Deck 25: Special Refrigeration System Components

Question 1

When a system pumps down, where is the refrigerant stored?

A) Condenser and receiver.
B) Evaporator and compressor.
C) Condenser and compressor.
D) Both a and c.

Answer 1

A

Question 2

The crankcase pressure regulator (CPR) puts a limit on the pressure that can return to the compressor.

Answer 2

True

Question 3

Two-temperature operation of a refrigeration system is necessary when ____.

A) the compressor must be protected from overloading
B) more than one evaporator is used with a compressor
C) the coil in the evaporator is excessively long
D) a multiple-circuit distributor is used

Answer 3

more than one evaporator is used with a compressor

Question 4

Which of the following is a type of low-ambient temperature head pressure control ?

A) CPR.
B) EPR.
C) Fan cycling.
D) Off-cycle defrost.

Question 5

EPR valves are also referred to as ____ valves.

A) DRP
B) ORC
C) ORN
D) ORI

Question 6

Defrost using internal heat is accomplished using ____.

A) a sail switch
B) electric heating elements
C) hot gas from the compressor
D) mullion heaters

Question 7

To protect the compressor during periods of hot pull down, a(n) ____ valve is used.

A) TXV (thermostatic expansion valve)
B) EPR (evaporator pressure regulator)
C) CPR (crankcase pressure regulator)
D) LAC (low ambient control)

Question 8

The normal position for a suction service valve during normal operation is ____.

A) back-seated
B) front seated
C) midseated
D) Any of the three.

Question 9

The EPR valve is installed in the suction line at the evaporator outlet and it ____.

A) modulates the refrigerant vapor to the compressor
B) prevents the boiling point in the evaporator from dropping below a pre-set point
C) when used with a TX valve the system has the characteristics of maintaining a constant superheat and keeping the pressure from going too low
D) All of the above.

Question 10

Frequently on smaller condensing units, one fan will run continuously and the other fan will be cycled on and off with a(n) ____.

A) ambient temperature controller
B) ambient pressure valve
C) thermal expansion valve
D) thermal control valve

Question 11

Refrigeration systems are designed to operate year round. For this reason they are equipped with ____.

A) relief valves
B) a low-ambient control
C) oversized evaporator coils
D) EEPR valves

Question 12

The refrigeration compressor motor can be operated at about ____% over its rated capacity without harm during the pulldown .

A) 5
B) 10
C) 15
D) 20

Question 13

How does the receiver ensure that only 100% liquid refrigerant enters the liquid line?

A) By means of a dip tube.
B) It only allows refrigerant to enter the liquid line when it is filled with liquid.
C) The spring loaded relief valve opens.
D) None of the above are correct.

Question 14

Which of the following is another type of low-ambient temperature head pressure control ?

A) Air volume control using shutters and fan cycling.
B) Programmed defrost timer.
C) Timer and liquid line solenoid for automatic pump down.
D) Compressor internal heat.

Question 15

Oil separators work on the principle of low refrigerant and oil velocity.

Question 16

____ are snap-acting valves that open and close very fast when the electrical energy is applied to the coil .

A) Contactors
B) Condensers
C) Relays
D) Solenoid valves

Question 17

Technician "A" says that a multi-evaporator system equipped with three evaporators (one high temperature, one medium temperature, and one low temperature) will use one evaporator pressure regulator and two flow check valves. Technician "B" says that the crankcase pressure regulator is used to keep the low-temperature compressor from overloading on a hot pulldown. Which of the following statements is correct?

A) Technician "A" is correct. Technician "B" is correct.
B) Technician "A" is correct. Technician "B" is incorrect.
C) Technician "A" is incorrect. Technician "B" is correct.
D) Technician "A" is incorrect. Technician "B" is incorrect.

Question 18

A suction line accumulator is used to ensure that liquid refrigerant enters the compressor.

Question 19

Random defrost is accomplished ____.

A) with a timer
B) using a high pressure control
C) using a low pressure control
D) when the refrigeration system has enough reserve capacity to cool more than the load requirement

Question 20

Two-temperature operation is desirable when more than one evaporator is used with a compressor .

Question 21

Where is the refrigerant filter drier found?

Question 22

The ____________________ is a mechanical control that keeps the refrigerant pressure in the evaporator from going below a predetermined point.

Question 23

What is a check valve?

Question 24

Discuss the king valve .

Question 25

The spring-loaded type of relief valve is normally brass with a(n) ____________________ seat.

Question 26

What prevents the oil pressure safety control from de-energizing a compressor immediately after start-up?

Question 27

List four causes of liquid floodback.

Question 28

The one-time relief valve is caused to relieve by ____________________.

Question 29

Automatic pumpdown systems are equipped with a(n) ____________________ to prevent refrigerant from reaching the evaporator .

Question 30

Where is the refrigerant sight glass normally located?

Question 31

Helical oil separators are about 58% efficient in separating oil.

Question 32

What are the two forces that control the EPR valve?

Question 33

To protect a refrigeration compressor when refrigerant loss occurs, a(n) ____________________ control is used.

Question 34

What is the temperature range in medium-temperature refrigeration?

Question 35

Two types of relief valves are the spring-loaded valve and the ____________________ valve .