Lubricating Oils and Additives

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Questions and Answers

What is the primary purpose of lubrication in machinery?

To increase friction between moving parts

To prevent surfaces from coming into direct contact (correct)

To facilitate thermal conduction between components

To enhance the density of the materials involved

Which of the following is not a purpose of using lubricants?

Friction increase (correct)

Corrosion reduction

Wear reduction

Temperature control

How do lubricants primarily minimize wear between bearing surfaces?

By facilitating direct metal-to-metal contact

By enhancing the heat conduction of surfaces

By evaporating quickly during operation

By forming a barrier that prevents direct contact (correct)

What is the effect of viscosity on lubrication?

Higher viscosity assists in maintaining film thickness Signup and view all the answers

Which additive is commonly used in lubricants for corrosion protection?

Rust inhibitors Signup and view all the answers

What is the primary purpose of anti-oxidants in lubricating oils?

To decrease the amount of oxygen combining with the oil Signup and view all the answers

Which characteristic is essential for turbine oils?

Functioning as both a lubricant and a cooling medium Signup and view all the answers

What may happen if the viscosity of air compressor cylinder oils is too low?

It will not properly seal piston rings Signup and view all the answers

How does the pour point depressant function in lubricating oils?

It lowers the pouring point of oil for better flow Signup and view all the answers

What is the consequence of carbon residue in lubricating oils?

Interferes with the functioning of engine and compressor rings Signup and view all the answers

What role do detergent-dispersants play in lubricating oils?

They keep substances that form deposits in suspension Signup and view all the answers

Which additive is specifically used to prevent foam formation in lubricating oils?

Antifoam agents Signup and view all the answers

What is floc point in the context of lubricating oils?

The temperature at which wax or suspended particles separate from oil Signup and view all the answers

What is the primary function of solid lubricants?

Provide lubrication under heavy loads and extreme temperatures Signup and view all the answers

What characteristic is essential for lubricants used in environments with high pressures?

Maximum adhesion to surfaces Signup and view all the answers

Which of the following is a common application for semi-solid lubricants?

Lubricating electrical instruments Signup and view all the answers

How does viscosity affect lubrication in machinery?

The appropriate viscosity ensures optimal film thickness and reduces wear Signup and view all the answers

What function do lubricant additives serve?

Enhance the physical stability of lubricants under various conditions Signup and view all the answers

Which factor does NOT influence the choice of lubricant class?

Type of machinery aesthetic design Signup and view all the answers

What is one of the essential services that lubricants must provide?

Reduce the likelihood of oxidation Signup and view all the answers

When are solid lubricants typically preferred over other types?

When exposed to chemicals that degrade other lubricants Signup and view all the answers

Study Notes

Lubrication and Oil Properties

Lubricating oils oxidize in service, resulting in acid formation.
Carbon residue indicates the potential carbon formation in oils at high temperatures, which can hinder engine performance and damage rings and valves.
Floc point is the temperature at which wax or other particles separate from oil.

Lubricant Additives

Anti-oxidants: Prevent oxidation, reducing corrosion and sludge buildup.
Detergent-dispersants: Keep potential deposits in suspension.
Viscosity index improvers: Minimize viscosity changes due to temperature fluctuations.
Antifoam agents: Neutralize air or vapor bubbles in oil.
Pour point depressants: Lower the pouring temperature of the oil.
Corrosion inhibitors: Form protective films on metal surfaces to combat corrosion.

Selecting Lubricating Oils

Turbine Oils: Serve as lubricants, cooling agents, and sealants; require good water separation and additives for corrosion, antifoaming, and oxidation prevention.
Air Compressor Cylinder Oils: Must have appropriate viscosity; too high causes drag, too low fails to seal properly; should maintain low carbon residue.
Internal Combustion Engine Oils: Must withstand high temperatures, resist evaporation, and prevent carbon buildup; essential for creating seals between pistons and cylinder walls.

Classes of Lubricants

Classification depends on surface nature, load, speed, and operating temperature.
Essential lubricant services include:
- Low coefficient of friction for efficient movement.
- High adhesion to surfaces being lubricated.
- Stability under varying conditions (temperature and pressure).
- Resistance to oxidation and emulsification.
- Maintenance of fluidity at low temperatures.

Types of Lubricants

Solids: Include graphite, soapstone, and molybdenum disulfide; suited for extreme temperatures and heavy loads, often used in difficult-to-service applications.
Semi-solids: Greases made from liquid lubricants mixed with thickening agents.

Lubrication Principles

Lubrication prevents direct contact between bearing surfaces to reduce wear and tear.
Lubricant separates surfaces, allowing smooth motions without direct metallic contact, thus minimizing wear.
Fluid friction occurs when layers of lubricant slide over each other.

Purposes of Lubricants

Reduce friction: Most critical purpose.
Diminish wear on surfaces.
Protect against corrosion.
Aid in temperature control.
Absorb shocks and impact forces.

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Description

This quiz covers essential concepts of lubricating oils, including oxidation, carbon residue, and floc point. It also delves into the role of additives that enhance oil performance and engine efficiency. Test your knowledge on these critical aspects of lubrication technology.