Deck 21: The Cooling System

Question 1

The compressor serves as a pump to draw the expanded refrigerant gas from the evaporator, boosts the ____ of the gas, and sends it to the condenser.

A)temperature
B)volatility
C)pressure
D)stability

Answer 1

C

Question 2

The hermetic compressor consists of a motor-compressor completely sealed in a gastight, ____ casing.

A)aluminum
B)cast iron
C)steel
D)plastic

Answer 2

C

Question 3

The tremendous popularity of mechanical refrigeration for household use in the 1930s and 1940s stimulated the development of a new series of nonexplosive and nontoxic refrigerants known as ____ of the halogen family.

A)chlorinated hydrofluorides
B)hydrocarbons
C)PCBs
D)dioxins

Answer 3

A

Question 4

The ____ component of the refrigerant cycle raises the energy level of the refrigerant so that it can be condensed readily to a liquid.

A)evaporator
B)compressor
C)condenser
D)expansion valve

Question 5

Under what conditions is "Branch-Circuit Selection Current" marked on a hermetic refrigerant motor-compressor?

Question 6

The cooling system for the drugstore and bakery in the chapter example is a ____ system with the compressor and condenser located on the ground adjacent to the building and the evaporator located in an air-handling unit in the basement.

A)joint
B)split
C)unified
D)dual

Question 7

____ is a method of removing energy in the form of heat from an object.

A)Compression
B)Circulation
C)Condensation
D)Refrigeration

Question 8

____ compressors are usually used in large installations.

A)Helical
B)Direct-drive
C)Hermetically sealed
D)Fin tube

Question 9

Where was the initial demand for hermetic compressors and what were the implications of this?

Question 10

NEC 110.9 states that equipment intended to interrupt current at ____ levels shall have an interrupting rating at nominal circuit voltage at least equal to the current that is available at the line terminals of the equipment.

A)fault
B)maximum
C)minimum
D)average

Question 11

The ampere rating of the disconnecting means for HVAC equipment must be at least ____ percent of the sum of all the individual loads within the equipment.

A)95
B)105
C)115
D)125

Question 12

Air-conditioning and refrigeration equipment is required by NEC 440.4(A)and (B)to be marked with a ____ marked with the maker's name, the rating in volts, frequency and number of phases, and other information.

A)removable label
B)sticker
C)color-coded pen
D)nameplate

Question 13

Overload protection of the internal components is covered in the ____ Standards.

A)ICEA
B)NFPA
C)TUV
D)UL

Question 14

One option for protecting a motor-compressor from overloads and failure to start is to use a time-delay fuse or inverse-time circuit breaker rated at not more than ____ percent of the rated load current.

A)95
B)105
C)115
D)125

Question 15

Where is the expansion valve located, and how does it function?

Question 16

Air-cooled condensers use ____ to drive air across the condensing coil.

A)ambient evaporation
B)a motor-driven fan
C)a pump
D)a temperature-difference fan

Question 17

In most instances, the rated load-current (RLA)is at least equal to ____ percent of the hermetic refrigerant motor-compressor's maximum continuous current (MCC).

A)16.1
B)32.1
C)64.1
D)96.1

Question 18

Can you cool your kitchen by leaving the refrigerator open? Explain why or why not.

Question 19

The evaporator in a commercial installation normally consists of a ____ coil, through which the building air is circulated by a motor-driven fan.

A)plate
B)helical tube
C)fin tube
D)fan plate

Question 20

What does NEC 440.14 require of the disconnecting means in terms of location, access, installation, and mount?