Compressor Lubrication Systems

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What is the main purpose of installing shaft seals in a compressor?

To cool down the compressed gases

To increase the efficiency of the compressor

To reduce the noise produced by the compressor

To prevent compressed gases from leaking around the shaft (correct)

Where are labyrinth seals commonly used?

In cooling systems to minimize wear

In hydraulic systems for reduced noise

In air compressors where some leakage is acceptable (correct)

In toxic gas compressors to trap escaping gases

Which type of seal has segments held together with a spring and can be easily removed from the compressor for maintenance?

Labyrinth Seals

Carbon Ring Seals (correct)

Liquid Film Seal

Stop Pin Clip Spring

What characteristic of carbon rings makes them susceptible to considerable wear?

Near zero clearance Signup and view all the answers

Why are liquid film seals named as such?

Because they create a thin liquid film between the seal and the rotating shaft Signup and view all the answers

Which type of seal presents an intricate path for escaping gases to negotiate before reaching the atmosphere?

Labyrinth Seals Signup and view all the answers

What is the purpose of the oil film in the seals described in the text?

To provide a barrier preventing compressed gases from leaking Signup and view all the answers

In what type of applications are mechanical seals commonly used?

Applications that require better sealing than labyrinth seals Signup and view all the answers

How do dry gas seals create a gap between the rotating and stationary rings?

By injecting an inert gas at high pressure Signup and view all the answers

Which type of dry gas seal is used for flammable and toxic gases?

Tandem dry gas seal Signup and view all the answers

What is the main purpose of oil-free packing ring seals in reciprocating gas compressors?

To increase oil leakage containment Signup and view all the answers

Why are compressor bearings lubricated?

To reduce friction and power loss Signup and view all the answers

What is the purpose of regenerating the adsorbent in air dryers?

To drive off the adsorbed moisture Signup and view all the answers

Why are absorbents not commonly used in air dryers?

They add significant pressure loss Signup and view all the answers

What is the function of an air receiver in a compressed air system?

To remove moisture and oil Signup and view all the answers

Why should safety valves be regularly tested in air receivers?

To avoid overpressure conditions Signup and view all the answers

What can happen if safety valves are defective in an air receiver?

System failures due to overpressure Signup and view all the answers

Why are check valves fitted between the compressor and the receiver in a compressed air system?

To allow air flow in one direction only Signup and view all the answers

In refrigerated air dryers, what happens in the refrigeration heat exchanger or evaporator?

Water and oil vapours condense Signup and view all the answers

Why should an air receiver be hydrostatically tested periodically?

To check for weakening of vessel material Signup and view all the answers

What should be done before opening an air receiver for inspection?

Thoroughly ventilate its interior Signup and view all the answers

What is the purpose of a check valve between a compressor and a receiver?

To prevent high-pressure air from blowing back into the compressor Signup and view all the answers

Why is it important to cool the air between compression stages?

To condense water and oil vapors for removal Signup and view all the answers

What is the purpose of using intercoolers and aftercoolers in the air compression process?

To cool the air to improve efficiency and remove contaminants Signup and view all the answers

What happens if the oil vapors in the air are not condensed and removed?

They might cause an explosion in pipes and reservoirs Signup and view all the answers

Why must aftercoolers be fitted with a safety valve if a shut-off valve is present between the aftercooler and the receiver?

To prevent overpressure incidents Signup and view all the answers

What is the function of separators installed close to aftercoolers?

To remove condensed moisture and other particles from the air stream Signup and view all the answers

Why is it important for control air to have low moisture content in instrumentation and control systems?

To prevent freezing in instrumentation lines Signup and view all the answers

What is the role of Tower 2 in an air dryer system?

Drying the air before it goes to the receiver Signup and view all the answers

How do adsorbents like silica gel remove moisture from the air in air dryers?

By attracting moisture to form a thin water film on their surface Signup and view all the answers

Why is it essential to pass dehumidified air through a cooling coil in some systems?

To elevate the temperature of the dehumidified air Signup and view all the answers

What is the purpose of passing compressed air through a cyclone separator after an aftercooler?

To remove condensed moisture and other particles from the air stream Signup and view all the answers

What is the main difference between internal lubrication and external lubrication in compressors?

Internal lubrication involves applying oil to cylinder walls and pistons, while external lubrication involves lubricating bearings and crossheads. Signup and view all the answers

What is the purpose of intercoolers and aftercoolers in a compressor system?

To cool the gas either between stages of compression or after compression is completed. Signup and view all the answers

How is the lubricating oil applied to cylinder walls in reciprocating compressors?

It is fed directly by a mechanical lubricator to specific points on the cylinder walls. Signup and view all the answers

Which type of compressors do not require internal lubrication?

Dynamic types such as centrifugal and axial flow compressors Signup and view all the answers

How is oil supplied to rotor shaft bearings in rotary and dynamic compressors?

Through a longitudinal hole in the rotor shaft Signup and view all the answers

Why do some applications like those in the food processing industry require oil-free compressors?

To prevent contamination of products with oil Signup and view all the answers

What are some common components that are externally lubricated in compressors?

Rotor shaft bearings and crankshaft bearings Signup and view all the answers

What method of lubrication is frequently used in small single-acting reciprocating compressors?

Splash system of lubrication Signup and view all the answers

How does a pressure lubricator supply oil in sliding vane rotary compressors?

By discharging it into the air intake Signup and view all the answers

Why are multi-stage compressors sometimes needed for applications requiring oil-free operation?

To attain the required pressure due to decreased efficiency without internal lubrication Signup and view all the answers