<VV> Re: Air compressor distribution lines - NO Corvair
Frank DuVal
corvairduval at cox.net
Tue Nov 1 22:50:08 EST 2005
>Message: 3
>Date: Tue, 1 Nov 2005 18:11:32 EST
>From: UltraMonzaWest at aol.com
>Subject: Re: <VV> Air compressor distribution lines - NO Corvair
>To: virtualvairs at corvair.org
>Message-ID: <1d7.48d0d7a9.30995024 at aol.com>
>Content-Type: text/plain; charset="US-ASCII"
>
>In a message dated 11/1/2005 11:52:58 AM Pacific Standard Time,
>Rt66Vairs at aol.com writes:
>
>
>
>>Honeywell did tests with PVC for compressed air in the early 70s.
>>
>>It failed to make the grade.
>>
>>We were shown the results at classes in Minneapolis that I attended in
>>1974.
>>
>>I suspect PVC is PVC. In 1974 and 2005.
>>
>>
>>
>******************************************************************************
>*****
>And in the 70's Corvairs still leaked oil! [ BUNA M] !!!!!
>
>PVC today is totally different......Sch. 40 has always been TOTALLY
>different then sch. 125!! What you're guys were surely testing....
>
>
>
>Matt Nall / Patiomatt / WCUH / Mr. DeckRug
>69 Monza Cpe., 66 Monza vert, 65 Crown v8 Cpe.
>Somewhere between Reno, NV and Coos Bay, Or.
>
>
>
>
>
In the 70's Clarks and others were selling/promoting silicone and viton
O rings to Corvair owners. Buna-N was not a good Corvair O ring.
Polyvinyl chloride is still polyvinyl chloride. If the formula changed
significantly, it would have a new acronym. Like the newer products PEX
and CPVC.
If you would do some research on the web you would see:
For those wondering what schedule 125 PVC is ( I had never heard of it
and I worked in a plumbing supply warehouse in the 70's) I went to:
From Jess Stryker's
Landscape Sprinkler Design Tutorial:
http://www.irrigationtutorials.com/sprinkler13.htm
snip "PVC is the type most commonly used in warm winter climates. PVC
pipe is rated by two different systems, the first is the "class" system
(Cl) the other is the "schedule" system (SCH). It is not possible to say
that one is always better than the other. Schedule pipe is rated by the
pipe's wall thickness, while class pipe is rated by the pipe's operating
pressure. All PVC pipe of the same size will have the same outside
diameter, regardless of which type or rating they are, so the same
fittings will fit all of them. Most PVC pipe is connected together using
"PVC fittings" which are glued in place. The fittings are typically
rated as SCH 40 (standard white PVC fittings), some are available as SCH
80 (stronger and normally gray color). Sometimes PVC pipe has threaded
ends just like steel pipe. PVC pipe and steel pipe have the same outside
diameters, and threaded steel pipe fittings will fit on threaded PVC
pipe." unsnip
Thus I learned PVC comes in schedule 40 and 80, and also class 125 (for
125 psi rating). No schedule 125 PVC pipe. More searching produced class
150 and class 200 pipes for water supply companies (large underground
utilities).
For suitability of PVC pipe for compressed air I went to a manufacturer
of PVC pipe, http://www.charlottepipe.com/
Here on page 15 of their technical and installation manual for PVC
pipe(http://www.charlottepipe.com/Documents/Industrial_Tech_Manual/Industrial_Tech_Manual/html/Industrial_Tech_Manual.html)
it states:
"PVC AND CPVC PIPING PRODUCTS ARE NOT RECOMENDED FOR SYSTEMS WHICH
TRANSPORT OR STORE COMPRESSED AIR OR GASES. DO NOT TEST PVC OR CPVC
PIPING SYSTEMS WITH COMPRESSED AIR OR GASES. ALWAYS BLEED ALL ENTRAPPED
AIR FROM THE SYSTEM PRIOR TO TESTING."
For another manufacturers statement I went to
http://www.harvel.com/piping-clear-pvc.asp
snip "Harvel Plastics, Inc. does not recommend the use of this product
or other rigid PVC/CPVC piping products for the transportation or
storage of compressed air or gases, nor the testing of these systems
using compressed air or gases." unsnip
I could find no manufacturer that recomended PVC pipe in any form,
class, or schedule for compressed air.
All you people using PVC for compressed air lines have been warned. It
could work for years, but when it fails.....There is a reason the ASME
has testing procedure for compressed air tanks before they can be sold.
Can you supply me with ASME data to support the use of PVC pipe or
components in a compressed air system? ASME is The American Society of
Mechanical Engineers
<http://searcht.netscape.com/ns/boomframe.jsp?query=asme&page=1&offset=0&result_url=redir%3Fsrc%3Dwebsearch%26requestId%3Db08acba8ac2ccbaf%26clickedItemRank%3D1%26userQuery%3Dasme%26clickedItemURN%3Dhttp%253A%252F%252Fwww.asme.org%252F%26invocationType%3D-%26fromPage%3DNSCPToolbarNS%26amp%3BampTest%3D1&remove_url=http%3A%2F%2Fwww.asme.org%2F>
. This kind of reminds me of those people using old water tanks to hold
compressed air, another Don't!
Frank DuVal
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