Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MK3 > HVAC And Refrigeration > Flashcards

HVAC And Refrigeration Flashcards

0
Q

Three states of matter

A

Solid, liquid, gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

Anything that has weight and occupies space

A

Matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The measurement of the presence and intensity of heat on a fahrenheit or Celsius scale

A

Temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Equal to 1/180th of the difference between the freezing point and boiling point of water at sea level

A

One degree fahrenheit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Equal to 1/100th of the difference between the freezing point and boiling point of water at sea level

A

One degree celsius

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Two types of heat

A

Sensible, latent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Measurable heat that causes a change in temperature without a change in the state of the matter

A

Sensible heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

This type of heat can be detected by touch and thermometer

A

Sensible heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What kind of heat is added to raise the water temperature

A

Sensible heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Hidden heat

A

Latent heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Causes a change in state of a substance without a change in temperature or pressure

A

Latent heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Cannot be detected by a thermometer

A

Latent heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Types of latent heat

A

Vaporization, condensation, freezing, melting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Heat added to a liquid to change it to a vapor without a change in temperature

A

Vaporization

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Heat removed from a vapor to change it to a liquid without a change in temperature

A

Condensation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Heat removed to change the state of a substance from a liquid to a solid, without a change in temperature

A

Freezing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Heat added to change the state of a substance from a solid to a liquid, without a change in temperature

A

Melting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Difference in heat energy causes

A

Heat flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Laws of heat flow

A

Heat will always flow from a warmer to a cooler substance, there must be a temperature difference for heat to flow, the greater the temperature difference the faster heat will flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Transfer of heat by direct rays

A

Radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Transfer of heat by direct contact of the two objects

A

Conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Transfer of heat by means of a medium being circulated

A

Convection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

BTU

A

British thermal unit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

The amount of heat required to change the temperature of one pound of pure water one degree fahrenheit, at atmospheric pressure

A

BTU

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Refers to the temperature of a substance measured in degrees by a thermometer

A

Heat intensity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

The theoretical point at which a substance would contain no heat and all molecular motion would cease

A

Absolute zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Absolute zero

A

-459.7•F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

The condition when a substance (vapor) contains all of another substance (liquid) that it can hold

A

Saturation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

The additional heat beyond that required to produce saturation at any specific pressure

A

Superheat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

The cooling of a liquid so that its temperature is reduced below the corresponding saturation temperature

A

Subcool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What temperatures is water considered to be subcooled

A

212•F - 32•F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

The physical change in state of a substance directly from a solid to a vapor without going through the liquid state

A

Sublimination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

The amount of sensible heat plus latent heat within a substance at a given state and temperature

A

Total heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

The ratio of the amount of heat required to change the temperature of one pound of a substance one degree fahrenheit as compared to water, at atmospheric pressure

A

Specific heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

The amount of heat absorbed in melting one ton (2000 lbs) of ice in 24 hours

A

Refrigeration ton

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

One refrigeration ton is equal to how many BTUs per day

A

288000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Any substance used in a refrigeration system to absorb heat and discard it

A

Refrigerant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Refrigerants used in refrigeration or air conditioning systems are rated by

A

Ozone depletion potential (ODP)

Global warming potential (GWP)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

GWP

A

Global warming potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

ODP

A

Ozone depletion potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Refrigerants are categorized based on two characteristics

A

Chemical makeup

Amount of damage they will inflict on the earths ozone layer if released into the atmosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

CFCs

A

Chlorofluorocarbons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Contain chlorine, fluorine, and carbon

A

Chlorofluorocarbons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Why CFCs are damaging to earths stratospheric ozone layer

A

Contain chlorine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

One chlorine molecule/atom can destroy ___ ozone molecules and takes _____ to repair

A

100000, 50 years

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Protects us from ultraviolet radiation

A

Ozone layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Chemically stable and do not breakup in the lower atmosphere. Have a high ODP and GWP rating

A

CFCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

R-12 refrigerant is sometimes referred to by its trade name

A

Freon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What gas does R-12 refrigerant produce when burned through a naked flame or subjected to high heat

