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SM Series Bearing Isolator

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SM Series - Bearing Isolator

SM – Split MILLENNIUM® metallic bearing isolator, for time-saving retrofit installation, flange mounted 

Split design, non-contacting metallic bearing isolator enables time-saving, no tear-down installation on rotary shaft equipment. Labyrinth design provides unsurpassed two-way protection. 


Technical Specifications

  • OPERATION TYPENon-Flooded 
  • MAXIMUM SURFACE SPEEDUp to 3,000 fpm (15 m/s) 
  • AXIAL MOVEMENT0.020 inch (0.51 mm) 
  • ECCENTRICITY0.020 inch (0.51 mm) 
  • OPERATING TEMPERATURE-40° to 400 °F / -40° to 204 °C 
  • SHAFT DIAMETER0.610 to 10.000 inch (15.5 to 254 mm) 
  • BORE DIAMETER1.319 to 11.575 inch (33.5 to 294 mm) 
  • SEAL MATERIALBronze, Stainless Steel, Carbon Steel, Other Alloys 
  • O-RING MATERIALFKM is standard. Alternates available 

Performance Advantages

Machine downtime due to bearing failure is costly, but getting up and running again without necessity of an exhaustive tear down lessens the pain. Due to its split configuration, the MILLENNIUM® SM design can reduce downtime hours to minutes when seal replacement is required. 

By keeping lubrication in and contaminants out, bearing isolators provide reliable, two-way sealing protection of rotating equipment for extended bearing life. Labyrinth sealing technology applied to high performance metallic materials allows the MILLENNIUM bearing isolators to operate far beyond the shaft speed limits of standard radial lip seals and avoid shaft wear. Because it is a precision-machined seal, costs can be eliminated on tooling charges, allowing retrofit of most shaft and bore combinations. 

The non-contact design has virtually no torque consumption, will not wear or groove shafts, and allows for non-lubricated dry running. It also accommodates the greatest axial movement in the industry, reducing the major factor that causes labyrinth seal failure. 

We can custom engineer solutions to meet exacting specifications for either new or retrofit applications. When used to replace seals during planned or unplanned rebuilds, the MILLENNIUM SM lowers shaft cost due to liberal surface finish specifications which require no wear sleeves or shaft refurbishment. 


The MILLENNIUM SM profile is split for easy installation. Once re-connected on the shaft, an external O-ring on the outside diameter of the stator allows for easy seal installation, maintains a press fit in the seal housing, and provides a static seal against the bore for lubricant retention. The stator has a sophisticated series of grooves to retain oil splash. On the shaft, the rotor uses an external O-ring to maintain a static press fit once the two halves are joined. Since the rotor spins with the shaft, it will not wear, groove, or damage the shaft. 


The MILLENNIUM SM profile is our standard, split metallic design for non-flooded applications where a split retrofit or replacement seal is preferred and flange mounting is required. The flange seats against the housing and acts as an installation guide by ensuring the seal alignment is correct. The SM design is excellent for retaining grease and oil splash, however the oil level must be below the inboard oil drainback of the seal (non-flooded). 

Total Eccentricity: 0.020” (.51 mm)
Shaft Speed: Up to 7,000 fpm (35 m/s)
Maximum internal pressure: 0 psi (0 bar)
Axial Movement: 0.020” (0.51mm). Special designs up to 0.100” (2.54 mm)
Shaft/Bore: Tolerances ±0.002” (±0.05mm). Special designs available 


Stator & Rotor: Available in various metallic materials, listed below. 

  • Bronze (Standard)
  • 304 Stainless Steel
  • 316 Stainless Steel
  • Carbon Steel

O-Rings: Come standard as FKM, but are also available in: 

  • NBR
  • FDA silicone
  • Fluorosilicone
  • EPDM
  • Aflas®

Size Range

The MILLENNIUM SM profile in standard shaft diameters ranging from 0.610” to 12” (15.5 mm to 305 mm). Because this is a precision machined seal, we can manufacture virtually any configuration. 













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