Joined: September 12th, 2014, 3:32 am

June 19th, 2018, 12:02 am #21

DocsMachine wrote:
jecook wrote:... I take it schedule 40 PVC is right out?
-Yes, it is in fact "right out". 😁

PVC has a poor "fatigue strength", and after a certain number of cycles near its pressure rating, will at some point crack and fail.

It's not really an "if", it's a "when". It will eventually fail.

And when it does, it throws out shrapnel- it doesn't "peel open" like a beer can, it shatters like glass, throwing sharp fragments.

If it were as easy as using PVC, I'd have had a nice air line up over a decade ago. 😁 But I want something that I can put up and have a high degree of trust in for years to come. The RapidAir/MaxLine stuff is relatively new enough it doesn't have a particularly long track record, but the technology behind it (the way the fittings work and such) is pretty mature. I should be able to be pretty confident that this MaxLine stuff will last me at least the next ten years, maybe twenty.

Doc.
Duly noted! That shop was notoriously cheap in just about every other regard I can think of- they didn't maintain the compressor that fed that system, so when the pressure relief valve on it failed after everyone went home one night- as no one bothered to turn it off, it just kept running and running, which is why it burned itself out.  I'm actually surprised that the PVC system didn't fail during my time there, it looked like it had been there forever. Instead of replacing a $10 valve, they instead got to replace a $400+ compressor. *shrugs*
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Joined: October 8th, 2014, 2:05 pm

June 19th, 2018, 12:22 am #22

We have 1/2 inch copper all over our plant for the occasional blowgun, but I don't know what they use in the paint shop (with lots of spray booths) or the metal shop (mostly sheet metal, punches and the like). But I'm pretty sure we don't use plastic for anything except low pressure recovery circuits. (We have a number of intakes for sucking up hazmat out of he ground and venting it to the outside. The building is over 100 years old and has alternately been a machine ship, a print shop, and a transformer factory. We haven't found any dioxin yet, but give it time.)
If it ain't broke, I'll fix it!
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Joined: September 16th, 2014, 7:01 am

June 19th, 2018, 3:52 pm #23

NEVER use PVC for shop air - it shatters into shrapnel.  They make a special Green CPVC for air at chemical plants where metal pipe won't work, but it's seriously spendy.  Black steel is okay, but you end up with crap in your air.  Galvanized steel you get crap and zinc bits.

Me, I use silver-brazed copper lines, Make the high point after the compressor and air dryer, then have a slight slope down to the far end (1/8" to 1/16" drop per foot, doesn't need much) and drop to a drain fitting.  All tap tees go UP from the main then lateral to the wall, so you leave the moisture in the main line to go get trapped.
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Joined: October 28th, 2014, 1:06 am

June 19th, 2018, 5:50 pm #24

I can confirm that PVC shatters a lot like glass, when hit by a 200 mph car.  But so do traffic cones when hit at that speed.
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Joined: October 8th, 2014, 2:06 pm

June 19th, 2018, 6:43 pm #25

jecook wrote:40 PVC is right out.
Also known as 5.
This is a test. Explosions are a happy side effect.
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Joined: September 16th, 2014, 7:01 am

June 19th, 2018, 9:47 pm #26

And the "Class 200" PVC they sell for sprinklers is Absolutely Out - that (*stuff)  is thin as tissue paper.  The extra thick Schedule 80 is marginally better, but still No. 

And anything with Aluminum tubes...  Well you get galvanic corrosion, and it doesn't live long, especially when the airflow itself will create static charges.

PEX may be marginally safer, but I want to see some real safety testing done first. And while the Counterstrike style stainless flex for gas lines is approved for 5 PSI Restaurants down to inches-of-water Residential service, it's not cleared for anything higher.

Copper. Bite the bullet and do it.
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Joined: February 17th, 2016, 1:31 am

June 20th, 2018, 12:05 am #27

Well, since the good clean fun of PVC shattering seems to discourage the less adventurous, ABS might be a thing
(a remember from the old rec.pyro days of all things)

On somebody else's screen this might be useful info?
https://www.engineeringtoolbox.com/abs- ... _1594.html
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Joined: June 2nd, 2015, 3:34 am

June 20th, 2018, 12:22 am #28

Mr. Plastic Person here.

I love plastic,   I even have plastic manufacturing equipment at home.

But for air-line duty I use copper tube.   I simply do not trust plastic pipe in the various combinations of conditions that will be found in a shop.  Chemicals,  heat, pressure...   exposure to this and that...   

Copper can take the abuse and not fail in some heretofore unknown manner.    It's robust, and it's easy to work.   Best part is unless you are an asshole and specify rare and challenging to source fittings... it's fairly universal.

I only suggest PVC airline to people I hate personally and want to see suffer.   Also rival businesses.    And politicians who have shop-work hobbies.   
It is possible to commit no mistakes and still lose. That is not a weakness. That is life.
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Joined: September 16th, 2014, 7:01 am

June 20th, 2018, 3:02 am #29

And if you need the rare and oddball fitting for copper pipe you go to the Refrigeration House.  They stock all the odd in-between sizes of fittings and threaded adapters because some idiot companies can't just use the next size up, they have to match the flow demands precisely.  So they have the 1/8", 1/4" and 3/8" NPT adapters, and every single size step in elbows, returns, tees, and step-down adapters. from several sizes of capillary tubes going up into the 3" and 4" range.  And they're all expensive, but available. 

Real fun when you have to rework a 1960's Gaffers & Sattler lineset into a modern condensing unit - combine the Three 5/8" OD Tube suction returns in parallel (one 5/8" for liquid) into a single 1-1/4" suction on the condensing unit - Oh, and make it all lay flat so the refrigeration oil doesn't puddle in a low spot.
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Joined: April 27th, 2015, 3:26 pm

June 20th, 2018, 3:43 pm #30

DocsMachine wrote:-That's part of why I like it, too. With the copper, I'd been trying to figure out a clean and easy way to have a "wall tap"- I want a solidly-mounted QD connection, so that tugging on the hose, accidentally or purposefully, doesn't stress and possibly damage the tubing.

I was hoping I could find something sweat-on that was suitable, but I haven't been able to find anything even close. Making a block out of aluminum would be possible, but I tended to worry- justifiably or not- about galvanic action at each connection, with copper screwed into aluminum.

Doc,


Have you considered using a shower head "drop ear brass elbow" for the wall mount?
They have mounting ears to let you mount it to the wall, and they are designed to be sweated onto the copper pipes.
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