Unit 25 Accessories

Two temperature operation of a refrigeration system is necessary when _____. the compressor must be protected from overloading "more than one evaporator, each at a different temperature, is operating from one compressor" the coil in the evaporator is excessively long a multiple circuit distributor is used

"more than one evaporator, each at a different temperature, is operating from one compressor"

The best way to adjust a CPR valve is by adjusting the CPR to produce an amperage draw of the compressor motor to the motor nameplate rating plus:______%

10

Refrigeration systems are designed to operate year round. For this reason they are equipped with _____. some type of head pressure control a low ambient control oversized evaporator coils

BOTH some type of head pressure control AND a low ambient control

"When a system pumps down, where is the refrigerant stored?" receiver evaporator condenser Both receiver AND condenser

Both receiver AND condenser

How does the receiver ensure that only 100% of liquid refrigerant enters the liquid line? By means of a dip tube It only allows refrigerant to enter the liquid line when it is filled with liquid The spring loaded relief valve opens

By means of a dip tube

As the adjusting spring on an evaporator pressure regulator is tightened, the pressure in the evaporator will _____.

Increase

"If the adjusting spring on the crankcase pressure regulator (CPR) is tightened, the range of refrigerant pressures that can enter the compressor will increase." True False

True

Oil seperators work on the principle of low refrigerant and oil velocity. True False

True

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

True

The EPR valve is installed in the suction line at the evaporator outlet and it _____. modulates the refrigerant vapor to the compressor prevents the boiling point in the evaporator from dropping below a pre set point operates like an AX valve when used with a TX valve all of these answers are correct

all of these answers are correct

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

backseated

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

crankcase pressure regulator (CPR)

An oil seperator is required at the suction intake of the compressor to ensure seperation of the refrigerant and oil before entering the compressor. true or false

false

Which of the following is a type of low ambient temperature head pressure control? CPR EPR fan cycling off-cycle defrost

fan cycling

Defrost using internal heat is accomplished using _____. a sail switch electrical heating elements hot gas from the compressor mullion heaters

hot gas from the compressor

Random defrost is accomplished _____. with a timer using a high pressure control using a low pressure control occurs automatically during the off cycle of the compressor

occurs automatically during the off cycle of the compressor

Which of the following is another type of low ambient temperature head pressure control? pressure-controlled dampers in the condenser air stream programmed defrost timer timer and liquid line solenoid for automatic pump down compressor internal heat

pressure-controlled dampers in the condenser air stream

"A condenser flooding system is sometimes used to provide low ambient temperature operation. To use this method, an extra device must be added to the system. The device is a(n) _____."

receiver

A hot pull down is when _____. there is excess ice on the evaporator the condenser contains an excess amount of liquid refrigerant the flow of refrigerant to the evaporator is reduced the load on the evaporator produces a suction pressure that increases the load on the compressor

the load on the evaporator produces a suction pressure that increases the load on the compressor

A suction line accumulator is used to reduce the possibility of liquid refrigerant entering the compressor. True False

true