A

Phosgene gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Replaced R-12

A

R-134a

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Which five refrigerants were targets of legislation that reduced their availability

A

R-11, 12, 113, 114, 115

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

HCFC

A

Hydrochlorofluorocarbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Contain chlorine, also contain hydrogen, which makes them less chemically stable. Decompose when released into the lower atmosphere. Lower ODP rating

A

HCFCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Two HCFCs

A

R-22, 123

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

HFC

A

Hydrofluorocarbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Refrigerants have been developed which contain no chlorine at all and have an ODP of zero

A

HFCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

These refrigerants have been proven to produce tumors in animals, although are safe for the environment

A

HFCs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

R-134a tetrafluoroethane is an example of

A

HFC refrigerant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

R-12 CFC Cylinder color

A

White

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

R-12 CFC boiling point

A

-21.6•F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

R-12 CFC main uses

A

Reciprocating, rotary, and large centrifugal compressors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

R-12 CFC characteristics 4

A

Nontoxic, noncorrosive, nonirritating, nonflammable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

R-22 HCFC cylinder color

A

Light green

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

R-22 HCFC boiling point

A

-41.4•F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

R-22 HCFC uses

A

Freezer units, refrigerators, and centrifugal compressors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

R-22 HCFC charateristics

A

Stable, nontoxic, noncorrosive, nonflammable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

R-134a cylinder color

A

Light sky blue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

R-134a boiling point

A

-14.9•F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

R-134a uses

A

Rotary and large centrifugal compressors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

R-134a characteristics

A

Stable, nontoxic, noncorrosive, nonflammable, 0 ODP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

Concentrations of R-134a of ____ may cause _____

A

75000 ppm

Cardiac irregularities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

ASHRAE classifies the toxicity of refrigerants by assigning

A

A letter A or B

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Refrigerants that have not been identified as having a toxicity level

A

Class A refrigerants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

Refrigerants that have a toxicity level that has been identified

A

Class B refrigerants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

ASHRAE classifies the flammability of refrigerants by assigning

A

A number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

Class 1 refrigerant

A

No flammability identified

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Class 2 refrigerants

A

Lower flamability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

Class 3 refrigerants

A

High flammability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

Fluids cooled by the refrigerant

A

Secondary refrigerants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

Cost effective way to reduce the amount of refrigerant and piping required to efficiently cool an area

A

Secondary refrigerants

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

Most common secondary refrigerants used in the coast guard are

A

Water, brine, antifreeze solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

Combination of water and water soluble substances to lower freezing temperatures

A

Brine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

Types of refrigerant cylinder types

A

Disposable
Refillable
Refillable nonshattering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

This refrigerant cylinder is used by commercial refrigerant technicians and is color coded to identify the refrigerant they contain

A

Disposable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

This refrigerant cylinder is used by the military and commercial technicians, portable cylinders are used to recover refrigerant, and the bottle is gray with the upper third painted yellow

A

Refillable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

This refrigerant cylinder is used by military and commercial technicians, and is painted orange in color. Stenciled with the refrigerant they contain on each side

A

Refillable nonshattering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

Commercial disposable cylinders are available in sizes from

A

1 pound can to a 50 pound cylinder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

Refillable non-shattering cylinders come in the following sizes (4)

A

10, 35, 50, and 100 pound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

When stowing refrigerant cylinders, stow in a _____ position with the valve ____

A

Upright position, valve on top

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

Do not store refrigerant cylinders where the temperature is expected to exceed ___

A

125•F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

Never fill a cylinder over ____ full

A

80%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

A safety disc is built into disposable refrigerant cylinders. It is designed to relieve the cylinder pressure if it should exceed

A

360 psi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

The carry handles on a disposable refrigerant cylinder can double as

A

Stands to invert a cylinder when charging a system with liquid refrigerant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

Disposable refrigerant cylinders have what printed on the side

A

Refrigerant weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

Do not use disposable refrigerant cylinders where

A

On board coast guard cutters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

What part of the NSTM states that refrigerant must be transferred to a refillable non-shattering cylinder/bottle

