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aerodan1

Active Member

1

Saturday, September 19th 2015, 12:04am

Poly valve manifold

Hi,

I'm doing a new install for which there will be several valve manifolds. Running 1" poly for all the mains and laterals. I don't need to be gluing PVC pipe to assemble the manifold, do I? It seems very simple - a couple of tees (insert x insert x male for the valves I have) and a short piece of poly to connect between the inserts, clamp them in place and done, am I missing anything? Thanks

Central Irrigation

Supreme Member

Posts: 371

Location: Central Minnesota

2

Saturday, September 19th 2015, 8:43am

Been doing it that way for years. I am not a fan of PVC manifolds as it requires complete disassembly when a PVC T fitting cracks.

Wet_Boots

Supreme Member

Posts: 5,223

Location: Metro NYC

3

Saturday, September 19th 2015, 9:13am

Avoid poly manifolds. It seems simple and logical, but pros don't use them for good reasons. Most important is the 'Murphy's Law' concept applied to the truth that poly pipe can randomly develop leaks over a long period of time, and you absolutely don't want that happening in a valve manifold. They are supposed to be strong points you never have to worry about. The best pro-built manifolds are made from all-slip PVC fittings and schedule 80 TOE nipples (TOE = threaded one end) - pros learn soon enough about a female-threaded-side-outlet sch 40 tee being a problem waiting to happen.

If you just don't want to be bothering with the gluing of PVC, then you can use Dura manifold fittings that can combine with zone valves that have a male pipe thread inlet and a barbed outlet for 1-inch poly (they also work with a standard female-threaded valve if you choose to use them)

{If you explore the Dura Manifold fittings, from the above link, note that some of the descriptions mistakenly include some generic wording about gluing. That gluing only applies to a fitting with the word "slip" in its name/description.}

aerodan1

Active Member

4

Saturday, September 19th 2015, 7:15pm

Thank you both for the feedback. Either of those options sound good for now as I'm short on time.

Wet_Boots

Supreme Member

Posts: 5,223

Location: Metro NYC

5

Sunday, September 20th 2015, 11:07am

One bit of advice on any system with a poly mainline, is to not cheap out on the mainline pipe. If it happens that the supply water pressure is above 100 psi, upgrade the mainline poly to a higher pressure rating than the usual 100 psi. Make the assumption that the mainline may find itself under 24/7 full pressure, and be certain it is a material you can count on surviving constant pressure (this lets out nearly any brand of "utility grade" poly, in favor of NSF-rated poly)

aerodan1

Active Member

6

Sunday, September 20th 2015, 8:45pm

I went with 1" PE 4710 SDR 15 125psi NSF poly for all the pipe (mains and laterals). The static is only 68 psi and I'll have a master valve but better to err on the safe side.
One bit of advice on any system with a poly mainline, is to not cheap out on the mainline pipe. If it happens that the supply water pressure is above 100 psi, upgrade the mainline poly to a higher pressure rating than the usual 100 psi. Make the assumption that the mainline may find itself under 24/7 full pressure, and be certain it is a material you can count on surviving constant pressure (this lets out nearly any brand of "utility grade" poly, in favor of NSF-rated poly)

Wet_Boots

Supreme Member

Posts: 5,223

Location: Metro NYC

7

Wednesday, September 23rd 2015, 2:53pm

That is a good grade of poly. You can give an offering to the sprinkler gods with extra clamps on mainline and manifold poly connections, maybe technically not so necessary, but something often done with manifolds, on the "if something has to give, let it be somewhere else" Murphy's Law principle.

aerodan1

Active Member

8

Friday, October 2nd 2015, 11:06pm

Thank you for the feedback. I made sure to double clamp every fitting throughout also.
That is a good grade of poly. You can give an offering to the sprinkler gods with extra clamps on mainline and manifold poly connections, maybe technically not so necessary, but something often done with manifolds, on the "if something has to give, let it be somewhere else" Murphy's Law principle.

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