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The last 10 posts

Thursday, September 6th 2007, 5:12am

by jusme

Rainbird calls their manifold kit parts "half union". But half union could also just be a fancy way of saying male/female threads. I don't know if any of the parts have O-rings in them, as I haven't picked them up. I'll try to follow-up here when I build the manifold and let you know how it does on leaks. I may have to replace the nipples in my diagram with Rainbird MS-NIP parts, and then add-in MS-MA parts to mate with the M-buttress threads. That would add extra cost and space into the design, so I'll try it with minimal special kit parts first.

Thursday, September 6th 2007, 5:06am

by HooKooDooKu

Do all those manifold pieces screw together line unions or like male x female and add tape to stop leaks.

If tape is needed, I wouldn't want to go that way. Too many threaded connections to make. I don't know why, but I've had a VERY difficult time at getting threaded connections perfectly leak free. A weeping leak might be ok on latteral lines, but on mainlines, I don't want even the smallest of leaks. Yet for some reason, I've had lots of trouble keeping things leak free.

About the only place I did pretty well at preventing leaks was at the nipple to valve connection using the "pink" thick tape rather than the typical white tape.

Otherwise, the little trick I have found to help get leak free connections is to wrap your tape on the male threads (about 7 times) and then "screw the male fitting to a rag"... basically, run a rag around the tape to help pre-press (or seat) the tape in the male threads before screwing it to the female fitting.

Thursday, September 6th 2007, 5:06am

by HooKooDooKu

Do all those manifold pieces screw together line unions or like male x female and add tape to stop leaks.

If tape is needed, I wouldn't want to go that way. Too many threaded connections to make. I don't know why, but I've had a VERY difficult time at getting threaded connections perfectly leak free. A weeping leak might be ok on latteral lines, but on mainlines, I don't want even the smallest of leaks. Yet for some reason, I've had lots of trouble keeping things leak free.

About the only place I did pretty well at preventing leaks was at the nipple to valve connection using the "pink" thick tape rather than the typical white tape.

Otherwise, the little trick I have found to help get leak free connections is to wrap your tape on the male threads (about 7 times) and then "screw the male fitting to a rag"... basically, run a rag around the tape to help pre-press (or seat) the tape in the male threads before screwing it to the female fitting.

Thursday, September 6th 2007, 4:19am

by jusme

Because I'm a masochist, here's the final design I'll probably use which utilizes RainBird manifold kit parts. My main reason for going this direction is because I like the idea of the RainBird manifold pipe (MS-DM, MS-TM, MS-QM) and not having to stress about building my own manifold. Plus the one-design design means I don't have to worry about leaks unless the pipe actually cracks.

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

I like the idea of using "risers" (upside-down U shape mentioned by HKDK) so the valves are easier to get to for installation/removal so I ended up doing away with most of the RainBird kit parts in favor of standard PVC fittings to form my upside-down U. If you want a "flat" manifold design, the connections starting from the mainline pipe would look like:

MS-125x100 (or MS-100x075 depending on your mainline sizes) -> MS-DM/MS-TM/MS-QM -> MS-MA -> 100-DVF (or similar) standard FPT valve -> MS-NIP -> MS-125x100 (or MS-100x075 depending on your lateral sizes) -> Laterals

Obviously the MS-MA -> Valve -> MS-NIP -> MS-125x100 part would be multiplied by how many valves are in that manifold.

If someone needs a diagram of this for kicks, I can probably make one similar to what I've done above, but it's really simple.

Thursday, September 6th 2007, 2:04am

by jusme

And just for anyone following along with the thread, here's that slip version for completeness:

http://www.jusme.org/manifold_design3.gif

Wednesday, September 5th 2007, 4:43pm

by HooKooDooKu

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by jusme</i>
...I'm curious why you don't just use a male x male valve straight into the slip x female ell? That would save you even more room by doing away with the nipples on either end...<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

I used Rainbird valves available from the local big box retailer. The only thing they sell is female x female valves.

Of course another alternate would be to use male x slip ells on either side of the female x female valve. But if you've got the choice, I'd still suggest replacing he female x female valve and female x slip ells with all slip connections. If so, I'd suggest that you turn on of the unions around. That way the entire secion above the union can be completely rebuilt, in needed, with only one union.

Otherwise, you've pretty much diagramed what I installed.

Wednesday, September 5th 2007, 11:51am

by jusme

Sheesh, I sure am having a hard time getting this thing right based on your description. I think I finally have it this time.

http://www.jusme.org/manifold_design2_rev2.gif

You're right about the terminology for the word "Nipple". I briefly saw somewhere that it was a short length of pipe and I missed the part about it usually being threaded. So I guess I was misusing the word in my design, which is good to know. I'm curious why you don't just use a male x male valve straight into the slip x female ell? That would save you even more room by doing away with the nipples on either end.

Yes, the drawing is not to scale, the leg of the pipe below the unions would be shorter than shown. But since I have an exploded view of the manifold, I needed to make the legs appear longer so everything looked nice visually.

