Butterfly valve: PTFE vs. TFE
Butterfly valve: PTFE vs. TFE
(OP)
I am selecting butterfly valves for Hydrochloric acid lines. There are two options for the liner/seat: PTFE and reinforced TFE. What is the major deference between these two teflons?





RE: Butterfly valve: PTFE vs. TFE
TetraFluoroEthylene is a gas. It polymerizes to become PolyTetraFluoroEtheylen, or PTFE.
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: Butterfly valve: PTFE vs. TFE
1. Filled with an inorganic fiber such as fiberglass. This hardens the polymer and will create a very high torque valve if bubble tight shut-off is desired. The need for glass reinforcement is questionable for just HCl service.
2. Dyneon TFM or Dupont NXT PTFE. These are modified PTFE's, which some people could use the term "reinforced", only for the purpose of separating these materials from the standard PTFE's. They exhibit better stability at elevated temperatures, therefore acting like a reinforced material. Again, for straight HCl, unless it's really hot, I don't understand the need.
RE: Butterfly valve: PTFE vs. TFE
On the subject of TFM and NXT, both of these are considered to be "modified PTFE", not "reinforced". My experince with the modified PTFE has been very successful. Permeation resistnace is improved and mechanical properties are enhanced.
All PTFE linings are not created equal. Investigate the thickness of the liner. One good measure is the spark testing. The higher the Kva used to check for pin holes the better.