Refrigeration System Operation

Question 1

Double suction riser are used in refrigeration system when

Answer 1

large fluctuations in system capacity will occur

Question 2

Suction risers are typically reduced by one size over that of the main suction run

Answer 2

to increase refrigerant velocity to aid in proper oil return

Question 3

When soldering a copper pipe connection which of the following processes allow for alloy to be draw into the space between copper pipe and the fitting connection?

Answer 3

capillary action

Question 4

Before proceeding to make any braze connection in a refrigeration system all of the internal piping should be purged of atmosphere with

Answer 4

CO² or nitrogen

Question 5

The liquid receiver is located between the?

Answer 5

condenser and the expansion device

Question 6

Which device is used in a refrigeration system to protect the compressor from liquid slugs?

Answer 6

suction accumulator

Question 7

Which device is used to stop the flow of liquid or vapor in a refrigeration system?

Answer 7

solenoid valve

Question 8

Why is it important to know the direction that a scroll compressor is rotating?

Answer 8

it will only pump refrigeration in one direction of rotation

Question 9

An electric motor that has a voltage rating of 120 volts will have an upper and lower allowable voltage limit of

Answer 9

108 to 132 V

Question 10

The flapper valve design is less efficient than the discus valve design because

Answer 10

the cylinder has more clearance volume than the discus

Question 11

Liquid refrigerant entering the compressor is potentially more damaging for this type of compressor over the others listed

Answer 11

reciprocating

Question 12

Discus, ring, and flapper valves are not used on

Answer 12

screw compressors & scroll compressors

Question 13

The main function of a condenser in a refrigeration system is?

Answer 13

reject the heat that is absorbed in the evaporator

Question 14

The shell and tube condenser is a type of

Answer 14

water cooled condenser

Question 15

One of the main disadvantages of a water-cooled condenser is that mineral deposits can build up acting as a/an

Answer 15

insulator

Question 16

A flow regulating valve could be used on this type of condenser

Answer 16

shell and tube & tube in tube

Question 17

On a water cooled condenser the water leaving the condenser is normally ______ lower than the condensing temperature of the unit

Answer 17

10º F

Question 18

On a standard efficiency air-cooled condenser the ambient air entering the condenser will be approximately ________ lower than the condensing
temperature if the unit is under normal load and properly charged

Answer 18

30º F

Question 19

A head pressure control system would be used on this type of application

Answer 19

unit located in a colder climate operating all year

Question 20

What type of expansion valve regulates its flow based from suction line superheat?

Answer 20

TXV

Question 21

Systems where the pressure drop across the evaporator is excessive would typically use a/an.

Answer 21

externally equalized TXV

Question 22

On a system equipped with a TXV, when the load on an evaporator decreases.

Answer 22

the TXV decreases the flow of refrigerant

Question 23

When referring to a power head on an expansion device the bulb is

Answer 23

normally charged with a fluid similar to that of the system refrigerant

Question 24

By subtracting the low side evaporator outlet temperature from the low side saturation temperature the technician would be calculating?

Answer 24

evaporator superheat

Question 25

On a typically evaporator employing a TXV the liquid refrigerant should be completely boiled to a vapor?

Answer 25

near the evaporator outlet

Question 26

What type of TXV would be best for an application that was exposed to fluctuating ambient temperatures?

Answer 26

balanced port TXVs

Question 27

Pressure-limiting TXV’s are generally applied on systems when

Answer 27

it is necessary to shut off the refrigerant flow to the evaporator when the suction pressure reaches a predetermined pressure

Question 28

Which of the following is not true regarding the evaporator in a refrigeration system?

Answer 28

it rejects heat from the conditioned space

Question 29

Heat that is added to the refrigerant stream after the 100% saturated vapor point is called?

Answer 29

superheat

Question 30

Multiple refrigerant circuits are preferred on evaporators that are?

Answer 30

large or long

Question 31

In a system where the evaporator temperature operators above 32º F the technician needs to be concerned with?

Answer 31

none of the above

Question 32

The fin spacing per inch on a medium-temperature evaporator is

Answer 32

closer together than on low-temperature evaporator

Question 33

A refrigeration system that utilizes two or three stages of low temperature refrigeration

Answer 33

is called a cascade refrigeration system

Question 34

When leak testing a refrigeration system using a high pressure nitrogen tank the technician should always

Answer 34

use a pressure regulator and safety relief value at the nitrogen tank

Question 35

The maximum pressure that can be applied to a refrigeration system when pressure testing is

Answer 35

determined by the systems rated nameplate test pressures

Question 36

The safest way to charge refrigerant into a system that is running is with

Answer 36

vapor into the low side

Question 37

When heating a refrigerant cylinder the technician should never use

Answer 37

any type of open flame

Question 38

Refrigeration systems must be fully evacuated before charging with refrigerant

Answer 38

to remove air and moisture from the system

Question 39

A vacuum pump will lose its ability to draw a deep vacuum over time because

Answer 39

the oil becomes full of moisture and acids which will decrease the capability of the vacuum pump

Question 40

A refrigerant service valve must be placed in the

Answer 40

mid position in order for the technician to access the system

Question 41

When using a micron gauge to measure vacuum the system should be evacuated to a level of _____ to ensure that non condensables and moisture have been adequately removed

Answer 41

500 microns