From: John De Armond
Newsgroups: misc.consumers.house,rec.autos.tech
Subject: Re: Piping an air compressor for home DIY?
Date: Fri, 01 Jun 2001 19:45:34 -0400

"Werehatrack [Russ Ault]" wrote:

> Kirk <kirkdarlingnotathome@mindspring.com> wrote:
>
> >
> >I intend to install a simple piping system for an air compressor for
> >my DIY mechanical auto work (impact wrench, etc) and remodeling
> >projects (framing nailer, etc).  I'll put the compressor in the
> >garage, but I'd like to be able to run a line with a couple of outlets
> >in the attached garage and then into my basement craft room.
> >
> >I'm looking at 1-inch soldered copper tubing for the materials.  But
> >I'm not seeing any readily available couplers to connect the tubing
> >with the air couplers.

1" is overkill.  3/4" trunks and 1/2" for spurs is more than
enough.  You can get the copper sweat-to-1/2" NPT female fitting
anywhere they sell copper fittings.  Either get a 1/2" to 1/4" NPT
bushing for each coupler or get couplers with 1/2" NPT male
nipples.  I install a 1/2" ball valve on each coupler so I can
isolate the coupler in case it leaks and depressurize a hose without
having to uncouple it.

If this isn't clear, drop me a note and I'll email you a photo.

Forget the lead-free solder.  You get one shot at getting it right.
If you don't, you get to take the joint apart, clean it and try
again.  Conventional 50-50 works great with acid flux and is very
forgiving - important when you're reaching out as far as you can to
get to that laasst joint. :-)

> >
> >How are other people doing this?  Any other tips or pitfalls to watch
> >out for?

Support the tubing well to prevent it from vibrating - very
annoying.  Put a block valve on each coupling.  Include trash legs
on trunk line vertical runs.  Include a water drain cock on the
trash leg.  Helps keep crap and water out of your tools.  Where
possible, slope the lines back toward the compressor or the nearest
trash leg.  This helps keep condensation out of your tools.  Install
a good moisture dryer/coalescer at the compressor tank to keep
moisture and oil out of the lines.  Do a full bore blowdown on each
line before putting it in service to blow out metal chips, trash,
etc.  Remove the coupler and crack the ball valve fully to do this.
If possible, flush the lines with soap and water before putting it
in service to get corrosive flux residue out of the lines.

DO NOT USE PVC WATER PIPE FOR AIR!  It is not designed for stored
energy (compressed gas) service and is not resistant to the oil that
is almost always in the air.  When the tube pipe fails, shrapnel is
propelled with enough force to injure or blind.  Circle Track
magazine did a feature on this a few years back where they showed
photos of catastrophic pipe failure and some injuries that
resulted.  Special thick wall high pressure PVC tubing rated for
compressed gas is available but it is as expensive as copper and
still less sturdy.

>
> The last person I saw trying to use soldered copper for this purpose
> regretted it.  Too much vibration, and too much strain on the end
> fittings; they kept getting snapped off.  Of course, he made a big
> mistake in trying to hook the compressor to the pipes without a flex
> hose, which is a mistake in my opinion.

Obviously it wasn't the copper tubing, it was the idiot
installation.  I've had copper tube air plumbing in my shops for
probably 20 years and have moved the same tubing to several shops as
I've moved.  I hook the trunk to my 5 hp compressor using corrugated
copper flex water heater line.  No vibration and no leaks.  This
flex tubing is designed to thread directly to 3/4" NPT male pipe.


John