[labnetwork] joining long PVDF pipe runs

[Paolini, Steven]

Iulian,
   In my experience over the years, I have seen PVDF replace PVC for DI piping with great success. PVDF is superior in keeping bacteria colonies at check and systems can be constructed with virtually no intermediate materials that would compromise its integrity. That being said, various construction methods can have various results. In the 4 methods you have listed, a fully welded system is superior to all others since there are less intermediate materials (O-rings, Teflon tape,Glue, etc.) and zero dead space at each joint. 
I can't imagine any other system being dramatically less costlier to install because the fittings you mention all require careful assembly. I would imagine using these fittings would require the same amount of labor that it would be to clamp a pipe and fitting into the infra-red heater then push them together. The tools designed for this operation are simple to use and once the settings are "zeroed in", the weld quality is consistent.  I am of the opinion that the quality of the product is a sum of the parts and would suggest a fully welded system with zero dead space valves designed for DI water.
Hope this helps,
  Steve Paolini
Harvard University Center For Nanoscale systems.

-----Original Message-----
From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Iulian Codreanu
Sent: Thursday, July 05, 2012 8:34 AM
To: Fab Network
Subject: [labnetwork] joining long PVDF pipe runs

Good Morning.

We are trying to determine how to best join long runs of PVDF pipe on our ultrapure water system (we are trying to achieve Type E-1.1 per ASTM D5127).  We are aware of the following methods:
- fully welded system
- systems using flanges
- systems using unions
- systems using GF sanitary couplings with clamps

Knowing how other University Fabs do it would be very helpful in making a decision (affecting water quality, cost, and schedule) and thus your input will be much appreciated.

Iulian
--
iulian Codreanu, Ph.D.
Director, Penn NanoFab
200 South 33rd Street
Room 376 GRW Bldg
Philadelphia, PA 19104-6314
P: 215-898-9308
F: 215-573-2068
www.seas.upenn.edu/~nanofab


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