PVC & CPVC are "no nos" for compressed air, brittle failure is
but it looks like PEX is ok
Tuesday, January 04, 2005
The introduction of PE tubing or pipes
Polyethylene (PE) is a thermoplastic material produced from the
polymerization of ethylene. PE plastic pipe is manufactured by
extrusion in sizes ranging from ? to 63". PE is available in rolled
coils of various lengths or in straight lengths up to 40 feet.
Generally small diameters are coiled and large diameters (>6" OD) are
in straight lengths.Polyethylene can be used in low temperatures (0 F
or colder) without risk of brittle failure. Thus, a major application
for certain PE piping formulations is for low-temperature heat transfer
applications such as radiant floor heating, snow melting, ice rinks,
geothermal ground source heat pump piping, and compressed air
PE pipe is recognized as acceptable plumbing piping for water services,
drainage, and sewer applications in most model plumbing codes. Verify
acceptance and installation of PE piping systems with the local code
enforcement authorities having jurisdiction.
PE pipe and fittings are available from plumbing supply houses and
various hardware retailers throughout the U.S.A. and Canada. PE pipe is
generally less expensive than metallic piping materials.
PE pipe must be labeled as follows:
1.The manufacturer's name or trademark
2.The standard to which it conforms
4.Material designation code (PE 2406 or PE 3408)
5.DWV if for drainage piping
6.Pressure rating if applicable
7.DR number or Schedule number
8.If the pipe is for potable water, a laboratory seal or mark attesting
This adresses hydrostatic pressure, not air pressure and the expansivness
and explosive power of it.
Yes, they are nuts too. OSHA forbids the use of plastic tubing for air
lines. If it was the right material, it would be rated for air and used by
industry. They don't, neither should you. I know of people that have had
serious injury when a system let loose.
Plastic tubing is rated for water pressure, not air pressure. There is a
difference and it can cause catastrophic failure and flying shrapnel. When
water is under pressure it expand very little and a blowout is minimal
damage. Not so with air that is compressed.
There are hoses and some tubing rated for air. Only use that or copper or
iron pipe. I've not seen any air ratings for pex yet.
I thought the same thing when I first saw this, but apparently PEX is OK
for compressed air:
Probably because it's flexible. But I don't think I'd trust it up here
in Minnesota where it occasionally gets down to -30 degrees F. I would
use it farther south, as long as it was protected from exposure to sunlight.
Unless I misread the info............
PEX-Al-PEX is ok for air but................. is regular PEX ok for air
I've seen it used in lots of labs for gas/air but at what pressures I
do not know.
The issue with PVC & CPVC is aging, brittle failure & the generation of
shards. My experience with PE is yielding failure, no frags.
I am not completely sure about the use of PEX for air & would suggest
further investigation before the OP does his installation.
PEX is not UV resistant & must not be exposed to sunlight.
I'd say not a good idea, by any stretch. Vanguard PEX cautions about
damages caused by solvents, etc (and kinks, scratches, gouges,
discoloring, evidence of grease, or "any chemical exposure shall not
be used"). As mentioned previously it's rated for water pressure.
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