thumb|right|236px|Compression seal example

A seal is a device or material that helps join systems, mechanisms, or materials together to contain pressure, prevent leakage of fluid (e.g. in a pumping system), or exclude contamination. The effectiveness of a seal depends on compression in the case of gaskets and adhesion in the case of sealants. Seals are installed in pumps in a wide range of industries including chemicals, water supply, paper production, food processing, and many other applications.

A stationary seal may also be referred to as a "packing".

Seal types:

Seals relying on compression

  • Closure (container)
  • Crown cork, a.k.a. bottle cap
  • Lid
  • Compression fitting
  • Compression seal fitting
  • Diaphragm seal
  • Double seam, the crimped seal used in canning
  • End-face mechanical seal
  • Face seal
  • Gasket or mechanical packing
  • Flange gasket
  • Hose coupling
  • Inflatable seal, a seal that inflates and deflates in three basic directions of operation: the axial direction, the radial-in direction, and the radial-out direction. Each of these inflation directions has its own set of performance parameters for measurements such as the height of inflation and the center-line bend radius that the seal can negotiate. Inflatable seals can be used for numerous applications with difficult sealing issues.
  • Obturating ring
  • Piston ring
  • Radial shaft seal
  • Stopper (plug), a.k.a. bung or cork
  • Drain plug
  • Laboratory rubber stopper
  • Washer
  • Bodok seal, a specialized gas sealing washer for medical applications
  • Bonded seal, also known as Dowty seal or Dowty washer. A type of washer with integral gasket, widely used to provide a seal at the entry point of a screw or bolt
  • O-ring
  • O-ring boss seal
  • Stuffing box (mechanical packing)
  • Wiper seal
  • Split seal, multi-part seals that offer easier installation and maintenance
  • Bridgman seal, a piston sealing mechanism that creates a high-pressure reservoir from a lower pressure source

Seals relying on fusion or adhesive bonding

  • Glass-ceramic-to-metal seals
  • Glass-to-metal seal
  • Heat seal
  • Hermetic seal
  • Induction sealing or cap sealing
  • Putty
  • Sealant or adhesive
  • Soldering and brazing
  • Welding

Seals made by liquids blocking gases

  • Ferrofluidic seal
  • Trap (plumbing) or siphon trap

Non-contact seals

  • Dry gas seal
  • Hydrodynamic seal
  • Hydrostatic seal
  • Labyrinth seal, a seal which creates a tortuous path for the escaping gas or liquid

See also

  • Joining technology
  • Leak

References