PTFE GASKET PERFORMANCE
Technical tightness of PTFE gaskets with microscopic glass bubble and barium modification
Third-generation PTFE materials have demonstrated suitability for use in both cryogenic and high-temperature hydrogen environments without sustaining damage , as detailed in a previously published Valve World article ( May 2024 ). To investigate the achievable tightness classes , GAIST , a spin-off of Münster University of Applied Sciences , conducted comprehensive tests . These tests measured the achievable technical tightness in two key areas : 1 . The cryogenic range , after ageing at
-196 ° C 2 . The gaseous range , with ageing at up to
200 ° C The tests were performed using a setup for component testing according to VDI 2290 ( pending approval ), as shown in Figure 1 . This rigorous testing methodology aimed to provide a thorough assessment of the gaskets ’ performance under extreme conditions .
Cryogenic sampling
Both images clearly show the effects of cryogenic storage before and after testing .
Results and technical tightness
The testing procedure involved two stages to compare the performance of the gaskets with different test gases . Initially , leakage was determined using helium in the first mounting of the flanges . In a subsequent test , the gas was switched to hydrogen , and leakage was measured at 1 bar . To address potential concerns about helium molecules potentially affecting the leakage paths for hydrogen molecules , the procedure was also conducted in reverse order , starting with hydrogen
1 . Result H2 first
2 . Result “ Helium behind ” Testing after H2 testing has already taken place
3 . Followed by renewed H2 testing
Figure 4 : Test procedure and results
Figure 2 : Deep-freeze test chamber with vacuum connection
“ Settling process ” / “ swing in ”: Until a constant leakage of molecules can be measured , only few H2 atoms escape .
Figure 3 : Deep-freeze test flange
Figure 5 : Result with barium modified PTFE gasket
26 Valve World September 2024 www . valve-world . net