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1

The slide valve as used with compressors, is used;

A) as a discharge valve
B) for capacity control
C) To prevent liquid return
D) As a suction valve

For capacity control

2

From the following information determine the net oil pump pressure. Compressor crankcase pressure = 12”hg vac, the pump outlet pressure = 32 psig

12\29 = 0.41 x 14.7 = 6.08 + 32 = 38

3

It is generally considered good practice to limit the compression ratios for a single reciprocating compressor to a

A) max 20:1
B) max 10:1
C) min 20:1

max 10:1

4

The clearance volume of a compressor;

A) increases as compression ratio increases

B) increases as compression ratio decreases

C) remains the same as compression ratio decreases

remains the same as compression ratio decreases

5

One end of the connecting rod is attached to the piston and the other end is attached to the

A) crankshaft counter weight
B) Crankshaft journal
C) Scotch yoke
D) none of the above

crankshaft journal

6

in a reciprocating compressor the one take and exhaust valves are located on the;

A) cylinder head
B) valve block
C) crank case
D) none of the above

D) none of the above

7

which of the following statements regarding piston rings is false?

A) A compression ring prevents pressurized refrigerant from blowing past the piston

B) The inner diameter of a piston ring is slightly larger than the piston diameter

C) The ends of piston rings are beveled to allow overlap

D) An oil ring prevents excess oil from entering the cylinder

B) The inner diameter of a piston ring is slightly larger than the piston diameter

8

A crankshaft that is fast with offset journals is called a;

A) integrated

B) eccentric

C) crank throw type

D) none of the above

C) crank throw type

9

During off cycle, refrigerant will migrate to the _________ of the system;

A) lowest part

B) Receiver

C) evaporator

D) lowest temperature part

D) lowest temperature part

10

longer cycles caused by reduced compressor capacity will normally lead to;

A) higher temperature

B) lower temperature

C) higher RH

D) lower RH

d) lower RH

11

A single, large cylinder and piston could cause vibration and;

A) power surges

B) pressure surges

C) temperature surges

D) capacity surges

B) pressure surges

12

A reed valve assembly usually consists of a valve plate, an intake valve, an exhaust valve, ___________, and valve retainers

A) valve stops

B) valve backer

C) spring valve

D) valve plate

A) valve stops

13

Cylinder blocks are normally ____________ to the crankcase

A) screwed

B) bolt

C) taper

D) tight fit

B) bolt

14

Hermetic compressors are normally run at;

A) a lower speed than open drive ones

B) the same speed as the open drive ones

C) higher speed than open drive ones

D) any speed compare to open drive ones

C) higher speed than open drive ones

15

In a hermetic compressor, it’s motor is lubricated by;

A) splashed oil

B) oil in refrigerant

C) oil brush

D) open points

B) oil in the refrigerant

16

The higher the RPM of a compressor the higher the pumping efficiency;

TRUE OR FALSE

False

17

Rotary compressors are equipped with a check valve located on the suction side of the compressor to prevent off cycle equalization;

TRUE OR FALSE

False

18

A scroll compressor is one type of rotary compressor classification group, rolling piston and sliding vane are the others placed in this classification. Capacity control for scroll compressors is accomplished by using either speed control or on-off cycling

TRUE OR FALSE

True

19

To prevent liquid slugging because of off cycle migration, you must ensure that there is a minimum 20F suction superheat maintained at all times during system operation;

TRUE OR FALSE

False

20

If you are servicing a refrigeration compressor and you front seat the compressor suction service, you will be isolating the suction line from your service manifold

TRUE OR FALSE

False

21

The most important gasket on a reciprocating compressor is located between the valve plate and the cylinder head;

TRUE OR FALSE;

False

22

Compressors which are equipped with oil pumps for forced lubrication can be operated in only one direction. Therefore, care must be taken to ensure proper phase connections on installation of multi phase compressors;

TRUE OR FALSE

False

23

The movement of blades in and out of their slots provide the pumping action for lubrications systems in some rotary compressors;

TRUE OR FALSE;

True

24

The pistons of some small hermetic compressors do not have piston rings;


TRUE OR FALSE

TRUE