Level 1 All Flashcards
State the chemical abbreviations for propane and natural gas.
Propane: C3H8, Natural Gas: CH4
State the ignition temperatures of propane and natural gas.
Propane: 920o to 1020oF, Natural Gas: 1100o to 1300oF
List the specific gravities for natural gas, propane vapour, and liquid propane.
Natural Gas: 0.6, Propane vapour: 1.5, Propane liquid: 0.51
What are the limits of flammability for natural gas and propane?
Natural Gas: 4 to 14%, Propane: 2.4 to 9.5%
What are the maximum flame temperatures that can be achieved with propane and with natural gas when mixed with air?
CH4:3500oF, C3H8: 3600oF
What are the boiling temperatures of propane and natural gas at sea level?
Propane: -44oF, Natural Gas: -258oF
What are the flame speeds of natural gas and propane?
25”/sec., 32”/sec. (tube method)
Define the term Btu.
British thermal unit. The amount of energy acquired or liberated when changing the temperature of 1 lb. of water 1oF
What is the energy content of 1 cubic foot of propane and 1 cubic foot of natural gas?
C3H8:2500 Btu/ft3, CH4:1000 Btu/ft3
List the products of complete combustion of natural gas and propane.
CO2 + H2O + N2
What are the expansion ratios from liquid to vapour for natural gas and propane?
CH4: 1:600, C3H8: 1:270
What are the percentages of nitrogen and oxygen found in air?
O2 = 20%, N2 = 80%
What is the air/gas ratio required to achieve complete combustion of natural gas and propane?
CH4: 10:1, C3H8: 25:1
What is the ratio of air to Btu content required to complete combustion of all hydrocarbon gases?
10ft3/1000Btu
How many Btu equal one kilowatt?
3413 Btu/Kw
Explain the term primary air, with reference to an atmospheric burner.
The air entrained and mixed prior to combustion
What is the term used to describe the additional air supplied to the combustion chamber of a gas appliance to ensure complete combustion?
Excess Air
What is the purpose of dilution air?
To reduce the velocity of the flue gasses
A gas appliance is considered to be high input when it exceeds what input?
400,000 Btu/hr., aka. 400MBH
What are the pressure limitations of a Class “B” license?
No pressure limitations however Safety Standards Act is limited to 700Kpa (100Psi)
pipe sizing
If the calorific value of a cubic meter of gas was 37,000 Btu.
What would the Btu content be per cu. ft?
What would the kW content be per cu. meter?
What would the kW content be per cu. ft?
Calculate the correction factor required when converting gas at 40 degrees F. to standard gas temperature conditions.
Calculate the correction factor required when converting gas under a pressure of
134.5 kPa absolute to standard gas pressure conditions.
100 cubic meters of gas is pressurized at 50 psig. Calculate the new volume if the gas is released to atmosphere at sea level.
a
A gas at sea level is contained under a pressure of 60 psig at 50 degrees F. Calculate the new pressure if the temperature is increased to 90 degrees F. Answer in psig.
Calculate the flow rate in Btuh and kW
Service pressure 60 psig
Inlet pressure to meter 5 psig
Manifold pressure 7” w.c
Test dial 5 Cu. Ft.
Time of 1 Revolution 1.5 Min.
Calorific Value of gas 1000 Btu/Cu. Ft.
Calculate the input under the following conditions.
Service pressure 50 psig
House line pressure 10 psig
Meter pressure 10 psig
Test dial 5 Cu. Ft.
1 Revolution 30 seconds
Ambient air temperature 700 F.
Gas temperature 500 F.
Local atmospheric pressure 14.73 psia.
Calorific value of gas 1000 Btu/Cu. Ft.
Calculate the time for 1 revolution of a 2 Cu. Ft. test dial.
Input 1,575,000 Btu/hr
Local atmospheric pressure 14.25 psia
Ambient air temperature 450 F.
Gas temperature 500 F.
Calorific value of gas 1050 Btu/Cu. Ft.
Meter pressure 10 psig
Three appliances are firing at 75,000 Btu/hr each; the time for 1 revolution of a 2 Cu. Ft. Test dial is 32 seconds when all of the appliances are operating. Is the total input correct? (Meter pressure is 7” WC.)
