Analysis Plus test predictors

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Introduction	Viscosity	Water/Coolant Contamination
Fuel Dilution	Solids	Fuel Soot
Oxidation	Nitration	Total Acid Number (TAN)
Total Base Number (TBN)	Particle Count	Wear Metal/Elemental Analysis
Quality Equipment Oil Analysis Program	Oil Sampling Methods

Introduction

Oil analysis is a series of laboratory tests used to evaluate the condition of lubricants and equipment components. By studying the results of the oil analysis tests, a determination of equipment/component condition can be made. Primarily, this is possible because of the cause and effect relationship of the condition of the lubricant to the condition of the component sampled. Many of these cause and effect situations are outlined in this manual.

Oil performs several vital functions with many of them being interrelated. The ability of the oil to perform as designed can be determined by oil analysis. The following is a list of some primary lubricant functions that can be evaluated:

Friction control
Contaminant control
Hydraulic pressure
Temperature control

Corrosion control
Shock control
Wear control
Sealing function

The inspection or analysis of lubricating oil has been used to check and evaluate the internal condition of oil-lubricated equipment since the beginning of the industrial age. Early methods included smelling the oil to detect the sour odor of excess acidity, rubbing it between finger tips to check lubricity, and observing its color and clarity for signs of contamination.

Today, oil analysis programs use modern technology and laboratory instruments to determine equipment condition and lubricant serviceability. Oil analysis uses state of the art equipment and techniques to provide the user with invaluable information leading to greater equipment reliability.

Viscosity

Viscosity is one of the most important properties of lubricating oil. Viscosity is a measurement of resistance to flow at a specific temperature in relation to time. The two most common temperatures for lubricating oil viscosity are 40°C and 100°C. Viscosity is normally evaluated with a kinematic method and reported in centistokes (cSt). In used oil analysis, the used oil's viscosity is compared to that of the new oil to determine whether excessive thinning or thickening has occurred.

Viscosity Index (VI) is the change in flow rate of a lubricant with respect to temperature. Oil with a high VI resists thinning at high temperatures. Use of high VI oil is recommended in engines and other systems that operate at elevated temperatures.

Cause

High Viscosity

Contamination soot/solids
Incomplete combustion-A/F ratio
Oxidation degradation
Leaking head gaskets
Extended oil drain interval
High operating temperature
Improper oil grade

Low Viscosity

Additive shear
Fuel dilution
Improper oil grade

Effect

High Viscosity

Increased operating costs
Engine overheating
Restricted oil flow
Accelerated wear
Oil filter bypassed
Harmful deposits/sludge

Low Viscosity

Engine overheating
Poor lubrication
Metal-to-metal contact
Increased operating costs

Solution

Check air-to-fuel ratio
Check for incorrect oil grade
Inspect internal seals
Check operating temperature
Check with lube supplier for advice
Check for leaking injectors

Evaluate equipment use vs. design
Evaluate operating conditions
Use trained operators
Change oil and filters
Check for loose fuel crossover lines

Water/Coolant Contamination

The presence of water in engines indicates contamination from outside sources, from condensation of moisture in the atmosphere, or from internal coolant leaks. Water is typically evaporated by engines at normal operating temperatures. However, water may remain in the oil when engine temperatures are too low for evaporation to occur. Other types of equipment, when operated at sufficient temperatures, also tend to evaporate contaminating water.

Oil analysis offers an effective method of recognizing water/coolant contamination before a major problem occurs. Infrared analysis is used to determine water content in used oil. Results are reported in percent volume. The Karl Fischer method is used to measure water in systems that are sensitive to low moisture content. Karl Fischer results are reported in parts per million (ppm).

Cause

Low operating temperature
Defective seals
New oil contamination
Coolant leak
Improper storage
Cracked Cylinder head
Weather/moisture
Product of combustion
Oil cooler leak

Effect

Engine failure
High viscosity
Poor lubrication
Corrosion
Engine overheating
Acid formation
Reduced additive effectiveness

Solution

Inspect for cracked cylinder head
Inspect heat exchanger and oil coolers
Evaluate operating conditions
Evaluate equipment use vs. design
Avoid intermittent use
Check for external water/moisture sources
Change oil filter

Fuel Dilution

Fuel dilution of crankcase oil by unburned fuel reduces lubricant effectiveness. The thinning of the lubricant can lead to decreased lube film strength adding to the risk of abnormal wear. Depending on certain variables, when fuel dilution of crankcase oil exceeds 2.5 to 5 percent, corrective action should be taken. Fuel dilution is measured by gas chromatography. The results are reported in percent volume.