Also, what's the deal with the Rain Bird manifold kit parts? It seems like it would be really nice to use a manifold pipe (Rain Bird part number MS-TM for the three-valve manifold I'm considering) instead of a homebuilt manifold using tees and short sections of SCH40 PVC? Then you can avoid that problem you mentioned with the tees twisting up on you and not aligning properly. I'm worried by this as well. With a one-piece manifold there is so much less to worry about. Anyone built one using these Rain Bird kit parts? The "buttress threads" make me feel pretty sure that you can't just assemble them using other mpt and fpt parts.

Wednesday, September 5th 2007, 3:09am

by HooKooDooKu

jusme,

First some terminology. Several places on your drawings refer to "nipples". From what I understand, nipples usually refer to short pieces of female x female threaded pipes. But based on where some of your "nipples" are located, it looks like some of your nipples would be more appropriately be short pieces of standard sch 40 used to glue two fittings together.

As you say, Rainbird seems to like female threads on their valves, and if your getting stuff from one of the big-box retailers, that's all that is available. But if you are going to someplace where you can order the type of valve you can get, I would suggest getting valves with Slip x Slip (glue) connections. The reason I say this is because if you every have to replace the entire valve, you have a better shot at getting the geometry to match up at the unions. Like I stated before, base on my (limited) experience, if you have any bending forces on the pipe at the union, it's going to leadk, so the geometry has to be perfect. In this case, that means you've got to have two pipes that are perfectly lined up (not much of an issue there) AND the exact distance between the pipes has to stay the same. Because both of these have to match, using threaded connections puts you at the mercy of how the threads were cut. Obviously you have to have the pipes screwed in so that they point down, but the question is once you've done that, is the distance between the two pipes (legs of the upside-down U) a specific distance apart. When it comes to trying to increase or decrease that distance, you are limited to +/- the distance between threads. Now if you are using Slip X Slip connections, the thing that you can do at the time of replacement is to rebuild and reglue everything with the unions already in place except for the final short piece of pipe that will connect the valve and the elbow on the lateral side. You can cut that piece of pipe just a hair too short, and glue this final joint with everything in place. Since you're talking about a pipe that is not under constant pressure (and Sch. 40 to boot), things will be ok if a 1" pipe is 1/8" or 1/4" short of being FULLY seated in the valve fitting.

BTW, I also suggest Slip x Slip valves because I've have problems with threaded connections leaking (even though I've followed what appear to be leading suggestions on how to properly assemble leak-free threaded connections). Glued connections are SOO much easier to make leak-free.

Your final drawing is very close to what I eventually used, except that I used nipples to connect the female threaded elbow to the female threaded valve. I then just used a short piece of regular sch40 to glue the Slip side of the elbow to the slip connection of the union (you show a nipple at this location, and I consider that to be a double threaded female pipe, and I didn't have access to any unions that had female threaded connections.

So let me try to restate my design (which still has the shortcoming of getting the geometry perfect if I ever have to replace the entire valve)... Here's the pieces I used described as the water would travel:

Slip x Slip x Slip TEE at the manifold
short piece of sch40
Slip x Slip Union
short piece of sch40
Slip x Female elbow
1" sch80 nipple (no such thing as a sch40 nipple)
Female x female valve
1" sch 80 nipple
Female x Slip elbow
short piece of sch40
Slip x Slip Union
short piece of sch 40
Slip x Slip elbow (turning out of the upside down "U" to lead out into the yard)

The last comment is that just like a mentioned I had to do things to make sure the distance from elbow to valve to elbow was short enough to fit inside the box, you also have to make sure that the vertical legs of the up-side-down U will also fit inside the box. At a minimum, the bottom of the unions must be above ground level inside the box, while still allowing the entire valve to still fit under the cover of the box. If your drawing were to scale, that extra long leg from the manifold to the union would cause me to hav

Tuesday, September 4th 2007, 11:26am

by jusme

It also occurred to me that I could still use the standard Female x Female valve (this seems to be the default for Rain Bird at least) and instead of a 1" Ell ST (fipt) I could use a 1" Street Ell (mipt). Any thoughts? Pros/Cons for each approach?

Tuesday, September 4th 2007, 11:16am

by jusme

HDK,

I've attached a new revision to my drawing based on your comments. Do I now have it correct?

http://www.jusme.org/manifold_design2_rev1.gif

I modified the design based on my specific needs. For each of my laterals, I need 1 1/4" CL200 pipe based on my system design. The mainline pipe is 1". Obviously smaller fittings are cheaper, so my manifold design shows 1" fittings used throughout, and then a 1"x1 1/4" bushing right before the lateral pipe to get to the right size. Does this look about right? Basically I changed the valve from Female x Female to Male x Male so I could remove the nipples and male adapters shown before.

Does anyone see any issues with using 1" fittings on the valve outlet and then 1 1/4" pipe? Since the fittings are small parts, I'm guessing the increased flow allowed by a 1 1/4" pipe won't affect them as much. Our favorite sprinkler design tutorial (IrrigationTutorials.com) suggests that 1" inlet x 1 1/4" outlet is pretty common. This is my best attempt at making that transition.