shop air lines

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mbensema

Re: shop air lines

Post by mbensema »

Sorry, I goofed! It was supposed to read type K or L. That is from the US Army online guide with their standards. http://www.usace.army.mil/inet/usace-do ... /chap8.pdf
You can check the properties of copper tubing at this website http://www.copper.org/tubehdbk/book.ihtml to see how what you are buying at the store compares to other grades.

Sorry for the confusion.

Mike
GeneT
Posts: 177
Joined: Sat Jan 04, 2003 9:36 am
Location: Albany, Oregon

Re: shop air lines

Post by GeneT »

Nice resource, thanks! I just checked my pipes and they are indeed Type 'L'. (As previously mentioned, just what I found at Home Depot.)
GsT
philinmt
Posts: 77
Joined: Mon Jan 06, 2003 7:57 pm
Location: missoula, montana

Re: shop air lines

Post by philinmt »

Use copper pipe and a flex hose to your tank...no rust....Phil in mt
NAMPeters
Posts: 50
Joined: Sat Jan 04, 2003 6:25 pm
Location: Phoenix & Arlington, Arizona USA
Contact:

Re: shop air lines

Post by NAMPeters »

One thing not mentioned about PVC is that it is not really impact resistant, hit it hard and volla an explosion with crap flying every which way. Now copper and iron may dent or kink and in worse case get punctured and make a hissing noise. Things do at times in a shop fly about or the hammer misses its mark etc and having PVC is just asking for trouble unless of course you want to learn the hard way and quallify for a Darwin Award.
Neil (Chief Hinder Scratcher) Peters
Doug_C
Posts: 1254
Joined: Sat Jan 04, 2003 6:48 pm

Re: shop air lines

Post by Doug_C »

Hey Jacin,

This is where I think the terms get confused in the rated pressure for PVC.

Considering water is not compressible and acts like a hydraulic fluid. Once a rupture occurs the release is rapid enough to eliminate the velocity factor to throw an object.

Air being compressible, the release is extended to an indeterminate velocity and whimpy plastic becomes a projectile.

The properties in elongation of PVC is close to zero. The elongation of copper can be 30%, give or take 15%.

When it goes off, will it be a pop gun or a dart gun? [img]/ubb/images/graemlins/confused.gif"%20alt="[/img]

Ya can't play Russian Roulett without it loaded, ya know!! [img]/ubb/images/graemlins/grin.gif"%20alt="[/img]

DC
Richard_W
Posts: 2031
Joined: Fri Jan 10, 2003 1:00 am
Location: Molalla, Oregon

Re: shop air lines

Post by Richard_W »

I seen PVC pipe explode and it's not pretty. The entire machine shop was plumbed with the stuff. They also had a short length of rubber hose connecting the compressor to the line. Where it blew was in the next room near the ceiling.
No one has mentioned the pulling on the pipe by the user, while pulling the hose in to position where they intend to use it.
I wouldn't use the stuff or suggest any one else use it.

Richard W.
Jacin
Posts: 1046
Joined: Sat Dec 21, 2002 12:14 am
Location: Near Cleveland, Ohio

Re: shop air lines

Post by Jacin »

Doug, I'm right there with ya.
Good design starts with a Risk analysis - this is often watered down to a cost/benefit analysis. In this case we Risk very predictable injury for what ? to save a couple bucks and make installation easier. No reasonable person can defend this - not to me.
Heck I won't even use PVC for my pressurized water lines! I've seen it fail there. As a matter of fact I seem to recall the LARGEST recall in manufacturing history was PVC water lines. Something about them not contracting expanding properly resulting in failure.
Nope! Just too risky. Throw in the potential energy of a compressed gas and it spells disaster.

It is the same reason they "hydro test" presure vessels with water instead of air. Can you say jet propulsion? Or better yet jet explosion - that's gonna be one heck of a POP GUN [img]/ubb/images/graemlins/smile.gif"%20alt="[/img]
Forrest_Addy
Posts: 76
Joined: Sat Dec 21, 2002 1:54 am
Location: WA

Re: shop air lines

Post by Forrest_Addy »

PVC works but there have been incidents. PVC is brittle.

Most guys seem to prefer sweated copper for air lines. It's clean, not too expensive, and doesn't rust. Just be sure your last joint before the drops are securely fixed to the wall and you use Sch 40 to get to your water trap/filter/regulator/QD.

A lot of guys buy needlessly large air line piping thinking it'll "help the flow" or "keep the pressure drop down". Air is lots skinnier than water and in 25 CFM bursts, 3/8" or 1/2" trade size is plenty for runs of less than 100 ft.
Jeff_Pack
Posts: 5
Joined: Wed Jan 08, 2003 9:26 am

Re: What type of solder?

Post by Jeff_Pack »

Solder, dunno, as was done by a professional.

Pressure, I run 175 at tha tank, 120 through the lines.

Only thing I wish, was I'd used 1/2in, instead of 3/8th's lines.
swellwelder
Posts: 2
Joined: Fri Jan 10, 2003 11:40 am

Re: shop air lines

Post by swellwelder »

I agree with everyone about not using pvc pipe as air lines, and will add this thought. Every airline is subject to being bumped, sometning will fall against it, or any of a hundred things that might not crack the tube, but may create a weak spot, that over time will cause the pipe to fail.
daryl_bane

Re: shop air lines

Post by daryl_bane »

Along with copper, if you can route your lines in ascending order to drains and feed your outlets over the top of your main line ( textbook style), you'll find you have very little water in your air.
Dave_V
Posts: 72
Joined: Sat Jan 04, 2003 7:16 pm
Location: SW Lower Michigan

Re: shop air lines

Post by Dave_V »

I'll chime in here and add the following:

In support of using smaller piping for air distribution, two things come to mind.

Smaller copper will have a higher pressure rating.

The higher velocity of the air stream ( in smaller piping ) will aid in separating water droplets from the air IF the system is PROPERLY designed and installed.

Always provide for a downward slope of the main and branch runs in the direction of the air flow ( down and away from the compressor ). This keeps the droplets moving and there is less of a tendency for them to re-evaporate ? into the air stream. Follow Daryl's advice and pull from the top of the runs. When the air turns the corner, the droplets are likely to be on there way to the drain points at the end of the line.

Dave
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