DF-(P)DGS6 Seal Concept Solves Problems with Pumping Light Vaporous Media


With the DF(P)DGS6 EagleBurgmann offers reliable shaft sealing for API 610 high-performance pumps, e.g. BB3 and BB4 process pumps, and vertical pumps applied in liquefied gas fractionation, in pump stations of downstream NGL (Natural Gas Liquids) pipelines and also in CO2 applications.

Numerous plant operators experience problems incurred by temperature and pressure fluctuations in the pump. In conjunction with the low vapor pressure margin of the medium (e.g. ethane, propane), this can cause phase transitions between liquid and gas at the seal faces - they run dry. Conventional mechanical seals consequently sustain damages which results in seal failures.

The innovative seal concept of the EagleBurgmann DF-(P)DGS6 was developed from the Dry Gas Seals technology for compressors. Due to the broad seal faces with bi-directional gas grooves, the DF-(P)DGS6 runs contact-free when the media is gaseous. Due to the EagleBurgmann DiamondFace bonding of the primary seal faces, the seal can even run dry but remains wear-free in transient conditions of the medium. If the medium is in liquid state, the seal acts as a conventional liquid-lubricated mechanical seal.

More than 150 of the DF-(P)DGS6 seals to date have been successfully deployed in the first installation of pumps or exchanged for "Bad Actors" in this field of application. Result: up to 80 % reduced pump leaks and more than 5 years of prolonged seal service life.

Advantages at a glance

  • DiamondFace-bonded primary seal faces
  • Fully operational in both liquid and gas phases
  • Bi-directional
  • Available as single, double, tandem and tandem seal with intermediate labyrinth arrangement
  • Version available for high pressure and both low and high temperature applications (DF-PDGS6)
  • Proven, reliable and economical solution
  • Can even be adjusted to extremely narrow installation spaces - Retrofits are easy to implement

Operating range

  • Shaft diameter: D = 25 … 280 mm (0.98" … 11.02")
  • Pressure: p = 0 … 100 bar (1,450 PSI),
  • DF-PDGS6: 0 ... 250 bar (3,625 PSI)
  • Temperature: t = -30 °C … +200 °C (-22 °F … +392 °F)
  • DF-PDGS6: -100 °C ... +200 °C (-148 °F ... +392 °F)
  • Sliding velocity: vg = 0.6 … 140 m/s (2 … 459 ft/s)

Picture: DiamondFace-bonded seal face of a DF-(P)DGS6 pump seal with bi-directional gas grooves (Image: Eagle Burgmann)

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