Brainscape's Knowledge GenomeTM

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


See full index

313D Prep > Quiz Questions > Flashcards

Quiz Questions Flashcards

1
Q

When a heat pump is operating in defrost mode, outdoor fan…

A

Is off

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

The amount of moisture in the air compared to the amount of moisture the air can hold at the temperature

A

Relative Humidity

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

Where will the refrigerant be superheated at the..

A

Outlet of compressor, inlet of the condenser, the outlet of the evaporator

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

R-410a cylinder colour

A

Rose

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

Pure water boils at 212F at what pressure?

A

14.7 psia

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

Refrigerant with low toxicity and no flame propagation is classifaction

A

A1

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

A substance that changes from the solid to the vapour state without going through liquid state. Is called

A

Sublimation

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

The amount of heat required to raise one pound of water, one degree Fahrenheit

A

Btu

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

Technician removes refrigerant from a system and stores it in an approved cylinder, this is

A

Recovery

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

Absolute Fahrenheit scale is called the

A

Rankin scale

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

What locations is does the saturated pressure correspond to the saturated temperature

A

Evaporator and condenser

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

If refrigerant has a quality of 75% it is

A

75% liquid 25% vapor

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

Latent heat of vaporization is

A

The amount of heat required to change liquid to vapour

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

Refrigerant vapour entering the metering device can be caused by

A

A restriction in liquid line, a dirty condenser coil, and undercharged system or leak

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

Fresh air brought into a house for ventilation purposes is usually

A

Connected to the return of duct system

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

Suction pressure being low can be caused by

A

Dirty condenser coil, low charge, low ambient air temp, dirty filter

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

Refrigerant leaving the condenser will be
(3)

A

Subcooled, liquid, high pressure

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

At a constant pressure the volume of gas varies directly at to absoloute temp and at a constant volume, the pressure of a gas varies directly with absoloute temp
This is called:

A

Charles law

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

System equipped with fixed orfice metering device has a sudden increase of indoor temp, what will be the effect on superheat if outdoor conditions remain the same

A

Superheat will increase

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

Technician found the the evaporator is operating at a very high superheat, they determined the metering device is ______the evaporator

A

Starving

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

410a is a near azeotropic blend, you should charge the system…

A

In liquid state through suction valve

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

A frosted suction line indicates

A

The suction line temp is below dee point if the ambient air or below 32F

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

Describe refrigeration

A

The process of removing heat from a place it is not wanted and transferring that heat to a place where it makes little or no difference

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

The liquid and vapour mixture in the condenser is a

A

Saturated temperature for the high side of the system

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

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

A

Dalton’s law

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

Water has a density of 62.4 lbs/cu ft. What’s it’s specific gravity

A

1

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

The term hygroscopic refers to

A

Moisture absorbing abilities of a substance

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

The refrigerant absorbs heat in the

A

Evaporator and compressor

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

Temp of gas leaving the compressor

A

Hot

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

Like txv, fixed orfice device controls superheat by losing the refrigerant pressure

A

Fixed orfice does not control superheat

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

Presssure in a refrigeration system is changed in the

A

Compressor and metering device

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

High temp refrigeration is an

A

AC System

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

The heat of compression that is generated in the compressor is removed from the refrigerant in the

A

Condenser

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

The capacity of a 2.5 ton ac system is

A

30,000 btu
(12,000 x 2.5)

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

What is the movement of heat through space called

A

Radiation

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

Heat transfer though space is called

A

Radiation

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

An external equalizer line on a txv is designed to

A

Compensate for pressure drop

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

As refrigerant passes through the metering device, the result is a drop in pressure and temp, with no change in heat content. This is known as

A

Adiabatic expansion

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

The amount of heat required to change the temp of one pound of a substance by one degree Fahrenheit
This is know as

A

Specific heat

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

What minimizes migration of refrigerant to compressor

A

Crank case heater

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

Removing heat from liquid refrigerant, below it’s condensing temp

A

Subcooling

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

Static pressure in a full oxygen cylinder is

A

2000

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

29” Hg. Vac is equal to

A

0.46 psia

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

What symptoms would an ac system exhibit if the condenser coil is dirty

A

High head pressure, low subcooling

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

Refrigerant flow into evaporator with a fixed orfice metering device is controlled by

A

Pressure different between condenser and evaporator

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

The ozone layer found in the stratosphere is made up of

A

3 oxygen atoms

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

Split systems installed with excessive liquid line length and lift, it could case

A

Flash gas in the liquid line

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

Cu ft/ lb is…

A

Specific volume

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

The volume of gas varies inversely with absolute pressure, provided the temp is constant
What law is this?

