Ans

‎(i) Oxidation:

‎Oxidation refers to the chemical reaction between lubricating oil and oxygen, often accelerated by high temperatures and the presence of catalytic metals such as iron or copper, resulting in the formation of harmful compounds like organic acids, sludge, varnish, and the increase in viscosity of the oil.

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‎(ii) Emulsification:

‎Emulsification is the process whereby water becomes finely dispersed within lubricating oil to form an unstable mixture. This occurs when oil and water, which are immiscible liquids, blend due to contamination or agitation, often forming a cloudy emulsion where the oil loses its lubricating properties.

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‎(iii) Acidity:

‎Acidity in lubricating oil indicates the presence of acid compounds, usually measured by Total Acid Number (TAN). Acidity arises due to oxidation or contamination, and elevated acidity accelerates corrosive wear on engine components and depletes additive effectiveness.

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‎(b) Maintenance Control of Each Condition

‎Oxidation:

‎Oxidation is controlled by regular oil changes, use of antioxidant additives, and maintaining oil temperature within safe operating limits. Routine oil testing for early detection of increased TAN or color changes also helps avoid severe oil degradation.

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‎Emulsification:

‎Controlling emulsification relies on frequent inspection and removal of water contamination through purification processes such as centrifuging or settling tanks, as well as ensuring seals and gaskets are intact to prevent ingress of water.

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‎Acidity:

‎Acidity is managed by monitoring TAN and TBN values during scheduled maintenance, timely oil replacement, and ensuring the correct lubricant specification and additives are used to neutralize acids formed during operation.

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‎(c) Consequences of Uncontrolled Changes

‎Oxidation:

‎If oxidation is unchecked, consequences include increased oil viscosity, formation of sludge and varnish, additive depletion, filter clogging, corrosion, and ultimately premature machinery failure due to poor lubrication.

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‎Emulsification:

‎Persistent emulsification leads to loss of oil film in bearings, increased friction, overheating, risk of adiabatic heating and bearing collapse, accelerated rusting, and electrochemical corrosion—especially in the presence of salt water.

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‎Acidity:

‎If acidity continues to rise and is not corrected, there will be intensified corrosive attack on non-ferrous and ferrous engine parts, increased abrasive wear, depletion of protective additives, shortened oil and machinery life, and increased risk of leakage and breakdown.