ACR-202-Unit 25 - Special Refrigeration System Components

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

• the compressor must be protected from overloading

• more than one evaporator is used with a compressor

• the coil in the evaporator is excessively long

• a multiple-circuit distributor is used

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

• when used with a TX valve the system has the characteristics of maintaining a constant superheat and keeping the pressure from going too low

• All of the above.

EPR valves are also referred to as ____ valves.

• DRP

• ORC

• ORN

• ORI

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

• TXV (thermostatic expansion valve)

• EPR (evaporator pressure regulator)

• CPR (crankcase pressure regulator)

• LAC (low ambient control)

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

• 5

• 10

• 15

• 20

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

• relief valves

• a low-ambient control

• oversized evaporator coils

• EEPR valves

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

• CPR

• EPR

• Fan cycling

• Off-cycle defrost

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

• Air volume control using shutters and fan cycling.

• Programmed defrost timer.

• Timer and liquid line solenoid for automatic pump down.

• Compressor internal heat.

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

• ambient temperature controller

• ambient pressure valve

• thermal expansion valve

• thermal control valve

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

• Contactors

• Condenser

• Relays

• Solenoid valves