A

Boyle law

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

External equalizer line should be installed

A

Downstream of bulb

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

Evaporator coils for ac are designed to have
(CFM)

A

350-400 CFM per TON

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

System designed to have 11F of subcooling this is important to

A

Prevent vapour from entering metering device

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

When ordering 7/8” copper tubing the 7/8” refers to the

A

Outside diameter

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

Red gauge also know as

A

Pressure gauge

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

Proper subcooling is normally an indication of

A

A properly charged system

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

A blend of 2 refrigerants that have similar boiling points and do not separate liquid or vapour state is known as

A

Azeotropic blends

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

Most residential condensing unit compressor are cooled by

A

Refrigerant

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

The temp above which vapour cannot be condensed regardless of the pressure placed upon it is known as

A

Critical temp (point)

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

A heat pump the uses reciprocating compressor should be equipped with what device to protect it from possible liquid flood back

A

Accumulator

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

What should a pump down system have

A

A receiver

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

During operation, the suction line should be

A

Slightly warmer then the evaporator saturation temp

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

The temp of the air leaving the condenser is______ then ambient air

A

Warmer

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

Amount of air flow per ton is required through the evaporator of an ac system is

A

400CFM

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

What not to pressure test with

A

Oxygen and compressed air

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

Technician wants to determine amount of sensible heat added to refrigerant above saturation point in the evaporator coil, they would

A

Perform a superheat check on suction line

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

A bourdon tube is often found in a

A

Pressure gauge

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

Technician has determined that a newly installed refrigeration system is leaking free, before charging the system with refrigerant they must

A

Evacuate system

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

Evaporator T.D is the difference between

A

Air temp entering the evaporator and saturated suction temp

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

Which valve is a mechanical control the keeps the refrigerant in evaporator from going bellow a predetermined point

A

EPR Valve
Evaporator pressure regulator

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

The bulb for txv should be located

A

On the suction line at the outlet of the evaporator

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

When installing a resi split system, the ______ line should be insulated

A

Suction

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

What meter uses its own power source

A

Ohmmeter

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

When defrost cycle is terminated, the evaporator fans will

A

Delay coming on

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

Natural refrigerants are

(3)

A

Ammonia, carbon dioxide and hydrocarbon(propane)

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

Only vapour is present, it is

A

Superheated

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

Only liquid is present, it is

A

Subcooled

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

More net refrigeration=

A

More cooling

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

Bubble point on the

A

Liquid side

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

Dew points on the

A

Vapour side

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

Refrigerant will always travel to the

A

Coldest part

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

1KW=______btu

A

3412
3.412 x1000

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

1HP=______btu/h

A

2545
3.412 x 745

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

1W=______btuh

A

3.412

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

Dentsity=

A

Mass- volume ratio(lbs/ft3)
1/specific volume

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

Volume of 1 pound of gas (ft3/lb)

A

Specific volume

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

1 ton of refrigerant per minute

A

200 Btu/min

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

1 ton refrigerant per hour

A

12000 Btu/hr

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

Low subcooling and high superheat means the systems

A

Undercharged

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

Backseat means

A

Valve is closed

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

Valve is ________ for pump down

A

Frontseated

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

Valves mid seated for

A

Standing pressure test and evacuation

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

As compression ratio of compressor is increased due to higher than normal head pressure

A

Less refrigerant is pumped though system

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

Refrigerant muffler is installed on the

A

Discharge line

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

What valve design helps to increase compressor efficiency by reducing clearance volume

A

Discus valve

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

Most hermetic motor windings are cooled by

A

Cool suction gas

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

A de-superheating valve in a hot gas bypass capacity control system is designed to

A

Mia some liquid with the hot gas to cool it down

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

Changed the pitch and diameter of a pulley will not effect amp draw
T/F

A

False

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

As the piston moved down in the cylinder of a reciprocating compressor

A

Suction valve will open, moves towards BDC, and re-expansion will occur

99
Q

One form of capacity control to prevent gas from entering the cylinder chamber is

A

Cylinder unloading

100
Q

What’s better scroll or reciprocating compressor and why

A

Scroll, no volumetric loaded from gas re-expansion

101
Q

As piston moves up in reciprocating comp cylinder

A

Volume is decreased, pressure is increased

102
Q

What conditions can lead to higher than normal compression ratios

A

Dirty condenser, low suction pressure, high discharge pressure

103
Q

When piston of reciprocating compressor at TDC, but suction and discharge valve are….

A

Closed

104
Q

Starting at TDC position, the 4 processes that occur in the cylinder of a reciprocating compressor are

A

Re-expansion, suction, compression, discharge

105
Q

Clearance volume for reciprocating compressor

A

Decreases volumetric efficiency

106
Q

A compressor which is driven by a variable frequency drive

A

Can change speed of the compressor

107
Q

Best location to measure discharge temp to ensure compressor isn’t running too hot

A

6” from discharge valve (downstream)

108
Q

Flapper or reed valves are used in the

A

Reciprocating compressor

109
Q

Capacity control method unique to scroll compressor

A

2 stage modulation by using bypass ports to reduce capacity to approximately 67%

110
Q

What is volumetric efficiency

A

How well compressors operating compared to theoretical design capacity

111
Q

Shell and tube type evaporator that has refrigerant passing though the tubs and the shell is full of water is known as

A

Direct expansion or dry type

112
Q

Refrigerant leaves metering device as

A

Saturated mixture of vapour and liquid

113
Q

Density of air is the

A

Weight of air per unit of volume

114
Q

To process refrigerant to new product specifications “off cite”

A

Reclaiming

115
Q

What does the condenser do

A

De-superheats the vapour, condenses the valour, Subcools liquid refrigerant before it leaves the condenser,

116
Q

Refrigerant entering the evaporator is

A

Low pressure, cold, saturated

117
Q

Evaporator TD is the difference between

A

Air temp entering the evaporator and saturated suction temperature

118
Q

Enters the compressor as____
Leaves as______

A

Low pressure, low temperature, superheated
High pressure, high temperature, superheated vapour

119
Q

Fahrenheit scale where molecular activity stops

A

-460 F

120
Q

If temperatures constant, volume of gas increased the pressure will…

A

Decrease

121
Q

Suction line pressure and temperature determine

A

Superheat leaving evaporator

122
Q

Subcooling important because…

A

Increases system capacity

123
Q

Tube-within-tube water cooled condenser operated more efficiently with counter flow, which means..

A

Refrigerant is flowing through in one direction and water in the other

124
Q

Condenser split refers to

A

Temperature of air entering coil compared to the saturated condensing temperature

125
Q

Functions of condenser

A

De-superheat discharge vapour from compressor, condense refrigerant to liquid, reject heat from system and subcool liquid refrigerant

126
Q

Shell and tube condenser is..

A

Water flows through tubes and are surround by refrigerant in the shell

127
Q

As water flows through water cooled condensers

A

Temperature increases

128
Q

Condenser operates at______ than evaporator

A

Higher pressure

129
Q

Condenser rejects

A

Sensible and latent heat

130
Q

As refrigerant passes through the condenser is

A

Gives up heat

131
Q

Shell and tube condensers must be cleaned

A

With brush after removing end caps

132
Q

Varied temperature of wastewater type condenser has an effect on the

A

Head pressure of condenser

133
Q

Shell and coil condenser must be cleaned

A

Chemically

134
Q

Tube within tube condenser is______ cooler

A

Water cooled

135
Q

Refrigerant entering condenser is

A

Superheated

136
Q

Air is made up of

A

78% nitrogen, 21% oxygen, 1% other gases

137
Q

Comfort enquires

A

Temperature, humidity, air movement, air cleanliness

138
Q

Human body runs at about

A

98.6 F

139
Q

Density is

A

Mass of substance per unit of volume lb/ft3

140
Q

Dry air weighs

A

0.75 lbs/ft3

141
Q

Dew point temp is

A

Temperature which water will begin to condense out of the air

142
Q

Specific humidity is

A

Actual amount of moisture in air measured in grains of moisture per pounds of air

143
Q

Approximate amount of grains of moisture per pound of water

A

7000 grains

144
Q

How many cubic feet of air equal to one pound

A

1/0.075 lbs/ft3= 13.33 lbs/ft3

145
Q

The spring of a txv is a

A

Closing force

146
Q

Automatic expansion valve

A

Meters refrigerant to evaporator by using a pressure sensing device

Maintains constant pressure in evaporator

147
Q

When does the AEV valve open

A

When pressure drops

148
Q

How to adjust AEC

A

Clockwise to open

Turning screw into valve increases suction pressure

149
Q

Capillary tube metering device

A

Controls refrigerant flow by pressure drop

Diameter and length determine flow

Doesn’t control superheat

150
Q

Orfice/ piston metering device

A

Similar to capillary

151
Q

Txv and atv need

A

Receiver

152
Q

Capillary tubes are charged

A

Critically

153
Q

Bulb pressure _____ valve

A

Opens

154
Q

Evaporator pressure______valve

A

Opens

155
Q

What does the 4 way reversing valve do

A

Allows heat pump to pump heat in 2 directions

156
Q

For way reversing valve function in heating cycle

A

Discharge gas is directed from compressor to indoor coil (condenser)

157
Q

Larger line on heat pump system is called
And functions as

A

Gas line
Suction line in cooling
Discharge in heating

158
Q

Smaller line on heat pump is called
And liquid flows

A

Liquid line
To inside unit in summer
To outside unit on winter

159
Q

Four port valve with slide mechanism for larger systems

A

Use pilot operated valve that use high side pressure to push slide

160
Q

Air to air heat pump resembles

Mode determined by

A

AC System

Direction of flow

161
Q

Auxiliary heat required when

A

Heat pump can’t provide all the heat needed

162
Q

Balence point is

A

When heat pump is can pump in exactly as much heat as structure leaking out

163
Q

Air to air heat pump COP IS

A

3.5:1

164
Q

Air to water COP

A

4:1

165
Q

for way reversing valve has

A

2 inlets 2 outlets

166
Q

Air source heat pump has

A

2 metering devices

167
Q

In heating mode, heat pumps gain efficiency as outdoor ambient temp drops
T/F

A

False

168
Q

Electric auxiliary heaters for a heat pump are turned on in stages using

A

Heat sequencers

169
Q

Defrost mode for air sources heat pump can be initiated by…

A

Pressure differential, temperature, time

170
Q

Outdoor coil operates at the_____ in the heating cycle

A

Evaporator

171
Q

Filter dryers installed in heat pump system should be of the byflow type or installed with…

A

Check valves

172
Q

Metering devices for most heat pumps are piped in parallel with

A

The check valves (bypass valve)

173
Q

Indoor coil of a heat pump operates as the_____ in the heating cycle

A

Condenser

174
Q

Defrost cycle in heat pump is used to melt the ice that forms on the

A

Outdoor coil

175
Q

During defrost, the indoor fan is turned off
T/F

A

False

176
Q

Heat pump that absorbs heat from surrounding air and rejects it into are in a different place is an…

A

Air to air

177
Q

EEV constantly monitoring superheat based on…

A

Pressure transducer and temperature sensor

178
Q

Capacity control for reciprocating compressor can be achieved by using

A

Unloaders

179
Q

Micron gauge should be…

A

Furthest point away from vacuum pump

180
Q

As compression ratio increase, the volumetric efficiency…

A

Decreases

181
Q

The suction valve of a reciprocating compressor opens based on

A

Pressure differential

182
Q

Efficiency of reciprocating compressor can reduce due to

A

Re-expansion of refrigerant in cylinder

183
Q

Advantage of open drive compressor is…

A

Motor can be replaced without recovering the refrigerant

184
Q

The top scroll in a scroll compressor is

A

Stationary

185
Q

Digital scroll compressor achieves capacity by..

A

Momentarily separating the orbiting scroll from the fixed scroll

186
Q

Suction gas contaminated heat absorbed while it’s in the..

A

Evaporator

187
Q

Rotary compressor requires..

A

2 full rotations to complete 1 compression process

188
Q

The temperature of suction gas entering the compressor can be described as.

A

Cool

189
Q

Clearance volume is..

A

The space between to top of the piston at TDC and the bottom of the valve plate

190
Q

Discus style reciprocating compressor design helps to eliminate the re-expansion of gas in cylinder changer

T/F

A

True

191
Q

Discus valve is more efficient than reed valve because..

A

Allows the cylinders to be designed with less clearance volume

192
Q

Most heat absorbed by suction gas…

A

Latent

193
Q

If compressor discharge is too high it will lead too

A

The oil breaking down and lead to compressor failure

194
Q

Air conditioning is considered to be a________ refrigeration

A

High temp

195
Q

No superheat can cause_____ in the evaporator

A

Flooding

196
Q

High superheat can cause _____ in the evaporator

A

Starving

197
Q

How many classes of leaks are there?

