[Shop-talk] Plumbing a shop (it's that time of the year again)

[David Scheidt]

On Mon, Nov 16, 2009 at 12:50 PM, Matt <mbarre at juno.com> wrote:

> I know some folks don't like it, but since I read some of the debate I have
> been watching how various places have handled their air and I continue to
> see
> the vast majority here in GA with PVC.  That includes garages, shops and
> light
> manufacturing.  I  used it in my shop and haven't had any problems.
>
> Are there any regulatory or OSHA prohibitions?
>
>

Hell yes.  PVC pipe is not allowed for above ground transport of compressed
gases, unless you put it in a conduit that will completely contain the
explosion.  (and protect the pipe from being shattered. )

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=INTERPRETATIONS&p_id=20202

(A 5(a)(1) violation is usually a fine and required corrective action (i.e.
replace the air lines with something safe), but depending on what else
you've done to piss the inspector off, he can tell you not to use any
compressed air on the premises until he's satisfied you do it safely.  And
when someone is injured because the pipes blow up, it's a slam dunk for
their civil case against you.)

there are plastic pipes that are approved for compressed air use.  They cost
a whole lot more than PVC (as much as copper, I think), but they're easier
to install, and are resistant to various contaminants, so they have their
place.


Eric: whatever piping you use, lay the system out properly.  The best
practice is a loop, with some slope to one corner.  Ideally, that's also
where your feeder riser is, so that condensate drains towards the
compressor.  You should feed the middle of the riser, so you can have space
below the compressor for condensate and sludge and scale to accumulate, with
a valve to allow you to drain.  Take your drops from the top of the loop, so
that they don't catch condensate running back to the riser.  Put a T-
fitting towards the end of the drop, and use the leg of the t for the
fittings.  Put a valve past the T to allow the drop to be drained.  Yes,
this requires more materials, but not that much, and you'll have cleaner,
drier air and better results because of it.
-- 
David Scheidt
dmscheidt at gmail.com