi) with the stop valve wide open, so I'd design the system around 14 GPM, because you will have friction loss from the pipe runs. You want to keep your running pressure above 40 psi if at all possible.

Hack.........

Dirty Water
07-11-2008, 10:19 PM
Hack.........

Don't make me hop on the ferry and kick your old ass :)

Want to quantify your response to my answer?

offshore1234
07-11-2008, 11:22 PM
At 40 psi the stop valve was not fully open.

Wet_Boots
07-11-2008, 11:39 PM
How many acres are you watering?

By the way, "just ahead of" means "upstream of" ~ if you bypass the water meter, things could get ugly.

offshore1234
07-12-2008, 12:20 AM
The lot is 1/3 acre.

Wet_Boots
07-12-2008, 12:30 AM
For 1/3 acre, you don't even need 15 gpm. Stick with 12 gpm or less, and gain the pressure that will make up for a lot of your inexperience. What backflow preventer are you installing?

AI Inc
07-12-2008, 07:35 AM
Yes I have considered it, however I would like to try this on my own. Thanks for the comments, however any comments that might help out would be greatly appreciated. Thanks in advance.

Alright , for starters I dont know how long your mainline is but there definatly is no need for a copper mainline beyond the backflow.With 3/4 laterals your just creating an assache for someone who may service the system for a future owner.

Wet_Boots
07-12-2008, 07:55 AM
Alright , for starters I dont know how long your mainline is but there definatly is no need for a copper mainline beyond the backflow.With 3/4 laterals your just creating an assache for someone who may service the system for a future owner.(Hey, we could direct him to the seven-spray thread. Then his head will explode)

offshore1234
07-12-2008, 03:31 PM
Why would 3/4 inch laterals be bad, are you saying I should use 1 inch. What should I set up for: 50psi @12.4 gpm, 45psi @ 16.6 gpm, or 40 psi @ 21.4 gpm.

Mike Leary
07-12-2008, 03:41 PM
Why would 3/4 inch laterals be bad, are you saying I should use 1 inch. What should I set up for: 50psi @12.4 gpm, 45psi @ 16.6 gpm, or 40 psi @ 21.4 gpm.

::::::backs out of thread after missing something:::::

Wet_Boots
07-12-2008, 03:49 PM
What backflow preventer are you installing?

offshore1234
07-12-2008, 05:19 PM
That was going to be part of my next question. I was just going to use a check valve.

Wet_Boots
07-12-2008, 05:33 PM
That was going to be part of my next question. I was just going to use a check valve.Go back and do some reading. You are not ready for prime time.

Mike Leary
07-12-2008, 05:54 PM
I agree, try this for a primer...any backflow preventer that cannot be tested is called
a "device", we use "assemblies". watts.com

lowvolumejeff
07-12-2008, 09:10 PM
Hi again. Was wondering if you ever visited the Free online tutorial I recommended at the start of your last post. Most of the subjects you raised are covdered there. User frfiendly, and will sure help insure a sucessful design and install. Link below.

Best wishes, Jeff

http://www.irrigationtutorials.com/

Mike Leary
07-12-2008, 10:09 PM
Hi again. Was wondering if you ever visited the Free online tutorial I recommended

Thanks Jeff, I learned lots.:rolleyes:

Kiril
07-13-2008, 10:23 AM
I'm in agreement with most of these blow hards. Design assuming 12-14 GPM is available, ditch the copper main, get a real backflow assembly.

CAPT Stream Rotar
07-13-2008, 02:00 PM
lol @ just use a check valve...

buddy, do some homework and come and hang with the big guns..

Thx

csr