A 4th appliance is added, rated at 27 kW. The time for 1 revolution is now 24 seconds. Is the input correct? Is it over fired or under fired?
The clocked input of an appliance is 2,000,000 Btuh. The test dial is 5 Cu. Ft. The local atmospheric pressure is 13.9 psia and the gas temperature is 200 F.
How many seconds will it take to complete 1 revolution of the test dial?
Calorific value of gas 1000 BTU/CF
Meter pressure is 20 psig
Calculate the input
Meter pressure 34 kpa
Local atmospheric pressure 97.3 kpa
Gas temperature 3 degrees C.
Test dial 0.5 Cubic Meters
Time for one revolution 31 seconds
Calorific value of gas 10.35 KW/Cu. M
When dealing with the combustion of hydrocarbon gases why is stoichiometric combustion of fuel and air not a viable option for most burners?
This will produce an unacceptable luminous flame
Burners are not capable of perfectly mixing air and fuel
This type of combustion produces unacceptable flue gas components
Stoichiometric combustion is unstable and unsuitable for heating applications
Burners are not capable of perfectly mixing air and fuel
Why is it important to add excess air to the combustion chamber?
To provide cooling for the heat exchanger
To ensure that perfect combustion occurs
To provide an adequate amount of dilution air
To ensure complete combustion occurs
To ensure complete combustion occurs
What is the ideal combustion ratio air-to-fuel ratio for natural gas?
20 ft3 to 1 ft3
25 ft3 to 1000 Btu
10 ft3 to 1000 Btu
2 ft3 to 100 Btu
10 ft3 to 1000 Btu
What is a colourless, odourless, tasteless, and potentially lethal by-product of incomplete combustion?
Oxygen
Carbon monoxide
Nitrogen
Aldehydes
Carbon monoxide
What is a colourless, acrid smelling toxic by-product of incomplete combustion?
Oxygen
Carbon monoxide
Nitrogen
Aldehydes
Aldehydes
What can be another cause of incomplete combustion other than insufficient air?
Flame temperature dropping below 1,200°F
Poor fuel to heat exchanger ratio
Combustion chamber too large
Too much humidity in the air
Flame temperature dropping below 1,200°F
At what point on the venting system should an analysis of the flue products be taken?
downstream of the draft control device
downstream of the flue collar
upstream of the draft control device
upstream of the fan assist burner
upstream of the draft control device
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?
Natural gas has higher air requirements and lower CO2
Propane has higher air requirements and higher CO2
Both have the same air requirements, but natural gas has higher CO2
Both have the same air requirements, but propane has higher CO2
Both have the same air requirements, but propane has higher CO2
How much excess air is added to the combustion process to achieve the ultimate percentage of CO2?
1/3 volume of combustion air
2/3 volume of combustion air
50% of combustion air
none is required
none is required
What percentage of excess air will produce equal percentages of O2 and CO2 in the flue products?
25%
33%
50%
100%
0.5
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?
lack of combustion air
lack of excess air
excessive dirt on fan blades
cracked heat exchanger
cracked heat exchanger
If a gas hot water tank was 100% efficient, what would the temperature of the flue products be?
same as ambient
100°F above ambient temperature
100°F below ambient temperature
minimum 127°F to maintain draft
same as ambient
A gas appliance is firing at 1000 Mbh on natural gas. Calculate the volume of CO2 produced each hour.
100 ft3
1,000 ft3
2,000 ft3
10,000 ft3
1,000 ft3
A gas appliance is firing at 3,000 Mbh on propane. Calculate the volume of CO2 produced each hour.
1,200 ft3
3,000 ft3
3,600 ft3
4,800 ft3
3,600 ft3
A gas appliance is firing at 5,000 Mbh on propane gas and condensing all water vapor to a liquid state. Calculate the volume of water produced each hour (expansion ratio vapor to liquid is 1700:1).
30 Imperial gallons
60 Imperial gallons
90 Imperial gallons
120 Imperial gallons
30 Imperial gallons
If a 2,350 Mbh forced draft burner was firing on natural gas with 23% excess air, what would be the expected percent of O2 when taking a combustion analysis?
2.3%
3.5%
4.1 %
5%
0.040999999999999995
If a 2,350 Mbh forced draft burner was firing on natural gas with 23% excess air, what would be the expected percent of CO2 when taking a combustion analysis?
8.85 %
9.2%
10.4 %
13%
0.0885
What is absolute zero equal to in:
Degrees F?
Degrees C?
Degrees F: -460 F, Degrees C: -273 F
Convert 30 degrees Fahrenheit to Celsius
30 – 32 / 1.8 = -1.1 C
Convert 30 degrees Celsius to Fahrenheit
30 X 1.8 + 32 = 86 F
Define sensible heat
Heat that can be measured
Define latent heat
Heat energy required or liberated during a change of state
State the number of BTU’s required to change 1 lb. of 32oF ice to 32oF water.
144 BTU
State the number of BTU’s required to change 1 lb. of 212oF water to 212oF steam
970.4 BTU
State the specific heat of water
1
State the specific heat of steam
0.48 (ice: 0.53)
What is the formula to find the efficiency of a gas fired appliance?
Output/Input
Why do air requirements differ for appliances with and without draft control?
All units require air to be supplied at a ratio of 30:1
Units with draft control require more combustion air
Units with no draft control require more excess air
Units with draft control require dilution air
Units with draft control require dilution air
In theory, which gas appliance will require more air per hour to operate?
1000 Mbh appliance with a draft hood and atmospheric burner
500 kW appliance operating on 50% excess air and no draft control device
1000 Mbh power burner using 30% excess air and a barometric damper
2200 Mbh power burner using 25% excess air and no draft control
1000 Mbh appliance with a draft hood and atmospheric burner
An atmospheric gas appliance has an input of 350 Mbh and is equipped with a draft hood. It is to be installed in a building that complies with code clause 8.2.1. A or B. What size duct is required to provide air to this appliance?
6 inch
7 inch
8 inch
9 inch
8 inch
A furnace room complies with code clause 8.2.1. (a) or (b). It contains a 200 Mbh furnace without draft control and a 100 Mbh hot water heater with a draft hood. Size the combustion air duct based on a length of 30’.
6 inch
7 inch
8 inch
9 inch
7 Inch
A boiler room contains the following five pieces of equipment:
one 2500 Mbh boiler with draft control
two 350 Mbh hot water heaters with draft hoods
two 650 Mbh duct heaters without draft control.
Calculate the required free area of the combustion air duct.
43 in2
300 in2
321 in2
343 in2
343 in2
The following gas appliances are installed in a mechanical room:
one 1200 Mbh steam boiler with a barometric damper
one 350 Mbh hot water heater with draft hood
two 500 Mbh direct fired make-up air units
Select a grill for the combustion air opening in the boiler room wall that will meet the minimum requirements of the B149.1 gas code (grills rated at 60% free area).
10” ´ 12”
10” ´ 14”
15” ´ 20”
20” ´ 20”
15” ´ 20”
The air supply to a 30,000 Mbh boiler, using a force draft burner, is provided by mechanical means through a horizontal duct 42 feet in length. What is the quantity of air required to be supplied to the boiler?
1 ft3 for each 1,000 Btu/h
10 ft3 for each 1,000 Btu/h
15 ft3 for each 1,000 Btu/h
30 ft3 for each 1,000 Btu/h
30 ft3 for each 1,000 Btu/h
What is the main reason for performing combustion analysis on gas fired equipment?
To ensure the equipment is operating in a safe and efficient manner.
How often should your combustion analyser be calibrated to ensure accurate test readings?
Once per year.
Where should the sampling probe take a sample from on a gas fired appliance?
Upstream of any draft control device or just downstream of a stack economizer.
What is the correct way to allow combustion analysis samples to be taken with plastic S636 systems?
Installing an access tee with a ½” tapped bushing as close as possible to the flue collar of the appliance where either a plastic or brass plug can be inserted.
What is a Peltier cooler used for in a combustion analyzer?
To drive out moisture from the sample
The gas cells in a combustion analyser are of what type?
Electrochemical
What can shorten the life span of the toxic sensors in a combustion analyser?
High gas concentrations or insufficient purging
What is the chemical formula for the Perfect combustion of Natural Gas?
