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Monday, July 27, 2009

Centrifugal Pump Mechanical Seals

Centrifugal Pump Mechanical Seals, mechanical seal have been used for many years to seal any number of liquids at various speeds, pressures, and temperatures. Today plant operators are benefiting from improved seal technologies driven by the US clean air act of 1980, and the American Petroleum Institute (API) Standard 682. These new seal technologies are based on advanced commence testing at simulated refinery conditions required by the API. The results to date indicate not only an improvement in emissions control, but also a major increase in equipment reliability.

Classes of seal technology
Emerging seal technologies are providing clear choices for sealing. Various plant services require the application of these new technologies for emissions control, safety, and reliability. Sealing systems are now available that are based on the preferred method of lubrication to be used.

These classes of seals are as follows:
1. Contacting liquid lubricated scale:

  • Normally a single seal arrangement is cooled and lubricated to the liquid being sealed. This is the most cost effective seal installation available to the industry.
  • Dual seal are arrange to contain a pressurized or non pressurized barrier or buffed liquid. Normally this arrangement will be used on application where the liquid being seal is not a good lubricating fluid for a seal and for emissions containment. These arrangements require a lubrication system for the circulation of barrier or buffer liquids.

2. Non contacting gas lubricated seals:

  • Dual non-contacting gas-lubricated seals are pressurized with an inert gas such as nitrogen.
  • Dual non-contacting, gas-lubricated seals are used in a tandem arrangement and pressurized by the process liquid being sealed, which is allowed to flash to a gas at the seal.

A tandem seal arrangement is used on those liquid that represent a danger to the plant environment. For non-hazardous liquids, a single seal can be used.