FEP encapsulated ‘O’ rings
These have a core of elastomer that is
completely covered with a seamless
sheath of fluorinated ethylene propylene
(FEP). The core is normally fluorocarbon
(FKM) or silicone (VMQ).
Encapsulated ‘O’ rings are generally used
when:
l A standard elastomeric ‘O’ ring has
inadequate chemical resistance for a
specific application, and
l A solid PTFE ‘O’ ring does not offer
sufficient elasticity for reliable, long-term
fluid sealing.
They are used where high levels of
chemical resistance or hygiene are
needed — typically in petrochemical,
chemical, food or pharmaceutical plant.
Although FEP encapsulated ‘O’ rings are
most suited to static duties, they may be
used with slow short movements on rotary
applications such as valve stem sealing.