Trend oxidation, nitration, soot, water, glycol and selected additive changes.
What this test measures
Spectral changes relative to a reference or established trend. It matters because trend oxidation, nitration, soot, water, glycol and selected additive changes. the result becomes more useful when trended with a stable sampling point and corroborated by companion measurements.
Where it is used
- In-service lubricants
Scientific principle and instrumentation
Infrared absorption is measured across diagnostic molecular-vibration regions.
The typical laboratory system is a Fourier-transform infrared spectrometer. A method designation controls details such as preparation, temperature, apparatus, calibration and calculation; similar test names do not automatically produce interchangeable results.
Why maintenance teams request this test
This test should answer a defined question about lubricant condition, contamination or machine wear. It is most effective when the likely failure mechanism predicts a measurable change and there is enough warning time to inspect or correct the source.
| Equipment | Why included | Maintenance use | Escalation trigger |
|---|---|---|---|
| Diesel Engine | Abrasive wear, Soot thickening, Fuel dilution, Coolant ingress | Routine trend | Rate-of-change or companion evidence supports the same failure mechanism |
| Industrial Gearbox | Gear tooth distress, Bearing wear, Water ingress, Particle contamination | Triggered / advanced investigation | Rate-of-change or companion evidence supports the same failure mechanism |
| Hydraulic System | Abrasive wear, Servo sticking, Oxidation, Water contamination | Triggered / advanced investigation | Rate-of-change or companion evidence supports the same failure mechanism |
| Gas Turbine | Varnish, Bearing wear, Water ingress, Additive depletion | Routine trend | Rate-of-change or companion evidence supports the same failure mechanism |
| Steam Turbine | Water ingress, Varnish, Rust, Bearing distress | Routine trend | Rate-of-change or companion evidence supports the same failure mechanism |
| Air Compressor | Oxidation, Deposit formation, Coolant ingress, Bearing wear | Routine trend | Rate-of-change or companion evidence supports the same failure mechanism |
| Generator Engine | Fuel degradation, Condensation, Fuel dilution, Corrosion | Triggered / advanced investigation | Rate-of-change or companion evidence supports the same failure mechanism |
| Power Transformer | Thermal faults, Electrical discharge, Cellulose degradation, Moisture ingress | Triggered / advanced investigation | Rate-of-change or companion evidence supports the same failure mechanism |
| Industrial Bearing | Fatigue, Abrasive wear, Lubricant starvation, Contamination | Triggered / advanced investigation | Rate-of-change or companion evidence supports the same failure mechanism |
| Mining Mobile Equipment | Dust ingress, Overload wear, Coolant ingress, Hydraulic contamination | Triggered / advanced investigation | Rate-of-change or companion evidence supports the same failure mechanism |
See how tests support preventive, predictive and proactive maintenance →
Sample requirements and precautions
Typical requirement: Typically 50–150 mL; confirm the complete panel before sampling. Confirm the complete panel before filling the bottle because particle count, volatile contamination, dissolved gases and trace-water testing may need dedicated containers.
| Control | Why it matters | Practical check |
|---|---|---|
| Representative location | Avoids stagnant or settled bias | Use a consistent live-zone point where safely available |
| Container | Prevents added particles, water or volatiles | Use the laboratory-specified clean compatible bottle |
| Context | Makes the result interpretable | Record hours, top-up, fluid, maintenance and operating state |
How results are interpreted
Interpretation should separate specification testing from condition monitoring. Specification work uses the exact product grade, method and decision rule. Condition monitoring emphasises comparable trends, rate of change and correlated evidence.
| Observation | Possible interpretation | Corroborating evidence | Recommended next step |
|---|---|---|---|
| Higher than baseline | May indicate a material or condition change relevant to trend oxidation, nitration, soot, water, glycol and selected additive changes. | Requires correlation with trend, companion tests and service history. | Compare with baseline and rate of change |
| Lower than baseline | May represent normal condition, dilution, depletion or a method-specific response depending on the parameter. | Do not infer acceptability without the governing specification or baseline. | Review correlated tests and maintenance events |
| Unexpected step change | Fluid, operating, sampling or analytical context may have changed | Top-up, overhaul, interval, location and method records | Verify sample identity and collection conditions |
Interferences, precision and limitations
Small differences can reflect normal method precision. Compare results only when method, temperature, preparation and reporting basis are equivalent.
Common interferences
- Non-representative sampling
- Incorrect container or preservation
- Matrix effects or particles outside the analytical response range
- Method or temperature changes
Key limitations
- Not independently diagnostic of a specific failure
- Acceptance criteria vary by fluid, equipment, method, grade and jurisdiction
- Copyrighted method procedures are not reproduced by the Wiki
Frequently asked questions
Can ftir oil condition monitoring be interpreted from one result?+
Usually not with confidence. A single result is evidence, not a complete diagnosis. Evaluate it with a comparable baseline, sampling history, operating context, companion tests and the relevant specification or OEM guidance.
What context should accompany ftir oil condition monitoring data?+
Asset, fluid, sampling and operating context. Record equipment and oil hours, fluid grade, make-up volume, sampling point, maintenance events, operating severity and historical results. These factors often change the meaning of the same measured value.
References and method context
References identify authoritative source families; they do not reproduce protected procedures or acceptance tables. Verify the current official edition before procedural or conformity use.