Cause

Incorrect air/fuel ratio
Extended idling
Stop and go driving
Defective injectors
Incomplete combustion
Incorrect timing

Effect

Metal-to-metal contact
Poor lubrication; oil thinning
Increased overall wear
Piston ring wear
Decreased additive effectiveness
Risk of fire or explosion
Reduced fuel economy
Decreased oil pressure
Reduced engine performance
High operating cost
Shortened engine life

Solution

Check fuel lines, leaking injectors or seals, pumps
Analyze driving/operating conditions
Check spark timing
Avoid prolonged idling
Change oil and filter more frequently
Evaluate equipment and use vs. design
Check fuel quality
Repair/replace worn parts

Solids

Solids represent a measurement of all solid and solid-like constituents in the lubricant. The makeup of solids depends on the system. In diesel engines, fuel soot is usually the major constituent measured. In non-diesel components, wear debris and oil oxidation products are measured. All solid material is measured and reported as a percentage of sample volume or weight.

Cause

Extended oil drain interval
Environmental debris
Wear debris
Oxidation byproducts
Filter leaking or dirty
Fuel soot

Effect

Shorter engine life
Filter plugging
Poor lubrication
Engine deposits
Sludge formation
Accelerated wear
Decreased oil flow
Lacquer buildup

Solution

Drain oil, flush system
Eliminate source of environmental debris
Evaluate equipment use vs. design
Evaluate operating conditions
Reduce oil drain intervals
Change filter

Fuel Soot

Fuel soot is composed of carbon and is always found in diesel engine oil. Laboratory testing is used to determine the quantity of fuel soot in used oil samples. Stringent exhaust emission regulations have placed greater emphasis on fuel soot levels. One of the most significant impacts of reduced emissions is control of particulate emissions, which resulted in greater soot levels in the crankcase. The fuel soot level is a good indicator of engine combustion efficiency and should be monitored on a regular basis for possible maintenance action.

Cause

Improper air/fuel ratio
Improper injector spray pattern
Poor quality fuel
Incomplete combustion
Clogged air induction
Defective injectors
Improper equipment operation
Low compression
Worn piston/rings

Effect

Poor engine performance
Harmful deposits or sludge
Increased wear
Shortened oil life
Lacquer formation
Clogged oil filters

Solution

Ensure fuel injectors are working properly
Change oil
Evaluate oil drain intervals
Check compression
Avoid excessive idling
Check fuel quality

Oxidation

Lubricating oil in engines and other components combines with available oxygen under certain conditions to form harmful byproducts. Heat, pressure and catalyst materials accelerate the oxidation process. Byproducts of oxidation form lacquer deposits, corrode metal parts and thicken oil beyond its ability to lubricate. Most lubricants contain additives that inhibit or retard the oxidation process.

Differential infrared analysis offers the only direct means of measuring the level of oxidation in oil. Note: A new oil reference is required for accurate measurement of oxidation. Results are reported on an absorbance scale.

Cause

Overheating
Extended oil drain interval
Improper oil type/inhibitor additives
Combustion byproducts/blow-by

Effect

Shortened equipment life
Lacquer deposits and engine sludge
Oil filter plugging
Increased oil viscosity
Corrosion of metal parts
Increased operating costs
Increased overall wear
Decreased engine performance

Solution

Use oil with oxidation inhibitor additives
Shorten oil drain intervals
Check operating temperature
Evaluate equipment use vs. design
Evaluate operating conditions

Nitration

Nitration products are formed during the fuel combustion process when combustion byproducts enter the engine oil during normal operation or as a result of abnormal blow-by past the compression rings. These products, which are more common in oils used to lubricate natural gas- and propane- fueled engines, are highly acidic and create deposits and accelerate oil oxidation. Infrared analysis represents the only method of accurately measuring nitration products in oil. Results are reported on an absorbance scale.

Cause

Improper crankcase scavenge
Low operating temperature
Defective seals
Improper air/fuel ratio
Abnormal blow-by

Effect

Nitrous oxides introduced into environment
Acidic byproducts formed
Increased cylinder and valve train wear
Oil thickening
Combustion chamber deposits
Increased acid number

Solution

Increase operating temperature
Check crankcase venting hoses and valves
Ensure proper air/fuel mixture
Perform compression check or cylinder leak-down test

Total Acid Number (TAN)

The total acid number is the quantity of acid or acid-like constituents in the lubricant. An increase in TAN from that of the new lubricant should be monitored. The TAN of a new oil is not necessarily zero since oil additives can be acidic in nature. Increases in TAN usually indicate lube oxidation or contamination with water or an acidic product. TAN is an indicator of oil serviceability.

