Gas (A-book) Flashcards
(158 cards)
1
Q
What are the 2 primary categories of burners?
A
Non-mechanical
Mechanical
2
Q
How are the 2 types of burners distinguished?
A
By how the combusion air is supplied
3
Q
What is a non-mechanical burner?
A
atmospheric burner
relies on natural draft to supply the required combusion air
Less common as they have lowefficiency / more susceptible to flue gas spillage.
4
Q
What do appliances today use to ignite the main burner?
A
The burner is ignited directly by a spark or hot surface igniter
Installer needs to be familiar with the service / troubleshooting procedures
5
Q
What are 3 things a control system of an appliance must do?
A
1) Initiate a safe light-up
2) Supervise the run period
3) Provide a safe shut down
6
Q
What is unique about appliance controls?
A
They are individual components of distinct circuits w/ specific functions
7
Q
What does the Combustion safety circuit include?
A
Thermocouple and safety shut off valve
8
Q
What does the main burner control circuit include?
A
Thermostate, high temperature limit / main gas valve.
9
Q
What are indoor non-vented gas appliances mainly used for?
A
Cooking equipment
Commercial kitchens = large exhaust fans = adequate air exchange
10
Q
What happens if non-vented appliances w/ no vent hood are used for a long time?
A
Contributes to poor air quality
11
Q
True or False: Unvented gas space-heating appliances can be used indoor.
A
False: they cannot
12
Q
How does air exchange work for a direct vent system?
A
Air is taken directly from outside
flue gas is taken directly outdoors
13
Q
What are the 2 piping - options for a direct vent system?
A
Concentric coaxial pipe
twin pipe
14
Q
How does a coaxial vent work?
A
Combustion air + exhaust flor directly through a single connection to appliance.
Hot exhaust exist –> interior tube
Combustion air enters –> outer layer
15
Q
What is a Thermal Trap?
A
Combustion air pot
Prevents loss of heated air when equipment is not firing
16
Q
How do Direct Fire Heaters work?
A
Has exposed flame (like a grill)
Combustion products added to air
17
Q
Can Direct fired heaters be used for places where people sleep?
A
Nope
Combustion products are not well contained…
No homes, hotels or clinic
18
Q
Why must a range not be installed in a bedroom?
A
Because of the possibility or producing carbon monoxide
19
Q
If a range is not used as a space heater can it be installed in a bed-sitting room?
A
Yes
20
Q
What are 5 factors to be considered when installing a gas range?
(CLARS)
A
1) Specific instal requirements -> manufacture’s instructions
2) Leveling the range
3) Anti-tipping devices
4) Restraining device for commercial cooking appliance on wheels
5) Clearance to combustibles.
21
Q
What are 4 specific install requirements for a gas range?
(CAPP)
A
1) Clearnace to combustable requirements (manu. instruc. / rating plate / applicable codes)
2) Access for cleaning, repairs / servicing
3) Proper distance to venting hoods, flues or ductwork
4) Proper positioning
22
Q
What are 4 basic components to an absorption refridgerator?
(GACE)
A
1) Generator (Boiler)
2) Condenser
3) Evaporator
4) Absorber
23
Q
Why arn’t Recessed wall furnaces common for new installations?
A
They are natural draft units –> require special oval (BW vent) configuration designed to fit inside a stud wall
24
Q
What are High-Intensity infrared heaters, burners made with?
A
Porous material like ceramic or metallic screen
25
What is the surface temp of a high-intensity infrared heater?
980 C or 1800 F
This temp helps retain the flame on the surface => increasing radiating efficiency.
26
Are high-intensity units vented or non-vented?
Non-vented => makes usage restricted
27
Where does the combustion occur in Low-intesity infrared heaters? (aka tube heaters)
In tubes or panels
Made of metal or ceramic
28
What type of gas fireplace is avoided in Canadian housing?
Vent-Free gas Fireplace
(is available in the US)
| NOT APPROVED IN CANADA
29
Gas storage water heaters have the option of 4 types of vents to use, what are they?
(NDPP)
1) Natural vent
2) Direct vent
3) Power vent
4) Power direct vent
30
What does FVIR stand for?
Flammable Vapour Ignition-Resistant
31
What are the 5 components of the FVIR burner?
(SR. SUP)
1) Stainless steel flame arrestor plate
2) Resettable thermal cut-off
3) Sight glass
4) Upshot multiport burner
5) Piezo ignitor
32
What does the stainless steel flame arrestor plate actually do?
Provides a one-way path for air to travel through
33
What does a Resettable thermal cut-off do?
It shuts the gas flow to the pilot / burner if flammable vapours enter the combustion chamber / ignite
34
What does a Sight Glass do?
Provides view of the operation of the pilot / burner in the sealed chamber.
35
What does a Piezo ignitor do?
Ignities the pilot burner in the sealed chamber
36
What stage can a furnace be?
1) single stage
2) two-stage
3) multi-stage (modulating) model
| This means that it can be combined w/ heat pump, solar system, AC
37
Condensing boilers are constructed w/ what?
More heat exchanger surfaces
made of stainless steel or aluminum
38
How efficient are condensing boilers?
98% -- very high
conventional boilers = 87%
39
True or False: A pump can move pressurized steam through boiler piping.
True
40
What happens when there is a discrepancy bn manufacture info / codes?
The most stringent requirments shall prevail
| AHJ can provide guidance
41
What happens when there is a discrepancy bn manufacture info / codes?
The most stringent requirments shall prevail
| AHJ can provide guidance
42
What info will be on a rating plate?
(There's 16 points :S)
1) Approvals (regulating authorities / agencies)
2) Input rating
3) Heat output (BTU/h, LPH, LB/h)
4) Approval altitude
5) Gas supply pressure (min/max)
6) Gas manifold pressure (high fire/low fire)
7) Orifice size
8) Temperature rise
9) Static pressure range (forced air furnaces)
10) Max water pressure (boilers / w.h)
11) Max water temp (boilers/ w.h)
12) Min relief valve capactiy (ib/h steam or btu/h)
13) Appliance clearance
14) Operating voltage / current
15) Max overcurrent protection
16) Electric motor HP
| WH = water heater
43
What happens when there's no national standard for a special gas equipment?
Inspection body accredited by Standards Council of Canada is permitted to apply an approval label --> known as a "field approval"
44
What equation do we have to remember?
45 GPH x 8.33 lb/US Gallon x 90 F T= 33,737 BTU/h
45
All installations must conform to requirements of...
applicable building, gas / electrical codes
Part 7 (specific types of appliances) and 4 (general requirements) of CSA B149.1
## Footnote
Look over those parts when installing any gas appliance
46
Why does the Canadian Standards Association (CSA) exist?
To develop standards
47
What does the CSA B149 Gas Code Series provide?
Important guidance on how to do your job as a gasfitter safely
(from handling / storage of NG / propane --> the safe / effective installation of related appliances / equipment)
48
Which crowd does CSA B149.1 target?
Canadian gas / propane industry workers
49
CSA B149.2 Holds what secrets?
The latest advances in industry best preactices / most current safety requirements.
50
CSA B149.3 is Code for..
- For the Field Approval of Fuel-Related Components on Appliances / Equipment
- It provides requirements for:
- fuel -related components / accessories
- assembly on appliances / equipment using gas
51
CSA = across Canada
Each province maintains their own what?
Regulation, licensing / registration of gas in various ways
52
Technical Safety BC put in place for public safety by creating rules in what areas?
(there's 8)
1) NG / propane appliances/ systems
2) Boilers, pressure vessels / refrigeration systems
3) Passenger ropeways --> aerial trams / ski lifts
4) elevating devices --> elevators / escalators
5) electrical equipment / systems
6) Alternative safety approaches
7) Amusement devices
8) Railways
53
Who performs gasfitting work in BC?
Certified gasfitters
54
Who is allowed to pull a gas permit?
Registered gas contractor
55
True of False: Gas installations permits can be pulled after work begins
False: Gas permits must be obtained before any work begins
56
Who is The Safety Standards Appeal Board?
Created by Safety Standards act
Appeal board: can review certain TSBC decisions when clients request a review.
57
The safety Standards act authorizes TSBC to what in the face of non-compliance
take enforcement
58
What products / work regulated are under the Standards act?
1) boilers/ systems
2) Electrical systems / equipment
3) Elevating devices / passenger conveyors
4) Gas system /equipment
5) pressure vessels / piping, refridgeration system/equipment
6) Amusement ride
7) Ski lifts
59
who does the gas safety regulation apply to?
Everyone who installs, alters, maintains or operates gas technologies in BC
60
What are Safety Orders?
They are instruments that are issued to prevent or reduce the risk of person injury or damage to property.
Compliance is mandatory and enforceable by TSBC
61
What is section one about in the gas code?
Scope --> mostly installation
62
What is section 2 of the gas code?
Reference Publicatons --> codes or standards that govern equipment, components methods or materials cited in the code.
63
What is section 3 of the B149.1 about?
Definitions
64
What's included in Section 4 of the gas code?
General --> explains the general application of the gas code
65
What is Section 5 of the gas code?
Pressure Control
66
What does Section 6 of the Gas Code include?
Piping and Tubing systems, Gas Hose / Fittings
67
What is Section 7 of the Gas Code about?
Installation of Specific Types of Appliances
68
What is Section 8 of the Gas Code?
Venting Systems / Air Supply for Appliances
69
What are the 3 requirements for combustion to occur?
1) Fuel
2) Heat
3) Oxygen
70
What are the ignition temps of NG, Propane / Butane?
NG = 1300 F - 700 C
Propane = 920 F - 495 C
Butane = 900 F - 480 C
71
What is produced when hydrocarbons are combined with oxygen to create combustion?
## Footnote
Fire tetrahedron
Carbon Dioxide, Water Vapour, Heat
72
The source of oxygen (for appliances) is air, what components are in air?
Oxygen = 20%
Nitrogen = 79%
Other = 1%
73
What are the 3 types of combustion?
1) Perfect combustion
2) Incomplete Combustion
3) Complete Combustion
74
Why is perfect combustion only theoretical?
Because most gas burners are not capable of mixing the exact gas / air volumes together to produce complete combustion
75
What type of gas is Nitrogen
It is an inert gas.
Remains stable / will not chemically react (as long as temperatures are not too high)
76
What chemical produces soot?
Carbon
77
What does soot indicate (most of the time?)
An idicator of incomplete combustion
(the absence of soot does not = complete combustion)
78
Why is Carbon Monoxide deadly?
Because it is colourless, odourless / tasteless gas
Small quantities inhaled can cause death
79
What are the 3 main categories of Air supply (for gas appliances)?
1) Combustion air (theoretical)
2) Excess air
3) Dilution air
80
What is Primary Air?
The combustion air that is mixed w/ fuel gas before the ignition point
81
For a non-mechanical burner, what is the amount of primary air used?
1/3 of combustion air
82
Is the primary air used in a mechanical burner higher or lower than non-mechanical burners?
Higher
83
Where is second air supplied from and what is it's purpose?
Supplied at the flame
Required to complete combustion
Is the other 2/3 of the combustion air required for perfect combustion
84
To ensure that all fuel is completely burned, what is added?
Excess air
85
How much excess air is needed for mechanical burners to achieve complete combustion?
20 - 30% excess air
86
How much excess air do atmospheric burners require?
50% excess air
87
Modern High-efficient appliances have significant lower flue - gas temp. What does that mean for Draft control devices?
They will not have a draft control device b/c they do not require dilution air.
88
What 2 ways create Draft Movement?
1) Naturally (aka natural draft)
2) Blower (aka mechanical draft)
89
Why must the amount and force of draft be controlled?
For combustion efficiency
90
What happens when a draft is too strong
It will pull too much combustion air = affects the efficiency of the appliance
91
Why are Power Venters used?
They are used to overcome venting problems
(ex: extra-long vents, excessive negatie pressures or improper venting design)
92
Where is the fan or blower located on a Forced-Draft Burner?
Located upstream of combustion zone
93
Under Appliances in the gas code, what are the different Categories?
Category 1: Flue loss = min 17% / negative vent static pressure
Category 2: Flue loss = max 17% / negative vent static pressure
Category 3: Flue loss = min 17% / positive vent static pressure
Category 4: Flue loss = max 17% / positive vent static pressure
| Static pressure = atm pressure inside the duct
93
Under Appliances in the gas code, what are the different Categories?
Category 1: Flue loss = min 17% / negative vent static pressure
Category 2: Flue loss = max 17% / negative vent static pressure
Category 3: Flue loss = min 17% / positive vent static pressure
Category 4: Flue loss = max 17% / positive vent static pressure
| Static pressure = atm pressure inside the duct
94
What is Backdrafting?
The reverse flow of gas in the flues = intrusion of combustion by-products into the living space
95
What is the building envelope?
Is the physical separator bn the conditioned / unconditioned environment
96
Why is the control of air flow important?
to ensure indoor air quality
97
What happens in a Loose Building Envelope?
- allows more natural gas transfer
- building is draftier = uncomfortable / harder to regulate temp
98
What happens if there is a Tight Building Envelope?
- allows a high level of control over air quality, temp. humidity levels / energy consumption
99
What is the main method used to control indoor air quality?
Ventilation --> removes indoor contaminants
100
What is Soil Gas?
the mixture of air, water vapours / pollutants
101
What happens when air enters a dwelling through below grade?
Can increase water vapour content of indoor air / number of pollutants picked up from soil
102
What is a colourless, odourless, radioactive gas?
Radon
103
What is necessary to reduce radon?
a subfloor depressurization system
(a measure required by the BCBC)
| BCBC = BC Building Code
104
Why is Make-up Air required?
To offset air removed by appliances with large exhaust fans
105
What must the building depressurization be at if a building contains any natural draft gas appliances?
5 Pa => eliminates risk of backdrafting
106
Where must outside air intakes be located ?
Away from sources of contminants and shielded from weather
(ex: vehicle exhaust or chemical vapours)
107
What is the fan size / air-flow based on?
the number of bedrooms / floor area of the dwelling
108
What is the most common method of recovering heat energy?
By preheating the ventilation supply air w/ exhaust air using a heat recovery ventilator
109
What are the 2 common methods of gas appliance air supply?
1) Direct-vent system
2) Room air systems (aka non-direct vent)
110
Why must mechanical air supply be properly sized / interlocked w/ appliances?
In order to shut off the gas in the event of air supply failure
111
What does section 8 of B149.1 Gas installation Code regulate?
Details the installation / sizing of passive combustion air supply openings / ducts
112
What is the most common pressure-measuring instrument?
Bourdon tube pressure gauge
113
What do pressure meters, pressure gauges or vacuum gauges have in common?
They are instruments used to measure / display pressure using integral units.
114
What is differential pressure?
the difference bn 2 contained working fluids
115
How many inlet ports do differential pressure guages have?
2
116
What can differential pressure gauges be used to monitor?
- air flow
- amount of filter clogging
- Test equipment operation
117
What is the simplest version on the fluid manometers
U-tube manometer
The tube half full of liquid / both legs open to atm -->level is the same on both sides
118
How is duct air flow measured?
- special tips are inserted into ducting via 9mm drilled holes
- Tips connected to pressure measuring instruments via silicone rubber tubing
119
What is the freezing point of water?
0 C - 32 F
120
What is the boiling point of water?
100 C - 212 F
121
How can there be more accurate readings from thermometers?
Longer the stem length = smaller the graduations can be
122
Dial stem thermometers use what style of temp sensing element in the stem?
Bimetallic
123
How are permanently installed thermometers mounted?
Mounted in a Thermowell (cylindrical fitting) --> closed at one end / mounted in the process stream
124
What does the Thermowell protect?
The sensor from the process fluid
If the sensor fails, it can easily be replaced w/o draining the vessel or piping.
125
True or False: Digital thermometers have better accuracy / larger temp range.
True
126
What type of material is RTD made of and why is it important?
Pure material (platinum)
Has a near linear resistance change w/ temperature
127
What is a thermistor?
Is a resistance sonsor that changes its resistance in a non-linear way.
128
How does the thermistor differ from a RTD?
- Thermistors are more sensitive to small temp changes
- have a quicker response time
129
Which type of thermocouples are used on digital multimeters?
Type K
It has a temp setting in selector dial
Uses conversion formula to convert output voltage level --> temp
130
What is the modern pyrometer?
A device that can determine the temp of a surface from a distance (does not need contact of surface)
131
How do portable dial thermimeters get out of calibration
- from the presence of mechanical linakes
- Being dropped
132
What is the Freezing point method?
- Simplest / most accurate
- fill glass w/ ice and add clean water + stir
- Wait for 3min + insert sensor
133
What is the boiling point method?
Reading should hold steady at 100 C if below 300 m in elevation.
Higher elevations will have lower boiling temps
134
How do you calibrate a dial thermometer?
There's a calibration nut on back on the dail head
Hold nut securely w/ wrench / rotate head until read correctly
Other styles = separate adjustment or reset screw
135
What does distance-to-spot (DS) ratio mean?
Distance (d) icrease = Spot Size (s) --> unit becomes larger
136
How do you get an accurate measurement from a D:S?
Make sure target is larger than unit spot size
Smaller the target = closer thermometer should be
137
How do you get accurate readings if there is a shiny metal surface? (d:s)
Surface measured can be covered w/ electrical tape or flat black paint.
Some intruments have an adjustable emissivity (can be finetuned)
138
What is voltage drop?
The potential difference bn 2 points in an electrical circuit
139
What is an Ammeter used for? (electrical)
to measure current in an electrical circuit
140
How does current work?
It flows through a circuit when a power source is connected to a device or load
141
What is current?
The flow of electrons in a circuit when voltage is applied to the circuit
142
What is current a measure of?
Amperes (A) --> Amp
Milliamperes (mA)
Microamperes (uA)
143
What is required when using a DMM to measure current (amps)?
Requires connecting the meter in series w/ the circuit being tested
(the meter would then be apart of the circuit)
144
What does clamp on current probe accessory do?
measures higher values / safely take current readings w/o opening a circuit.
145
What does the ohmmeter function on a DMM do?
The current flows through the tested circuit's resistance
When set to ohms the DMM must not be on an energiezed circuit
146
What does OL (infinity) indicate on a DMM?
Faulty fuse
147
What should you do before you connect a meter to a circuit?
Ensure that the meter is on the right setting.
When in doubt use high range (will not overload then)
148
AC and DC voltmeters must be connected how?
In parallel with the device or circuit being measured.
149
Voltage measurement page 55
150
What are the 2 common methods of measuring current using DMM
1) in-line ammeter method
2) clamp-on ammeter method
151
AC current uses what method?
Clamp on method
152
Current measurement w/ clamp on page 58
153
Why is it important that while using an ohms meter the circuit must not be live
the battery supplies the current flow that is eventually measured by the meter
154
The display will show what on an ohms meter when the test leads are clipped together?
0 ohms sign
155
What type of sensor does not have to be placed into gas to detect it?
Infrared sensors
Can be used remotely at distances up to 30 meters
156
When there is a propane leak, should you investigate high ground or low ground first? why?
Low locations first.
Propane is heavier than air
157
What would indicate an outside below-grade leak?
If readings are strong but the smell is weak
