Hi Sajit
you should have not slept through your chemistry classes.
By removing the salts from the water any buffering effect (remember buffering and chemical equilibrium?) is removed. That means any small change in acidity or alkalinity has a large effect on the "negative of the logarithm of the concentration of the hydronium ions (I think these ions may have fallen from fashion; it may now be hydrogen ions)", or pH. As you know high or low pH tends to attack (pipe) materials. So the demin water staying neutral is a little like walking on a tightrope; any tiny change and bang. Normally the minor action of the "neutral" water itself in contact with the pipe wall is enough to upset the equilibrium and cause a big pH swing.
Don't ask me to describe buffering in detail; I also slept through chemistry classes.
Hopefully, Bruce will give a more sensible reply, and correct my mistakes.
Cheers
Steve
-----Original Message-----
From: Sajit Viswan [mailto:sviswan@tebodin.co.om]
Sent: Saturday, July 10, 2004 5:20 PM
To: PipingDesign@yahoogroups.com
Subject: RE: [PipingDesign] water leak at PVC connection
[bcc][faked-from][bayes]
Bruce,
Why is deionized water more corrosive? Can you pls. reason.
Sajit
-----Original Message-----
From: Bruce Bullough [mailto:bbullough@sebesta.com]
Sent: Thursday, July 08, 2004 6:03 PM
To: PipingDesign@yahoogroups.com
Subject: RE: [PipingDesign] water leak at PVC connection
[bcc][faked-from][bayes]
Rommel:
You indicate that the PVC is being used for DI. I assume that is deionized water. Don't assume that DI water is an easy, straightforward use for PVC. DI water is quite corrosive and PVC (and typical PVC pipe cements) is not always a good choice for DI, depending on the conductivity of the water. CPVC and CPVC joint cement are better, but still often not the best solution. Your problem might not be the quality of the installation but the materials selection.
... Bruce D. Bullough ...
Sebesta Blomberg & Associates, Inc.
2381 Rosegate
Roseville, MN 55113 USA
+ 651-634-7344
www.sebesta.com
-----Original Message-----
From: rommel noderama [mailto:nrommelh@yahoo.com]
Sent: Wednesday, July 07, 2004 6:51 PM
To: pipingdesign@yahoogroups.com
Subject: [PipingDesign] water leak at PVC connection
[bcc][faked-from][bayes]
Dear All,
We are having a problem with our plant regarding the newly installed PVC pipes, we have encountered a lot of leaks from the joints, our current DI pressure is 80 psi.Can any one send me the procedure of PVC pipe installation, i know this problem is workmanship, they are using Weld-on as pipe cement for PVC joints.
Thanks,
Rommel
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