HVAC And Refrigeration Flashcards
(304 cards)
0
Q
Three states of matter
A
Solid, liquid, gas
1
Q
Anything that has weight and occupies space
A
Matter
2
Q
The measurement of the presence and intensity of heat on a fahrenheit or Celsius scale
A
Temperature
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
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
5
Q
Two types of heat
A
Sensible, latent
6
Q
Measurable heat that causes a change in temperature without a change in the state of the matter
A
Sensible heat
7
Q
This type of heat can be detected by touch and thermometer
A
Sensible heat
8
Q
What kind of heat is added to raise the water temperature
A
Sensible heat
9
Q
Hidden heat
A
Latent heat
10
Q
Causes a change in state of a substance without a change in temperature or pressure
A
Latent heat
11
Q
Cannot be detected by a thermometer
A
Latent heat
12
Q
Types of latent heat
A
Vaporization, condensation, freezing, melting
13
Q
Heat added to a liquid to change it to a vapor without a change in temperature
A
Vaporization
14
Q
Heat removed from a vapor to change it to a liquid without a change in temperature
A
Condensation
15
Q
Heat removed to change the state of a substance from a liquid to a solid, without a change in temperature
A
Freezing
16
Q
Heat added to change the state of a substance from a solid to a liquid, without a change in temperature
A
Melting
17
Q
Difference in heat energy causes
A
Heat flow
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
19
Q
Transfer of heat by direct rays
A
Radiation
20
Q
Transfer of heat by direct contact of the two objects
A
Conduction
21
Q
Transfer of heat by means of a medium being circulated
A
Convection
22
Q
BTU
A
British thermal unit
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
24
Refers to the temperature of a substance measured in degrees by a thermometer
Heat intensity
25
The theoretical point at which a substance would contain no heat and all molecular motion would cease
Absolute zero
26
Absolute zero
-459.7•F
27
The condition when a substance (vapor) contains all of another substance (liquid) that it can hold
Saturation
28
The additional heat beyond that required to produce saturation at any specific pressure
Superheat
29
The cooling of a liquid so that its temperature is reduced below the corresponding saturation temperature
Subcool
30
What temperatures is water considered to be subcooled
212•F - 32•F
31
The physical change in state of a substance directly from a solid to a vapor without going through the liquid state
Sublimination
32
The amount of sensible heat plus latent heat within a substance at a given state and temperature
Total heat
33
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
Specific heat
34
The amount of heat absorbed in melting one ton (2000 lbs) of ice in 24 hours
Refrigeration ton
35
One refrigeration ton is equal to how many BTUs per day
288000
36
Any substance used in a refrigeration system to absorb heat and discard it
Refrigerant
37
Refrigerants used in refrigeration or air conditioning systems are rated by
Ozone depletion potential (ODP)
| Global warming potential (GWP)
38
GWP
Global warming potential
39
ODP
Ozone depletion potential
40
Refrigerants are categorized based on two characteristics
Chemical makeup
| Amount of damage they will inflict on the earths ozone layer if released into the atmosphere
41
CFCs
Chlorofluorocarbons
42
Contain chlorine, fluorine, and carbon
Chlorofluorocarbons
43
Why CFCs are damaging to earths stratospheric ozone layer
Contain chlorine
44
One chlorine molecule/atom can destroy ___ ozone molecules and takes _____ to repair
100000, 50 years
45
Protects us from ultraviolet radiation
Ozone layer
46
Chemically stable and do not breakup in the lower atmosphere. Have a high ODP and GWP rating
CFCs
47
R-12 refrigerant is sometimes referred to by its trade name
Freon
48
What gas does R-12 refrigerant produce when burned through a naked flame or subjected to high heat
Phosgene gas
49
Replaced R-12
R-134a
50
Which five refrigerants were targets of legislation that reduced their availability
R-11, 12, 113, 114, 115
51
HCFC
Hydrochlorofluorocarbon
52
Contain chlorine, also contain hydrogen, which makes them less chemically stable. Decompose when released into the lower atmosphere. Lower ODP rating
HCFCs
53
Two HCFCs
R-22, 123
54
HFC
Hydrofluorocarbon
55
Refrigerants have been developed which contain no chlorine at all and have an ODP of zero
HFCs
56
These refrigerants have been proven to produce tumors in animals, although are safe for the environment
HFCs
57
R-134a tetrafluoroethane is an example of
HFC refrigerant
58
R-12 CFC Cylinder color
White
59
R-12 CFC boiling point
-21.6•F
60
R-12 CFC main uses
Reciprocating, rotary, and large centrifugal compressors
61
R-12 CFC characteristics 4
Nontoxic, noncorrosive, nonirritating, nonflammable
62
R-22 HCFC cylinder color
Light green
63
R-22 HCFC boiling point
-41.4•F
64
R-22 HCFC uses
Freezer units, refrigerators, and centrifugal compressors
65
R-22 HCFC charateristics
Stable, nontoxic, noncorrosive, nonflammable
66
R-134a cylinder color
Light sky blue
67
R-134a boiling point
-14.9•F
68
R-134a uses
Rotary and large centrifugal compressors
69
R-134a characteristics
Stable, nontoxic, noncorrosive, nonflammable, 0 ODP
70
Concentrations of R-134a of ____ may cause _____
75000 ppm
| Cardiac irregularities
71
ASHRAE classifies the toxicity of refrigerants by assigning
A letter A or B
72
Refrigerants that have not been identified as having a toxicity level
Class A refrigerants
73
Refrigerants that have a toxicity level that has been identified
Class B refrigerants
74
ASHRAE classifies the flammability of refrigerants by assigning
A number
75
Class 1 refrigerant
No flammability identified
76
Class 2 refrigerants
Lower flamability
77
Class 3 refrigerants
High flammability
78
Fluids cooled by the refrigerant
Secondary refrigerants
79
Cost effective way to reduce the amount of refrigerant and piping required to efficiently cool an area
Secondary refrigerants
80
Most common secondary refrigerants used in the coast guard are
Water, brine, antifreeze solution
81
Combination of water and water soluble substances to lower freezing temperatures
Brine
82
Types of refrigerant cylinder types
Disposable
Refillable
Refillable nonshattering
83
This refrigerant cylinder is used by commercial refrigerant technicians and is color coded to identify the refrigerant they contain
Disposable
84
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
Refillable
85
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
Refillable nonshattering
86
Commercial disposable cylinders are available in sizes from
1 pound can to a 50 pound cylinder
87
Refillable non-shattering cylinders come in the following sizes (4)
10, 35, 50, and 100 pound
88
When stowing refrigerant cylinders, stow in a _____ position with the valve ____
Upright position, valve on top
89
Do not store refrigerant cylinders where the temperature is expected to exceed ___
125•F
90
Never fill a cylinder over ____ full
80%
91
A safety disc is built into disposable refrigerant cylinders. It is designed to relieve the cylinder pressure if it should exceed
360 psi
92
The carry handles on a disposable refrigerant cylinder can double as
Stands to invert a cylinder when charging a system with liquid refrigerant
93
Disposable refrigerant cylinders have what printed on the side
Refrigerant weight
94
Do not use disposable refrigerant cylinders where
On board coast guard cutters
95
What part of the NSTM states that refrigerant must be transferred to a refillable non-shattering cylinder/bottle
NSTM Chapter 516-1.10.3
96
Refillable refrigerant cylinders have what two weights stamped into the neck
Tare weight
| Water content
97
Weight of the cylinder
Tare weight
98
Bottle capacity in pounds of water
Water content
99
These safety devices are designed to relieve pressure in the cylinder if pressure becomes excessive
Pressure relief valve
100
Actual relief pressure is dependent on the type of refrigerant in the cylinder, with a maximum value of ____
360 psig
101
Do not store refrigerant in a ____
Refillable refrigerant cylinder
102
The fusible plug melts at ____
165*F
103
If it becomes necessary to warm a cylinder, use _____, not _____. And never use _____
Bucket of warm water
Hot water
A torch or open flame
104
What kind of bottom do refillable nonshattering refrigeration cylinders have
Concave
105
This cylinder must be painted orange and stenciled with the type of refrigerant on both sides
Refillable nonshattering refrigeration cylinder
106
What must be stenciled on the side of a refillable nonshattering refrigeration cylinder
Type of refrigerant
107
Store refrigeration cylinder ____, where the temperature will not exceed ____
Cool and dry place
| 125*F
108
Never attempt to refill a ____ refrigeration cylinder
Disposable
109
Which part of the NSTM states that carbon tetrachloride should not be used for cleaning
NSTM, Chapter 510, A.8 OPERATION
110
Who can render a disposable refrigeration cylinder unfit for use by puncturing them through the safety disc
EPA certified technicians
111
The DOT prohibits the use of empty disposable refrigerant cylinders as ____
Compressed air storage tanks
112
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 ____
$25000
| Confinement
113
Force exerted by the molecules of a substance over a given area
Pressure
114
If the state of matter is solid then the pressure is created by ___
The weight (density) of the molecule
115
If the state of matter is liquid then the pressure is created by ____
The weight of the molecules and the action of a force upon a combined liquid
116
If the state of matter is gas then the pressure is created by ____
The bombardment of the molecules upon the walls of a closed container and ricocheting action as the molecules collide
117
The total pressure of a confined mixture of gases is the sum of the partial pressures of each of the gases in the mixture
Dalton's Gas Law
118
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
Vapor pressure
119
Three items are required for a pressure temperature relationship
Confined container
Liquid
The confined liquid's vapour
120
By controlling the ____ in the evaporator, the boiling temperature of the refrigerant can be controlled
Vapor pressure
121
By controlling the ____ in the condenser, the condensing temperature of the refrigerant can be controlled
Vapor pressure
122
Where the latent heat of condensation is removed from the refrigerant by the cooling medium
Condenser
123
Where the refrigerant absorbs its latent heat of vaporization from the refrigerated space
Evaporator
124
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
Pressure temperature chart
125
Listed vertically along the side of the pressure temperature chart
Ambient temperature listing
126
Listed horizontally along the top of the pressure temperature chart
Most common types of refrigerants
127
Enables a certified technician to obtain pressure readings from an AC&R system
Refrigeration service gauge manifold
128
Provides a means to perform several services to a system including recovery, charging, evacuating, adding oil (refrigeration system)
Refrigeration service gauge manifold
129
Purging refrigeration from a system to the atmosphere is ____
A violation of EPA regulations
130
Cast body with hand valves, gauge connections, and three tubing connections
Manifold
131
Located at both ends of the manifold (at the high and low pressure ports)
Hand valves
132
The gauge on the low side of the refrigeration service gauge manifold is
A compound gauge reading 30 in Hg to 250 psi
133
The gauge on the high side of the refrigeration service gauge manifold is
A standard pressure gauge rating 0 psi to 500 psi
134
Four stages in the basic refrigerant cycle
Compression
Condensation
Expansion
Evaporation
135
Refrigerant vapor temperature is raised above the cooling medium temperature by the compressor
Compression
136
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
Condensation
137
Allows high-pressure, high-temperature liquid refrigerant to pass through an orifice and then rapidly expand in volume, lowering the refrigerant pressure
Metering device
138
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
25
139
The refrigerant enters the evaporator as
A saturated vapor
140
Extends from the discharge side of the compressor to the inlet of the metering device, gives up heat to the cooling system
High-pressure side
141
Extends from the outlet of the metering device to the inlet of the compressor, absorbs heat from the refrigerant and the space
Low-pressure side
142
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
Compressor
143
Compressors are classified according to ____
Their principle of operation
144
Four major types of compressors
Reciprocating
Rotary
Scroll
Centrifugal
145
Most commonly used compressor in the Coast Guard and HVAC industry
Reciprocating
146
Compressor used primarily in large capacity systems of 50 - 5000 tons
Centrifugal
147
Types of compressor body designs
Open
Hermetic
Semi-hermetic
148
Used in a system to reduce refrigerant from its vapor phase into a liquid phase through heat transfer
Condenser
149
___ are located between the compressor and the metering device. If the system has a receiver, it is located between the compressor and the receiver
Condensers
150
Refrigeration condensers are categorized by ____
Their cooling medium
151
Two styles of refrigeration condensers
Water-cooled
| Air-cooled
152
Condensers remove what kinds of heat from the refrigerant vapour
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
This condenser permits lower and more constant condensing pressures
Water-cooled condensers
154
Three types of water-cooled condensers
Shell and tube
Shell and coil
Tube-within-a-tube
155
Three types of air-cooled condensers
Fin and tube condenser
Wire static condenser
Static plate condenser
156
Controls the amount of refrigerant entering the evaporator coil, provides a pressure drop between the high and low sides of the system
Metering device
157
This device is located in the liquid line, after the dehydrator
Metering device
158
Different metering devices in a refrigeration system
Thermostatic expansion valve
Automatic expansion valve
Capillary tube
159
Used to maintain a constant superheat between 4*F and 12*F (10*F is preferred)
Thermostatic expansion valve
160
Used to maintain constant evaporator pressure
Automatic expansion valve
161
Predetermined length and diameter of copper tubing used to maintain constant refrigerant flow
Capillary tube
162
Acts as a heat exchanger. It contains the refrigerant which absorbs heat from the refrigerated space
Evaporator coil
163
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.
Evaporator
164
Physically mounted on the bulkhead or overhead of the refrigerated space
Evaporator
165
Three types of evaporators
Bare tube evaporator
Fin and tube evaporator
Plate evaporator
166
Type of evaporator used on large units due to ease of cleaning
Bare tube evaporator
167
Type of evaporator used in air-conditioning and refrigeration systems, both commercial and domestic
Fin and tube evaporator
168
Type of evaporator used in refrigerators as a shelf, and the product is placed directly on it
Plate evaporator
169
When refrigerant flows from the metering device into the evaporator coil then ___
The refrigerant will flash off as it absorbs heat from the evaporator coil
170
When the evaporator coil temperature decreases then ____
The difference in temperature between the coil and ambient air causes the coil to absorb heat from the ambient air
171
When the evaporator coil absorbs heat then ____
The refrigerant will absorb the heat from the evaporator and continue to flash off
172
Tubing that has been preformed into a multiple pass heat exchanger. The bare tube is in contact with the air in the refrigerated space
Bare tube evaporator
173
Continuous copper tube running back and forth with hundreds of thin fins bonded to the tubing
Fin and tube evaporator
174
Types of plate evaporators
Dual plate
| Tube and plate
175
Refrigerant storage tank, located between the condenser and the metering device
Receiver
176
A receiver is sized to hold complete system charge and be ____ full
80%
177
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.
Receiver
178
Contains baffles to prevent sloshing of liquid refrigerant and the loss of the liquid seal
Receiver
179
Normally copper tubing which directs liquid refrigerant to the metering device. This line is normally not insulated which permits the refrigerant to subcool
Liquid line
180
Located between the condenser or receiver and the system metering device
Liquid line
181
Used to control the supply of liquid refrigerant to the metering devices
King valve and king solenoid valve
182
Located in the liquid line as close to the receiver as possible
King valve and king solenoid valve
183
The king valve is a ____ valve
Stop
184
The kind solenoid valve is a _____ valve that is normally ____ when energized
Two-position, electrically operated
| open
185
Prevents liquid floodback during an emergency shutdown of the compressor (refrigerant)
King solenoid valve
186
Installed in a refrigeration system to remove or add liquid refrigerant to the system
Liquid line service valve
187
Located in the liquid line ahead of the dehydrator
Liquid line service valve
188
Used in refrigeration systems to remove moisture from the refrigerant
Dehydrator
189
Normally installed in a bypass line connected to the fluid line. On small systems it is installed in the liquid line
Dehydrator
190
Filled with a moisture-absorbing compound. As the liquid refrigerant passes through it, water is trapped and held within the moisture-absorbing compound
Dehydrator
191
If the dehydrator is warm to the touch, it is _____
Working properly
192
Gives the technician the ability to view the refrigerant in the refrigeration system
Sight glass
193
Normally located in the liquid line, usually after the dehydrator
Sight glass
194
Allow technicians to isolate the compressor or to attach a service gauge manifold to troubleshoot a system
Packed service valve
195
The packed service valve has three connections
Compressor
Suction/discharge line
Service connection
196
Loosen the packing glands ____ before operating the valve (packed service valve)
1/2 to 1 turn
197
Front seat, turn the valve ____ to isolate the compressor from the system and to open the system to the service connection
Clockwise
198
Back seat, turn the valve _____ to open the compressor to the system, while securing the service connection
Counter-clockwise
199
With the packed service valve _____, all three ports are open to each other; called the _____
Between the two seats
| Gauge or center position
200
Always do what after using the packed service valve
Replace the valve caps
201
The packed service valve should be ____ when the system is operating
Back seated
202
Service port caps should only be removed while valve is in the _____ position
Back seated
203
Used throughout refrigeration systems. This type of valve incorporates a durable, compact design with quick, positive seating
Packless hand stop valve
204
____ turns will fully open a closed packless hand stop valve
2 1/2
205
A new packless hand stop valve will last longer if it is tightened _____ versus ______
Finger tight
| Hand tight
206
Secures the compressor in the event of high discharge pressure
High-pressure switch
207
High-pressure switch sensing line is connected to ______. The contacts _____ on on increase of pressure and ____ on a decrease in pressure
The compressor discharge
Open
Close
208
Will protect the compressor against excessive discharge pressure in the event the high-pressure switch fails
High-pressure relief valve
209
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
High-pressure relief valve
210
Direct acting switch. It stops the compressor after the last box solenoid valve closes
Low-pressure switch
211
Specially prepared mineral oil. Refining steps are taken to remove excess wax, moisture, sulfur, and other impurities. Most have a foaming inhibitor added
Refrigeration oil
212
Three viscosities for refrigeration oil are available
150, 300, 500
213
Most automatic refrigerating systems use this viscosity of oil
300
214
Refrigerant oil must be kept in ____
Sealed containers
215
How often should refrigeration oil be checked and changed
Check oil monthly and change oil as needed
216
Which part of the NSTM states "Check oil monthly and change oil as needed" (refrigeration oil)
NSTM, Chapter 516-8.8
217
Who can recover, reclaim, and recycle refrigerants
EPA certified technicians
218
To remove refrigerant in any condition from a system and store it in an external container
Recover
219
To clean refrigerant for reuse by oil separation and single or multiple passes through devices such as replaceable filters/dryers
Recycle
220
To reprocess refrigerant to new product specifications by means which may include distillation
Reclaim
221
Any technician opening a refrigeration system must be properly certified in accordance with ___
608 of the Clean Air Act
222
Designed specifically for the air-conditioning and refrigeration industry. It enables you to evacuate a system after repairs
Deep vacuum pump
223
If the compressor is to be secured for more than four hours or to use an alternate unit, ____
Close the compressor shutoff valves
224
Changing the air in a work place or living space
Ventilation
225
Most economical way to maintain the health and comfort conditions of the space is by ___
Replacing the air
226
The ventilation systems of machinery spaces should be operated to provide a mechanical exhaust air quantity ____ than the mechanical supply air quantity
Greater
227
In a machinery space, the exhaust system removes the supply air plus approximately ____ extra to ensure in-draft through the natural supply
5%
228
If there is no excess exhaust, hot air from the machinery space will be ____
Forced through accesses into the ship
229
Type of ventilation used aboard ships in the engine rooms or machinery spaces
Total replenishment ventilation
230
Type of ventilation used in living spaces
Partially replenished ventilation
231
Partially replenished ventilation
Recirculated air is 75%, replenished air is 25%
232
Convection heaters are generally used in spaces ____
Not served by mechanical supply systems or recirculation systems
233
Duct heater, generally installed near a supply system intake
Pre-heater
234
Pre-heater heats the intake weather air sufficiently to prevent ____
Condensation on supply system ducts
235
The supply duct air after pre-heating should be in the vicinity of _____
4.4*C to 10*C (40*F to 50*F)
236
Duct heaters that raise the temperature of the preheated supply or recirculation system air. Electric powered
Re-heaters
237
Two types of heating systems
Zone heating
| Individual space heating
238
Single duct re-heater serving several spaces
Zone heating
239
Has a re-heater for each space served
Individual space heating
240
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
Coast Guard standard electric duct heaters
241
The enclosure for the electrical connections located on the side of the heater casing is of ____ construction for safety
Sea-spray tight
242
Each electric duct heater uses the ____ as its power source
Fan's electrical circuit
243
Trips when the heating element temperature has reached a predetermined temperature
Safety cutout switch
244
Reason the duct heater uses the fan's electrical circuit as its power source
Safeguard against fire and heater damage due to excessive heat
245
The duct heater's element is made of ___
Copper tubing that has been expanded into the heat transfer fins, and has twin headers
246
Duct heaters use ____ to heat the air as it passes through
Low pressure hot water
247
Often referred to as coils, radiators, or base board heater
Convection heaters
248
Considered low maintenance, so they are used extensively to heat spaces that receive indirect ventilation
Convection heaters
249
Convection heaters use ____ as the energy source
Hot water or electricity
250
Convection heaters are used in compartments where flammable liquids are stored because they ___
Are considered explosion proof
251
Consists of a weather inlet, fan, ductwork, and supply terminals
Supply ducting
252
Consists of exhaust terminals, ductwork, a fan, vent closures, and a weather outlet
Exhaust ducting
253
Challenges with machinery space exhaust
Significant buildup of dirt, debris, and oil due to oil laden air in the space
254
Challenges with laundry exhaust ducting
Most rapid buildup of dirt and debris
255
Challenges with head space exhaust systems
Tend to buildup dirt and debris very rapidly, second only to laundry exhaust ducts
256
The cooling coils, cooling coil condensate drain pans, and ducting downstream from the cooling coils are a potential location for ____
Bacteria and fungus growth due to water and high humidity
257
Methods of spray removal (5)
```
Hoods and baffles
Airlift types
Moisture separator
Waterproof ventilators
Closures
```
258
Draws the weather air upward at a low velocity to permit entrained drops of water to fall out of the airstream
Airlift
259
Removes water from the weather air by a sudden change in the direction of the airstream
Moisture separator
260
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
Vane-axial fan
261
On the vane-axial fan, the vanes are located on ____, and serve to ____
The fan discharge
| Increase fan efficiency by straightening the airstream created by the rotating blades
262
Consists of a scroll shaped housing that is bolted to the motor support base
Centrifugal fan
263
The spaces to be ventilated will be rated in ___
Cubic feet per minute of air to be delivered at each outlet
264
Begins at the air inlet and continues to the most remote outlet of the ventilation system
Main duct
265
Branched from the main duct and has two or more outlets
Main branch duct
266
Branched from either the main duct or the main branch duct and has only one outlet
Branch duct
267
Used to isolate ducts during emergencies
Ventilation valves
268
Type of valve used in ventilation valves
Lightweight round butterfly
269
Incorporated in ducting for ventilation balance, load control, system performance, and emergency situations such as fire
Dampers
270
Means of distributing the conditioned air throughout the space to perpetuate the heat transfer process
Diffusers
271
Used for supply ventilation and return ventilation for filtration and recirculation
Diffuser
272
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
Vent screens
273
Required only in the exhaust ducts from compartments or spaces such as fuel transfer stations or aviation fuel spaces that contain flammable vapors
Flame arresters
274
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
Flame arresters
275
House the air filter
Filter grilles or air filter housings
276
Purify the air
Filters
277
Two most commonly used air filters in the Coast Guard
Disposable filter
| Reusable filter
278
Air filters are typically located
On the intake side of the air handler or plenum chamber
279
This kind of filter cannot be used with flame arresters
Disposable filters
280
This air filter is manufactured from
Non woven synthetics
281
Three types of approved disposable air filters
Internal ring panel filter
Cube filter
Filter pads and holding frames (Pinch and door)
282
This air filter type has an internal metal (or other acceptable material) sealed between the filter layers
Internal frame panel filter
283
This air filter requires no additional frame and will slide into the existing filter housing. Disposed of at the end of the filter life
Internal frame panel filter
284
This air filter has an internal metal frame similar to the internal ring panel. Shaped similar to tapered shopping backs, approx. 15 inches deep
Cube filter
285
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.
Filter pads and holding frames
286
Cleanable, high-velocity impingement type metal filters
Standard/reusable filters
287
After cleaning a standard filter
It shall be recoated with a filter adhesive
288
Air filter adhesive must be
Nontoxic, odorless, water soluble
Flashpoint of not less than 350*F
Viscosity that it can be applied by mechanical spraying at temps between 50*F and 100*F
289
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
Three times
290
System specific technical data on pressure drops (air systems) can be found in ____
Manufacturer's technical manual
291
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
Fan coil assembly (FCA)
292
Most important factor in maintaining adequate cooling and airflow to spaces
Keeping cooling coils clean
293
When cleaning heating/cooling coils it is paramount that you never ___
Use sharp instruments or tools that could damage the coils or fins
294
Simple device consisting of a heating and/or cooling coil and fan (cooling) to make a space or spaces comfortable
Fan coil unit (FCU)
295
Fan coil units are divided into two types
Two-pipe fan coil units
| Four-pipe fan coil units
296
Cools water (chill water) and pumps the cold water to the various fan coil units where they absorb the heat from the spaces
Refrigerant chiller
297
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
Coil
298
Fan motors are typically
120 volt AC motors
299
Easy to remove for service access to motors and blowers at, or away from, the unit
Fan deck assembly
300
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
Water control valve
301
Water control valve actuators are typically
Low (24VAC) voltage
302
Tool used to repair damaged coil fins
Fin comb
303
Disposable and reusable filters are designed to remove ____ percent of the dust particles if maintained properly
90
