Dry gas seal

Dry gas seals are non-contacting, dry-running mechanical face seals consist of a mating (rotating) ring and a primary (stationary) ring. When operating, grooves in the rotating ring generate a fluid-dynamic force causing the stationary ring to separate and create a gap between the two rings. Dry gas seals are mechanical seals but use other chemicals and functions so that they do not contaminate a process. These seals are typically used in a harsh working environment such as oil exploration, extraction and refining, petrochemical industries, gas transmission and chemical processing.

The dry gas seal has spiral grooves, with provides for lifting and maintaining separation of seal faces during operation. Grooves on one side of the seal face direct gas inward toward a non-grooved portion of the face. The gas that is flowing across the face generates a pressure that maintains a minute gap between the faces, optimizing fluid film stiffness and providing the highest possible degree of protection against face contact. The seal's film stiffness compensates for varying operations by adjusting gap and pressure to maintain stability.


Design and use

Grooves on the seal direct gas inward toward the non-grooved portion. The action of the gas flowing across the seal generates pressure that keeps a minute gap, therefore optimizing fluid film stiffness and providing protection against face contact.[1][2]

The use of these seals in centrifugal compressors has increased significantly in the last two decades because they eliminate contamination and do not use lubricating oil. Non-contacting dry gas seals are often used on compressors for pipelines, off-shore applications, oil refineries, petrochemical and gas processing plants.[3] Dry Gas Seal configurations: there are many dry gas seal configurations base on their application. 1- Single gas seal 2- Tandem gas seal 3- Tandem gas seal with intermediate labyrinth 4- Double opposed gas seal

Also the dry gas seal can be unidirectional or bidirectional.


John Crane Inc. issued the first patent for dry gas seals in 1968 with field applications beginning in 1975. When the technology was introduced, it was aimed at correcting the problems with dry gas film environments by eliminating friction. Soon, the technology became a common replacement for other lubricated seals. The patented spiral-groove technology of the dry gas seal allows for easy lifting and separation of seal faces during operation. There are three common types of lubrication for these seals: full liquid film, which contains oil and requires light-duty conditions; partial liquid/gas film, which requires a 50 percent balance of liquid to preserve the seal; and dry gas film, which has an absence of liquid that creates hot localized areas that may lead to cracking or damage to the seal. Seal failure results from a flooded compressor with oil or liquid, foreign contaminants and alignment problems.[4][5]

See also

  • Hydrogen turboexpander-generator


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Seal (mechanical) — Compression seal example A mechanical seal is a device which helps join systems or mechanisms together by preventing leakage (e.g., in a plumbing system), containing pressure, or excluding contamination. The effectiveness of a seal is dependent… …   Wikipedia

  • Dry sump — A dry sump is a lubricating motor oil management method for four stroke and large two stroke piston internal combustion engines that uses external pumps and a secondary external reservoir for oil, as compared to a conventional wet sump system.… …   Wikipedia

  • Dry suit — A dry suit or drysuit provides thermal insulation or passive thermal protection to the wearer while immersed in water,[1][2][3][4] and is worn by divers, boaters, water sports enthusiasts, and others who work or play in or near cold water. A dry… …   Wikipedia

  • Gas holder — A gasometer, or gas holder, is a large container where natural gas or town gas is stored near atmospheric pressure at ambient temperatures. The volume of the container follows the quantity of stored gas, with pressure coming from the weight of a… …   Wikipedia

  • Gas spring — A gas spring is a type of spring that, unlike a typical metal spring, uses a compressed gas, contained in a cylinder and variably compressed by a piston, to exert a force. Gas springs are used frequently in automobile construction, where they are …   Wikipedia

  • Dry dilution refrigerator — A dry dilution system A dry (or cryogen free) dilution refrigerator is a type of dilution refrigerator that does not require the use of any external cryogens, in particular liquid helium, to operate. In the traditional design of a dilution… …   Wikipedia

  • End face mechanical seal — An end face mechanical seal, also referred to as a mechanical face seal but usually simply as a mechanical seal, is a type of seal utilised in rotating equipment, such as pumps and compressors. When a pump operates, the liquid could leak out of… …   Wikipedia

  • CS gas — IUPAC name …   Wikipedia

  • Sewer gas — is a mixture of gases produced and collected in sewage systems by the decomposition of organic household or industrial wastes. These gases include hydrogen sulfide, ammonia, methane, carbon dioxide, sulfur dioxide and nitrogen oxides. Other… …   Wikipedia

  • Buffer gas — A buffer gas is an inert or nonflammable gas. In the Earth s atmosphere, nitrogen acts as a buffer gas. A buffer gas adds pressure to a system and controls the speed of combustion with any oxygen present. Any inert gas such as helium, neon, or… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.