Line B ALL Flashcards
(125 cards)
1
Q
Describe the relationship between the % values of CO2 and O2 in the flue gas when you adjust the air shutter on a fan-assist burner during set-up?
A
The greater the amount of excess air, the higher the % of O2 and the lower the % of CO2
2
Q
If three flue samples were taken, the first with 20% excess air, and the second with 32% excess air, and the third with 44% excess air which would contain the higher CO2 reading?
A
The sample with 20% excess air
3
Q
If a natural gas appliance and a propane appliance were firing at the same rate and under the same conditions, which would have the greater air requirements and which would have the greater percentage of CO2 in the flue products?
A
Both have the same air requirements, but propane has higher CO2
4
Q
When performing an analysis of the products of combustion using natural gas, what percentages of carbon dioxide and oxygen you would expect to find if the excess air is set at 30%?
A
8.3% CO2, 5% O2
5
Q
A gas appliance is firing at 5,400 Mbh on propane gas and condensing all water vapor to a liquid state. Calculate the capacity of water produced each hour in US Gallons.
A
38 US Gallons
6
Q
What is the formula for perfect (stoichiometric) combustion?
A
Fuel + O2 + N2 = CO2 + H2O + N2
7
Q
What is the formula for complete combustion?
A
Fuel + O2 + N2 + Excess Air = CO2 + H2O + N2 + Excess Air
8
Q
How does tertiary air control NOx emissions?
A
It slightly cools the flame
9
Q
What can be done to control NOX emissions from a burner?
A
Inject steam around the flame
10
Q
What can be used to control the combustion air for a burner system?
A
A Variable Frequency Drive or Electronically Commutated Motor
11
Q
List three factors that can create CO in the products of combustion?
A
Running too much fuel, not enough combustion air or a failing draft inducer
12
Q
What is the maximum air-free CO level allowed to be produced during combustion?
A
400 ppm
13
Q
How many pounds of CO2 are produced per hour from a 54,784,000 BTUH fuel oil fired boiler?
A
8765 lbs
14
Q
How many pounds of CO2 are produced per hour from a 7,312,000 BTUH natural gas fired boiler?
A
856 lbs
15
Q
According to legislation, how much ppm sulfur content does heating oil need to be below?
A
500 ppm
16
Q
What chemical compounds from combustion are collectively called SOX?
A
SO2 & SO3
17
Q
What are two results when NO2 reacts with other pollutants?
A
Ozone and Acid Rain
18
Q
What chemical compounds from combustion are collectively called NOX?
A
NO & NO2
19
Q
What would be the calculated theoretical draft developed by a stack 55 feet in height with an average temperature of 310°F, and the ambient temperature is 70°F?
A
0.246” w.c.
20
Q
A boiler is firing natural gas at 4,000 Mbh with 30% excess air. What would be the calculated the volume in cubic feet per minute of flue gases leaving the flue outlet if the temperature is 450°F, and the outside air temperature is 70°F?
A
1603 cfm
21
Q
A natural gas boiler is firing at 3 million Btu/h with 40% excess air. The ambient air temperature is 66°F and the stack temperature is 410°F. What would be the calculated velocity of the flue gas if the boiler is equipped with a 16-inch diameter stack?
A
889 fpm
22
Q
If a stack has a velocity of 1000 fpm, what would be the calculated draft produced?
A
0.06 w.c.
23
Q
A boiler equipped with a power burner is firing at 11 million Btu/h with 35% excess air. The combustion air duct is sized to meet the Gas Code requirements. What would be the calculated velocity through the combustion air duct if the boiler is operating at full input, the ambient air temperature is 70°F, and the stack temperature is 460°F?
A
972 fpm
24
Q
You are called on to commission an installation of a 4,750,000 Btu/h natural gas boiler.
- Excess air set at 30%
- Stack diameter 18 inch
- Combustion chamber and heat exchanger pass volume 188 ft3
- Gross stack temperature 485 deg. F
- Ambient temperature 76 deg. F
Based on this information what is the expected draft in the stack?
A
0.0762” w.c.
25
What factors would achieve the highest draft in a chimney?
Tall chimney, hot combustion products, hot ambient (outside) air
26
A mechanical draft produced by a device upstream from the combustion zone of an appliance is a definition of what type of draft?
Forced draft
27
A mechanical draft produced by a device downstream from the combustion zone of an appliance is the definition of what type of draft?
Induced draft
28
What reading would the draft pressure gauge indicate when measuring in the combustion chamber of a gas fired appliance using a force draft burner?
Positive pressure
29
What reading would the draft pressure gauge indicate when measuring in the combustion chamber of a gas fired appliance using a fan-assisted burner?
Non-positive pressure (Negative over-fire pressure)
30
What does a balanced draft system incorporate?
