old Flashcards
1
Q
Bonnet
A
Top cover, often removable. Connects the valve operator to the movable valve disk assembly
2
Q
Valve operator
A
Any device used to move the stem valve disk assembly
3
Q
Globe valve has high or low pressure difference
A
High
4
Q
2 types of three way valves
A
Diverting and mixing
5
Q
What are 2 applications that use reversing valves
A
Heat pumps and defrost controls
6
Q
ASHRAE
A
American Society of Heating Refrigeration and Air conditioning Engineers
7
Q
Flammability levels of refrigerants
A
1-3 no flammability to high
8
Q
Toxicity levels of refrigerants
A
A or B low or high toxicity
9
Q
Due diligence
A
Took all reasonable steps for prevent a comission
10
Q
Which code prevails if they conflict?
Appliance installation or government
A
Government
11
Q
Do you need certified appliances when placed in mobile homes?
A
No
12
Q
What must you do with defective heat exchangers in residential and commercial?
A
Can be repaired temporarily but must be replaced in residential.
Can be repaired upon certification in commercial.
13
Q
Maximum allowable pressure drop on a low pressure system (7-14”WC)
A
1”WC
14
Q
Rough in piping
A
Between the meter and finish piping
15
Q
Maximum allowable pressure drop on a high pressure system (above 14”WC)
A
50% standing pressure
16
Q
When making an extension gas line, where can you connect the extension
A
Within 2 ft of the gas meter of the existing piping
17
Q
Can you install gas lines in stairwells
A
No
18
Q
Teflon tape must be applied wrapping it _, with _% overlap, and leaving the first _ starter threads bare
A
clockwise, 50% overlap, first 2 starter threads
19
Q
What’s the min depth of dirt pockets
A
3”
20
Q
What type of control system are bimetal strips
A
Electromechanical
21
Q
What’s an ORI and CRO
A
Open on rise in inlet
Close on rise in outlet
22
Q
What’s the difference between cut in and cut out in temp control
A
Controller differential
23
Q
What are the 2 terms for the difference between the controller temp setpoint and the control point (measured temperature).
A
Overshoot and undershoot
24
Q
Deviation
A
The time it takes for the control point (measured temp) and the set point to equalize
25
Offset
The sustained difference between the control point and the setpoint
26
Differential
The difference between cut in and cut out temps
27
The OFC stops the compressor because there is no oil in the head but there is not leaks, should you add oil?
No
28
Contactors normally have both NO and NC contacts
FALSE
29
When should you use a contactor vs a relay
Contactors for more than 15A
30
Mullion heater
Doorframe heater
31
Compressors that have _ use oil failure controls
Oil pumps
32
What must you do to thermostats before mounting them.
Level them
33
What's one of the most common applications for flexible diaphragm sensors
Combustion aiproving control
34
Oil failure control
Senses the differential pressure by sensing the difference between the crankcase and oil pump pressure
35
Hygroscopic sensors
Electromechanical devices that consists of organic materials that absorb and releases moisture
36
Humidistats close on (rise/fall) in RH
Fall
37
Enthalpy controllers
Measure actual beat content in the ambient air
38
Transformer
Induces a secondary alternating current with use of coils of varying amounts
39
Relays or contactors can be repaired
Contactors
40
Electromechanical TDR (time delay relay)
Energizes a resistive heater to switch at least 1 bimetal after a predictable time
41
Overload devices
Protects end use devices. Either line duty or pilot duty
42
Line duty
Interrupts current to the motor
43
Pilot duty
Interrupts a control system by opening another control system such as a contactor or relay
(Solenoid valve <-> refrigerant system)
44
Overcurrent devices
Protects conductors from excessive current
45
Magnetic overcurrent device
Usually an underpowered NC contactor that energizes when excessive current causes it to open
46
Low ambient limit thermostats are often used how?