A

NSTM Chapter 516-1.10.3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

Refillable refrigerant cylinders have what two weights stamped into the neck

A

Tare weight

Water content

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

Weight of the cylinder

A

Tare weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

Bottle capacity in pounds of water

A

Water content

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

These safety devices are designed to relieve pressure in the cylinder if pressure becomes excessive

A

Pressure relief valve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

Actual relief pressure is dependent on the type of refrigerant in the cylinder, with a maximum value of ____

A

360 psig

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

Do not store refrigerant in a ____

A

Refillable refrigerant cylinder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

The fusible plug melts at ____

A

165*F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

If it becomes necessary to warm a cylinder, use _____, not _____. And never use _____

A

Bucket of warm water
Hot water
A torch or open flame

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

What kind of bottom do refillable nonshattering refrigeration cylinders have

A

Concave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

This cylinder must be painted orange and stenciled with the type of refrigerant on both sides

A

Refillable nonshattering refrigeration cylinder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
106
Q

What must be stenciled on the side of a refillable nonshattering refrigeration cylinder

A

Type of refrigerant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
107
Q

Store refrigeration cylinder ____, where the temperature will not exceed ____

A

Cool and dry place

125*F

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
108
Q

Never attempt to refill a ____ refrigeration cylinder

A

Disposable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
109
Q

Which part of the NSTM states that carbon tetrachloride should not be used for cleaning

A

NSTM, Chapter 510, A.8 OPERATION

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
110
Q

Who can render a disposable refrigeration cylinder unfit for use by puncturing them through the safety disc

A

EPA certified technicians

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
111
Q

The DOT prohibits the use of empty disposable refrigerant cylinders as ____

A

Compressed air storage tanks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
112
Q

The penalty for a violation of the law that prohibits the use of empty disposable refrigerant cylinders as compressed air storage tanks will result in a fine up to ____ and/or ____

A

$25000

Confinement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
113
Q

Force exerted by the molecules of a substance over a given area

A

Pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
114
Q

If the state of matter is solid then the pressure is created by ___

A

The weight (density) of the molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
115
Q

If the state of matter is liquid then the pressure is created by ____

A

The weight of the molecules and the action of a force upon a combined liquid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
116
Q

If the state of matter is gas then the pressure is created by ____

A

The bombardment of the molecules upon the walls of a closed container and ricocheting action as the molecules collide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
117
Q

The total pressure of a confined mixture of gases is the sum of the partial pressures of each of the gases in the mixture

A

Dalton’s Gas Law

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
118
Q

When a liquid and its vapor are confined together in a container, the ____ determines the boiling temperature of the liquid and the condensing temperature of the vapor

A

Vapor pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
119
Q

Three items are required for a pressure temperature relationship

A

Confined container
Liquid
The confined liquid’s vapour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
120
Q

By controlling the ____ in the evaporator, the boiling temperature of the refrigerant can be controlled

A

Vapor pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
121
Q

By controlling the ____ in the condenser, the condensing temperature of the refrigerant can be controlled

A

Vapor pressure

122
Q

Where the latent heat of condensation is removed from the refrigerant by the cooling medium

A

Condenser

123
Q

Where the refrigerant absorbs its latent heat of vaporization from the refrigerated space

A

Evaporator

124
Q

When combined with an accurate gauge manifold, a _____ is a basic tool for the refrigeration technician to use to identify refrigerant, monitor system operation, and troubleshoot systems

A

Pressure temperature chart

125
Q

Listed vertically along the side of the pressure temperature chart

A

Ambient temperature listing

126
Q

Listed horizontally along the top of the pressure temperature chart

A

Most common types of refrigerants

127
Q

Enables a certified technician to obtain pressure readings from an AC&R system

A

Refrigeration service gauge manifold

128
Q

Provides a means to perform several services to a system including recovery, charging, evacuating, adding oil (refrigeration system)

A

Refrigeration service gauge manifold

129
Q

Purging refrigeration from a system to the atmosphere is ____

A

A violation of EPA regulations

130
Q

Cast body with hand valves, gauge connections, and three tubing connections

A

Manifold

131
Q

Located at both ends of the manifold (at the high and low pressure ports)