1CO2 + 2H2O = 8N2
What is the chemical formula for the Perfect combustion of Propane?
3C02 + 4H2O = 20N2
What is added to the combustion process to produce Complete combustion?
Excess Air
What is the expected percentage range of O2 produced by a forced draft burner with CH4 as the fuel?
3% - 6%
What are four characteristics of Carbon Monoxide?
Toxic, colourless, odourless and tasteless
What can cause too much draft in a venting system?
High stack temperatures
What percentage gain in efficiency is achieved by lowering stack temperature by 45⁰F?
Less than 1%
Calculate the net stack temperature if the ambient temperature is 72⁰F and the stack temperature is 420⁰F? Is this temperature within typically expected values?
348⁰F, Yes (330 - 500⁰F)
If the measure percent O2 reading is 4.1% and the measured NOx reading is 55 ppm, what would the NOx ppm be when corrected to standard?
58.58 ppm
If the measured CO reading is 38 ppm, and the measured %O2 reading is 4.2% what would the calculated air-free ppm reading be?
47.56 ppm
What is the power end of the Honeywell, Series 90 Modutrol used for?
It is used to drive linkages
What is the auxiliary end of the Honeywell, Series 90 Modutrol used for?
It is used to devices like auxiliary switches
In what orientation should motors with crankshafts be installed?
Horizontal
How is strain avoided on the motor and linkage of a fuel/air system?
The drive lever rotational start point is kept off of the shaft centerline
Fixed Stroke Actuators are available in what two opening ranges?
90⁰ or 160⁰
Adjustable stroke model actuators can be field adjusted between what range?
90⁰ - 160⁰
What controls the speed and the amount of rotation of the driven lever pivot point?
It is controlled by the starting position of both levers and the connection distance of the linkage to the lever pivot points
Placing the drive lever closer to the shaft centerline than the driven lever is placed will do what to the rotation of the driven lever?
It will be reduced
Placing the driven lever closer to the shaft centerline than the driver lever is placed will do what to the rotation of the driven lever?
It will be increased
How are precise changes made on the linkage for a fuel valve?
By adjusting the cam spring
The gas butterfly valve is used to control modulation and to stop gas flow?
TRUE / FALSE
FALSE, It is not used to stop gas flow
How can high and low fire be adjusted on a gas butterfly valve?
By using the stop screws
Where would you find information for making initial set up adjustments to linkages?
From the equipment manufacturer
What must be done while making any adjustments to linkages?
Combustion analysis must be performed
How do we balance safety and efficiency when adjusting our linkages with the use of a combustion analyzer?
- Adding more oxygen reduces the chance of CO and increases safety
- Reducing oxygen increases our efficiency but has the potential to increase CO thus being less safe.
- Always prioritize safety
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?
The greater the amount of excess air, the higher the % of O2 and the lower the % of CO2
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?
The sample with 20% excess air
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?
Both have the same air requirements, but propane has higher CO2
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%?
8.3% CO2, 5% O2
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.
38 US Gallons
What is the formula for perfect (stoichiometric) combustion?
Fuel + O2 + N2 = CO2 + H2O + N2
What is the formula for complete combustion?
Fuel + O2 + N2 + Excess Air = CO2 + H2O + N2 + Excess Air
How does tertiary air control NOx emissions?
It slightly cools the flame
What can be done to control NOX emissions from a burner?
Inject steam around the flame
What can be used to control the combustion air for a burner system?
A Variable Frequency Drive or Electronically Commutated Motor
List three factors that can create CO in the products of combustion?
Running too much fuel, not enough combustion air or a failing draft inducer
What is the maximum air-free CO level allowed to be produced during combustion?
400 ppm
How many pounds of CO2 are produced per hour from a 54,784,000 BTUH fuel oil fired boiler?
8765 lbs
How many pounds of CO2 are produced per hour from a 7,312,000 BTUH natural gas fired boiler?
856 lbs
According to legislation, how much ppm sulfur content does heating oil need to be below?
500 ppm
What chemical compounds from combustion are collectively called SOX?
SO2 & SO3
What are two results when NO2 reacts with other pollutants?
Ozone and Acid Rain
What chemical compounds from combustion are collectively called NOX?
NO & NO2
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?
