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jusme

Senior Member

1

Tuesday, August 28th 2007, 4:08am

Valve Manifold Diagram

Does anyone have a diagram of a good valve manifold design? As I understand it, probably the best design utilizes a manifold (basically a multi-tap tee, as opposed to multiple tees and nipples) and unions. I just can't visualize how a union works because this is my first plumbing-related project and I haven't actually picked up a union to see how it works mechanically. So is there an exploded diagram or even a good explanation of how to build your manifold? Also, what are these "buttress" parts Rainbird offers to build a manifold? How do they work mechanically?

mrfixit

Moderator

Posts: 1,465

Location: USA

2

Tuesday, August 28th 2007, 8:12am

Just glue everything. I can't stand unions. It's just one more place for it to leak. I do prefer threaded valve ports vs slip though. I always build the manifold above ground. Then install it all at once. Then the valves. That way it's easier to make everything symmetrical and straight. If you're putting the manifold in a box you can easily make sure it fits above ground. Good luck!
If I can't fix it, it's broken!

HooKooDooKu

Supreme Member

3

Thursday, August 30th 2007, 2:53am

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by mrfixit</i>
<br />Just glue everything. I can't stand unions. It's just one more place for it to leak. I do prefer threaded valve ports vs slip though. I always build the manifold above ground. Then install it all at once. Then the valves. That way it's easier to make everything symmetrical and straight. If you're putting the manifold in a box you can easily make sure it fits above ground. Good luck!
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

nrfixit,
Can you offer any suggestions on what to do to try to get those manifolds symmetrical and straight. The problem I ran into was that the proceedure for gluing PVC includes that final twisting of the parts. I would hold the parts in place for the prescribed period. But what I kept experiencing time and time again was that as everything set, the parts would untwist just a little.

As an example, I would glue two Tee to a short piece of pipe and carefully twist everything together to make sure the Tees lined up... mater of fact I usually dry fitted a couple of 1 foot line pieces of pipe the the legs of the Tees so that it was very easy to visually line up the Tees. I'd hold everything in place for the prescribed 30-60 seconds and everything would line up perfectly. But when I would check on it an hour later after letting the joins cure, my one foot dry fitted pipes didn't line up anymore. It was as if the twisting was streaching the glue, and as it dried, the glue would shrink and untwist just a little bit in the process.

To jusme, the warning I have about unions is that they have to line up perfectly. As a part of my install, I tried to use a pair of unions to allow me to make a particular section of my instilation removable/replaceable. Well something happened that required me to replace what ever was between to two unions. But when I have everything back together, the unions were just a hair out of alignment. It didn't matter how hard I'd try to tighten those unions, they leaked.

Now on the other hand, I built my manifold with the valves installed in an up-side down U shape. Both Legs of the U contain unions and it allows me to completely remove a single valve from the system for maintainence. Now as long as I never have to replace the base of the valve, the unions will line up and everything works great. But if I ever have to completely replace a valve, I'm screwed because I'll never be able to get the new unions to line up with the old ones.

Let me try to explain it this way... you want to glue two Tees side by side pointing in the same direction for a manifold. You start by gluing a short piece of pipe to the first Tee. Details on exactly how much twisting you do as you connect these two pieces together don't matter. But now it's time to glue the second Tee. The twist matters alot now. So when you slide the Tee You and let it stand for about an hour (that way you don't risk damaging the joint as you go to glue the So you get y0need two Tee and a short piece of pipe. Step one is to glue the first Tee to the pipe. After letting

jusme

Senior Member

4

Thursday, August 30th 2007, 3:07am

Alright let's start with a visual diagram, and maybe with your help I can tweak it accordingly. Is this like what you had in mind mrfixit? Note that everything is not to scale, but you get the idea. I completely understand what you're trying to illustrate HooKooDooKu because I saw you mention the upside-down U with unions in another post and made a quick little sketch of it to visualize on my notepad which I happen to have right next to me. It seems like a good idea too. Here's my current rough draft based on mrfixit's suggestions. Any thoughts anyone?

http://www.jusme.org/manifold_design.gif

jusme

Senior Member

5

Thursday, August 30th 2007, 3:31am

Here's HooKooDooKu's manifold design illustrated (I hope it's right). Use your imagination with the 3D perspective, it's hard to simulate in Visio. Basically that mainline pipe is going into and coming out of the page (Z-axis). The mainline then tees vertically to one valve with an upside-down U design. The rest of the valves would be similar, each having an upside-down U shape. Correct HooKooDooKu?