A

Hand valves

132
Q

The gauge on the low side of the refrigeration service gauge manifold is

A

A compound gauge reading 30 in Hg to 250 psi

133
Q

The gauge on the high side of the refrigeration service gauge manifold is

A

A standard pressure gauge rating 0 psi to 500 psi

134
Q

Four stages in the basic refrigerant cycle

A

Compression
Condensation
Expansion
Evaporation

135
Q

Refrigerant vapor temperature is raised above the cooling medium temperature by the compressor

A

Compression

136
Q

Superheat is removed from the refrigerant vapor, the refrigerant condenses, giving up its latent heat of condensation to the cooling medium, liquid refrigerant is subcooled

A

Condensation

137
Q

Allows high-pressure, high-temperature liquid refrigerant to pass through an orifice and then rapidly expand in volume, lowering the refrigerant pressure

A

Metering device

138
Q

As the refrigerant begins to boil (flash) due to the heat contained within it. As the refrigerant turns into a vapor, it occupies _____ times the volume it would as a liquid

A

25

139
Q

The refrigerant enters the evaporator as

A

A saturated vapor

140
Q

Extends from the discharge side of the compressor to the inlet of the metering device, gives up heat to the cooling system

A

High-pressure side

141
Q

Extends from the outlet of the metering device to the inlet of the compressor, absorbs heat from the refrigerant and the space

A

Low-pressure side

142
Q

Located in the machinery space close to the refrigerated space. It circulates the refrigerant, maintains a low pressure in the evaporator, raises the temperature and pressure of the refrigerant vapor so that is may be condensed by the cooling medium

A

Compressor

143
Q

Compressors are classified according to ____

A

Their principle of operation

144
Q

Four major types of compressors

A

Reciprocating
Rotary
Scroll
Centrifugal

145
Q

Most commonly used compressor in the Coast Guard and HVAC industry

A

Reciprocating

146
Q

Compressor used primarily in large capacity systems of 50 - 5000 tons

A

Centrifugal

147
Q

Types of compressor body designs

A

Open
Hermetic
Semi-hermetic

148
Q

Used in a system to reduce refrigerant from its vapor phase into a liquid phase through heat transfer

A

Condenser

149
Q

___ are located between the compressor and the metering device. If the system has a receiver, it is located between the compressor and the receiver

A

Condensers

150
Q

Refrigeration condensers are categorized by ____

A

Their cooling medium

151
Q

Two styles of refrigeration condensers

A

Water-cooled

Air-cooled

152
Q

Condensers remove what kinds of heat from the refrigerant vapour

A

Superheat from the vapor to lower it to condensing temperature
Latent heat to cause the change in state from a vapour to a liquid
Sensible heat is removed to subcool the liquid refrigerant to lower its temperature below its condensing temperature

153
Q

This condenser permits lower and more constant condensing pressures

A

Water-cooled condensers

154
Q

Three types of water-cooled condensers

A

Shell and tube
Shell and coil
Tube-within-a-tube

155
Q

Three types of air-cooled condensers

A

Fin and tube condenser
Wire static condenser
Static plate condenser

156
Q

Controls the amount of refrigerant entering the evaporator coil, provides a pressure drop between the high and low sides of the system

A

Metering device

157
Q

This device is located in the liquid line, after the dehydrator

A

Metering device

158
Q

Different metering devices in a refrigeration system

A

Thermostatic expansion valve
Automatic expansion valve
Capillary tube

159
Q

Used to maintain a constant superheat between 4F and 12F (10*F is preferred)

A

Thermostatic expansion valve

160
Q

Used to maintain constant evaporator pressure

A

Automatic expansion valve

161
Q

Predetermined length and diameter of copper tubing used to maintain constant refrigerant flow

A

Capillary tube

162
Q

Acts as a heat exchanger. It contains the refrigerant which absorbs heat from the refrigerated space

A

Evaporator coil

163
Q

In the refrigeration system, the ______ is located at the end of the liquid line, directly after the metering device in the flow diagram of the refrigerant.