A

6

198
Q

In refrigerant classification chart the higher the number, the higher…

A

Flammability

199
Q

I’m the refrigeration classification chart, the B section means…

A

Higher toxicity

200
Q

Can you vapour charge with 410a

A

No, it will fractionate
Because it’s a blended refrigerant

201
Q

Can you vapour charge R22

A

Yes.
Because it’s a single component

202
Q

Can you use a torch to warm up a refrigerant cylinder

A

No

203
Q

Blended compound refrigerant series are…

A

400 and 500 series

204
Q

Liquid refrigerant can be added through the..

A

Liquid line or receiver

205
Q

When charging with blended refrigerant the refrigerant must leave the cylinder as a…

A

Liquid

206
Q

Superheat method of charging is used for

A

Fixed orfice or capillary tube

207
Q

To charge a heat pump it should be set in

A

Cooling mode

208
Q

Subcooling charging method is used for

A

TXV

209
Q

Heat pump is more efficient in what mode

A

Heating mode

210
Q

Dew point and bubble point are for _____ refrigerants

A

Zeoptropic

211
Q

400 series are

A

Zeotropic

212
Q

500 series are

A

Azeotropic

213
Q

Fractionation is

A

Part of the blend will epaporate or condense before the other part

214
Q

What type of oil absorbs moisture

A

POE

215
Q

High td means

A

Low humidity

216
Q

Four way reversing
Top is:
Bottom middle:

A

Top: always permanent discharge
Bottom middle: always permanent suction

217
Q

What causes
Head pressure will go down
Suction will go up
Compression ratio will decrease

A

Four way reversing valve is leaking

218
Q

A four way reversing valve with an internal leak can be confused with

A

Be confused with a compressor not pumping to capacity

219
Q

Loose bulb leads to

A

High suction heat (feeling more heat)

220
Q

Psig of acetalyn tank is

A

250 psig

221
Q

Psig of nitrogen is

A

2200 Psig

222
Q

Psig of oxygen tank is

A

2000 Psig

223
Q

A before O and off you go

A

Acetylene, then Oxygen

224
Q

Difference between tube and pipe

A

Pipes-measured inside diameter (black pipe)
Tube-measured outside diameter (copper)

225
Q

Pressure(Psig) for torch would be same as

A

Tip size

226
Q

Liquid condensate line connects

A

Condenser to receiver

227
Q

Velocity is

A

Ft/min (fpm)

228
Q

Pipe diameter increases the velocity

A

Decreases
Visa versa

229
Q

Temperature is an indication of the:

A

Amount of molecular activity in the material

230
Q

When heat transfers by convention, it

A

Is transported from one place to another by air or liquid

231
Q

The temperature in the Celsius scale where all molecular activity stops is:

A

-273C

232
Q

When a vapour no longer corresponds to to pressure/ temperature relationship, it is known as_____vapour

A

Superheated

233
Q

As refrigerant passes through the metering device, the result is a drop in pressure and temperature, with no change in heat content
This is known as:

A

Adiabatic expansion

234
Q

While inspecting an AC system, a tech finds the head pressure running significantly higher than normal for the current outdoor temp. They also notice that the liquid line temp and the outdoor temp are the same.
What could be the cause?

A

System is overcharged

235
Q

R-value represents

A

An insulations resistance to heat transfer

236
Q

As the temperature of a material increases, the molecules in the material

A

Increase in speed

237
Q

134a, Vapour enters the condenser at 124psig and 100F, it leaves the condenser at 80F what’s the pressure?

A

124psig

238
Q

The role of the metering device in a heat pump is to

A

Meter refrigerant

239
Q

If the sensing bulb in txv developed a leak and started to loose charge, the result would be

A

The evaporator would be starved and superheat would be high

240
Q

If a system has a restriction in the metering device, a technician should expect:

A

High superheat and normal subcooling

241
Q

When the refrigerant enters the evaporator, it is:

A

At low pressure, cold and saturated

242
Q

The blue gauge is know as

A

A compound gauge

243
Q

Many rating for components in HVAC systems are not completely accurate due to many different operating conditions are called:

A

Nominal

244
Q

When do potential relays close

A

Loss of counter EMF

313D Prep (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions