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Re: Air Compresser - Phase 2

To: Michael Tanner <Firesmith@voyager.net>
Subject: Re: Air Compresser - Phase 2
From: Bob Bownes <bownes@emi.com>
Date: Tue, 18 Mar 1997 11:48:27 -0500
Michael Tanner wrote:
> 
> Ok, now you have my interest as well.  I can't see that anyone else has
> warned about the hazards of using copper pipe for air, so I will ask the
> question.  Why not use either schedule M or L copper for air use?  I was
> initially planning on running about a hundred plus feet from my garage
> where my big compressor is located thru the basement into my other
> workshop.  I opted for a little portable nailer compressor in the shop, and
> scrapped the copper based primarily on hassle and cost.  What else argues
> against its use?
> 

The primary issue is that it work hardens over time. If exposed to
vibration
(by connecting directly to the compressor, easy to avoid) and thermal
cycling
(air out of a compressor, esp with a small tank, can be QUITE warm) it
tends to
work harden, get brittle and split. In large paint facilities, you will
used to see
'radiators' on the wall of black iron to cool the air down to extract
max moisture.
With newer technologies and better traps it's not quite so common. 

Now, this is easy speculation, so I'll throw in the real world
experience. Whilst
working at a college theater long ago & far away, we kept a 5Hp single 
stage 60 gal compressor in the basement. It feeds the iron air lines 
in the building with a section of flexible hose to isolate the
vibration. 
HOWEVER, the section that goes from the compressor itself to the tank
got 
crunched whilst moving the compressor during renovations. On of our more 
entrprising members replaced it with a short (~2ft) loop of copper water 
pipe that was handy. Time passes,(about 2 yr) I, along with a few 
others are working hard one night putting something together (we use 
almost exclusivly air tools btw, less likely to walk on campus...) 
when we hear something like a large caliber gunshot but with less 
boom to it and the air tools stop. Didn't take an RPI engineer to 
figure out what happened. The copper pipe burst. Now it didn't shrapnel, 
it just split along a linear seam, but it was in the basement, and it
was LOUD. 


Moral of the story: It's *probably* OK in *most* cases, but I'd be REAL
carefull
using copper. Yes, it is easier to work with, but not substantially
cheaper than
galv or black iron for home use.

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