The seal that a teflon o ring creates can either exist in a motionless joint, such as between piping, or a movable joint, such as a hydraulic cylinder. However, movable joints often require that the teflon O-ring be lubricated. In a moving enclosure this ensures slower deterioration of the teflon O-ring and therefore, extends the useful life of the product.
Teflon O-rings are both inexpensive and simple in design and are therefore very popular in manufacturing and industry. If mounted correctly, teflon O-rings can withstand a very large amount of pressure and are therefore used in many applications where leaks or loss of pressure are unacceptable. For instance, teflon O-rings used in hydraulic cylinders prevent leakage of hydraulic fluid and allow for the system to create and withstand the pressures required for operation.
Teflon O-rings are even used in highly technical construction such as space ships and other aircraft.
Of course, different types of O-rings made out of different materials are used for various tasks. The teflon O-ring needs to be matched to its application. Do not confuse however, similar inventions that are not round. These objects are brother to the O-ring and are instead simply called seals.