0.246” w.c.
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?
1603 cfm
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?
889 fpm
If a stack has a velocity of 1000 fpm, what would be the calculated draft produced?
0.06 w.c.
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?
972 fpm
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?
0.0762” w.c.
What factors would achieve the highest draft in a chimney?
Tall chimney, hot combustion products, hot ambient (outside) air
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
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
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
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)
What does a balanced draft system incorporate?
A forced draft burner and an induced draft fan
What type of draft control does a gas-fired appliance incorporate when using a forced draft burner?
Internal damper
Why is the draft reduced when using flue gas recirculation to control NOx?
Lower flame temperatures
Why is the draft reduced when using a scrubber (air pre-heater)?
Heat is removed from the flue gases
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
What is the primary concern with ICI hydronic system design?
Protection of the equipment
What are two major concerns for the boiler in an ICI hydronic system installation?
Thermal shock and condensing combustion products
What is the typical system design temperature difference for a non-condensing ICI boiler?
20°F
What is the standard system design temperatures for a non-condensing ICI hydronic boiler?
180°F supply, 160°F return
What type of boiler is best suited to handle the thermal shock?
Flex tube
What minimum return water temperature must be maintained to avoid condensing of combustion products?
140°F
On an ICI hydronic heating system, what is the best location to install an air separator?
Immediately after the boiler supply outlet.
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.
Where is it recommended the system feed water be connected?
Into the air vent piping on the air separator
What is the purpose of a hydraulic de-coupler?
To isolate the source pump(s) from the load pump(s)
Which type of boiler installation will a stack economizer be most effective?
High pressure water-tube steam boiler
What is the purpose of a steam trap?
To hold steam upstream while allowing condensate to pass.
What device controls the water level in a steam boiler?
Low water cut-off
What is the sparge tube used for?
Preheating feed water
What is done to remove dissolved oxygen from boiler feed water?
Heat the feed water
What is the major concern with steam systems?
Water chemistry
What is installed to remove dissolved gasses by mechanical means from the boiler feed water?
Deaerator
What is the main advantage of installing a deaerator?
Reduces feed water chemical treatment costs
What is the advantage of a thermal fluid heating system?
High fluid temperatures without high pressure
To protect against a low water condition how many fuel cutoff devices are required on an automatically fired steam boiler?
2
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
In relation to steam system what is the pressure of a thermal fluid system?
They have a lower pressure than steam systems
How high a temperature could thermal fluid operate at?
750°F
Why can we not use typical hydronic circulators in a thermal fluid system?
They are not rated for the high temperatures
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.
List some of the uses for thermal fluid systems?
Baths, kettles, rolls, reactors, steam/hot water generators, storage tanks, pressure moulds, fryers, ovens
Referring to Figure 1, What is this is the ASME symbol for?
Power boiler safety valve
Referring to Figure 2, What is this is the ASME symbol for?
Heating boiler relief valve
Referring to Figure 3, What is this is the ASME symbol for?
Unfired pressure vessel safety valve
Referring to Figure 4, What is this is the ASME symbol for?
Unfired pressure vessel rupture disc
Who can repair and set pressure relief devices?
Organizations authorized by the regulatory authority
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
What is the recommended time interval for a pressure relief device to be tested?
12 months
What is the recommended time interval for a pressure relief device to be serviced?
3 to 5 years
What type of opening characteristics does a Safety Valve have?
Pop opening from pressure
What type of opening characteristics does a Relief Valve have?
Gradual opening from pressure
Where is the Rupture Disk commonly installed on a boiler?
Upstream in series with a relief valve
The set point on a safety valve can be greater than the Maximum Operating Working Pressure (MAWP) of the vessel or piping.
TRUE / FALSE
Referring to Figure 5, What type of vessel would you find this mechanical safety valve on?
High pressure steam boiler
Referring to Figure 6, What type of vessel would you find this mechanical safety valve on?
Unfired steam vessel
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
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
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
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
A safety relief valve inlet can be smaller than the boiler outlet it serves.
TRUE / FLASE
True
The piping connected to the outlet of a relief valve can be reduced by what size?
The size cannot be reduced
On a steam system, the safety valve must be installed in what orientation?
Vertically
All attached discharge piping for a steam safety valve must be supported___________.
Independently supported
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
How many inches should the center-to-center distance from the drip pan elbow to the safety valve not exceed?
24 inches
Referring to Figure 7, the slash in the discharge pipe should be cut at what angle?
45 degrees
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
What is the set relief pressure for a propane tank installed on a premise?
250 psi
What is the set relief pressure for a propane tank installed on a vehicle?
312 psi
What is the set relief pressure for a propane cylinder?
375 psi
Where is the primary relief valve installed for a vehicle’s LNG tank?
To the top fill line
Where is the secondary relief valve installed for a vehicle’s LNG tank?
To the vapour withdrawal line
What is the primary relief valve discharge setting set to for a vehicle’s LNG tank?
Set at the MAWP of the tank
What is the secondary relief valve discharge setting set to for a vehicle’s LNG tank?
1.5 times the MAWP of the tank
Referring to the figure below, what must be done to the discharge of this relief valve?
Nothing
Which code regulates the installation and testing of safety relief valves?
ASME Boiler and Pressure Vessel code
What is the maximum servicing interval for a pressure relief device installed on a 50 psig steam boiler?
Every five years
How often should a lift test be performed for a pressure relief device installed on a 50 psig steam boiler?
Annually
What is the maximum servicing interval for a pressure relief device installed on a 12 psig steam boiler?
Every five years
How often should a lift test be performed for a pressure relief device installed on a 12 psig steam boiler?
Annually
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
What fluid should a pressure relief device that has been serviced and installed on a steam boiler be tested on?
Steam
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
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
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
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
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
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
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
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
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
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
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%
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
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
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
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
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
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
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
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
The ultimate percentage of CO2 in the flue products of natural gas is:
1) 8%
2) 12%
3) 15%
4) 20%
2) 12%
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
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
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
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
What is the voltage limitation on the secondary side of a control power transformer for a safety control circuit of a gas fired appliance?
120 V
What is the primary purpose of the design of an isolation transformer?
To physically and electrically separate primary and secondary windings from each other.
What type of transformer is used for power conditioning?
Isolation transformer
What is protected by fusing the secondary side of a control power transformer?
The transformers secondary winding
Referring to the figure below, what type of transformer is represented?
Control power transformer
Referring to the figure below, what primary and secondary voltage is the transformer configured for?
Primary 480 V / secondary 120 V
What information is required from the loads energized to size a control power transformer?
Total inrush VA
What is the minimum ignition transformer secondary voltage required for direct spark ignition of main burner gas?
6000 V
What is the minimum ignition transformer secondary voltage required for ignition of an oil burner?
10,000V
For control point instrumentation, what does RTD stand for?
Resistance temperature detector
What type of RTD is mostly used in the industrial sector?
Coiled element RTD
The known electrical resistance at a specific temperature of the metal that makes up an RTD allows the RTD to be accurate within its temperature limits.
True
What metal is most commonly used in an RTD in industrial applications?
Platinum
How does an RTD work?
The resistance increases as the temperature of the sensor increases
Which is the most common RTD wiring configuration that gives a good combination of accuracy and convenience?
3-wire
A 4-wire RTD gives the best accuracy even though most industrial controllers/measurement devices cannot make a true four wire measurement.
True
What is the characteristic of a 3-wire RTD configuration?
It allows the measurement to factor out the resistance of the leads
What type of circuit is used in an RTD to measure the resistance?
Wheatstone bridge
How does a thermocouple interpret changes in temperature?
Change in Voltage
A ____________ has wider operation ranges than an RTD.
Thermocouples
RTDs are more sensitive than thermocouples thus they react faster.
False
Which statement is true when comparing thermocouples to RTDs?
Thermocouples react faster than RTDs, but RTDs are more accurate
What can limit the maximum range of a thermocouple?
Its diameter
How does a pressure transducer work?
It converts pressure into an electrical signal
What produces the electrical signal in a pressure transducer?
Strain gauge
What types of electrical output is available for a pressure transducer?
Millivolt, 0-10 Voltage, 4-20 mA
How many platinum RTDs does a thermal mass flow meter use?
2
In a thermal mass flow meter, what task does each RTD perform?