Cause

High-sulfur fuel
Overheating
Excessive blow-by
Extended oil drain interval
Improper oil type

Effect

Corrosion of metallic components
Promotes oxidation
Oil degradation
Oil thickening
Additive depletion

Solution

Shorter oil drain intervals
Verify correct oil type in service
Check for overheating
Check fuel quality

Total Base Number (TBN)

The total base number is an expression of the amount of alkaline additives in the lubricant that are capable of neutralizing the acid products of combustion. A new oil starts with the highest TBN it will possess. During the time the lubricant is in service, the TBN decreases as the alkaline additives neutralize acids. TBN is an essential element in the establishment of oil drain intervals since it indicates whether the additives are still capable of providing sufficient engine protection.

Cause

High-sulfur fuel
Overheating
Extended oil drain interval
Improper oil type

Effect

Increased acid number
Oil degradation
Increased wear
Corrosion of metal parts
Acid buildup in oil

Solution

Use low-sulfur fuel
Follow manufacturer's recommendations for oil drain interval, and decrease if engine is operated under severe conditions
Verify TBN of new product and use correct oil type
Change oil or top off with fresh oil
Test fuel quality

Particle Count

Fluid cleanliness is critical in hydraulic and other systems where high fluid pressure and velocity are involved. Excessive fluid particulate contamination is a major cause of failure of hydraulic pumps, motors, valves, pressure regulators and fluid controls. Failure due to excessive particulate contamination is normally segregated into three areas:

Performance degradation
Intermittent failure
Catastrophic failure

Particle count measurements allow the user to monitor hydraulic system contamination levels on a scheduled basis. Scheduled analysis of hydraulic fluid to include particle count is recommended by most equipment and hydraulic component manufacturers.

Cause

Water contamination
Machining burrs
Filling techniques
Oil oxidation
Contaminated new oil
Worn wiper seals
System generated debris
Built in contamination
Defective breather

Effect

Performance degradation
Intermittent failure
Wear
Plugging
Leakage
Pressure overshoot
Momentary hesitation
System failure

Solution

Filter new oil
Change hydraulic fluid
Inspect/replace filters
Check particle sizes
System flushing at high pressure
Check air breather
Evaluate equipment vs. design
Evaluate operating conditions

Wear Metal/Elemental Analysis

Elemental analysis is used to evaluate and quantify wear metal elements, additive elements and contamination elements. Wear metals are analyzed to pinpoint problem areas through trend analysis. By analyzing the additive elements, the oil type can be verified, i.e., hydraulic oil, transmission fluid or engine oil. Contamination elements are reviewed to determine lubricant serviceability and to pinpoint causes of problems indicated by other test results.

Following are the sources of the elements analyzed and their function in a component:

Wear Metals

Element	Source	Function
Iron (Fe)	Engine blocks, gears, rings, bearings, cylinder walls, cylinder heads, rust	Because of its strength, iron is the base metal of steel in many parts of the engine. Since iron will rust, it is alloyed with other metals (i.e., Cr, Al, Ni) making steel.
Chromium (Cr)	Shafts, rings, chromate from cooling system	Because of its strength and hardness, chromium is used to plate rings and shafts that are usually mated with steel (softer). Chromium is also alloyed with iron (steel) for strength.
Aluminum (Al)	Bushings, some bearings, pistons, turbocharger, compressor wheels	Aluminum is a strong light-weight metal (smaller mass) that dissipates heat well and aids in heat transfer.
Copper (Cu)	Bearings, bushings, oil coolers, radiators	Copper is utilized to wear first in order to protect other components. Copper conforms well so it is used to seat bearings to the crankshaft.
Lead (Pb)	Bearing overlay, leaded gasoline contamination	Lead is a conforming material used to plate bearings. Lead will appear in new engines while the bearings are melding and conforming. If lead appears later, misalignment may be indicated.
Nickel (Ni)	Valve stems, valve guides, ring Inserts on pistons	Nickel is alloyed with iron in high strength steel used to make valve stems and guides.
Silver (Ag)	Bearing cages (anti-friction bearings), Silver Solder, turbocharger bearings and wrist pin bushings	Silver is used to plate some components because it conforms well, dissipates heat and reduces coefficient of friction.
Tin (Sn)	Bearings, pistons	Tin is a conforming material used to plate and protect surfaces to facilitate break-in.
Molybdenum (Mo)	Piston rings, oil additives	Molybdenum is used as an alloy in some piston rings in the place of Chromium. Molybdenum is also used as a friction-reducing additive in some oils. Soluble Mo can be used as an antioxidant additive.

Additive Elements

Element	Function
Zinc (Zn)	AW, EP, Antioxidant
Phosphorus (P)	AW, EP, Antioxidant Phosphorus is added to extreme pressure oils to provide a protective film. EP oils are characterized by high phosphorus and sulfur levels.
Barium (Ba)	Detergent Barium is toxic and expensive, but it is advantageous because it does not leave excessive ash residue.
Sodium (Na), Calcium (Ca) and Magnesium (Mg)	Alkaline (base) additives used to neutralize acids formed by products of combustion in engine oils. They also have some detergent qualities and corrosion inhibition.
Boron (B)	Inhibitor Boron is also found as an additive in coolant as borate.
Copper (Cu)	Antioxidant Copper is added to engine oils to prevent oxidation.