A

Evaporator

164
Q

Physically mounted on the bulkhead or overhead of the refrigerated space

A

Evaporator

165
Q

Three types of evaporators

A

Bare tube evaporator
Fin and tube evaporator
Plate evaporator

166
Q

Type of evaporator used on large units due to ease of cleaning

A

Bare tube evaporator

167
Q

Type of evaporator used in air-conditioning and refrigeration systems, both commercial and domestic

A

Fin and tube evaporator

168
Q

Type of evaporator used in refrigerators as a shelf, and the product is placed directly on it

A

Plate evaporator

169
Q

When refrigerant flows from the metering device into the evaporator coil then ___

A

The refrigerant will flash off as it absorbs heat from the evaporator coil

170
Q

When the evaporator coil temperature decreases then ____

A

The difference in temperature between the coil and ambient air causes the coil to absorb heat from the ambient air

171
Q

When the evaporator coil absorbs heat then ____

A

The refrigerant will absorb the heat from the evaporator and continue to flash off

172
Q

Tubing that has been preformed into a multiple pass heat exchanger. The bare tube is in contact with the air in the refrigerated space

A

Bare tube evaporator

173
Q

Continuous copper tube running back and forth with hundreds of thin fins bonded to the tubing

A

Fin and tube evaporator

174
Q

Types of plate evaporators

A

Dual plate

Tube and plate

175
Q

Refrigerant storage tank, located between the condenser and the metering device

A

Receiver

176
Q

A receiver is sized to hold complete system charge and be ____ full

A

80%

177
Q

Acts as a surge tank during operation, serves as a storage tank for the refrigerant when the system is secured, provides a liquid seal between the vapor and liquid refrigerant.

A

Receiver

178
Q

Contains baffles to prevent sloshing of liquid refrigerant and the loss of the liquid seal

A

Receiver

179
Q

Normally copper tubing which directs liquid refrigerant to the metering device. This line is normally not insulated which permits the refrigerant to subcool

A

Liquid line

180
Q

Located between the condenser or receiver and the system metering device

A

Liquid line

181
Q

Used to control the supply of liquid refrigerant to the metering devices

A

King valve and king solenoid valve

182
Q

Located in the liquid line as close to the receiver as possible

A

King valve and king solenoid valve

183
Q

The king valve is a ____ valve

A

Stop

184
Q

The kind solenoid valve is a _____ valve that is normally ____ when energized

A

Two-position, electrically operated

open

185
Q

Prevents liquid floodback during an emergency shutdown of the compressor (refrigerant)

A

King solenoid valve

186
Q

Installed in a refrigeration system to remove or add liquid refrigerant to the system

A

Liquid line service valve

187
Q

Located in the liquid line ahead of the dehydrator

A

Liquid line service valve

188
Q

Used in refrigeration systems to remove moisture from the refrigerant

A

Dehydrator

189
Q

Normally installed in a bypass line connected to the fluid line. On small systems it is installed in the liquid line

A

Dehydrator

190
Q

Filled with a moisture-absorbing compound. As the liquid refrigerant passes through it, water is trapped and held within the moisture-absorbing compound

A

Dehydrator

191
Q

If the dehydrator is warm to the touch, it is _____

A

Working properly

192
Q

Gives the technician the ability to view the refrigerant in the refrigeration system

A

Sight glass

193
Q

Normally located in the liquid line, usually after the dehydrator

A

Sight glass

194
Q

Allow technicians to isolate the compressor or to attach a service gauge manifold to troubleshoot a system

A

Packed service valve

195
Q

The packed service valve has three connections

A

Compressor
Suction/discharge line
Service connection

196
Q

Loosen the packing glands ____ before operating the valve (packed service valve)

A

1/2 to 1 turn

197
Q

Front seat, turn the valve ____ to isolate the compressor from the system and to open the system to the service connection

A

Clockwise

198
Q

Back seat, turn the valve _____ to open the compressor to the system, while securing the service connection

A

Counter-clockwise

199
Q

With the packed service valve _____, all three ports are open to each other; called the _____

