Lubricating Oil
Viscosity:
1. A measure of internal resistance to flow.
2. Viscosity of an oil changes with temperature, falling when temperature rises and vice versa.
3. For crankcase oil, viscosity is between 130 – 240 Sec. Redwood No. 1 at 60°C.
4. For cylinder oil, viscosity is 12.5 – 22 Cst.
1. A measure of internal resistance to flow.
2. Viscosity of an oil changes with temperature, falling when temperature rises and vice versa.
3. For crankcase oil, viscosity is between 130 – 240 Sec. Redwood No. 1 at 60°C.
4. For cylinder oil, viscosity is 12.5 – 22 Cst.
Viscosity Index, VI:
1. The rate of change of viscosity of an oil, in relation to change of temperature.
2. Oil of low VI has greater change of viscosity with change in temperature,
than the oil of high VI.
3. For crankcase oil, VI is between 75 – 85; For cylinder oil, VI is 85.
4. Highest VI of mineral oils is about 115 and with special additives, this may be raised to about 160.
5. Hydraulic oils, used in remote control hydraulic circuits must have very high VI; otherwise erratic response to the controls can be troublesome. (Telemotor hydraulic system oil has VI of 110.)
1. The rate of change of viscosity of an oil, in relation to change of temperature.
2. Oil of low VI has greater change of viscosity with change in temperature,
than the oil of high VI.
3. For crankcase oil, VI is between 75 – 85; For cylinder oil, VI is 85.
4. Highest VI of mineral oils is about 115 and with special additives, this may be raised to about 160.
5. Hydraulic oils, used in remote control hydraulic circuits must have very high VI; otherwise erratic response to the controls can be troublesome. (Telemotor hydraulic system oil has VI of 110.)
Pour Point:
- Lowest temperature at which an oil will barely flow.
- Pour point indicates that oil is suitable for cold weather or not.
- or crankcase oil, Pour Point is, – 18°C.
TAN and TBN:
1. TAN is the ability of an oil, to react with basic reagent, which indicates the acidity
expressed as TAN.
2. TBN is the ability of an oil, to react with acidic reagent, which gives an Alkali figure, the TBN.
3. Expressed in milligrams of KOH required to neutralise one gram of sample oil, for both TAN and TBN.
4. For crosshead type engine crankcase oil: TBN is 8 mg KOH/gm of oil.
5. For Trunk type engine using HO, crankcase oil: TBN is 30 mg KOH/gm of oil.
1. TAN is the ability of an oil, to react with basic reagent, which indicates the acidity
expressed as TAN.
2. TBN is the ability of an oil, to react with acidic reagent, which gives an Alkali figure, the TBN.
3. Expressed in milligrams of KOH required to neutralise one gram of sample oil, for both TAN and TBN.
4. For crosshead type engine crankcase oil: TBN is 8 mg KOH/gm of oil.
5. For Trunk type engine using HO, crankcase oil: TBN is 30 mg KOH/gm of oil.
Detergency/Dispersancy:
1. Deposits occur in engine crankcase or ring zone, due to semi-solid precipitation from LO.
2. High temperature effect accelerates the rate of such deposition.
3. To reduce formation of such deposits, oil is treated with Detergent/Dispersant Additives, for keeping the system clean and trouble-free.
4. When using conventional mineral oils, these deposits block exhaust passage and prevent free movement of piston rings.
5. Addition of Detergent Additive prevents deposition of such deposits and washes them away with LO.
6. By addition of Dispersant Additive, tiny particles are carried in colloidal suspension, and dispersed evenly throughout the bulk of oil.
7. Detergent/Dispersant Additives are complex chemical compounds, such as metallic based Sulphonates, Phosphonates, Phenates and Salicylates.
1. Deposits occur in engine crankcase or ring zone, due to semi-solid precipitation from LO.
2. High temperature effect accelerates the rate of such deposition.
3. To reduce formation of such deposits, oil is treated with Detergent/Dispersant Additives, for keeping the system clean and trouble-free.
4. When using conventional mineral oils, these deposits block exhaust passage and prevent free movement of piston rings.
5. Addition of Detergent Additive prevents deposition of such deposits and washes them away with LO.
6. By addition of Dispersant Additive, tiny particles are carried in colloidal suspension, and dispersed evenly throughout the bulk of oil.
7. Detergent/Dispersant Additives are complex chemical compounds, such as metallic based Sulphonates, Phosphonates, Phenates and Salicylates.
Function of Lubricant:
1. Reduce friction.
2. Remove heat.
3. Flush away contaminants.
4. Protect corrosion.
5. Dampen noise.
6. In some case, act as sealant.
2. Remove heat.
3. Flush away contaminants.
4. Protect corrosion.
5. Dampen noise.
6. In some case, act as sealant.
Types of Lubrication:
1. Hydrodynamic lubrication.
2. Boundary lubrication.
3. Hydrostatic lubrication.
4. Elasto hydrodynamic lubrication.
2. Boundary lubrication.
3. Hydrostatic lubrication.
4. Elasto hydrodynamic lubrication.
Hydrodynamic lubrication:
1. Moving surfaces are completely separated by continuous unbroken film.
2. Lubricant, because of its viscosity, is drawn between the surfaces and builds up a film, by the action of moving parts.
3. Thickness of film: 0.025 – 0.10 mm.
4. Essential requirement is formation of oil wedge between the surfaces.
5. Lubrication for Journal Bearing, Bottom End Bearing, Tilting Pad Thrust Bearing.
1. Moving surfaces are completely separated by continuous unbroken film.
2. Lubricant, because of its viscosity, is drawn between the surfaces and builds up a film, by the action of moving parts.
3. Thickness of film: 0.025 – 0.10 mm.
4. Essential requirement is formation of oil wedge between the surfaces.
5. Lubrication for Journal Bearing, Bottom End Bearing, Tilting Pad Thrust Bearing.
Boundary lubrication.
1. It exists when full fluid film lubrication is not possible.
2. High friction between surfaces, and a degree of metal to metal contact occurs.
3. Lubricant oil film decreases, until asperities of mating surfaces touch.
1. It exists when full fluid film lubrication is not possible.
2. High friction between surfaces, and a degree of metal to metal contact occurs.
3. Lubricant oil film decreases, until asperities of mating surfaces touch.
Hydrostatic lubrication:
1. A form of Hydrodynamic lubrication, but instead of being self-generated, it is supplied from external source of oil under pressure, from a pump.
2. Lubrication for Crosshead Bearings, with attached pump.
1. A form of Hydrodynamic lubrication, but instead of being self-generated, it is supplied from external source of oil under pressure, from a pump.
2. Lubrication for Crosshead Bearings, with attached pump.
Elasto-hydrodynamic lubrication:
1. Applied to line contact or nominal point between rolling or sliding surfaces, as in ball bearings, roller bearings and gear trains.
2. Thin film lubrication limits metal to metal contact.
3. Elastic deformation of metals occurs, and there is high-pressure effect on the lubricant.
1. Applied to line contact or nominal point between rolling or sliding surfaces, as in ball bearings, roller bearings and gear trains.
2. Thin film lubrication limits metal to metal contact.
3. Elastic deformation of metals occurs, and there is high-pressure effect on the lubricant.
Contaminants in LO:
(1) Water:
1. Owing to condensation of water vapour in crankcase.
2. Leakage from cooling water system for cylinder or piston.
3. Combined with oil in the form of emulsion.
4. Combined with sulphurous products of combustion to form Sulphuric Acid, in trunk engine.
1. Owing to condensation of water vapour in crankcase.
2. Leakage from cooling water system for cylinder or piston.
3. Combined with oil in the form of emulsion.
4. Combined with sulphurous products of combustion to form Sulphuric Acid, in trunk engine.
(2) Fuel Dilution:
1. Presence of fuel oil in crankcase oil is indicated by reduction in viscosity and flash point.
2. Result from poor atomisation of fuel injectors.
1. Presence of fuel oil in crankcase oil is indicated by reduction in viscosity and flash point.
2. Result from poor atomisation of fuel injectors.
(3) Oxidation Products:
1. Mineral oils react with oxygen in air and form oil-soluble organic acid, lacquers, resin and sludge, depending upon temperature and degree of contact with air.
2. Accelerated by contact with copper and iron, which act as catalyst.
1. Mineral oils react with oxygen in air and form oil-soluble organic acid, lacquers, resin and sludge, depending upon temperature and degree of contact with air.
2. Accelerated by contact with copper and iron, which act as catalyst.
(4) Fuel Combustion Products:
1. Mainly acids and incompletely burnt fuel form sludge and deposits.
2. Inorganic acids from combustion of high-sulphur residual fuel.
1. Mainly acids and incompletely burnt fuel form sludge and deposits.
2. Inorganic acids from combustion of high-sulphur residual fuel.
(5) Foreign Mineral Matters:
1. Rust and scales from storage tanks and pipes, etc.
2. Dust from surrounding atmosphere.
3. Wear debris from lubricated surface [not entirely hydrodynamic], and from corrosion of cylinder liner.
1. Rust and scales from storage tanks and pipes, etc.
2. Dust from surrounding atmosphere.
3. Wear debris from lubricated surface [not entirely hydrodynamic], and from corrosion of cylinder liner.
(6) Biological contamination:
1. Associated with ‘wet oil’ caused by leakage from cooling system.
2. It causes formation of organic acids, sludge and additive depletion, corrosion of shaft and bearings.
3. If happened, complete oil change may be necessary, thorough sterilisation and cleaning out of cooling system, and leakage to be stopped.
4. Addition of biocides to both oil and water, helps.
1. Associated with ‘wet oil’ caused by leakage from cooling system.
2. It causes formation of organic acids, sludge and additive depletion, corrosion of shaft and bearings.
3. If happened, complete oil change may be necessary, thorough sterilisation and cleaning out of cooling system, and leakage to be stopped.
4. Addition of biocides to both oil and water, helps.
Symptoms of LO Contamination:
1. Increased Sump sounding (severe SW contamination).
2. Change in pressure and colour (Emulsification of oil, with water and residues of treated cylinder oil from diaphragm or scrapper box leakage).
3. Change in pressure (Reduction in viscosity and flash point, due to fuel oils.)
4. Frequent choking of filters due to sludge formation and Additive depletion, due to biological contamination.
5. Darkened oil colour and yellowish colour film on surface, pungent smell & sludge formation, due to microbial degradation.
6. Particles of rust and scales, mostly ferrous, trapped in magnetic filter (Corrosion of shaft and bearings, due to water, fuel combustion products.)
7. Wear debris, and welding spatter trapped at magnetic filter (Contamination of foreign mineral matters.
2. Change in pressure and colour (Emulsification of oil, with water and residues of treated cylinder oil from diaphragm or scrapper box leakage).
3. Change in pressure (Reduction in viscosity and flash point, due to fuel oils.)
4. Frequent choking of filters due to sludge formation and Additive depletion, due to biological contamination.
5. Darkened oil colour and yellowish colour film on surface, pungent smell & sludge formation, due to microbial degradation.
6. Particles of rust and scales, mostly ferrous, trapped in magnetic filter (Corrosion of shaft and bearings, due to water, fuel combustion products.)
7. Wear debris, and welding spatter trapped at magnetic filter (Contamination of foreign mineral matters.
How to remove contaminants:
1. Filtering – removed large oil insoluble matter.
2. Gravity separation – heavy matters, sludge and water.
3. Adding special additives – reduce acids, sludge, finer oil insoluble matter.
4. Centrifuging – Sludge, foreign matter and water.
5. Water washing – only for straight mineral oil or oil without additives, can remove acids.
1. Filtering – removed large oil insoluble matter.
2. Gravity separation – heavy matters, sludge and water.
3. Adding special additives – reduce acids, sludge, finer oil insoluble matter.
4. Centrifuging – Sludge, foreign matter and water.
5. Water washing – only for straight mineral oil or oil without additives, can remove acids.
Water washing:
1. It can be carried out on straight mineral oil but not for detergent / dispersant type oil
2. The purpose is to remove acids, salts and other impurities from the oil.
3. Water should be injected before purification at a rate of 3% to 5% of oil flow.
4. Oil temperature should be around 75˙C and water temperature about 5˙C higher than oil temperature.
1. It can be carried out on straight mineral oil but not for detergent / dispersant type oil
2. The purpose is to remove acids, salts and other impurities from the oil.
3. Water should be injected before purification at a rate of 3% to 5% of oil flow.
4. Oil temperature should be around 75˙C and water temperature about 5˙C higher than oil temperature.
Batch purification:
1. If oil is contaminated with strong acids, high insoluble contents or water, batch purification of the entire charge oil should be done.
