Friction Testing of Faces in Bearing Isolators

andOil 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.

Friction

Wear

-0.0008

-0.0006

-0.0004

-0.0002

0

0.0002

0.0004

0.0006

0.0008

Temperature

0

20

40

60

80

100

120

140

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 sumpWet 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.