A

Between the two seats

Gauge or center position

200
Q

Always do what after using the packed service valve

A

Replace the valve caps

201
Q

The packed service valve should be ____ when the system is operating

A

Back seated

202
Q

Service port caps should only be removed while valve is in the _____ position

A

Back seated

203
Q

Used throughout refrigeration systems. This type of valve incorporates a durable, compact design with quick, positive seating

A

Packless hand stop valve

204
Q

____ turns will fully open a closed packless hand stop valve

A

2 1/2

205
Q

A new packless hand stop valve will last longer if it is tightened _____ versus ______

A

Finger tight

Hand tight

206
Q

Secures the compressor in the event of high discharge pressure

A

High-pressure switch

207
Q

High-pressure switch sensing line is connected to ______. The contacts _____ on on increase of pressure and ____ on a decrease in pressure

A

The compressor discharge
Open
Close

208
Q

Will protect the compressor against excessive discharge pressure in the event the high-pressure switch fails

A

High-pressure relief valve

209
Q

Will open and divert high-pressure refrigerant vapor back to the compressor inlet in the event the high-pressure switch fails to secure the compressor

A

High-pressure relief valve

210
Q

Direct acting switch. It stops the compressor after the last box solenoid valve closes

A

Low-pressure switch

211
Q

Specially prepared mineral oil. Refining steps are taken to remove excess wax, moisture, sulfur, and other impurities. Most have a foaming inhibitor added

A

Refrigeration oil

212
Q

Three viscosities for refrigeration oil are available

A

150, 300, 500

213
Q

Most automatic refrigerating systems use this viscosity of oil

A

300

214
Q

Refrigerant oil must be kept in ____

A

Sealed containers

215
Q

How often should refrigeration oil be checked and changed

A

Check oil monthly and change oil as needed

216
Q

Which part of the NSTM states “Check oil monthly and change oil as needed” (refrigeration oil)

A

NSTM, Chapter 516-8.8

217
Q

Who can recover, reclaim, and recycle refrigerants

A

EPA certified technicians

218
Q

To remove refrigerant in any condition from a system and store it in an external container

A

Recover

219
Q

To clean refrigerant for reuse by oil separation and single or multiple passes through devices such as replaceable filters/dryers

A

Recycle

220
Q

To reprocess refrigerant to new product specifications by means which may include distillation

A

Reclaim

221
Q

Any technician opening a refrigeration system must be properly certified in accordance with ___

A

608 of the Clean Air Act

222
Q

Designed specifically for the air-conditioning and refrigeration industry. It enables you to evacuate a system after repairs

A

Deep vacuum pump

223
Q

If the compressor is to be secured for more than four hours or to use an alternate unit, ____

A

Close the compressor shutoff valves

224
Q

Changing the air in a work place or living space

A

Ventilation

225
Q

Most economical way to maintain the health and comfort conditions of the space is by ___

A

Replacing the air

226
Q

The ventilation systems of machinery spaces should be operated to provide a mechanical exhaust air quantity ____ than the mechanical supply air quantity

A

Greater

227
Q

In a machinery space, the exhaust system removes the supply air plus approximately ____ extra to ensure in-draft through the natural supply

A

5%

228
Q

If there is no excess exhaust, hot air from the machinery space will be ____

A

Forced through accesses into the ship

229
Q

Type of ventilation used aboard ships in the engine rooms or machinery spaces

A

Total replenishment ventilation

230
Q

Type of ventilation used in living spaces

A

Partially replenished ventilation

231
Q

Partially replenished ventilation

A

Recirculated air is 75%, replenished air is 25%

232
Q

Convection heaters are generally used in spaces ____

A

Not served by mechanical supply systems or recirculation systems

233
Q

Duct heater, generally installed near a supply system intake

A

Pre-heater

234
Q

Pre-heater heats the intake weather air sufficiently to prevent ____

A

Condensation on supply system ducts

235
Q

The supply duct air after pre-heating should be in the vicinity of _____

A

4.4C to 10C (40F to 50F)

236
Q

Duct heaters that raise the temperature of the preheated supply or recirculation system air. Electric powered

