Power mains question: wire gauge

wrote:


I bet people are using Pex to carry air these days. Pex is displacing copper pipe for residential water service as well. The plumber installing Pex for part of my circulating hot water heating system commented that if one bids straight copper, one does not win the job.
Joe Gwinn
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On Mon, 14 Jan 2013 09:44:47 -0500, Joseph Gwinn

I thought about using PEX, though wasn't sure if it could take the pressure. A faulty regulator can easily dump 120-200lbs into the system. At least it wouldn't shatter like PVC, though. It's an idea, though I think I already have about half the copper I need for the job. ..though that probably means I'm short 3/4. ;-)
My other house has PEX for its water supply. I have no idea if the house is "normal" but I don't like the stuff. Only one of the outside faucets has any volume and the inside faucets are all weak. It seems there is a lot more pressure/volume lost in the distribution than there is in either the copper systems I've had in the past or the PVC in the new place. One big advantage of PEX for water is temperature stability (someone flushing a john doesn't scald the person taking a shower). Another is the manifold allows one to turn off individual appliances. It's handy for turning off the silcocks in the Winter, though I added ball valves to the distribution system (copper) in my VT house to accomplish pretty much the same thing.
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wrote:

Here is some PEX data: <http://www.pexuniverse.com/pex-tubing-technical-specs
At 74 F, the rating is 160 psi. The installation proof test is 1.5 times that, or 240 psi. That ought to work.
As for broken regulators, if it's a real problem, I would add a simple overpressure relief valve to handle regulator blowout, protecting more than just the tubing.

Sounds like the installer cheaped out and used too small a diameter of tubing/pipe. This never happens with copper pipe. Never....
Joe Gwinn
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On Tue, 15 Jan 2013 10:35:53 -0500, Joseph Gwinn

Depending on the result, it might be something to worry about. With copper, not so much. PEX probably not, either, but it's failure mode would be important. PVC, absolutely!

I've never seen anything less than 3/4" and 1/2" in homes. Sure, I've seen problems with temperature regulation when they cheaped out but never a supply problem. Even 1/2" was plenty for a hose bib or a kitchen sink. ISTM, that PEX has a *lot* more resistance than copper.
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wrote:

The inside of PEX is just as smooth as the inside of copper pipe, and there are usually fewer ells needed with PEX (or copper tubing for that matter). Something else is the matter.
Joe Gwinn
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looking on the internet I see lots of installations with what appears to be very fine PEX tubing.
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On Fri, 18 Jan 2013 17:22:34 -0500, Joseph Gwinn

There are NO straight runs, either. Anyway, from my experience, it sucks for water distribution. I'm not all that happy with the PVC I have now, either. Copper is so easy...
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On 1/15/2013 12:47 PM, snipped-for-privacy@attt.bizz wrote:

Just to be sure, I pulled out an ohm meter to check it and yup, you're right, PEX has a *lot* more resistance than copper.
Rick
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;-)
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On 1/14/2013 9:44 AM, Joseph Gwinn wrote:

The Romans used lead to carry their water and as a result some developed lead poisoning. Plastic is the new lead.
Rick
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Utter nonsense. I'd expect as much, though.
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rickman wrote:

No, idiot. They used a lead acetate compound to sweeten their wine.
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John Larkin wrote:

Hose? What's wrong with iron pipe? Good old fashioned black iron pipe. That has been beat to death on news:rec.crafts.metalworking
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On Mon, 31 Dec 2012 17:39:35 -0500, "Michael A. Terrell"

Pretty expensive at the per foot level compared to modern plastic solutions.
And hose would work too.
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On Mon, 31 Dec 2012 17:33:05 -0800, DraconisExtinctor

The plastic (PVC) I've seen is *not* recommended for air supply. It will shatter. Do you have other information? Cite?

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On Tue, 01 Jan 2013 11:10:37 -0800, DraconisExtinctor

PVC can shatter and fling bits at high velocity. Other plastics are better for air.
If a PVC pipe is pressurized by water, and it breaks, the shards have a much lower velocity than if the pipe carried air.
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On Tue, 01 Jan 2013 18:20:48 -0800, DraconisExtinctor

Correction: Go back to your blatantly obvious hard core senility onset. Anyone who has seen your posts over the years can see it. it is so obvious. Sad for you.
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On Mon, 31 Dec 2012 13:50:29 -0800, John Larkin

Pressure would remain constant. Flow *can be* constricted over that distance.
Think hysteresis. Pressure does have a slight drop as one "loads" the available flow (stored energy). Once you cross that threshold and the flow rate becomes the bottleneck, pressure can drop on a continuous duty "draw".
Just run plastic pipe. They even have tool-free fittings for pneumatic service.
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On Mon, 31 Dec 2012 17:31:33 -0800, DraconisExtinctor

Oh shit. not the plastic pipe for air thing!
Don't you know that will explode and kill everyone on the block.
This will be good for another 100 posts. ;-)
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On Tue, 01 Jan 2013 11:36:53 -0500, snipped-for-privacy@aol.com wrote:

You should watch the "How It's Made" show on how they make big racing sails.
The point being that piping technology has come a long way since the stuff they use for water came out.
Sails have come a long way in the thousands of years it took us to get to that level.
It is a really good episode. You should check it out.

http://www.youtube.com/watch?v=kVa1-pwARmI

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