Supplement 12

Question 1

List 4 types of compressors. Which is most common:

Answer 1

1. Axial
2. centrifugal
3. Reciprocating
4. Rotary
   - reciprocating

Question 2

What is the purpose of an intercollegiate on an 2 stage compressor

Answer 2

Reduce air intake temperatures between the low and high cylinders + removes condensation

Question 3

What is the purpose of an aftercooler

Answer 3

To remove condensed water and oil from the air

Question 4

Why is the air receiver required on most compressor installations

Answer 4

-acts as a storage reservoir to provide reserve capacity and to smooth out pumping air pulsation. Allows compressor to remain idle yet have continual supply of air

Question 5

List essential parts of a compression refrigeration system

Answer 5

1. evaporator
2. Compressor
3. Condenser
4. Receiver
5. Expansion valve

Question 6

What vacuum pump is suitable for very high vacuums

Answer 6

-special rotary pump with close clearances and oil seals

Question 7

How’s is the efficiency of a compressor affected by intake air temperature

Answer 7

For every 5 degrees lower air temperature an efficiency of 1% is obtained

Question 8

Why are most compressors equipped with unloading valves

Answer 8

-because air flowing into and out of the cylinders during unloaded periods helps cool them putting less strain on both motors and generators

Question 9

List 6 possible causes for an compressor overheating

Answer 9

1. Broken valve strips
2. wrong direction of rotation
3. filter clogged
4. Discharge pressure higher than rated
5. internal leakage
6. Insufficient oil

Question 10

What type of cleaner should be used to clean intake filters, why

Answer 10

-hot water or steam, immersion in string solution of sal soda. Never use gasoline or kerosene because explosive fumes may collect in compressor or air receiver