http://www.jusme.org/manifold_design2.gif

mrfixit

Moderator

Posts: 1,465

Location: USA

6

Thursday, August 30th 2007, 8:23am

Hi HKDK, I can think of one thing that may give the appearance the fittings are turning. The dry fitting of the pipe. The pipe itself may not have been straight in the fitting initially. The pipe rocks back and forth easily when not glued. As far as holding it 30 seconds, that's more than enough. The twisting is a very good thing. I believe it says to do it right on the can. This eliminates dry spots. Also it depends on the type of glue you're using. The thicker grey glue takes longer to set so I hold it longer than the blue glue. I just eyeball the tees. I look down the top of them while twisting. I never use the red hot blue glue. It dries way too fast.
If I can't fix it, it's broken!

jusme

Senior Member

7

Friday, August 31st 2007, 3:40am

Anyone have any comments on these two manifold designs? Are there any pro's/con's to the first one? I don't really see what threads buy you in a manifold anyway, it just seems like you'll have to cut pipe to replace a valve no matter what.

HooKooDooKu

Supreme Member

8

Friday, August 31st 2007, 6:59am

jusme,
The up-side down u that you've got is conceptually right, but the design as you have it laid out takes up too much space.
I wanted to be able to fit 4 valves side-by-side in a 12x17 irrigation box. To get the valves to fit, I had to use red (?) elbows (slip fitting on one side, female threads on the other). Then I was able to connect the elbows directly to the valves with sch80 nipples. With 1" pipe, the pair of male adapters effectively add two or three inches to the length of the valve. Once you add the valve and pair of 1" elbows, they just don't fit inside a 12" box.

If you should adopt the upside down U with unions, let me suggest the following... If you use valves with threaded connections, have the the female side of both unions closest to the valve. If you use valves with slip connections, have one union with the male side closest to the valve and the other side have the femaile side of the unions closest to the valve.

If you ever have to replace a valve with slip connections, because everything is glued together, you'll have to toss all the pieces glued to the valve (because none of the pipes will be long enought to cut and repair). So to avoid having to purchase TWO unions to redo the valve, you'll only have to purchase one to rebuild the valve. If you are using threaded connections, then you will be able to reuse the unions and elbows. Once in the ground, it is easier (physically and mentally) to screw and unscrew the unions together if the female sides are on top (i.e. the side with the "nut" you tighten).

mrfixit,
This isn't a case of the fittings appearing to turn. I would insert the 1' dry fitted pipes to eyeball the lineup, leave the dry fitted pipes in the tees while the setup dried, and come back an hour later and the pipes that lined up would now be as much as about 10 degrees out of alignment.

Another similar type of thing would happen to be with bushings. I used 1" pipe and fittings everywhere with 3/4" threaded connections leading to spray heads. The cheapest and neatest solution I could come up with to make that transission was to use 1" slip x 3/4" threaded bushings glued inside standard elbow/coupling/tee fittings. Often, the bushings would try to push there way back out as the glue dried. This would be very easy to spot because the bushing could always be inserted into the fittings all the way to the neck of the bushing. I could hold a bushing in place of 30 seconds, and set it aside to dry. Come back 10 minutes later and the neck of the bushing would be about 1/16th" to 1/8th" away from the fitting (even more if I held it for less than 30 seconds). I found the only way to insure that the bushings didn't push out of the fittings was to glue the bushing to the fitting (before gluing the fitting to the pipe) and hold the bushing in place with a vice while the glue dried. If I didn't have a vice handy, I'd have to use something else to keep pressure on the bushing for about 2 minutes or more to keep them from pulling out as the glue dried.

mrfixit

Moderator

Posts: 1,465

Location: USA

9

Friday, August 31st 2007, 8:28am

HKDK, that's really bizarre. I've never heard of such a thing. I don't have to hold the fitting more than 10-15 seconds ever with 3/4 or 1 inch fittings for them to stay in place. I'm very picky about my work as well. If something's not just how I want it, I'll start over without charge. I'm grasping at straws here. Maybe the fittings you use are tad bigger than they're supposed to be on the inner diamater. Maybe it's the type of glue you use. Something's not right though. Beats me what.
I use mostly Spears fittings. I like the deep sockets and nested couplings. I use the medium blue glue.
If I can't fix it, it's broken!

HooKooDooKu

Supreme Member

10

Tuesday, September 4th 2007, 9:32am

mrfixit,

I'm using what's available at the local Big Box retail stores. Generally that means LASCO fittings, Oatey medium clear cement (the black can), Oatey purple primer, and I'm not sure who's making the 1" Sch40 pipe.

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