Type 28ST
Non-contacting Gas Seal for Steam Turbines
![](/-/media/j/johncrane_com/images/products/mechanical-seals/dry-gas/type-28st/img1421.jpg?w=800&h=800&bc=ffffff&r=ddd74dc8-84ed-4ebc-a01a-40537f5d790d&hash=0E4481B32969FB0D5D27F6B85CD71011)
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."
![](/-/media/j/johncrane_com/images/products/mechanical-seals/dry-gas/type-28st/img1421.jpg?w=800&h=800&bc=ffffff&r=ddd74dc8-84ed-4ebc-a01a-40537f5d790d&hash=0E4481B32969FB0D5D27F6B85CD71011)
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Features
- 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.
Parameters
- Temperature Limits
- 40°F to 750°F/-40°C to 400°C
- Pressure Limits
- 400 psi(g)/27.6 bar(g)
- Speed Limits
- 400fps/122m/s
- Size Limits
- 6.5"/165mm
Recommended Applications
- Steam turbines
- Turbo compressor machinery