Chap. 116

Question 1

Which of the following is not a function of the compressor in a refrigeration system?

a) draw low pressure refrigerant out of the evaporator
b) draw low temperature refrigerant out of the evaporator
c) lower the temperature of the refrigerant
d) maintain sufficiently low pressure in the evaporator
e) raise the pressure of the refrigerant

Answer 1

c) lower the temperature of the refrigerant

Question 2

Which of the following is the compressor responsible for doing?

i) Maintains a high pressure in the condenser
ii) Maintains a low pressure in the evaporator
iii) Raises the pressure of the refrigerant
a) i only
b) both i and iii
c) both ii and iii
d) iii only
e) i, ii, and iii

Answer 2

e) i, ii, and iii

Question 3

In a refrigeration system, the purpose of the compressor is to:

a) establish two pressure levels
b) reject the heat from the system
c) absorb the heat into the system
d) regulate the flow of the refrigerant
e) heat the refrigerant

Answer 3

a) establish two pressure levels

Question 4

Which of the following compressor types uses impellers to draw in vapour?

a) Centrifugal compressors
b) Rotary compressors
c) Reciprocating Compressors
d) None of the above
e) All of the above

Answer 4

a) Centrifugal compressors

Question 5

One negative factor of Hermetic type reciprocating
compressors is:
a) the compressor and motor are mounted within the same housing
b) the motor is cooled by the low pressure, low temperature vapour being drawn into the housing
c) it does not have or require shaft sealing
d) field servicing is not possible
e) the compressor is driven by an electric motor

Answer 5

d) field servicing is not possible

Question 6

In a rotating vane design rotary compressor, a good seal is maintained between the vanes and the cylinder by:

a) centrifugal force
b) the oil
c) high pressure refrigerant vapour
d) low pressure suction

Answer 6

a) centrifugal force

Question 7

For a Helical Rotor Design rotary compressor which of the following statements is true?
a) The compressor consists of 3 opposing grooved rotors.
b) The driving rotor has less helical lobes than the driven rotor has flute.
c) The vapour is drawn in via the closed space between the driving rotor and the casing.
d) The cylinders around the rotor screws must be
considerably larger in diameter than the screws.
e) All of the above

Answer 7

b) The driving rotor has less helical lobes than the driven rotor has flute.

Question 8

Piston displacement is defined as:

a) the distance along which the piston travels
b) the cylinder bore
c) the volume of refrigerant that can be circulated through all the cylinders per unit time
d) piston stroke length
e) the revolutions per minute of the compressor motor

Answer 8

c) the volume of refrigerant that can be circulated through all the cylinders per unit time

Question 9

Refrigerant compressors:

a) must have inter-coolers
b) could be a centrifugal type
c) are of the positive displacement type only
d) are used with vapour absorption systems only
e) discharge directly into the evaporator

Answer 9

b) could be a centrifugal type

Question 10

Pistons and connecting rods are found in which of the
following types of compressors?
a) Reciprocating
b) Rotary
c) Centrifugal
d) Both Rotary and Centrifugal
e) Both reciprocating and centrifugal

Answer 10

a) Reciprocating

Question 11

Calculate the piston displacement in cubic metres per minute, if given the following:
piston stroke 12 cm
piston diameter 10 cm
piston speed 1100 working strokes per minute
Answer = ____________________ cubic metres per minute

Answer 11

.037 % .05 LEARN HOW TO DO IT THOUGH!!

Question 12

A typical stationary crankshaft seal consisting of a metallic bellows soldered at one end to a ring (seal nose) which bears either against a shoulder on the shaft or against a seal ring on the shaft is called a:

a) packing gland seal
b) diaphragm seal
c) bellows seal
d) rotating mechanical seal
e) setscrew seal

Answer 12

c) bellows seal

Question 13

In rotating mechanical seals the sealing ring is held in
position by:
a) a nut, bolt, and washer
b) centrifugal force
c) oil suction
d) high pressure refrigerant vapour
e) a spring

Answer 13

e) a spring

Question 14

Which compressor type requires the use of a shaft seal?

Answer 14

Serviaceable

Question 15

What type of reciprocating compressor is the one that one end extends of the crankshaft extends outside of the crankcase and sealing arrangement is required to prevent the refrigerant from escaping along the shaft?

a) Open
b) Hermetic
c) Serviceable

Answer 15

a) Open

Question 16

What type of reciprocating compressor is driven by an electric motor directly connected to the crankshaft?

a) Serviceable
b) Open
c) Hermetic

Answer 16

c) Hermetic

Question 17

How many cylinders reciprocating compressor have and how they are classified according to their arrangement?

Answer 17

single stage- one or two cylinders
double stage-two cylinders
classified as:
Vertical
Horizontal
45* inclined
V-type
W-type
Radial

Question 18

Refrigeration compressors with pistons arranged vertically are :

Answer 18

Single acting type

Question 19

Refrigeration compressors with pistons arranged horizontally are :

Answer 19

Double acting type

Question 20

Reciprocating Compressor parts are:

Answer 20

Compressor Body
Crankshaft
Pistons and connecting rods
Suction and discharged valves
Safety head
Compressor bearings