Keith and others: Regardless of the rated pressure, PVC is *NOT* safe
for use with air, and no manufacturer of PVC pipe or compressed air
equipment will tell you otherwise. And while it's true that sheetrock or
plywood may not contain shrapnel, the important thing is that metal pipe
does not turn into shrapnel. It just ruptures. PVC *will* turn into
shrapnel, and this is no myth, urban or otherwise. For more information
than you want, probably, and more stories than you can read go to
DejaNews and search in rec.crafts.metalworking for "PVC." Black Iron
pipe is a good material for airlines. So is copper pipe, provided it is
installed so as to allow free movement during expansion and
contraction--and it's a very good idea to convert to iron for the last
couple of feet at each termination. And install a flexible connection
between the compressor/air tank and the piping with either material. I
used a hydraulic hose for my isolator.
Keith Kaplan wrote:
>
> I think we all agree it would be bad to have an air line rupture. I
> don't think sheetrock or plywood would contain the shrapnel, regardless
> of pipe material.
>
> Schedule 40 PVC air piping is better than OK. It's much safer than iron
> pipe.
>
> I'd be scared to buy a house with old rusty iron pipe -- I can't tell
> how often the previous owner drained it, and I don't know how close it
> is to rusting through from the inside. I'd feel unsafe and I'd replace
> it with schedule 40 PVC immediately. Old PVC is still PVC, and it's
> still just as strong as ever. (I can't remember if PVC deteriorates
> long term with UV exposure, but there's not much danger of that indoors
> anyway. Heck, here in Seattle there's not much UV exposure outdoors
> either <g>.) Half-inch schedule 40 pvc is rated to 480 psi -- that's a
> whole lot more than most flexible air lines can say. If any line in
> your shop is going to rupture, it's probably going to be a flexible
> line, since they get dragged around, get stuff dropped on them, and are
> rated for less pressure to begin with. This is extra scary considering
> the fact that we all tend to work with flexible lines in close proximity
> to our bodies.
>
> Can anyone document a firsthand example of a schedule 40 pvc air system
> (meaning schedule 40 pipes & fittings) rupturing? Is this an urban
> myth?
>
> BTW -- Not that these considerations are anywhere near as important as
> safety, but pvc is much easier to work with (easy to cut, no threading
> machine needed) and it is much cheaper (10:1 last time I looked) than
> iron.
>
> keithka
> > -----Original Message-----
> > From: Berry Kercheval [SMTP:kerch@parc.xerox.com]
> > Sent: Thursday, October 02, 1997 10:25 AM
> > To: Eric Murray
> > Cc: shop-talk@Autox.Team.Net; kerch@parc.xerox.com
> > Subject: Re: PVC air piping
> >
> > I don't think anyone -- or at least very few people -- here is going
> > to tell
> > you "Yes, your PVC air piping is OK". Basically: no, PVC air piping
> > is
> > fundamentally unsafe. A (guessing here) 5 gallon tank and who knows
> > how much
> > pipe at 100psi holds a LOT of energy. When it all comes out a little
> > hole
> > spectacular things can happen. Bad things.
> >
> > And sheetrock really isn't very strong where impact is concerned. It
> > is quite
> > easy to punch your fist through it.
> >
> > Now, what would I do in your place? I don't think I'd use it. I'd
> > take some
> > measurements, go to the hardware store, get $40 worth of black pipe
> > and
> > fittings and screw it to the outside of the sheetrock. Sure it's
> > ugly, but
> > it's a garage, not your living room. And it's safe.
> >
> >
> > --berry
> >
> > Berry Kercheval :: kerch@parc.xerox.com :: Xerox Palo Alto Research
> > Center
> >
--
==brake cylinders sleeved with brass==
==One-Wire conversions and rebuild
kits for GM alternators 1963-85==
==Quincy, CA==
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