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Supreme Member

Posts: 309

Location: Northern New Jersey


Tuesday, May 15th 2012, 8:25am

Adding manifold to existing manifold

Hi everyone;

Planning phase 3 of my system. I will add a manifold with 3 or 4 valves to an existing manifold with 3/4" valves. I have 35-40 working psi and 8.5 gpm. Will use MP Rotators.

Planning to install 1" valves and use 1" PE for new phase. Ok to connect these to existing 3/4" manifold?


Tuesday, May 15th 2012, 8:31am



Supreme Member

Posts: 309

Location: Northern New Jersey


Tuesday, May 15th 2012, 8:34am

Thank you


Starting Member


Monday, June 18th 2012, 6:17pm

I'm in the same boat. I've basically got an entire 3/4" piped system (except the manifolds use 1" fittings and are 1" valves).

I'm also going to run a line about 100' and add another manifold for a garden area. Is there an advantage to using 1" for this new line when the water already runs through ~100' of 3/4" pipe before it gets to the new 1" pipe?


Tuesday, June 19th 2012, 8:17am

Technically, yes.
In a class 200 pipe, if you are pushing 10 gpm (for example) through a 3/4" pipe you lose 4.3 psi of pressure per 100 feet. With a 1" pipe you lose 1.3 psi.
For a comparison chart go HERE

You are using PE. I couldn't find a chart off hand but the idea carries through.

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