PTFE VS PCTFE 2

[kpm21443]

What is the difference between PTFE & PCTFE. I have to order PARKER ball valve with PTFE seat but they are offering PCTFE seat. Can I accept PCTFE seat in place of PTFE seat

 

[ehbadger]

From Wikipedia:
(

https://en.wikipedia.org/wiki/Polychlorotrifluoroethylene)

Differences from PTFE

PCTFE is a homopolymer of chlorotrifluoroethylene (CTFE), whereas PTFE is a homopolymer of tetrafluoroethylene. The monomers of the former differs from that of latter structurally by having a chlorine atom replacing one of the fluorine atoms. Hence each repeating unit of PCTFE have a chlorine atom in place of a fluorine atom. This accounts for PCTFE to have less flexibility of chain and hence higher glass transition temperature. PTFE has a higher melting point and is more crystalline than PCTFE, but the latter is stronger and stiffer. Though PCTFE has excellent chemical resistance, it is still less than that of PTFE.[22] PCTFE has lower viscosity, higher tensile strength and creep resistance than PTFE.[1]

PCTFE is injection moldable and extrudable whereas PTFE [23] is not.[1]


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So, I would say it depends on the application of the valve. Do you have temp/pressure limits? What fluid/vapor service is it in? Seems like it would be OK for the vast majority of applications where PTFE is used, but there are bound to be specific, niche applications where PTFE is required rather than PCTFE.

 

[bcd]

Or in short, use of trade names may help.

PTFE = Teflon
PCTFE = Kel-F

Both are suitable for use for ball valve seats. Big difference is the PCTFE is harder and has higher friction. Impact of both factors is that it tends to require more torque to turn the valve open and closed.