PTFE lip rotary shaft seals

PTFE and composite rotary seals

A lip of PTFE rather than rubber, usually in a metal case or bonded to rubber. PTFE runs dry, takes chemicals rubber cannot, and reaches speeds a rubber lip cannot, at the cost of a stiffer lip that is less forgiving of runout.

When to use it

Dry running, chemical service, and speeds a rubber lip cannot hold. The fluid attacks rubber, the seal may run dry, or the surface speed is beyond a rubber lip. PTFE also runs at lower friction.

When another type fits better

• SC: Single lip, rubber-covered outside diameter, when an elastomer lip will do the job, since it is more forgiving of runout.

Watch for

A PTFE lip is stiffer than rubber and less able to follow runout, and it is measured on the Shore D scale rather than Shore A.

Also covered on this page

• ptfe-aux-lip: PTFE lip with an auxiliary lip. PTFE duty with contamination on the outboard side. As the PTFE lip, where dirt must be excluded as well.
• ptfe-rubber-composite: PTFE lip with a rubber outside diameter. PTFE lip duty where the bore also needs a rubber outside diameter. The combination: a PTFE lip for the shaft and an elastomer outside diameter for a bore that a metal case would not seal.