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Which is Superior for a PTFE Rotary Shaft Seal: A Metal Case or a Non-Metal Case?

INTRODUCTION:metal_vs_non_metal_ptfe_rotary-shaft-seals

The two main parts of a rotary shaft seal are a rigid outer case and the flexible sealing lip (typically made of an elastomeric material).  The outer case provides the stiffness and structure needed to keep the seal stable, and protects the lip during installation. 

A popular choice for the sealing lip is PTFE, better known as Teflon.  Its chemical compatibility, low friction, and outstanding performance at high speeds have made it a favorite among engineers.  However, what is the best case material to combine with a PTFE lip for rotary shaft seals?

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6 Things You Should Know about Cryogenic Seals

PTFE cyrogenic seals

Cryogenic seals provide a mechanical containment mechanism for materials held at cryogenic 
temperatures, such as cryogenic fluids. Various techniques, including soldering and welding are available for creating seals, however specialized materials and processes are necessary to hermetically entrap cryogenic constituents under vacuum-tight conditions. Most commonly used are liquid helium and liquid nitrogen, which boil at very low temperatures, below -153 °C (120 K), as well as hydrocarbons with low freezing points and refrigerating mixtures. – information from Wikipedia.com.

The demand for seals for use in cryogenics applications is increasing, and there are certain facts about them that all engineers should now.  Here are six things you should know about cryogenic seals…

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