Contaminant Elements

Element	Cause
Sodium (Na)	External contamination, coolant leak or salt in the air.
Silicon (Si)	External (dirt), additive, sealants Silicon can be an antifoam additive and from gasket material in the form of silicone.
Potassium (K)	Coolant leak Potassium is a coolant additive, and its presence in oil is indicative of coolant contamination.

Quality Equipment Oil Analysis Program
Industry	Machine Type	Recommended Sampling Frequency
	Diesel engines	150 hours, 10,000 miles
	Gasoline engines	3,000 to 5,000 miles
Mining, construction,	Transmissions	300 hours, 20,000 miles
agriculture, bus lines,	Gears, differentials	300 hours, 20,000 miles
railroads, forestry,	Final drives
automobiles	Hydraulics	300 hours, 20,000 miles


	Reciprocating engines	25 to 50 hours
	Turbines	100 hours
	Gearboxes	100 to 200 hours
	Hydraulics	100 to 200 hours



Manufacturing, processing,	Diesel engines	Monthly, 500 hours	Quarterly
power generation, natural gas	Natural gas engines	Monthly, 500 hours	Quarterly
distribution, oil and gas	Gas turbines	Monthly, 500 hours	Quarterly
exploration, marine equipment	Steam turbines	Bimonthly	Quarterly
	Air, gas compressors	Monthly, 500 hours	Quarterly
	Refrigeration compressors	Beginning, midpoint and end of season
	Gears, bearings	Bimonthly	Quarterly
	Hydraulics	Bimonthly	Quarterly

Oil Sampling Methods

To properly evaluate machine conditions, the oil samples submitted for analysis must be representative of the system from which they are taken. For best results, follow these guidelines:

The machine being sampled should be brought to normal operating temperature. Oil should be recirculated, if appropriate. This will ensure that insoluable and semisoluable contaminants are uniformly dispersed throughout the system. Samples taken from machines that have been inactive for long periods are not representative.
Oil samples should always be taken in the same manner and from the same sampling point.
Do not sample a machine immediately after an oil change or after a large amount of makeup oil has been added.
Use a clean dry container to draw the oil sample. Ship samples in the plastic bottles provided in the package. Hydraulic fluids or other oils submitted for a particle count analysis should be submitted in the super clean bottles, which are provided when special testing is requested.

Sample Gun Method

The oil test package includes a plastic sampling bottle used for collecting and shipping samples. A special inexpensive sampling gun is also offered as an option, together with convenient lengths of plastic sampling tubing. The plastic sampling bottle fits directly into the sampling gun, and the oil sample can be drawn directly from the machine into the sampling bottle. The sampling gun allows the user to draw representative samples quickly and with a minimum of effort. Procedures are as follows:

Measure a sufficient length of plastic sampling tubing to reach from the sampling gun through the sample aperture and into the machine sump or reservoir. If the machine has a dipstick, the tubing should be measured against the dipstick to establish the proper sampling depth.
Loosen the nut on the sample gun head, insert the free end of the sampling tubing through the nut (about 1/2 inch past nut) and tighten the nut to compress the sealing ring to obtain a vacuum-tight seal. Screw a clean plastic sampling bottle into the gun adaptor.
Holding the sampling gun upright, draw oil into the bottle using the piston lever until oil is within 1/2 inch of the top. To stop the oil flow, break the vacuum by partially unscrewing the bottle. Remove the bottle from the adaptor, screw the cap on tightly and wipe the bottle clean. Fill out the unit or machine identification number on the bottle label.
Replace the plastic tubing after each sampling to avoid sample cross-contamination.

Sample Valve/Petcock Method

Care should be taken to install the valve on the lube system in a location that will ensure representative oil samples can be drawn. The exterior of the valve should be wiped clean prior to sampling to ensure that no external contamination finds its way into the oil. Stagnant oil should be drained from the valve by drawing a small oil sample into a waste oil container just prior to collecting the oil sample in the plastic sampling bottle. Screw the bottle cap on tightly and wipe the bottle clean. Fill out the unit or machine identification number on the bottle label.

Oil Drain Method

Clean the area around the drain plug thoroughly to avoid sample contamination. Allow some of the oil to drain into a waste oil container prior to collecting the oil sample. Place a clean dry sample bottle into the oil stream and fill it to within 1/2 inch of the top. Screw the cap on tightly and wipe the bottle clean. Fill out the unit or machine identification number on the label.

Note: When taking oil samples from hydraulic systems for particle count analysis, special care must be taken to assure the samples are representative and that they are contamination free. Use the special super clean bottles to sample oils for particle count analysis.