Have you ever used this funky style 2" PVC sliding pipe connection

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In belched:

FYI: if you can, put a little waterproof grease on the o-ring before assembly. It helps make a better seal. Mine leaked a bit for a couple days until it got a crud seal
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On Sun, 16 Jun 2013 21:44:39 -0500, ChairMan wrote:

I didn't like the way the funky fitting sealed. The o-ring was on the end of the sliding pipe in the direction of the flow of water ... whereas, with a union ... the o-ring is in the middle of the screw-together connection, away from the direct flow of water.
With all that pressure, I was worried the funky tool would leak. So, in the end, I opted for the schedule 80 union instead:

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DADD-
omg...you're at it again!
Making a mountain out of a mole hill..... injecting your substandard logic & experience into a simple situation, dragging out the thread ad nauseum
I know you're close to SV....does Google not work in your area?
http://bit.ly/19cHvMs
The unit is a "telescoping coupling", a simple / effective means for following application ........ http://flexpvc.com/cart/agora.cgi?&product=PVC-Couples-Telescoping
S119-20 2 inch repair coupling, slip x slip If you need to make a repair on pipe that is not easily moved, this is what you need. Telescoping couple, 2" socket by 2" socket. One end moves in and out to match up with existing pipe. Saves digging up the whole pipe to make a repair. NSF Rated for potable water, pressure up to 200PSI.
I've only installed two, the largest unit I've used is 3/4". Last one installed in ~2005...no issues on either install.
Kinda like "Shark Bites"... might seem like magic but the design concepts are sound
and in the age of internet, bad product performance would "blow back" onto the mfr & sellers post haste.
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re

ing

Still not sure what makes this so great versus a piece of PVC and two repair couplings.
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On Mon, 17 Jun 2013 05:18:41 -0700, snipped-for-privacy@optonline.net wrote:

Now that I've taken the thing apart and compared it with a union, I think that in certain applications they might be great. For example, if your pipes *move* in use, and if you're below 200 psi, they might be useful.
Also, in my case, I knew I had limited clearance between the bottom of the pipe and the concrete slab - so I had reasoned (in the store) that it was "thinner" at its greatest width than a normal schedule 80 union was.
It turns out though that the schedule 80 union just about made it, so I had room enough for that "fatter" union. Plus, when I took the expansion coupling (aka telescopic coupling) apart, I was worried that the o-ring, which goes around the end of the sliding pipe, was directly in the path of the onrushing water - and I reasoned that it could cause turbulence compared to the little nub on the inside of the union - and - worse yet - it might leak since the o-ring is directly in the path of the onrushing water.
Googling for the PSI of a 2 inch union, I am dismayed that they are only pressure rated to 150 psi: http://www.1pvc.com/PVC-schedule-40/pvc40-Union-Slip-x-Slip/
So, I guess, in hindsight, *both* unions and expansion couplings don't handle high PSI. (I forget what the PSI is in the pool pipes though.)
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On Sun, 16 Jun 2013 22:45:29 -0700, DD_BobK wrote:

I was looking for people's experience in using this "telescopic coupling" aka *expansion coupling*.
It looks like the DIY pool repair guy here did exactly what I did: http://www.troubleshooters.com/pool/repipe/
He *bought* the same coupling that I did; he took it apart, and looked at where the single o-ring was - and given that it's on the *end* of the slider pipe, he concluded, as I did, that it might not hold pressure as well as a union would.
I find out here that even the really fancy ones with multiple Viton/EPDM o-rings (over $300 each!) are rated only to about 235 PSI: http://tinyurl.com/k5r6lyg
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DADD-
I guess the results of your "Googling" means that
flexpvc.com is wrong when they call the item a PVC-Couples- Telescoping?
http://flexpvc.com/cart/agora.cgi?&product=PVC-Couples-Telescoping
btw 200psi isn't enough for your pool application?

k that in certain applications they might be great. For example, if your pipes *move* in use, and if you're below 200 psi, they might be useful.<<<
Totally awesome! DADD has pronounced the telescoping couple as "in certain applications they might be great." I'm certain the mfr will be glad to hear that & continue making them.
Question...got any idea of the operating pressure rating for 2" Sch 40 PVC pipe?
hmmm probably less than 200 psi
Question...got any idea of the operating pressure for a pool filter system?
Question...got any idea of the length changes in a typical piping system?
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On Sun, 16 Jun 2013 22:45:29 -0700, DD_BobK wrote:

Here is a picture of the o-ring location of the union versus the telescopic slide:slide coupling:

Notice the location of the o-ring in the expansion coupling is in line with the fluid, while that of the union is off to the side.
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In belched:

you could have turned the expansion one around so that it flowed with the water
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On Mon, 17 Jun 2013 21:16:48 -0500, ChairMan wrote:

That might help; but it's still inline with the water flow, whereas the union is off the flow direction (AFAIK).
Still - that would have been a good idea had I used the expansion coupling for the repair.
Next repair I'm going to try just couplings and pipes, to see if it can be done without a union.
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whereas the union is off the flow direction (AFAIK).<<<<
your analysis is wrong... there is no O-ring location problem.
The real problem is "AFAIK" actually means "you really have no idea what you're talking about...you make stuff up based on faulty logic"
ever heard the punchline "frogs with no legs cannot hear"?
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+1
good point but the o-ring is not vulnerable to the water flow in any case
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In belched:

I know, mine is installed exactly like that and hasn't leaked. I was just pointing out the obvious<g>
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On Tue, 18 Jun 2013 11:34:26 -0500, ChairMan wrote:

I took both apart to visually analyze how they work:

Laying them side by side, the o-ring is in a different position:

Each o-ring seems to be blocking flow slightly differently:

DD_BobK says he knows exactly how they work so I'll let him explain as they seem to work slightly differently, admittedly to my inexperienced eyes (having never even seen the telescopic coupling before).
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Same here. I'll be looking the next time I'm in a good hardware store.
Harry K
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On Wed, 19 Jun 2013 08:20:54 -0700, Harry K wrote:

Having stared at the two fittings side by side, I'm scratching my head to find the real *value* of the telescopic fitting over the union (other than the installation process is a bit easier):

Telescopic PROS: - Telescopic makes measuring easier on the installer - Telescopic slider *may* handle length fluctuations better - It's slightly lower in height (for space-challenged locations) - Telescopic doesn't need a "repair pipe" (it only needs a coupling)
Telescopic CONS: - Telescopic cost about 50% *more* than the union did for me - Minimum repair is larger with the telescopic than the union - Telescopic will leak *differently* than does the union (if it leaks) - Total cost is (far) higher with telescopic than with union
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DADD-
You're preaching to the choir.... I know exactly how these things are designed & how they work.
They work just fine otherwise you'd find tons of complaints about them.
Your concern about "O-ring in the expansion coupling is in line with the fluid" is unfounded, more novice / non-mechanically inclined hand wringing.
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On Mon, 17 Jun 2013 01:49:20 +0000, Danny D wrote:

The o-ring in the funky fitting is in a different place than in a union; so in the end, I opted for the union (worried that the o-ring would leak).

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On 06/16/13 06:52 pm, Danny D wrote:

Yes, I used one to repair the connection to the manifold of our sprinkler system. Nobody talked me into it: as soon as I saw it, I knew that it was what I needed to do the job in the simplest possible way.
Perce
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*It looks like an expansion coupling. Probably just what you need to fit a new piece in.
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