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Tom

Supreme Member

11

Sunday, January 11th 2004, 8:54am

You also have pressure losses starting at your connection in the street, which includes the house main line, the sprinkler mainline, your water meter etc. You will lose whatever wilkins stats in their literature.

You may want to look at irrigationtutorials.com there is a lot of info there.

RVLI

Supreme Member

Posts: 460

Location: USA

12

Sunday, January 11th 2004, 9:26am

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Tom</i>
<br />Your pressure is WAY TOO LOW! You will have a minimum pressure loss of 25 psi leaving you with 15 psi for the heads. Double check your pressure readings!
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Give me some details where all this pressure will be lost.

RVLI

Supreme Member

Posts: 460

Location: USA

13

Sunday, January 11th 2004, 9:27am

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Tom</i>
<br />You also have pressure losses starting at your connection in the street, which includes the house main line, the sprinkler mainline, your water meter etc. You will lose whatever wilkins stats in their literature.

You may want to look at irrigationtutorials.com there is a lot of info there.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Ok you say that you lose pressure through the connection at the street, main house line. That pressure loss is before the pressure gauge already so there is no need to subtract it twice from the reading????? [?]

Tom

Supreme Member

14

Sunday, January 11th 2004, 10:54am

the pressure reading Paterjb gave is static......the pressure losses I'm talking about are dynamic, that is when the system is running. For instance, I have 70 psi static pressure. When my system is running, I have about 45 to 50 psi dynamic pressure measured at the backflow.

If he starts with 40 psi static, he will lose 20 to 25 psi at the first head in his system.

RVLI

Supreme Member

Posts: 460

Location: USA

15

Sunday, January 11th 2004, 1:02pm

Alright

The reason I question you is because I have basically the same setup. 115' mainline with 40 psi, and I still have 25 left to play with at the end head of each zone. I've installed many the same way also.

drpete3

Supreme Member

Posts: 375

Location: USA

16

Monday, January 12th 2004, 2:41am

Tom I am not following the pressure loss either. I assume the reson your pressure drops is because of how many heads you are running at one time. If you turn on one faucet in your home does your pressure drop to 40-50? Now what if you turn on all of the faucets in your home? The dynamic pressure will be lower. I think paterjb will be fine.
Thanks,

Pete

Tom

Supreme Member

17

Monday, January 12th 2004, 6:28am

You are right, but you also lose pressure through all the pipe and fittings from your sprinkler connection to the main connection.

Im saying that Paterjb has to account for all the pressure losses in his systems before he starts digging.

If he starts with 40psi he will lose at least 20psi(remember he has to install a psi robbing rpz) by the time the water reaches his first sprinkler head. Is this 20 psi enough to feed the heads on each zone? Spray heads will work at as little as 15 psi, but that is marginal. Most rotors need 25 psi to work properly. I think he needs to do a pressure loss calculation since his starting pressure is so low.



RVLI

Supreme Member

Posts: 460

Location: USA

18

Monday, January 12th 2004, 11:04am

Peterjb,

Go to the Hunter Industries website at www.hunterindustries.com. Go to resourses and download the irrigation design calculator. This will help you best with the pressure problem.

Rays Sprinklers

Supreme Member

Posts: 493

Location: USA

19

Friday, January 16th 2004, 6:36am

im a little confused about all this pressure loss.....the design calculator is really helpful...and i would use RVLI's suggestion and go with that!
Thanks
Ray
Rays Above and Beyond Automatic Lawn Sprinklers

RVLI

Supreme Member

Posts: 460

Location: USA

20

Saturday, January 17th 2004, 6:51am

Do you really need an RPZ? If you use a PVB there is less pressure loss, only about 4-5 psi I believe.

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