A

Re-heaters

237
Q

Two types of heating systems

A

Zone heating

Individual space heating

238
Q

Single duct re-heater serving several spaces

A

Zone heating

239
Q

Has a re-heater for each space served

A

Individual space heating

240
Q

Consist of three or more electrical heating elements. Each element consists of a helically coiled resistance wire centered in a densely packed insulating material which in turn is enclosed in a hermetically sealed finned metal sheath. Each end of the element has a threaded stud-type terminal for connecting the element to the electrical power circuit

A

Coast Guard standard electric duct heaters

241
Q

The enclosure for the electrical connections located on the side of the heater casing is of ____ construction for safety

A

Sea-spray tight

242
Q

Each electric duct heater uses the ____ as its power source

A

Fan’s electrical circuit

243
Q

Trips when the heating element temperature has reached a predetermined temperature

A

Safety cutout switch

244
Q

Reason the duct heater uses the fan’s electrical circuit as its power source

A

Safeguard against fire and heater damage due to excessive heat

245
Q

The duct heater’s element is made of ___

A

Copper tubing that has been expanded into the heat transfer fins, and has twin headers

246
Q

Duct heaters use ____ to heat the air as it passes through

A

Low pressure hot water

247
Q

Often referred to as coils, radiators, or base board heater

A

Convection heaters

248
Q

Considered low maintenance, so they are used extensively to heat spaces that receive indirect ventilation

A

Convection heaters

249
Q

Convection heaters use ____ as the energy source

A

Hot water or electricity

250
Q

Convection heaters are used in compartments where flammable liquids are stored because they ___

A

Are considered explosion proof

251
Q

Consists of a weather inlet, fan, ductwork, and supply terminals

A

Supply ducting

252
Q

Consists of exhaust terminals, ductwork, a fan, vent closures, and a weather outlet

A

Exhaust ducting

253
Q

Challenges with machinery space exhaust

A

Significant buildup of dirt, debris, and oil due to oil laden air in the space

254
Q

Challenges with laundry exhaust ducting

A

Most rapid buildup of dirt and debris

255
Q

Challenges with head space exhaust systems

A

Tend to buildup dirt and debris very rapidly, second only to laundry exhaust ducts

256
Q

The cooling coils, cooling coil condensate drain pans, and ducting downstream from the cooling coils are a potential location for ____

A

Bacteria and fungus growth due to water and high humidity

257
Q

Methods of spray removal (5)

A 
Hoods and baffles
Airlift types
Moisture separator
Waterproof ventilators
Closures
258
Q

Draws the weather air upward at a low velocity to permit entrained drops of water to fall out of the airstream

A

Airlift

259
Q

Removes water from the weather air by a sudden change in the direction of the airstream

A

Moisture separator

260
Q

Consist of a flanged cylindrical casing with stationary vanes and an internal mounted electric motor with a bladed fan wheel mounted directly on the motor shaft. The motor is mounted in a ring that is supported to the casing by stationary vanes

A

Vane-axial fan

261
Q

On the vane-axial fan, the vanes are located on ____, and serve to ____

A

The fan discharge

Increase fan efficiency by straightening the airstream created by the rotating blades

262
Q

Consists of a scroll shaped housing that is bolted to the motor support base

A

Centrifugal fan

263
Q

The spaces to be ventilated will be rated in ___

A

Cubic feet per minute of air to be delivered at each outlet

264
Q

Begins at the air inlet and continues to the most remote outlet of the ventilation system

A

Main duct

265
Q

Branched from the main duct and has two or more outlets

A

Main branch duct

266
Q

Branched from either the main duct or the main branch duct and has only one outlet

A

Branch duct

267
Q

Used to isolate ducts during emergencies

A

Ventilation valves

268
Q

Type of valve used in ventilation valves

A

Lightweight round butterfly

269
Q

Incorporated in ducting for ventilation balance, load control, system performance, and emergency situations such as fire

A

Dampers

270
Q

Means of distributing the conditioned air throughout the space to perpetuate the heat transfer process

A

Diffusers

271
Q

Used for supply ventilation and return ventilation for filtration and recirculation

