Does it matter at all whether PVC unions are on one way or the other?

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I'm a big believer in doing things the right way, or, at least knowing what the right way is (so that the next time you do it the right way).
So I ask what seems like a very basic question: Q: Does it matter which direction I put these 2" PVC unions on?

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ot by this site
No.
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harry;3060927 Wrote:

+1
If it mattered, then the manufacturer of the union would mold an arrow into the side of the union indicating the direction of flow; just like they do on check valves.
You see arrows like that on globe valves (and I'd expect needle valves too)cuz the disk is meant to close against the flow. You don't see them on gate valves, butterfly valves or ball valves cuz in those cases the closure isn't affected by the direction of flow.
--
nestork

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On Sun, 12 May 2013 20:53:33 +0200, nestork wrote:

This makes sense.
BTW, I just noticed that what I *thought* were schedule 40 unions were actually schedule 80 unions:

I wonder why these schedule 80 unions are white and not gray?
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On 5/12/2013 10:05 AM, Danny D wrote:

The black and white one seems to be mismatched. I learned the hard way that even though they seem to go together, the threads may not fully mate, allowing the outside ring to slip when tightened.
Also, if the "O" ring is in the removable part, you will be able to better keep track of it when it comes out of the groove.
A union that is vertical should have the ring on the upper part. that way gravity will help getting the threads started.
Otherwise, as stated, not much difference.
Paul
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the right way, or, at least knowing

g

Doh! I warned him about that a few days ago. Said I wasn't sure that half of one union would mate correctly with half of another, because they may not be designed exactly the same. I've never tried to do that because I'd be concerned about it leaking. And also you have the other half of the new union whether you use it or not.
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On Sun, 12 May 2013 14:39:30 -0700 (PDT), " snipped-for-privacy@optonline.net"

He could still get the all black** union at a plumbing supply store, right?
I just looked for a black 2" checkvalve and had no trouble finding one.
**I can't remember if black is PVC, APS, JPG, or whatever.

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On Sun, 12 May 2013 21:06:57 -0400, micky wrote:

The black is black paint on top of white schedule 40 plumbing.
The reason for the black paint is to prevent UV degradation of the PVC pipes.
I looked it up a while back, and, it turns out that the pipes get "brittle" in the sun; so they're almost always painted black if they're outside (like mine are) in the blazing sun.
Here you can see the white pipe hasn't been painted black yet as I just finished the plumbing today ...

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wrote:

Ah, you mean in the pictures in this thread. At first I thought you meant all black 2" plastic pipe was white pipe painted black.

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On Mon, 13 May 2013 04:06:36 -0400, micky wrote:

I'm no expert, but my pool equipment is white schedule 40 PVC pipe painted black to protect it from the sun.
When I went to Home Depot, all the schedule 40 PVC was white; the schedule 80 PVC was mostly gray (the schedule 80 unions were white); and the drain pipe was black.
Not sure if that holds true elsewhere though ...
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wrote:

Hardware stores, maybe including HD used to sell mostly black plastic pipe, and no white plastic pipe, but white came in later and I guess it's better in some way, because that is all HD has now. (Maybe grey pipe too but that's the flexible stuff I havent' used.) To get black recently (so it would mach my basement sink drain and my sump pump drain) I had to go to a plumbing supply store.
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It seems to me a curious thing that they paint them black. Not only is black ugly, but it absorbs more heat from the sun. White paint would offer UV protection, look better, and absorb less heat. That's what I use where that is an issue.
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On Mon, 13 May 2013 06:37:41 -0700, snipped-for-privacy@optonline.net wrote:

You have an interesting point there, in that it's the 'paint' and not the 'color' of that paint that protects PVC from UV radiation.
Dunno why mine are black ... but ... since they are ... I'm going to get out my license to prove I'm over 18 and have them unlock the double padlocked spray paint cage at Home Depot when it's all working and buttoned up ... and grab me some flat black stuff to go!
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wrote:

I thought the minimum age for paint was 35.

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ngs the right way, or, at least knowing

).

That isn't the issue. He has a PVC union. The issue is that one half of a 10 year old union from manufacturer A may not seal correctly with one half of a new union he buys today from manufacturer B. It might work, it might not. Unless it's difficult for some reason to replace the whole union, I don't see why anyone would screw around. And you already have the other half paid for, because you can't buy half a union.

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On Mon, 13 May 2013 06:31:45 -0700, snipped-for-privacy@optonline.net wrote:

I understand.
If it leaks, I'll replace that part of the plumbing, since, with the unions, everything should be easy.
If it's any consolation, that unused "yellowed" union is, in fact, the same age and batch as the existing "blackened" union is.

To explain further, about a year or so ago, I had replaced a broken Jandy valve after draining the pool, and at that time, I added the one now-blackened union on the outlet of the pump. I knew that a union only on the outlet pipe without a union on the inlet pipe was useless, but I was adding it knowing that someday (like yesterday) I would be adding a union to the inlet side of the pump.
I had bought two unions at the time, so I left the unused union outside in a plastic bucket. Over time, that unused union yellowed.
So, the good news is that the unions are 'matched' in time and batch; the bad news is that one sat outside in the hot sun for a year.
I'll let you know if it leaks; but if it does, it will be easy to replace, since the hard part was always the inlet side, and not the outlet side.

Note: If it wasn't easy to replace, you can rest assured I would have used all new equipment!
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wrote:

Is this just a swimming pool or is it something bigger?
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On Wed, 15 May 2013 18:46:39 -0400, micky wrote:

It's a big swimming pool ...
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On Sun, 12 May 2013 14:39:30 -0700, snipped-for-privacy@optonline.net wrote:

I did read that; and I do agree that I'm putting half an old union with half a new union.
Time will tell.
Now that the hardest part (the parts at the Jandy valves) has been cut out, repairs on all other sections should be much simpler, in case they leak.

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On Sun, 12 May 2013 13:06:13 -0700, Paul Drahn wrote:

Makes sense.
Since all mine were horizontal, I simply arbitrarily faced them all in the same direction (as each other).
That way, I can swap pumps if I ever need to.

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