A forced draft burner and an induced draft fan
31
What type of draft control does a gas-fired appliance incorporate when using a forced draft burner?
Internal damper
32
Why is the draft reduced when using flue gas recirculation to control NOx?
Lower flame temperatures
33
Why is the draft reduced when using a scrubber (air pre-heater)?
Heat is removed from the flue gases
34
Calculate Draft Loss
Referring to the figure below, to maintain a draft of 0.08” w.c. at E what will the draft pressure need to be across the damper B?
The draft at A should be 0.6’ w.c. and the draft losses through the appliance are as follows:
- C = 0.12” w.c.
- D = 0.11” w.c.
- Elbow = 0.05” w.c. each
Across damper B = 0.19 “w.c.
- calculation: 0.6 – (0.08 + 0.12 + 0.11 + 0.10) = 0.19
35
What is the primary concern with ICI hydronic system design?
Protection of the equipment
36
What are two major concerns for the boiler in an ICI hydronic system installation?
Thermal shock and condensing combustion products
37
What is the typical system design temperature difference for a non-condensing ICI boiler?
20°F
38
What is the standard system design temperatures for a non-condensing ICI hydronic boiler?
180°F supply, 160°F return
39
What type of boiler is best suited to handle the thermal shock?
Flex tube
40
What minimum return water temperature must be maintained to avoid condensing of combustion products?
140°F
41
On an ICI hydronic heating system, what is the best location to install an air separator?
Immediately after the boiler supply outlet.
42
Why is it recommended to install the boiler outlet, air separator and expansion tank on the suction side of the system circulator pump?
To decrease air entry into the system piping and prevent imposing system head on the boiler supply.
43
Where is it recommended the system feed water be connected?
Into the air vent piping on the air separator
44
What is the purpose of a hydraulic de-coupler?
To isolate the source pump(s) from the load pump(s)
45
Which type of boiler installation will a stack economizer be most effective?
High pressure water-tube steam boiler
46
What is the purpose of a steam trap?
To hold steam upstream while allowing condensate to pass.
47
What device controls the water level in a steam boiler?
Low water cut-off
48
What is the sparge tube used for?
Preheating feed water
49
What is done to remove dissolved oxygen from boiler feed water?
Heat the feed water
50
What is the major concern with steam systems?
Water chemistry
51
What is installed to remove dissolved gasses by mechanical means from the boiler feed water?
Deaerator
52
What is the main advantage of installing a deaerator?
Reduces feed water chemical treatment costs
53
What is the advantage of a thermal fluid heating system?
High fluid temperatures without high pressure
54
To protect against a low water condition how many fuel cutoff devices are required on an automatically fired steam boiler?
2
55
Why would a thermal fluid system be used instead of a water boiler?
Thermal fluid systems are used when higher temperatures are required than can be generated by water and without the added expense of a steam system
56
In relation to steam system what is the pressure of a thermal fluid system?
They have a lower pressure than steam systems
57
How high a temperature could thermal fluid operate at?
750°F
58
Why can we not use typical hydronic circulators in a thermal fluid system?
They are not rated for the high temperatures
59
What must be done when initially firing a thermal fluid system to remove the air?
Slowly raising the temperature of the fluid so the air can be vented off and the moisture driven out.
60
List some of the uses for thermal fluid systems?
Baths, kettles, rolls, reactors, steam/hot water generators, storage tanks, pressure moulds, fryers, ovens
61
Referring to Figure 1, What is this is the ASME symbol for?
Power boiler safety valve
62
Referring to Figure 2, What is this is the ASME symbol for?
Heating boiler relief valve
63
Referring to Figure 3, What is this is the ASME symbol for?
Unfired pressure vessel safety valve
64
Referring to Figure 4, What is this is the ASME symbol for?
Unfired pressure vessel rupture disc
65
Who can repair and set pressure relief devices?
Organizations authorized by the regulatory authority
66
What three things must be done to a safety valve to show it has been reserviced by an authorized service organization?
a. Affix a dated service nameplate to the reclosing pressure relief device
b. Use a uniquely embossed seal to seal all adjustable parts
c. Ensure the manufacturer’s nameplate remains on the relief device
67
What is the recommended time interval for a pressure relief device to be tested?
12 months
68
What is the recommended time interval for a pressure relief device to be serviced?
3 to 5 years
69
What type of opening characteristics does a Safety Valve have?
Pop opening from pressure
70
What type of opening characteristics does a Relief Valve have?
Gradual opening from pressure
71
Where is the Rupture Disk commonly installed on a boiler?
Upstream in series with a relief valve
72
The set point on a safety valve can be greater than the Maximum Operating Working Pressure (MAWP) of the vessel or piping.
TRUE / FALSE
FALSE
73
Referring to Figure 5, What type of vessel would you find this mechanical safety valve on?
