USED OIL ANALYSIS

INDIAN OIL CORPORATION LIMITED

(Marketing Division) Gujarat State Office

May 2007

S FOR SERVICE

E FOR EFFICIENCY

R FOR RELIABILITY

V FOR VERSATILITY

O FOR ORIGINALITY

SERVO WORLD CLASS LUBRICANTSSERVO SIGNIFIES

DETERGENCY

DISPERSANCY

TBN RETENTION

THERMO - OXIDATIVE

STABILITY

ANTI - WEAR

WATER SHEDDABILITY

LUBE OIL REQUIREMENTS

OXIDATION OF OIL.

LOSS OF ADDITIVE EFFECTIVENESS.

COMBUSTION PRODUCTS AND FUEL DILUTION.

SOOT BUILT UP AND WEAR METALS.

WRONG TOP UP, COOLANT / WATER

CONTAMINATION.

REASONS FOR OIL DEGRADATION AND CONTAMINATION

CHECK QUALITY OF FRESH OILS

CHECK CONDITION OF OIL IN USE / EXTEND

DRAIN INTERVAL.

ASSESS THE CONDITION OF MACHINE.

ESTABLISH THE DRAIN INTERVAL BY TRIAL

RUN.

REDUCE THE UNSCHEDULED DOWNTIME BY

PREVENTIVE MAINTENANCE.

CONDITION MONITORING OFLUBRICANTS HELPS TO:-

APPEARANCE / COLOR.

WATER CONTENT.

VISCOSITY.

TOTAL ACID NUMBER / TOTAL BASE NUMBER.

WEAR METALS.

FOURIER TRANSFORM INFRARED SPECTROSCOPY.

HEXANE AND TOLUENE INSOLUBLES.

PARTICLE COUNT.

DEMULSIBILITY.

FLASH POINT

TESTS FOR CONDITION MONITORING.

USED OIL TESTS AND THEIR SIGNIFICANCE

1. Appearance

In this procedure the oil samples is placed in narrow glass container and is visually examined for colour. The results are reported as clear, hazy cloudy, milky or opaque.

Significance: The appearance of an oil can provide a number of distinctive clues about oil condition and contamination. A hazy or cloudy appearance often indicates water contamination, while a gradual darkening occurs as the oil is oxidised. Particles as small as 40 microns can be detected by the unaided eye, providing an indication of gross particulate contamination. This test is limited by the subjective nature of the observer and it cannot be used for the oils that are dark to begin with.

2. WaterASTM D 95 procedure determines water content by distillation and expresses the results in volume percent (vol%) Water content can also be determined as per ASTM D 1744 by reacting the oil sample with Karl Fischer reagent. This method is particularly accurate for small quantities of water and results are express in ppm.

Significance:Water reduces the lubricity of the oil and leads to corrosion of metal parts. Higher levels of water may emulsify the oil. In circulating system water enters from oil cooler leakages. In steam turbines water can also enter due to condensation of flue gases.

3. Kinematic ViscosityTime taken for a given volume of oil to pass through a specific size orifice at a given temperature is measured and is converted into kinematic viscosity in centistokes.

Significance: This is the most important property. Used oil viscosity may increase due to oxidation, ingress of insoluble products or contamination with higher viscosity products. Viscosity reduces due to fuel dilution to ingress of low viscosity products e.g. refrigerants. Oils incorporating polymeric compounds as viscosity index improvers may have viscosity loss due to permanent shear of VI improvers

4. Viscosity Index

This is calculated or read from viscosity of the oil at 40oC and 100oC it is reported in whole number.

Significance: Generally viscosity index of used oils does not change from original value. Higher or lower value indicates contamination. Used Engine oils may show high VI due to fuel dilution.

5. Flash Point Flash point of lubricating oils is measured by ASTM D 93 (PMCC) procedure as they may contain lighter fractions. The test oil is heated in the prescribed apparatus and the oil temperature at which vapour flashes in the presence of pilot flame is noted. Values are expressed in oC.Significance: Reduced flash point values indicate presence of volatile products like solvents of fuel. Cracking of oil also reduces flash point. Higher flash point indicates admixture with wrong grade of oil

6. Total Base Number

ASTM D 2896 procedure determines the level of alkalinity in an oil sample by measuring the change in electrical conductivity during titration with Perchioric Acid. The results are expressed as mg KOH/g.

Significance: Most motor oils are formulated with a variety of additives that enhance lubricity, retard oxidation, improve viscosity characteristics and pour point and reduce the tendency for sludge and deposit formation. The level of additives is determined by measuring the TBN. With use TBN value decreases from new oil value. When it reaches a critical limit oil requires change

7. Total Acid Number

ASTM D 974 procedure determines the level of acidity by mixing in an indicator solution and then adding potassium hydroxide (KOH) until solution changes colour. Some samples may be too dark to use a colour in indicator and for such cases ASTM D 664 procedure measures the change in electrical conductivity as the KOH is added. The acidity is expressed as mg KOH/g.

Significance: As oils oxidise they form acidic by-products which can be corrosive to metal components. The greater the oil degradation, higher would be the level of corrosive acids and greater the danger of components failure. Some oils, like hydraulic fluids, have additives which are themselves acidic. For such cases, the most meaningful measure is the change in acidity from new oil value. TAN should not be used as the sole criterion for oil deterioration due to oxidation and other properties such as viscosity, insolubles and sludge contents must also be considered.

8. Hexane & Toluene Insolubles

ASTM D 893 procedure measures quantum of insolubles remaining undissolved in Hexane solvent after centrifuging. Insoluble matter is further dissolved in toluene solvent and centrifuged and insoluble matter is weighed. Insolubles are reported as percent mass.

Significance: Hexane insoluble products, consists of oxidation resins plus extraneous matter like carbon, soot, wear particles, dust and dirt etc. Toluene dissolves the oil oxidation products and therefore Toluene insolubles consists of only extraneous matter. Difference between Hexane Insolubles and Tolune insolubles indicates amount of oil oxidation products. Low Hexane insolubles indicate that the oil is in good condition. If Hexane insolubles are high, the subsequent Toluene insolubles indicate whether contamination is due to oil oxidation or extraneous matters or both.

9. Sediments

In this test the oil sample is kept in tumbler and is washed with a solvent in the specified apparatus. The sediments so collected are weighed and results are reported as percent mass.

Significance:

A. Less than 0.05% by volume of sediment is reported as trace

B. No more than a trace of sediment indicates

- Relatively little oxidation or no contamination and the product being in satisfactory condition

- The purification system is functioning properly

C. More than a trace (0.05%) of sediment indicates:

- Oxidation, accompanied by increased neutratisation

number and viscosity.

- The presence of inorganic impurities (e.g.metal particles, dust, dirt, etc.)when accompanied by a high ash value.

- The purification system is not functioning properly.

The nature of sediments is determined by their solubility on chloroform. If the sediments are soluble in chloroform the presence of oxidised oil and/or metalic sops is indicated. If the sediment is completely or even partially insoluble in the chloroform, further analytical work is required to determine the exact nature. Where more than a trace of sediment is reported, efforts should be made to correct the condition

10 Rust Test:

The procedure consists of two parts-Procedure A: using distilled water and Procedure B: using synthetic sea water. Most new lubricants are formulated to pass either Procedure a or B. Premium quality turbine oils, gear oils and hydraulic fluids are formulated to pass procedure B. In this method the oil to be tested is mixed with 10% distilled water or synthetic sea water and a polished grade 1018 carbon steel specimen is inserted in the solution and system is kept at 60oC for 12 hrs. or 24 hrs. The steel specimen is observed for rusting. Results are reported as “Pass or Fail”.

Significance

Lubricating oil in turbine or other system incorporating oil cooling often gets contaminated with water, resulting in rust Particles of rust in the oil can act as catalysts and tend to increase the rate of oil oxidation. Rust particles being abrasive can also cause wear and clogging of service valves. The used oil in circulation must show ‘pass’ value under this test to be fit for further use.

11. Demulsibility:

40 ml sample of oil and 40 ml of distilled water are mixed in a 100 ml cylinder and kept at 54oC. The time taken for emulsion to reduce to 3 ml or less is recorded in steps, of 5 minutes.

If the emulsion is more than 3 ml after one hour the test is discontinued and the remaining amount 1(in ml) of oil, water and emulsion are recorded.

Significance: Water promotes rusting of ferrous parts and accelerates oxidation of the oil for effective removal of water the oil must have good demulsibility characteristics.

12. Foaming:

The test oil is kept at 23.9oC temperature and air is passed through the oil sample for 5 minutes. The amount of foam generated and the time taken by foam to collapse is noted. A fresh sample of the oil is tested at 93.3oC. In the 3rd stage, after carrying out the test at 93.3oC. The results are reported as volume of foram in ml, at the end of blowing period and at the end of setting period for 3 different test temperatures. The foam volume at the end of blowing period is termed as the foaming tendency of the oil, while the foram volume at the end of blowing period is termed as the foaming tendency of the oil, while the form volume at the end of the setting period is termed as the stability of the foam.

Significance: Foaming in a circulating oil system is a serious service condition that may interface with satisfactory system performance and even lead to mechanical damages. Foaming consists of bubbles that rise quickly to the surface of the oil and it should be distinguished from air entrainment which consists of slow rising bubbles dispersed throughout the oil. Foaming can be both system oriented and oil related. Excessive turbulence of the oil or air leakage in the oil flow may lead to foaming. Trace contamination of the lubricant by surface active materials such as rust preventives and detergents can also cause foaming. Foaming in an industrial oil is undesirable because the foam may overflow the reservoir and create a nuisance.