2. In port, the entire charge oil is pumped by purifier or circulating pump into Renovating Tank, fitted with steam heating coils.
3. Allowed to settle for at least 24 hours at about 60˙C.
4. Water and sludge must be periodically drained out.
5. Then oil is passed through the purifier at its optimum throughput and pumped back to Sump Tank.
6. During the time when the sump tank is empty, its interior should be cleaned and examined.
7. This should be done at least once a year.
1. If oil is contaminated with strong acids, high insoluble contents or water, batch purification of the entire charge oil should be done.
2. In port, the entire charge oil is pumped by purifier or circulating pump into Renovating Tank, fitted with steam heating coils.
3. Allowed to settle for at least 24 hours at about 60˙C.
4. Water and sludge must be periodically drained out.
5. Then oil is passed through the purifier at its optimum throughput and pumped back to Sump Tank.
6. During the time when the sump tank is empty, its interior should be cleaned and examined.
7. This should be done at least once a year.
Throughput of a purifier: The best purification result is obtained if oil is kept inside the bowl as long as possible, i.e. throughput should be as low as possible and also more frequent desludging once every hour.
If LO is contaminated with SW:
1. When sump oil is contaminated with SW, find sources of leakage [may be from LO cooler during ME stoppage] and rectified.
2. In port or while ME is stopped, transfer contaminated oil through purifier or transfer pump into Renovating Tank, settled for at least 24 hours at about 60°C, and water and sludge drained out periodically.
3. Oil passed through purifier at 78°C with optimum efficiency, and pump back to Renovating Tank.
4. When Sump Tank is empty, interior cleaned and examined.
5. Purified oil sent to Laboratory and tested.
6. During this time, new oil should be used.
7. Oil should be reused, if Lab results recommended that it is fit for further use.
[Straight mineral oil: 3% water washed. Additive oil: 1% water washed.]
2. In port or while ME is stopped, transfer contaminated oil through purifier or transfer pump into Renovating Tank, settled for at least 24 hours at about 60°C, and water and sludge drained out periodically.
3. Oil passed through purifier at 78°C with optimum efficiency, and pump back to Renovating Tank.
4. When Sump Tank is empty, interior cleaned and examined.
5. Purified oil sent to Laboratory and tested.
6. During this time, new oil should be used.
7. Oil should be reused, if Lab results recommended that it is fit for further use.
[Straight mineral oil: 3% water washed. Additive oil: 1% water washed.]
L.O. for Crankcase Viscosity 130 – 240 Sec. Redwood No. 1 at 60’C.
VI 75 – 85 Pour pt. – 18’C Closed flash pt.220’C
TBN (trunk type) 30 mgKOH/gm of oil
TBN ( X-Head Type ) 8 mgKOH/gm of oil.
VI 75 – 85 Pour pt. – 18’C Closed flash pt.220’C
TBN (trunk type) 30 mgKOH/gm of oil
TBN ( X-Head Type ) 8 mgKOH/gm of oil.
Water in LO
Effects:
1. Can form Acids.
2. Can cause corrosion on m/c parts.
3. Microbial degradation. [Reduce centrifuging efficiency; promote local pitting and corrosion].
4. Reduce load carrying capacity.
5. Reduce L.O. properties, and TBN of oil.
6. Form sludge due to emulsification.
Remedies:
1. Proper purification with minimum throughput.
2. Batch purification if heavy contamination.
Effects:
1. Can form Acids.
2. Can cause corrosion on m/c parts.
3. Microbial degradation. [Reduce centrifuging efficiency; promote local pitting and corrosion].
4. Reduce load carrying capacity.
5. Reduce L.O. properties, and TBN of oil.
6. Form sludge due to emulsification.
Remedies:
1. Proper purification with minimum throughput.
2. Batch purification if heavy contamination.
Maximum Allowable % of water in LO
1. For crosshead engine, < 0.2% is satisfactory. 2. If water content exceed 0.5 ~ 1.0%, immediate action should be taken. If > 1%, engine can be damaged.
3. For trunk type engine, < 0.1% is satisfactory. If > 0.5%, immediate action should be taken and
it is maximum permissible content.
1. For crosshead engine, < 0.2% is satisfactory. 2. If water content exceed 0.5 ~ 1.0%, immediate action should be taken. If > 1%, engine can be damaged.
3. For trunk type engine, < 0.1% is satisfactory. If > 0.5%, immediate action should be taken and
it is maximum permissible content.
LO tests onboard:
Tests carried out on used diesel crankcase oil:
1. Viscosity {changes caused by dilution with fuel oil}.
2. Closed flash point {changes caused by dilution with fuel oil}.
3. Insoluble
4. Water content
5. Acidity.
1. Viscosity {changes caused by dilution with fuel oil}.
2. Closed flash point {changes caused by dilution with fuel oil}.
3. Insoluble
4. Water content
5. Acidity.
(1) Viscosity determination:
– Viscosity and closed flash point will fall by fuel oil contamination.
– Changes in these values are a measure of dilution, and up to 8% contamination can be tolerated.
Three Tubes Rolling Ball Viscometer:
1. Assume that system oil is SAE 30.
2. One tube filled with minimum safe viscosity, SAE 20.
3. One tube filled with maximum safe viscosity, SAE 40.
4. Last tube filled with test sample.
5. All tubes placed in warm water, until at same temperature.
6. All tubes placed on tilted board and inverted, so that internal hollow balls rise to surface, with different time taken.
7. If time taken for test sample is between upper and lower limit oils, this sample oil is fit for further use.
– Viscosity and closed flash point will fall by fuel oil contamination.
– Changes in these values are a measure of dilution, and up to 8% contamination can be tolerated.
Three Tubes Rolling Ball Viscometer:
1. Assume that system oil is SAE 30.
2. One tube filled with minimum safe viscosity, SAE 20.
3. One tube filled with maximum safe viscosity, SAE 40.
4. Last tube filled with test sample.
5. All tubes placed in warm water, until at same temperature.
6. All tubes placed on tilted board and inverted, so that internal hollow balls rise to surface, with different time taken.
7. If time taken for test sample is between upper and lower limit oils, this sample oil is fit for further use.
(2) Insoluble Content:
» Insoluble are soot, dust, metallic particles, asphaltene, oxidation products, and products of deterioration.
Blotter Test:
1. Single drop of sample oil is released from a given height onto a sheet of Special Filter Paper.
2. The result is compared with Standard Test Paper, of similar oil with known varying insoluble content.
3. Test oil should be below the upper limit:
Upper limits of insoluble are: 1.00% to 1.5% for Straight Mineral Oil,
5% for Detergent/Dispersant type Oil.
(3) Water and other contaminants by:
» Insoluble are soot, dust, metallic particles, asphaltene, oxidation products, and products of deterioration.
Blotter Test:
1. Single drop of sample oil is released from a given height onto a sheet of Special Filter Paper.
2. The result is compared with Standard Test Paper, of similar oil with known varying insoluble content.
3. Test oil should be below the upper limit:
Upper limits of insoluble are: 1.00% to 1.5% for Straight Mineral Oil,
5% for Detergent/Dispersant type Oil.
(3) Water and other contaminants by:
Crackle Test:
1. Pour a known amount of sample oil into a test tube.
2. Hold the test tube over small spirit lamp, shaking it while doing so.
3. If there is no crackling, the oil is dry.
A slight crackle indicates a trace of water.
1. Pour a known amount of sample oil into a test tube.
2. Hold the test tube over small spirit lamp, shaking it while doing so.
3. If there is no crackling, the oil is dry.
A slight crackle indicates a trace of water.
(4) Acidity Determination:
1. Tested by extracting the acids from sample oil, by means of shaking with known amount of distilled water, in a test tube.
2. Acidic extract is placed on a watch glass, with Indicator Solution of known strength.
3. The mixture is drawn into a glass tube, and compared with Colour Standards, each representing a known pH value. Sample can be determined quite accurately.
2. Acidic extract is placed on a watch glass, with Indicator Solution of known strength.
3. The mixture is drawn into a glass tube, and compared with Colour Standards, each representing a known pH value. Sample can be determined quite accurately.
Microbial Degradation:
- If free water is present in crankcase, micro-organisms may grow, at oil water interface, by consuming hydrocarbons in oil.
- Infestation at early stage may not be harmful but in case of severe infestation, corrosion within machinery parts may arise.
- Complete oil change is necessary.
Indication:
1) Darkened oil colour and yellowish colour film on surface.
2) Pungent smell
3) Sludge formation.
2) Pungent smell
3) Sludge formation.
Poor quality fuel:
High pour point.: Needs extra heating for storage tank.
High density: Causes purification difficulties.
High viscosity: Pumping difficulties and more heat required getting suitable injection
viscosity at injector.
Low cetane number. Late injection and after burning. It is considered as poor fuel, if C 37 .
Abrasive group: (ash, silica, nickel, catfines): Cause wear on cylinder liner, piston rings, ring
grooves and fuel injection equipment.
Corrosion group: (Sulphur, Vanadium, Sodium): Low temperature corrosion due to sulphur.
Acid dew point is 120 – 160°C
High temperature corrosion due to Vanadium, Sodium and Sulphur
at 460 – 570°C
Corrosion or vapour locking at fuel injection equipment, due to water.
Fouling group: (catfines, CCR): Slow burning due to Asphaltine, combustion space fouling
and T/C fouling due to CCR.
High density: Causes purification difficulties.
High viscosity: Pumping difficulties and more heat required getting suitable injection
viscosity at injector.
Low cetane number. Late injection and after burning. It is considered as poor fuel, if C 37 .
Abrasive group: (ash, silica, nickel, catfines): Cause wear on cylinder liner, piston rings, ring
grooves and fuel injection equipment.
Corrosion group: (Sulphur, Vanadium, Sodium): Low temperature corrosion due to sulphur.
Acid dew point is 120 – 160°C
High temperature corrosion due to Vanadium, Sodium and Sulphur
at 460 – 570°C
Corrosion or vapour locking at fuel injection equipment, due to water.
Fouling group: (catfines, CCR): Slow burning due to Asphaltine, combustion space fouling
and T/C fouling due to CCR.
Flash Point:
1. Lowest temperature at which an oil will give off sufficient flammable vapour, to produce a flash when a small flame is brought to the surface of the oil.
2. Minimum flash point for on-board use is 60°C.
3. Fuel storage temperature must be kept at least 14°C lower than its flash point.
4. Average closed flash points: Petrol – 20°C: Paraffin 40°C: Diesel Oil 65°C:
LO 220°C: 70 cst Fuel Oil 71°C: Heavy Oil 100°C:
1. Lowest temperature at which an oil will give off sufficient flammable vapour, to produce a flash when a small flame is brought to the surface of the oil.
2. Minimum flash point for on-board use is 60°C.
3. Fuel storage temperature must be kept at least 14°C lower than its flash point.
4. Average closed flash points: Petrol – 20°C: Paraffin 40°C: Diesel Oil 65°C:
LO 220°C: 70 cst Fuel Oil 71°C: Heavy Oil 100°C:
Pour Point:
1. Lowest temperature at which the oil barely flow.
2. It is just above the lowest temperature at which liquid flows under its own weight.
3. It must be low, otherwise fuel tends to solidify and due to poor heat transfer property, fuel cannot be returned to its original state by heating.
4. Fuel storage temperature must be kept at least 10°C higher than its pour point.
5. At least 40 – 50°C higher than its pour point, for cold weather condition.
1. Lowest temperature at which the oil barely flow.
2. It is just above the lowest temperature at which liquid flows under its own weight.
3. It must be low, otherwise fuel tends to solidify and due to poor heat transfer property, fuel cannot be returned to its original state by heating.
4. Fuel storage temperature must be kept at least 10°C higher than its pour point.
5. At least 40 – 50°C higher than its pour point, for cold weather condition.
Homogenizer:
1. It is a device to create stable oil and water emulsion, which can be bunt in boilers and diesel engines.
2. This emulsion can burn more efficiently and reduce solid emission in exhaust gas.
3. It can reduce catfines into finely ground particles, which do not harm.
1. It is a device to create stable oil and water emulsion, which can be bunt in boilers and diesel engines.
2. This emulsion can burn more efficiently and reduce solid emission in exhaust gas.
3. It can reduce catfines into finely ground particles, which do not harm.
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