High pressure steam boiler
74
Referring to Figure 6, What type of vessel would you find this mechanical safety valve on?
Unfired steam vessel
75
A 150 Psig 8,000 MBH boiler has a safety valve with a relief capacity of 8,350 lbs/hr. Can this safety valve safely relieve the boiler?
8000000/970 = 8274Lbs YES
76
What is the minimum relief capacity of a safety valve (in lbs/h) installed on a 150 Psig, 4,600 MBH steam boiler with an efficiency of 82%?
4600X33475/970 3888 lbs/h
77
What is the minimum relief capacity of a safety valve (in lbs/h) installed on a 150 Psig, 400 Horse Power steam boiler with an efficiency of 79%?
400bhpX33475btu/970btu/lb 13,801-4 lbs/h
78
A 150 Psig, 500 HP, 82% efficient steam boiler has two safety valves, one with a relief capacity of 6,576 lbs/hr and the other at 6,303 lbs/hr. Do the combined relief valves have enough capacity to relieve this boiler safely?
NO 500bhpX33475btu/970 btu per lbs = 17255 6576+6303=12879
79
A safety relief valve inlet can be smaller than the boiler outlet it serves.
TRUE / FLASE
True
80
The piping connected to the outlet of a relief valve can be reduced by what size?
The size cannot be reduced
81
On a steam system, the safety valve must be installed in what orientation?
Vertically
82
All attached discharge piping for a steam safety valve must be supported___________.
Independently supported
83
What is best practice when the relief discharge piping from a safety valve is installed vertically to outdoors?
Install a drip pan elbow to allow moisture to drain away form the valve
84
How many inches should the center-to-center distance from the drip pan elbow to the safety valve not exceed?
24 inches
85
Referring to Figure 7, the slash in the discharge pipe should be cut at what angle?
45 degrees
86
Referring to Figure 8, if the safety valve is 3 Inches in size, what must the bet he minimum size of the drain-open to waste pipe be?
3/8 inch
87
What is the set relief pressure for a propane tank installed on a premise?
250 psi
88
What is the set relief pressure for a propane tank installed on a vehicle?
312 psi
89
What is the set relief pressure for a propane cylinder?
375 psi
90
Where is the primary relief valve installed for a vehicle’s LNG tank?
To the top fill line
91
Where is the secondary relief valve installed for a vehicle’s LNG tank?
To the vapour withdrawal line
92
What is the primary relief valve discharge setting set to for a vehicle’s LNG tank?
Set at the MAWP of the tank
93
What is the secondary relief valve discharge setting set to for a vehicle’s LNG tank?
1.5 times the MAWP of the tank
94
Referring to the figure below, what must be done to the discharge of this relief valve?
Nothing
95
Which code regulates the installation and testing of safety relief valves?
ASME Boiler and Pressure Vessel code
96
What is the maximum servicing interval for a pressure relief device installed on a 50 psig steam boiler?
Every five years
97
How often should a lift test be performed for a pressure relief device installed on a 50 psig steam boiler?
Annually
98
What is the maximum servicing interval for a pressure relief device installed on a 12 psig steam boiler?
Every five years
99
How often should a lift test be performed for a pressure relief device installed on a 12 psig steam boiler?
Annually
100
How often should a lift test be performed for a pressure relief device installed on a 150 psig hot water heating boiler?
Every two years
101
What fluid should a pressure relief device that has been serviced and installed on a steam boiler be tested on?
Steam
102
What fluid should a pressure relief device that has been serviced and installed on a hot water heating boiler be tested on?
a. Air
b. Steam
c. Water
103
When performing a lift test for a safety valve installed on a low-pressure steam boiler, at what percent must the pressure be under the device disk prior to lifting the test lever?
At least 75% of the Device set pressure
104
When dealing with the combustion of hydro carbon gases, why is stoichiometric combustion of fuel and air not a viable option for most burners?
1) This will produce an unacceptable luminous flame
2) Burners are not capable of perfectly mixing air and fuel
3) This type of combustion produces unacceptable flue gas components
4) Stoichiometric combustion is unstable and unsuitable for heating applications
2) Burners are not capable of perfectly mixing air and fuel
105
It is important to add excess air to the combustion chamber to:
1) Provide cooling for the heat exchanger
2) To ensure perfect combustion occurs
3) To provide an adequate amount of dilution air
4) To ensure complete combustion occurs
4) To ensure complete combustion occurs
106
Which of the air to fuel ratios shown below is for natural gas?
1) 20 ft3 to 1 ft3
2) 20 ft3 to 100 Btu’s
3) 10 ft3 to 1000 Btu’s
4) 2 ft3 to 100 Btu’s
3) 10 ft3 to 1000 Btu’s
107
Why do air requirements differ for appliances with and without draft control?
1) All units require air to be supplied at a ratio of 30:1
2) Units with draft control require more combustion air
3) Units with no draft control require more excess air
4) Units with draft control require dilution air
4) Units with draft control require dilution air
108
In theory, which gas appliance will require more air per hour to operate?
1) 1000 MBH appliance with a draft hood and atmospheric burner
2) 500 kW appliance operating on 50% excess air and no draft control device
3) 1000 MBH power burner using 30% excess air and a barometric damper
4) 2200 MBH power burner using 25% excess air and no draft control
1) 1000 MBH appliance with a draft hood and atmospheric burner
109
At what point on the venting system should an analysis of the flue products be taken?
1) Downstream of the draft control device
2) Downstream of the flue collar
3) Upstream of the draft control device
4) Upstream of the fan assist burner
3) Upstream of the draft control device
110
If a natural gas appliance and a propane appliance were firing at the same rate and under the same conditions, which would have the greater air requirements and which would have the greater % of CO2 in the flue products?
1) Natural gas has higher air requirements and lower CO2
2) Propane has higher air requirements and higher CO2
3) Both have the same air requirements but natural gas has a higher CO2
4) Both have the same air requirements but propane has a higher CO2
4) Both have the same air requirements but propane has a higher CO2
111
How much excess air is added to the combustion process in order to achieve the ultimate percentage of CO2?
1) 1/3 the volume of combustion air
2) 2/3 the volume of combustion air
3) 50% of combustion air
4) None is required
4) None is required
112
What percentage of excess air will produce equal percentages of O2 and CO2 in the flue products?
1) 25%
2) 33%
3) 50%
4) 100%
3) 50%
113
Analyzing the flue products after servicing a burner shows acceptable levels of CO2 and O2 but unacceptable levels of CO. What type of circumstances could cause this to happen?
1) Lack of combustion air
2) Lack of excess air
3) Excessive dirt on fan blades
4) Poor mixing ability of burner system
4) Poor mixing ability of burner system
114
If a gas hot water tank was 100% efficient, what would the temperature of the flue products be?
1) Same as ambient
2) 100°F above ambient temperature
3) 100°F below ambient temperature
4) Minimum 127°F to maintain draft
1) Same as ambient
115
A gas appliance is firing at 1000 Mbh on natural gas. Calculate the volume of CO2
produced each hour.
1) 100 CFH
2) 1000 CFH
3) 2000 CFH
4) 10000CFH
2) 1000 CFH
116
A gas appliance is firing at 3000 Mbh on propane. Calculate the volume of CO2 produced each hour.
1) 1200 CFH
2) 3000 CFH
3) 3600 CFH
4) 4800 CFH
3) 3600 CFH
117
A gas appliance is firing at 5000 Mbh on propane gas and condensing all water vapour to a liquid state. Calculate the volume of water produced each hour (note: the expansion ratio for water from liquid to vapour is 1700:1).
1) 30 imperial gallons
2) 60 imperial gallons
3) 90 imperial gallons
4) 120 imperial gallons
1) 30 imperial gallons
118
The theoretical perfect combustion of natural gas requires an air/gas ratio of:
1) 10:1
2) 15:1
3) 25:1
4) 30:1
1) 10:1
119
The complete combustion of propane in air (include 50% excess air) requires an air/gas ratio of:
1) 10:1
2) 15:1
3) 25:1
4) 37:1
4) 37:1
120
A furnace operating at the rated input on propane is converted to natural gas. The total air requirements for the furnace will:
1) Increase by 5%
2) Increase by 10%
3) Decrease by 15%
4) Remain the same
4) Remain the same
121
The ultimate percentage of CO2 in the flue products of natural gas is:
1) 8%
2) 12%
3) 15%
4) 20%
2) 12%
122
Some flue gas analyzers can test for combustibles. Which of the following could not be detected?
1) Carbon
2) Hydrogen
3) Carbon monoxide
4) Carbon dioxide
4) Carbon dioxide
123
The difference between the flue stack temperature and the room temperature is called the:
1) Net stack temperature
2) Ambient temperature
3) Gross stack temperature
4) Critical temperature
1) Net stack temperature
124
A fan assist burner operating at its rated input is producing flue gas with 8.6% CO2. In order to increase the CO2 level you must:
1) Increase the air supply
2) Decrease the air supply
3) Increase the fuel supply
4) Decrease the fuel supply
2) Decrease the air supply
125
A fan assist burner operating at its rated input is producing flue gas with 10% oxygen content. The efficiency of the appliance could be increased by:
1) Increasing the air supply
2) Decreasing the air supply
3) Decreasing the CO2 content
4) Decreasing the fuel supply
2) Decreasing the air supply
