Friction Testing of Faces in Bearing Isolators and Oil Mist Lubrication  By  Hrishikesh Gadre

Outline  Part I: Testing of seal faces.  About Isomag Bearing Isolators.  Problem definition.  Experimental Apparatus.  Part II: About Oil Mist Lubrication.  Introduction  Generation, Transportation and Reclassification  Typical Oil-mist system  Dry sump Vs Wet sump oil mist system  Lubricants

Bearing Isolators  Isolate the bearings from outside environment.  Prevents oil from leaking.  Combine the advantages of labyrinth and contacting seal faces.  Magnetic force as a closure means.  Runs dry as well as lubricated. Photo courtesy: Isomag Corporation

Flat face seal basics Photo courtesy: Isomag Corporation

Magnum C bearing Isolator Photo courtesy: Isomag Corporation

Magnum S bearing Isolator Photo courtesy: Isomag Corporation

Problem Statement  ExxonMobil uses these isolators.  Usage hasn’t been for long enough to determine life of the isolator.  Aim is to conduct various tests to calculate the wear life and/or to suggest a better solution.  Effect of introduction of Oil Mist.  Also, performance of another material pair.

Experimental Apparatus LRI-1a Tribometer

Test samples Stator Rotor

Experimental Apparatus Rotor Temperature probe Stator

Experimental Apparatus Modifications for introducing Oil Mist

Testing outline  Parameters that can be changed:  Pressure: 5, 7, or 12 psi.  Speed: 1800 or 3600 rpm.  Material pair: 17-4PH – Composite or SS 416 – Carbon.  Lubrication: Dry or mist lubricated.  Total of 24 tests.

Results  COF decreases as load increases.  It increases with increase in speed.  Presence of oil helps reducing the friction.  Temperature is also comparatively lower.

Part II: Oil Mist Lubrication

Introduction  Need for this kind of lubrication.  Centralized lubrication system.  Where it is successfully used?  Hydrocarbon processing industry, refineries  Process pumps, electric motors

Generation of mist  Vortex type or Venturi type.  Air with high speed and low pressure at exit.  Low pressure pulls oil.  High speed air breaks the oil.  Optimum size of particles.  Line condensate  Stray mist Photo courtesy: Bloch & Shamin

Transportation  Can be conveyed over long distances.  97% of the mist reaches the application point.  Optimum velocity of flow.  Gravitational settling  Turbulent settling

Main header Application point Photo courtesy: Bloch & Shamin

Reclassification  Type of fitting – depends upon the application  Low speed – Condensing type  High speed – Mist or Spray type Photo courtesy: Bloch & Shamin

Typical Oil-Mist system Photo courtesy: Bloch & Shamin

Dry sump Vs Wet sump Photo courtesy: Bloch & Shamin Dry sump Wet sump

Lubricants  Virtually any oil can be used.  Some specific properties needed.  Good aerosol characteristics  Thermal and oxidation stability  Special additives designed.  To reduce stray mist  Anti-wear, anti-foaming etc

Case study

Acknowledgement  Dr. Michael Khonsari.  Center for Rotating Machinery.  David Hertel.  Michael Ciolino.  Everybody in this group who helped me.