The nature of sediments is determined by their solubility on chloroform. If the sediments are soluble in chloroform the presence of oxidized oil and/or metallic sops is indicated. If the sediment is completely or even partially insoluble in the chloroform, further analytical work is required to determine the exact nature. Where more than a trace of sediment is reported, efforts should be made to correct the condition

13. Trace Metals:

Emission spectroscopy and atomic absorption are two common methods for determining trace metals in used or new lubricating oils. Both these techniques require small quantity of oil sample. Results are reported in parts per million or parts per billion concentration of inorganic metals in the oil sample.Significance: New oils contain metallic additives and the quantum of these additives can be determined by concentration of trace metals like zink, calcium, phosphorus, etc. Trace metal analysis in used oil indicates depletion of additives and wear metal particles concentration. The analysis of wear metal particles can be used for monitoring condition of the equipment. The following is the list of elements generally found in used industrial and engine oils and their sources

CANNON AUTOMATIC VISCOMETER

CAUSES , EFFECTS & RECOMMENDATION FOR VISCOSITY CHANGES.

CAUSES EFFECTS RECOMMENDATIONSHIGH VISCOSITY•Contamination soot/solids•Oxidative degradation.•Leaking headgasket.•Water Ingress•Over extended oil drain.•High operating temperature.•Incorrect oil grade or type.•Cross contamination.

•LOW VISCOSITY

•Polymer shearing

(multigrade oils)•Fuel dilution.•Incorrect oil grade or type.

Cross contamination

•Restricted oil flow.

•Machine overheating.

•Accelerated wear.

•Impeded low temperature operation

Increased friction

•Machine overheheating•Machine overheating.•Metal to metal contact.•Accelerated wear.•Increased leakage

•Check fuel pipes and injector calibration.

•Check for correct oil grade / type.

•Check for correct operating temperature.

•Check for leaking injector.

•Check operating condition.

•Change oil and filters.

Evaluate equipment suitability for use.

DIRECT READING EMMISSION SPECTROMETER

IT IS USED FOR.

DEPLETION OF ADDITIVES IN USED OILS.

WEAR ELEMENTS / CONTAMINANTS BUILD UP.

TO IDENTIFY COOLANT/ WATER

CONTAMINATION.

QUALITY CHECK OF FRESH OILS.

DIRECT READING EMMISSION SPECTROMETER

RESULT OF WEAR-PARTICULATE CONTAMINATION

Abrasion. Cavitation and Erosion. Corrosion Adhesion Surface Fatigue

Conaminant Monitoring - Predictive Maintenance

ELEMENT / CONTAMINANTS & THEIR SOURCES

ELEMENT IRON CHROMIUM LEAD COPPER TIN ALUMINIUM NICKEL SILICON ZINC VANADIUM BORON POTASSIUM

• TYPICAL SOURCE • CYLINDER,RUST,CRANKSHAFT,WATER.

• CYLINDER,RING,COOLANT,CRANKSHAFT

• GASOLENE,BEARING,GREASE,PAINT.

• BEARING,BUSHING,BRONZE.

• BEARING,SOLDER,COOLERS.

• DIRT, DEPOSITS.

• SHAFT,GEARS,RINGS,TURBINE COMPONENTS.

• DEFOAMANTS,DIRT.

• ADDITIVES,BEARINGS,PLATINGS.

• FUEL,CATALYSTS,TURBINE BLADES,VALVES.

• COOLANTS,ADDITIVES,SEA WATER.

• COOLANTS,ADDITIVES,DIRT.

FUEL DILUTION

Amount of Dilution Viscosity Effect5% SAE 30207% SAE 3010

Change oil when fuel dilution exceeds 2% Reduces lubrication and dilutes additives Tests for fuel dilution: Viscosity,FTIR,Flash

Point(ASTM D-93), Gas Chromatography(ASTM D3524), Steam Distillation.

CAUSES OF SOOT BUILD UP

Incomplete combustion Low compression High fuel /air ratio Improper scavenge operation Excessive ring wear / blow by.Tests for Soot:-Toluene Insol.(D-

893), MembraneFiltration, TGA.

Plugged air filter. Excessive idling. Cool engine temperatures. Poor fuel nozzle. Defective turbo operation.

MAXIMUM CONTAMINATION LIMITS(BASED ON A 100 ML SAMPLE)

MAXIMUM CONTAMINATION LIMITS(BASED ON A 100 ML SAMPLE)

SAMPLING FREQUENCY

EQUIPMENT Diesel engines. Hydraulics Gas Turbine industrial Steam turbines. Air/gas compressors Gear Boxes-high speed Gear boxes-low speed Marine /DG Set Stationary engines

HOURS 150-300 200 500 500 500 300 1000 500 1000