Some may be interested in the related discussion thread at
<a href="http://www.eng-tips.com/viewthread.cfm?qid=125930&page=10">http://www.eng-tips.com/viewthread.cfm?qid=125930&page=10</a>
Randy Conner
-----Original Message-----
From: <a href="/group/PipingDesign/post?postID=OVM8wniJoLhqyjuHkRQdNhOSyCM0fBx2_aa1f6SffzoN0MaSSdscsgR6-y7BxIVBmAHu-M1tGua65fArtXkOZ7IVptkunQ">PipingDesign@yahoogroups.com</a>
[mailto:PipingDesign@yahoogroups.com]On Behalf Of Geoff Stone DD&D
Australia
Sent: Thursday, August 18, 2005 4:18 PM
To: <a href="/group/PipingDesign/post?postID=OVM8wniJoLhqyjuHkRQdNhOSyCM0fBx2_aa1f6SffzoN0MaSSdscsgR6-y7BxIVBmAHu-M1tGua65fArtXkOZ7IVptkunQ">PipingDesign@yahoogroups.com</a>
Subject: Re: [PipingDesign] Re: Code Velocity Maximums Plastic Pipe
Materials
Hi,
I am well aware of the waterhammer implications as this is the field in which I specialise in. Trust me I try and get engineers to do surge analysis of their systems however it appears they are only interested when the lawyers get involved after a failure. refer the paper on www.pipingdesoign.com about risk of surge.
One problem wih the closing of valves in a plastic pipe system is that because of the reduced wall roughness and thus reduced friction the pressure waves do not decay quickly. Also the celerity is lower as the modulus of plastics is lower than for ferrous pipe materials. Hence the time taken for the transient to travel to the end of the line and returns is longer. Therefore the critical valve closing time is increased.
I was hoping that there was plumbing code out there that has a specific limit to fluid velocity.
regards
Geoff Stone
jcluf <jcluf@yahoo.com> wrote:
ASME B31.3 does not specifically adress steady state velocities...
however the higher the flowing the velocity the greater the water
hammer possibilty. This to a great extent is reduced by the elastic
walls of plastics but on the other hand they have less strength for
surge pressures.
So before you start sending flow screaming down the line check the implications of this as far as water hammer is concerned... a good reference text is any of the books written by A.R. Thorley...
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