To prevent the compressor from starting at low temps
47
What do change-over thermostats and enthalpy controllers do
Function as a low ambient temperature limit and change to free cooling from the economizer cycle
48
What are mixed air thermostats
Proportional temperature controllers that modulates the dampers of an economizer
49
Freezestats
Evap low limit thermostats, prevent the system from running when the evaporator is too cold. Safety
50
What's used to interrupt a roll out
Rollout limit
51
What's used to interrupt a backdraft
Spill limit
52
What class and symbol of fire extinguisher should be used for electrical fires
Class C blue circle
53
What is the ratio for ladder placement
4:1
54
What percentage of OHS injury claims were musculoskeletal?
67%
55
What percentage of all work related injury claims involved the back?
37%
56
How far should extension ladders overreach the top
1m/3ft/3 rungs
57
What is a type 1A ladder
Extra heavy duty ladder rated for 300lbs
58
What are the cons of Aluminum ladders?
It's electrically conductive
59
What is the ratio for scaffolds
3:1
60
What must be installed on any scaffolds?
Guardrails 0.92-1.07m
61
What are outriggers
Side extensions that add lateral stability to the scaffold
62
What’s a type of natural fibre for ropes
Number One Grade manila
63
What's the refrigeration code called
B52-5
64
How many sections are there in the refrigeration code
15
65
LFL
Lower flammability limit
66
TLV-TWA
Threshold limit value - Time weighted average
67
Annexes
Provides information to the overall code and archived code
68
Zeotropic
Blend of different refrigerants with varying saturation
69
What are some factors that affect the probability of arc faults
Condensate, equipment failure, corrosion, dust, over voltage
70
Factors affecting the severity of an arc flash
Proximity of the worker
Amount of heat from the arc flash
Exposure time
71
What code book determines arc flash safety
Z462
72
What clothing material shouldn't be worn when dealing with electrical
Synthetic
73
What is the code for Mechanical refrigeration code book and who developed it
B52-5 by the Alberta Boilers Safety Association
74
What refrigerants and systems does B52-05 not apply to
Water and air, systems connected to railcars, airplanes, motor vehicles, ships
75
Superheating
Adding heat when the refrigerant is at a temperature which exceeds that of saturation (vapour) at the same pressure
76
Subcooling
Removing heat when the refrigerant is at a temperature which is below that of saturation (liquid) at the same pressure
77
What is the typical temperature difference of superheating and subcooling. And where at what distance?
15°F 6" out the evaporator and 10°F 6" out the condenser
78
IDLH
Immediate Danger to Life or Health
79
How many joules does it take to heat 1kg of water by 1°C?
4.2kJ
80
What is specific heat (c)?
The amount of energy required to change the temperature of a substance by 1°C
81
How is British thermal unit defined?
The amount of heat required to heat 1lb of water by 1°F
82
What are the 2 laws of thermal dynamics?
First law: energy cannot be created or destroyed
Second law: heat moves from high to low heat
83
Desuperheating
Removing heat from the superheated hot refrigerant gas down to the condensing temperature.
84
What are the three methods of heat transfer
conduction, convection, radiation
85
back pressure
the low side pressure of a refrigerant system
86
head pressure
the high side pressure of a refrigerant system
87
head, static
Fluid pressure based on the height of a column of fluid.
88
sublimation
solid to gas
89
Ton of Refrigeration
The amount of heat necessary to completely melt one ton of 32 deg. F ice in 24 hours. (200 BTUs per minute or 12,000 BTUs per hour)
90
Threshold limit value (TLV)
Refers to airborne concentrations of refrigerant and represents conditions under which it is believed that nearly all workers may be exposed to without adverse effect
91
positive displacement
Class of compressors that increase pressure by squeezing.
92
centrifugal/non-positive displacement
Class of compressors that increase pressure by using centripetal force and speed.
93
What must rotary and scroll compressors must have
check valves
94
Pollutant of electronic air cleaning
Ozone gas
95
ASHRAE
American society of heating, refrigeration, air conditioning engineers
96
Three categories of filters
Dry, wet and electronic
97
IAQ
Indoor air quality
98
PM
Preventive maintenance
99
Sick building syndrome
Legionnaire syndrome
100
Glide
Range of saturation temperature for a zeotropic refrigerant
101
Def of heat vs temperature
Heat: energy of molecular (kinetic) motion
Temperature: average amount of molecular motion
102
The amount of energy an object has depends on what
It's composition and size
103
What current can cause heart failure
100mA-200mA
104
What are ohmmeters?
Inserted around a resistive element (NON-POWERED) to measure resistance
105
What safety measures should be followed before using the ohmmeter on the system?
Remove the power sources
106
What is the three-step voltage test
1. Test the meter to a known voltage
2. Test the equipment
3. Test the meter again
107
How many keys must there be to open the lock during lockouts?
1
108
Uses for CAT III rated electrical metering instruments
600V or less building distribution systems, located after the utility company connection
109
Uses for CAT IV rated electrical metering instruments
Utility connections and power lines
110
What is the r.m.s voltage?
The value of direct voltage that produces the same power as the alternating voltage.
111
What are the 2 plates in a battery.
Anode and Cathode
112
How many electrons are in a Coulomb
6.28x10¹⁸
113
What is conventional flow and electron flow?
Conventional current is positive to negative, and electron flow is the flow of electrons from negative to positive
114
You can apply pressure to what kinds of materials to produce EMF
Crystals of bone, wood, metal, or minerals
115
What does Ohm's law state?
The current in a circuit is directly proportional to the emf and inversely proportional to the resistance
116
What’s the effect of producing electricity from pressure?
Piezoelectric effect
117
The energy lines that magnets emit are called
lines of magnetic flux
118
When a conductor crosses a magnetic field, what is this process called
Electromagnetic induction or generator action
119
Faraday’s law of induction
The magnitude of the voltage induced is proportional to the rate at which the conductor cuts the lines of magnetic flux
120
What are the 2 ways electrostatics are used in HVAC/R
In air filtration with precipitators and with power coating painted surfaces on equipment
121
Magnetic domain
When all the magnetic moments in a group of atoms align.
122
Cathode and anode
Positive and negative plate in a battery
123
Connecting various electrodes in different configs can what
Create batteries of different voltages
124
Permeability
Ability of a material to concentrate magnetic flux
125
Reluctance
A materials resistance to magnetic flux.
Opposite of permeability
126
Magnetic saturation
When the magnetic material cannot be magnetized any further
127
Inductance
Current in a circuit creates a voltage that opposes the change in current
128
How many degrees is one alternation
180°
129
What's one cycle of electrical generated
Cutting across 1 pair of N S pole.
130
What angle of sine wave is used to calculate RMS value
45°
131
What's effective AC value
RMS value, or value read from multimeter
132
3 factors making up impedance in AC circuit
Resistance, inductive reactance, and capacitive reactance
133
Inductance opposes any change of
Capacitance opposes any change of
Inductance opposes current
Capacitance opposes voltage
134
Example of process plant
The furnace, heat exchanger
135
What does the comparator in the controller do?
Compares the value of the controlled variable and the set point
136
What is the controlled medium?
The process material in the control system in which the variable to be controlled exists e.g. the air
137
What is the controlled variable?
The measurement of the controlled medium e.g. temp of the air
138
Final Control Element
a controlled device that receives its signal from a controller and meters the flow of the control agent
139
RGYWC
Red - hot wire
Green - Blower motor
Y (blue) - cooling
W (black) - heat
C (white) - common
140
What are the 3 most common proportional analog signals?
0-10V DC
2-10V DC
4-20mA DC
141
actuator
An actuator is a device that converts a pneumatic or electromagnetic signal to force.
142
anticipating control
Anticipating control is the ability to foresee potential changes and take proactive measures to artificially active this control earlier than otherwise
143
averaging element
A thermostat that responds to the average duct temperature
144
Coefficient of linear thermal expansion
(Thermal expansion) Change in length of a metal due to temperature change
145
opposed blade damper
each alternating blade rotates in the opposite direction of the one besides it to throttle airflow without changing the direction of the air
146
parallel blade damper
each alternating blade rotates in the same direction of the one besides it to throttle airflow and change the direction of the air
147
direct acting
The output signal changes in the same direction of the controlled variable changes. E.G: an increase in resistance from an increase in temperature
148
Reverse acting
The output signal changes in the opposite direction of the controlled variable changes. E.G: a decrease in resistance from an increase in temperature
149
thermistor
A heat sensitive resistor, worse than RTD but can be positive or negative acting
150
Transducer
An electronic pressure sensor utilizing piezoelectric effect to create impedance in a control loop
151
What's the difference between P, PI, and PID electric control systems
P - proportional no algorithm
PI - proportional integral time algorithm
PID - proportional integral derivative time and temperature algorithm
152
What the difference between pump down and solenoid drop
solenoid drop -> everything shutdown at the same time
pump down -> waits for low pressure controller to open
153
another name for allen keys
Hex keys are also known as Allen keys.
154
another name for pump pliers
Another name for pump pliers is slip-joint pliers.
155
bourdon tube
Only bourdon tubes can measure both pressure and vacuum
156
How much microns of vacuum should refrigeration systems be at
500 or below microns
157
What angle do flaring tools flare at
45°
158
What tank size do we normally use for acetylene
B tank
159
From what pressure does acetylene regulators reduce them to what pressure
250psi to 15psi
160
What colour is the oxygen hose
Green
161
What is brass composed of?
Copper and zinc
162
What is a street coupling
A copper fitting with on side flared
163
What can be used in compression fittings instead of flaring
Ferrule
164
What are the 2 common black pipe sizes
Sched 40 and sched 80
165
What temps r considered soft soldering and brazing?
Solf soldering: <800°F
Brazing: >800°F
166
Is steel a ferrous material
Yes
167
Is brass a ferrous material
No
168
Cast iron is very porous and brittle?
TRUE
169
Aluminum is a ferrous material
No
170
What is brass composed of
Copper and zinc
171
What is Teflon
A plastic polymer. Can be used for thread sealing.
172
What is white, yellow, and pink Teflon tape used for?
Plumbing, natural gas, and refrigerant
173
How do you grade bolts with the lines on the bolts
Lines + 2 = grade
174
What are these
Set screws
175
How many stages are recommended for torquing procedures
3
176
At what pressure is gas regulated at at the service regulator at the house meter?
7" to 14"WC
177
1 psi = __ “WC
1 psi = 28"WC
178
Adsorption
Water vapour is removed by passing through granular solids that attract water.
179
Absorption
Water vapour is removed by bubbling the natural gas through a liquid desiccant often a glycol solution. The desiccant absorbs the water
180
How many BTUs can gas fitter Bs work on
Up to 400k BTUs
181
input rating
The heat produced in BTU/hr per unit of fuel burned.
182
1 gallon
10 lbs of water
183
propane boiling point
-44°F
184
methane boiling point
-258°F
185
How many times does propane expand compared to its original size when changing from liquid to gas?
270x
186
specific gravity of propane
1.5
187
specific gravity of methane
0.6
188
calorific value
The quantity of heat per unit mass obtained. BTU/gallon
189
BTU per cu ft for propane
2500Btu/cuft
190
BTU per cu ft for methane
1000Btu/cuft
191
Ignition temperature of methane
1200°F
192
Ignition temperature of propane
950°F
193
Maximum flame temperature of methane
3350°F
194
Maximum flame temperature of propane
3500°F
195
Flame speed of methane
26"/s
196
Flame speed of propane
32"/s
197
Range of Flammability
The percentage of gas present in a gas/air mix between the upper an lower limits that will burn
198
Flame speed
the measured rate of expansion of the flame front in a combustion reaction.
199
combustion air required for methane
10cuft
200
combustion air required for propane
24cuft
201
Gas pressure test for finish piping
10min, working pressure test
202
Gas pressure at finish piping
3-4"WC
203
Propane pressure after low pressure regulator
11” - 14” WC
204
Why does lowering the pressure lower the boiling point
Lowering the pressure reduces the boiling point because it decreases the force holding the liquid molecules together, making it easier for them to escape as vapor.
205
atmospheric pressure in psiA and kpaA
atmospheric pressure: 14.7 psi and 101.3 kpaA
206
absolute zero in Celsius and Fahrenheit
Absolute zero: -273°C and -460°F
207
How much excess air do you generally need for a complete combustion?
40%
208
Boyle’s law
Increase in pressure = decrease in volume
Temp is constant
209
Charles’ first law
Increase in temp = increase in pressure
Volume is constant
210
Charles second law
Increase in temp = increase in volume
Pressure is constant
211
What are slinger rings
Slings condensate onto the condenser which increases heat transfer of the condenser
212
What are swamp coolers
Also called evaporative coolers that are most often used with exhaust systems (restaurants). Feeds water to a media that sends moist water as cooling.
213
What are terminal units
Heat exchangers that receives are from the central air handling unit.
214
What are makeup airs
Exchanges indoor air
215
Direct-fired vs indirect-fired makeup air
Direct-fired: exposed flame that adds heat.
Indirect-fired: has heat exchanger.
Both need running exhaust systems
216
What are the 2 types of fans
Centrifugal (blowers, squirrel cages) and propellers
217
For blowers, air enters at a _ degree to the fan
90 degree
218
What kind of bearings don't need lubrication
When they are made of an alloy with lead
219
What are axial fans also called
propeller fans
220
Are propeller fans overloading fans
Yes because they push instead of throw/slap air
221
Propeller fans are seated to sit how far out the shroud
1/3 of propeller blade height
222
Examples of light duty and heavy belts
Light duty: 4L, 5L.
Heavy duty: A, B.
223
When the belt starts squeaking, it needs lubrication.
No
224
In a mixing chamber, outdoor air makes up at minimum how much of the total air
10-20%
225
Portable air conditioners do what to moisture in the air
Extract moisture
226
Why do you always close the covers of fan housings
So they don't overload
227
What type of backward inclined fan blade is the most efficient
Curved airfoil
228
Which type of fan blade is good for moving dirty air
Radial fan
229
What color is r717 cylinder
Silver
230
How much ppm differentiates low and high toxicity refrigerants
400ppm
231
What weight must refrigerant cylinders not exceed
300lbs
232
Blended refrigerants are numbered what
Zeotropic: 400s
Azeotropic: 500s
233
Zeotropic refrigerants experiences what
Temperature glide when saturated
234
Do azeotropic refrigerants experience glide?
Yes, but it's negligible
235
Zeotropic vs azeotropic
Zeotropic is a mixture and can be distilled whereas azeotropic cannot
236
What's good practice when charging and evacuating refrigerant
Charge and evacuate as a liquid
237
Montreal Protocol when
1987
238
Hygroscopic
Attracts/retains moisture
239
Floc point
Temperature which waxy stuff comes from the oil
240
How much refrigerant do you need for push pull recovery
20lbs
241
You must report refrigerant leaks over
10kg or 22lbs
242
What can you use for ammonia leaks
Litmus paper or sulphur sticks
243
What should you do to vacuum pumps before every use
Replace oil
244
What's the triple evacuation process
Vacuum -> inert gas (nitrogen) x3
245
POE oil max exposure time to atmosphere
5min
246
TDG
Transportation of Dangerous Goods Act
247
What's an easy indication of a leak of refrigerant in refrigerant system
Oil
248
What are hydronics
Use of water for heating and cooling
249
What's an application specific controller
Controls 1 type of equipment
250
What are the three most common networking protocols
Lontalk, BACnet, Modbus
251
Pneumatic receivers store pressures between what PSIs and has a pressure relief at what PSI
Stored at 60 - 90psi, and reliefs it at 120psi
252
Air dryers cool the air to what temperature
34°F
253
Are zone valves NC or NO for cooling valves
NC. But NO for heating valves
254
Prefered RH
30% - 60%
255
What are VOCs
Volatile organic compounds: toxic carbon based substances. Stuff like bleach and drain cleaners
