Experimental Study on the Sealing Mechanism of Bidirectional PTFE Lip Seals

Seals made of polytetrafluorethylene (PTFE) are resistant to heat and chemicals and can run dry, but they do not pump back fluid. PTFE lip seals with a spiral groove do pump back fluid but only in one rotational direction. PTFE lip seals for both rotational directions (bidirectional) are not available on the market. At the Institute of Machine Components (IMA) of the University of Stuttgart, PTFE lip seals with bidirectional sealing aids were developed and analyzed. During the research, the leak-tightness in static and dynamic conditions was continuously improved. The latest design is leak-tight in both rotational directions. The sealing mechanism for this design is explained. The resulting seals can be used in conditions where elastomeric lips seals will fail.