Post on 01-Feb-2016
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Vibration Institute Piedmont Chapter 14
Barry Schoch
PREDICT
Ferrography / Used Oil Analysis
February 25, 2005
Phone 800-543-8786
www.predictusa.com
“First Sample in your Trend”
What your Lab can
and
cannot tell you
Why Do Ferrography / UOA?
To Identify Abnormal Wear Conditions Before They Become Significant Enough To Adversely Effect Component Life.
Used Lubricant Analysis
Trends the physical properties of the lubricant
Determines the chemical breakdown or contamination of the fluid
Determines the concentration of dissolved elements & additives
• Oil Bath • RDE Spectrometer
• FTIR Spectrometer
• Titration– TAN & TBN
• Water– Crackle – Karl Fischer
• Particle Count
• Gas Chromatography• Flash Point
UOA Tests Viscosity Elemental Concentration
Oxidation, Nitrates, Sulfates, Water, Fuel, Glycol, Additive Degradation
Acid & Base Level Trends
Concentrations to 800ppm Concentrations to 10ppm
NAS & ISO Cleanliness Ratings
Fuel Dilution
Observations
• Large particles in sample
– Likely to settle in sample bottle– Particles over 80 microns are easily visible to
naked eye
Observations
• Crackle Test– Hot Plate set at 115-125C
– Sensitive to between 800 and 1000 ppm depending on oil viscosity and additives
• Measure of shear rate vs. shear stress; i.e. resistance to flow
• Measured at constant temperature (40oC or 100oC)
Viscosity
ASTM D-445Constant Temp.Oil Bath40oC or 100oC
Nametre OscillationViscometerNon-ASTM TestAmbient Temp.
Emissions Spectrometer(ELEMENTAL SPECTROSCOPY)
EXCITATION SOURCE
SIGNAL PROCESSING
RDE
ICP
AA
LIGHT EMISSIONS
DETECTORS
DIFFRACTION
GRATING
FT-IR: Used Mineral Oil Spectrum
Water by Karl Fischer Titration
Particle Count Test Results
This shows a typical print out from a particle counter displaying results by number of particles in any one group.
Total Acid Number
• TAN looking for acidity changes– In this application, more likely to find
oxidation products– Acid contaminant likely only through process
contamination– Causes corrosive wear debris and general
increases in the wear rate
Total Base Number
• TBN looking for alkalinity– Overbase additive applications most likely
(Large Diesel Engines)– Absence of additive (low TBN) will cause
increases in rates of wear, corrosion, and solid combustion product generation
– Process contamination possible, but not observed
Ferrography
• Separation of Wear Debris from Lubricant• Quantitative and Qualitative evaluation of Wear
Debris using Trend Analysis• Assessment of the Severity, Origin &
Development Mechanism of Particles;• Predict Equipment Wear Condition & Failure
Potential
Wear
• Results from ordinary wear or equipment damage• Missing volume goes into the lube system in the
form of fine particles• Wear is generated initially as small particles over
time, not large chunks
Wear• Since most of the wear debris is some form of
steel, a magnetic field is used for separation• Debris is so small that a high gradient field
rather than a steady field is required• Larger particles are affected more strongly than
smaller ones, so a rough separation according to size is possible
• Uses optics to determine concentration of wear debris• Is able to evaluate concentrations of magnetically
attracted wear debris• Particle size limitation is 300 microns• Effective trending tool for most types of industrial
equipment• Limitations are for extremely clean lube systems, i.e,
hydraulics, some turbines
DR Ferrograph
DR Acceptance LimitsWEAR PARTICLE CONCEN. ACCEPTANCE LIMITS
Vacuum Pumps WPC = 1-5Boiler Feed Pumps WPC = 1-100Gas CompressorsTurbinesFans
WPC = 1-50
Journal Bearings WPC = 1-20Roller Bearings WPC = 5-100EnginesTransmissions
WPC = 10-150
Extruder Gearboxes WPC = 100-600Dragline GearboxesHoist Gearboxes
WPC = 1,000-50,000
• View slide made by FM• Several magnifications
–Speed–Detail
• Identify debris using–Reflected light–Transmitted light–Polarized light–Color filtered light
Analytical Ferrography
BEARING WEAR
Low Alloy Steel
Steel Prior to Heat Treatment Lead/Tin Babbitt Metal
Copper Alloy
Particle Classification
•Size
•Shape
•Concentration
•Composition
Analytical Ferrography
Analytical Ferrography
Rating 1 Rating 2 Rating 3 Rating 4 Rating 5
Rating 6 Rating 7 Rating 8 Rating 9 Rating 10
Analytical Ferrography Correlation w/ DR FerrographCorrelation w/ DR Ferrograph
WPC=10 WPC=50 WPC=100 WPC=500 WPC=1000
Equipment Condition Report
Equipment Condition Report (cont)
YesYes• Detect Dissolved up to
8m Particles
• Determine Lubricant Additive Depletion
• Detect Fluid Contamination
• Determine Lube Physical Condition
No• Problems detecting Onset
of Abnormal Wear
• Determining Sources of Wear (bearings, gears, seals, rings, etc.)
• Reliable Estimate of Machine Wear Condition
SummarySummaryFirst Sample AnalysisFirst Sample Analysis
First Sample AnalysisFirst Sample Analysis• Observation i.e., water, large
particles
• Viscosity
• RDE Spectroscopy (21 metals)
Yes
Yes
Limited w/ Ref.
First Sample AnalysisFirst Sample Analysis• FT-IR Spectroscopy
• Water by Karl Fischer Titration
• TAN, TBN
• DR Ferrograph
• Analytical Ferrography
No
Yes
No
Limited
Yes
Questions