Five Ways that PTFE Rotary Seals Differ from ElaomstericSeals

The PTFE Rotary Seal Difference 

PTFE rotary seals are often the answer when elastomeric seals just can’t handle the demands.  In this article we are going to look at just five ways that PTFE seals differ in performance and behavior from elastomeric seals.

Here are some additional blog posts from the Advanced EMC Technologies Blog:

•Out of Whack: Eccentricity and Runout in PTFE Rotary Seals

•PTFE Rotary Lip Seals - 6 Feature Competitors Don't Want You to Know!

•Rotary Seals for Dummies: Four Questions about Shaft Surfaces for PTFE Rotary Seals

Low Friction

Because of the incredibly low coefficient of friction that PTFE has, it can be used in applications where lubricant cannot be used.  This is referred to as “dry running,” and PTFE seals excel in these types of applications where elastomeric seals fail.

Speed

Because of the low friction and excellent wear capabilities of PTFE, most PTFE seals can withstand running speeds of up to 5,900 feet per minute, or 30 m/s.  This makes them ideal for speed-intensive applications where reliable sealing is vital.

Chemical Compatibility and FDA Approval

PTFE is known for its incredible compatibility with a variety of chemicals, which sets it apart from the elastomeric materials typically used in sealing applications. Many PTFE compounds already FDA approval and are commonly used in pharmaceutical, food, and dairy applications
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Operating Temperatures

Another benefit of PTFE rotary seals over traditional elastomeric rotary seals is the temperature range over which they can operate.  Most PTFE seals can perform in the cryogenic temperatures all the way down to -95°F up and up to extremely high temperatures of 480°F.

Relationship between Speed and Friction

The hydrodynamic film all the separates the seal lip from the movie.How much friction exists between the seal and the sealing surface is a function of the thickness of the hydrodynamic film.  The film pulled into the gap between the seal and the surface by viscous drag.  When the shaft is at rest, this layer will be at its minimum thickness and a certain amount of torque will be required to overcome the initial resistance to motion. Friction decreases as the velocity increases up to a point; after that speed is reached, friction will again begin to rise and the seal may begin to experience wear.  However, PTFE has a very low coefficient of friction to begin with, and may often be an exception to this rule.

PTFE Seals Alternative

The next time you are choosing a dynamic seal for an application that involves high speeds, extreme temperatures, a need for low friction, FDA approval, or chemical resistance, don't forget to look into PTFE seals as an alternative to the traditional elastomeric dynamic seals.
For more detailed information on PTFE Rotary Shaft Seals download Advanced EMC Technologies resource guide.

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