A

Diffuser

272
Q

Installed on ventilation systems to prevent large objects from entering the ductwork which could damage the fans, and to prevent fouling of the fans, ducts, and fittings, as well as to prevent injury to personnel

A

Vent screens

273
Q

Required only in the exhaust ducts from compartments or spaces such as fuel transfer stations or aviation fuel spaces that contain flammable vapors

A

Flame arresters

274
Q

Consist of a frame and an arresting cell (screening cell) are installed on the intake side of the exhaust fan outside the compartment or space protected, and in a non-watertight section of the exhaust ductwork

A

Flame arresters

275
Q

House the air filter

A

Filter grilles or air filter housings

276
Q

Purify the air

A

Filters

277
Q

Two most commonly used air filters in the Coast Guard

A

Disposable filter

Reusable filter

278
Q

Air filters are typically located

A

On the intake side of the air handler or plenum chamber

279
Q

This kind of filter cannot be used with flame arresters

A

Disposable filters

280
Q

This air filter is manufactured from

A

Non woven synthetics

281
Q

Three types of approved disposable air filters

A

Internal ring panel filter
Cube filter
Filter pads and holding frames (Pinch and door)

282
Q

This air filter type has an internal metal (or other acceptable material) sealed between the filter layers

A

Internal frame panel filter

283
Q

This air filter requires no additional frame and will slide into the existing filter housing. Disposed of at the end of the filter life

A

Internal frame panel filter

284
Q

This air filter has an internal metal frame similar to the internal ring panel. Shaped similar to tapered shopping backs, approx. 15 inches deep

A

Cube filter

285
Q

This air filter is inserted into reusable metal filter holding frames of the same dimensions as standard filters. Only the pad is disposed of at the end of the filter life.

A

Filter pads and holding frames

286
Q

Cleanable, high-velocity impingement type metal filters

A

Standard/reusable filters

287
Q

After cleaning a standard filter

A

It shall be recoated with a filter adhesive

288
Q

Air filter adhesive must be

A

Nontoxic, odorless, water soluble
Flashpoint of not less than 350F
Viscosity that it can be applied by mechanical spraying at temps between 50F and 100*F

289
Q

When the pressure drop difference from one side to the other side of an air filter is greater then ____ the pressure drop across a new filter, it should be changed

A

Three times

290
Q

System specific technical data on pressure drops (air systems) can be found in ____

A

Manufacturer’s technical manual

291
Q

Consists of a fan and motor, a cooling coil, and air filters provided in a singe cabinet. Supply and returns ducts are connected to the assembly, as well as electrical power, a condensate drip pan and drain line and chilled/hot water supply and return lines

A

Fan coil assembly (FCA)

292
Q

Most important factor in maintaining adequate cooling and airflow to spaces

A

Keeping cooling coils clean

293
Q

When cleaning heating/cooling coils it is paramount that you never ___

A

Use sharp instruments or tools that could damage the coils or fins

294
Q

Simple device consisting of a heating and/or cooling coil and fan (cooling) to make a space or spaces comfortable

A

Fan coil unit (FCU)

295
Q

Fan coil units are divided into two types

A

Two-pipe fan coil units

Four-pipe fan coil units

296
Q

Cools water (chill water) and pumps the cold water to the various fan coil units where they absorb the heat from the spaces

A

Refrigerant chiller

297
Q

Receives the hot or cold water from a chiller, boiler or emersion heater, and removes or adds heat to the air through heat radiant transfer

A

Coil

298
Q

Fan motors are typically

A

120 volt AC motors

299
Q

Easy to remove for service access to motors and blowers at, or away from, the unit

A

Fan deck assembly

300
Q

Driven open with a spring return (bypass) when there is a demand for heating or cooling to maintain space temperature. Energized, the bypass port is blocked, and water can flow through the unit’s water coil to heat or cool the space

A

Water control valve

301
Q

Water control valve actuators are typically

A

Low (24VAC) voltage

302
Q

Tool used to repair damaged coil fins

A

Fin comb

303
Q

Disposable and reusable filters are designed to remove ____ percent of the dust particles if maintained properly

A

90

MK3 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions