Unit 25 special refrigeration system components

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

solenoid valves

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

10%

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

A low ambient control

9. Which of the following is another type of low ambient head pressure control.

Air volume control using shutters and fan cycling

10. Frequently on smaller condensing units, one fan will run continuously and the other will be cycled on and off with an ___.

Ambient temperature controller

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

Back-seated

15. How does a receiver ensure that only 100% liquid refrigerant enters the liquid line.

By means of a dip tube

12. When a system pumps down where is the refrigerant stored.

Condenser and receiver

2. The EPR valve is installed in the suction line at the evaporator outlet and it ___. A- Modulate the refrigerant vapor to the compressor, B-Prevents the boiling point in the evaporator from dropping below a preset point, c-When used with a TXV valve the system has the characteristics of maintain a constant superheat and keeping the pressure from going too low, D-all of the above.

D-all of the above

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

EPR

19. T or F A suction line accumulator is used to ensure that liquid refrigerant enters the compressor.

False

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

False

8. Which of the following is a type of low ambient temperature head pressure control.

Fan Cycling

14. Defrost using internal heat is accomplished using ____.

Hot gas from the compressor

27. To protect a refrigeration compressor when the refrigerant loss occurs an ___ control is used.

Low pressure

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

More than one evaporator is used with a compressor

25. The spring loaded type of relief valve is normally brass with an ___ seat.

Neoprene

3. EPR valves are also referred to as ___ valves.

ORI

24. The two types of relief valves are the spring loaded and the ___ valve.

One time

22. Automatic pumpdown systems are equipped with an ___ to prevent the refrigerant from reaching the evaporator.

Solenoid valve

5. To protect the compressor during periods of hot pull down a ____ valve is used.

TXV

4. Technician A says that a multievaporator system equipped with three evaporators one high temp one medium temp and one low temp will use one evaporator pressure requlator and two floe check valves. Technician B says that the crankcase pressure regulator is used to keep the low temperature compressor from overloading on a hot pull down. Which statement is correct.

Technician A is Incorrect and Technician B is Correct

26. The one time relief valve is caused to relieve by ____.

Temperature

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

True

18. T or F The crankcase pressure regulator puts a limit on the pressure that can return to the compressor.

True

20. T or F Oil separators work on the principle of low refrigerant and oil velocity.

True

13. Random defrost is accomplished ___.

When the refrigeration system has enough reserve capacity to cool more than the load requirement.