Teflon vs PEEK valve seats

[Ken_438]

Hi guys,
I am purchasing some valves for a client using their datasheets.

1. The CL 150 valves specify RPTFE seats however the supplier is providing filled PTFE and High performance PTFE seats.

2. The CL 600 valves specify PEEK seats however the supplier is providing Teflon seats.

Are these acceptable alternatives? What properties should I compare to deem these materials as acceptable alternatives?

 

[chez311]

Teflon is the brand name for PTFE, so it looks like whatever your supplier you're using is only supplying one type of seat (PTFE) regardless of what is specified. RPTFE is just Reinforced PTFE - in order to determine what was specified vs. supplied you would have to consult the specs for the exact material specified to determine the filler material (probably glass) and what percent fill.

I know its not helpful but it is highly dependent on your application. I can say though that if an application calls for PEEK, PTFE will very likely not be an acceptable alternative. PTFE has excellent chemical resistance over a broad range of chemicals, but PEEK has far superior mechanical properties - especially so at high temperatures. I believe though PTFE being a fluoropolymer has slightly better chemical resistance than PEEK. "Better" is a relative term here though - you would have to again look at the material specs for each to determine if whatever chemical(s) in your working fluid is compatible with the material specified.