A rotating shaft often transmits rotary motion through a wall and the two sides of the wall have to be isolated from each other.     A rotary seal is used to provide the necessary isolation.    A seal is generally used to prevent the leakage of a fluid from one side of a containing wall to the other.

This page simply lists the different types of seals used for rotary motion applications. :A more detailed review of seals is provided on this site :Ref...Seals Index

Types Of Seals

Seal Type Description
O- Ring Used very rarely and then on very slow rotation /oscillation. Low Cost
Lip Seal Widely used for shaft sealing. Seal and shaft wear likely over time. Used extensively throughout engineering industry
Labyrinth Seal No friction or shaft wear. Leakage can take place when there is no shaft rotation
Mechanical Seal Widely used. When correctly installed seal is very reliable an can seal at high pressures and speeds. Leakage can occur when shaft is stationary. This seal has many design variations many of which are complicated.
Gland Packing Low Cost and reliable. Requires regular maintenance and adjustment.
Magnetic Fluid Very novel seal design. Uses fluid with metallic particles. Used for high sealing levels at high speeds at low dp( 0.5 bar and less)

Shaft Seal References
  1. Ferrotec Magnetic Fluid Seal
  2. James Walker Well known UK Supplier
  3. Garlock A supplier of a wide range of seal products
  4. Supaseal -Lots of information and seal dimensions