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MN Series Bearing Isolator

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MN Series - Bearing Isolator

MN – MILLENNIUM® design metallic bearing isolator, flush mounted 

This metallic non-contact, labyrinth design provides unsurpassed two-way protection and extreme temperature compatibility. Designed for flush mounted non-flooded applications where aggressive contaminants need to be excluded from the system. 


Technical Specifications

  • OPERATION TYPENon-Flooded 
  • MAXIMUM SURFACE SPEEDUp to 7,000 fpm (35 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 12.000 inch (15.5 to 304.8 mm) 
  • BORE DIAMETER1.358 to 13.575 inch (34.5 to 344.8 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. By keeping lubrication in and contaminants out, bearing isolators provide reliable, two-way sealing protection of rotating equipment for extended bearing life and zero shaft wear. 

Labyrinth sealing technology applied to high performance materials allows MILLENNIUM® MN bearing isolator to operate far beyond shaft speed and temperature limits of standard radial lip seals. 

The non-contact design has virtually no torque consumption and therefore 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 leakage. 

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 MN Profile lowers shaft cost due to liberal specifications. Costs can also be eliminated on tooling charges due to the fact that ProTech is a precision-machined seal. 


The MILLENNIUM profile is the first and only metallic isolator that is unitized without internal o-rings or locking rings. A proprietary unitization mechanism reduces potential leak paths while a non-wearing internal diffuser provides optimal spacing during installation and eliminates metallic dusting during start-up. 

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 oil retention. The stator has a sophisticated series of grooves to retain oil splash, which is proven to be the most effective design for oil retention when compared to various competitor designs. 

The rotor uses an external O-ring to maintain a static press fit on the shaft. Since the rotor spins with the shaft, it will not wear, groove, or damage the shaft. This eliminates costs associated with having to recondition the sealing surface of the shaft. 

The rotor and stator are assembled at the facility where they are permanently unitized, allowing for a one-piece installation. This unitized design also maintains the seal’s integrity by keeping high-pressure water spray, vibration or axial movement from separating or increasing the gap between the rotor and stator.

Additional design features include: 

  • Non-flanged design for flush fit of seal with equipment housing
  • Internal PTFE diffuser eliminates metallic dusting during initial start-up
  • Minimal gap between the diffuser and rotor minimizes vapor flow through seal
  • Specifically designed for heavier water spray exclusion.
  • Not compatible with vertical down, oil lubricated systems.
  • Not recommended for vertical up position. For vertical up position, the MX design is recommended.


The MILLENNIUM MN profile is our standard metallic design for non-flooded applications where a metallic seal is preferred for flush-fit mounting. It is ideal for sealing and protecting the bearing housings of electric motors, pumps, mixers, gear boxes, turbines, blowers and custom equipment against heavy water spray and dry contaminants. The MN 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). If external contamination is heavy in vertical up mounting position, MILLENNIUM MX profile may be a preferred de sign. 

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

The MILLENNIUM MN shaft mounting positions and respective compatible lubrication types are: 

  • Horizontal Mounting: Grease, oil, dry
  • Vertical Up Mounting: Not recommended. If contaminant level is heavy, see the ML design.
  • Vertical Down: Grease, dry

Size Range

The MILLENNIUM MN 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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