Type 28ST Dry Gas Seals | John Crane Mechanical Seals
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Type 28ST

Non-contacting Gas Seal for Steam Turbines

Type 28ST combines proven rotating groove technology and high-temperature secondary seals to reduce steam leakage by nearly two orders of magnitude, as compared to traditional sealing devices, such as segmented carbon rings and labyrinths. This steam-lubricated, end-face cartridge seal reacts instantaneously and automatically to maintain a safe face gap despite sudden changes in operating conditions. A stable seal face gap, typically 0.0001" to 0.0002"/0.0025mm to 0.0051mm, is the result of specially designed rotating grooves, which pump steam radially inward into a nongrooved portion of the seal known as the "sealing dam."

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  • California Residents: PROPOSITION 65 WARNING
  • Bearing oil steam contamination reduced.
  • Standard designs fit most single-stage turbines.
  • Reduced noise levels and hazards associated with leaking steam.
  • Support equipment eliminated.
  • Unidirectional and bidirectional capability.


Temperature Limits

40°F to 500°F/-40°C to 260°C

Pressure Limits

400 psi(g)/27.6 bar(g)

Speed Limits


Size Limits


Recommended Applications

  • Steam turbines
  • Driven machinery

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