One RTD measures the fluid temperature and the second maintains a constant temperature differential above the process fluid
What three things is an automatic O2 trim system designed to compensate for?
Fuel characteristics, temperature, barometric pressure
What sensor is the critical component used to reduce emissions in a modern biomass boiler?
O2 sensor
To give better control and more consistent/accurate positioning for a modulating burner, in what system are servo motors used?
In a parallel positioning system
What is the standard voltage used for industrial control circuitry?
120 volts
Why are separate ignition transformers used for industrial burner systems?
To generate a big and hot enough spark to ensure the fuel ignites quickly and efficiently
Are limit circuits wired in parallel or series?
In series
List four specific conditions that a limit in a circuit control can control for?
Temperature, Pressure, Liquid Level and Liquid Flow
What are the two types of reset for limit switches?
Manual or Automatic
Referring to Figure 1, what type of limit is represented?
A High pressure limit switch
What does an operating control do and what are the two most common limits associated with them?
An operating control turns the burner system on and off based on temperature or pressure.
Referring to Figure 2, what is this the symbol for in a limit circuit?
Pressure switch
Referring to Figure 3, what is this the symbol for in a limit circuit?
Temperature switch
Referring to Figure 4, what is this the symbol for in a limit circuit?
Float switch
Referring to Figure 5, what is this the symbol for in a limit circuit?
Flow switch
What is one purpose of a permissive circuit?
To ensure two incompatible events don’t occur at the same time.
Define an interlock:
An interlock is a feature that makes the state of two mechanisms or functions mutually dependent (one can’t work without the other)
A DFMAH shall be ______ in such a way as to prevent its operation unless the exhaust system is functioning.
Interlocked
What must be proved when using automatically operated louvres for the inlet and discharge of a DFMA?
They must be proved fully open.
What is the purpose of a purge interlock?
To prove that the purge air flow rate is at maximum during the purge
An airflow switch is an example of what type of interlock.
Running interlock
The low fire start interlock permits the ignition of the pilot of main flame at an input of:
40% or less of the rated maximum input
What will the size of the wire be from the mag starter to motor if 230 volts is used?
6 AWG
What will the size of the mag starter be if 460 volts is used?
NEMA 2
What size overloads are required for the motor starter if 460 volts is used?
31.25 Amps
25 amps
1.15 service equals 125% of 25 amps
less than 1.15= 115%
rule 28 -208?
What will be the rated size of the disconnect time-delay fuses if 230 volts is used?
87.5 Amps
For a PID controller, what does the proportional do?
It produces an output value that is proportional to the current error value
For a PID controller, what does the derivative do?
It sums the error over time
For a PID controller, what does the proportional gain do?
It determines the ratio of output response to the error signal
For a PID controller, what does the integral do?
It acts as a brake or dampener on the control effort
A VFD or variable frequency drive is also know by what other names?
Variable speed drives, adjustable drives, adjustable frequency drives, frequency converts
What are some of the reasons why we would want to adjust motor speeds?
Save energy (improve efficiency), Match the speed to process requirements, match the torque to process requirements, lower noise levels, reduce mechanical stress, and improve working environment.
What are some applications where a gas fitter may see a VFD used?
DFMA, pumps, fans, compressors
What process takes AC power and turns it into DC power in a VFD?
The converter phase, also known as rectification.
AC-DC –DC– DC-AC
converter DC BUS Inverter
What smooths out the DC power in a VFD?
The DC bus phase
AC-DC –DC– DC-AC
converter DC BUS Inverter
What is the phase called were the DC power is turned back into AC power called?
The inverter phase
AC-DC –DC– DC-AC
converter DC BUS Inverter
Why do we go through the process of changing AC power to DC power and then back to AC power?
This is done so that we can control the frequency (hertz) and voltage and in this way better control the motor.
What electrical component is used to rectify the AC power and convert it into DC power?
Diodes
How is the DC power smoothed out during the DC bus phase?
Through the use of capacitors which add energy to the DC waveform when voltage drops
What is used to change the DC power back to AC power?
IGBT (insulated gate bipolar transistors)
For what two reasons is an overcurrent protection device required in the AC supply to the VFD?
- To provide thermal protection for the VFD cables between the location of the overcurrent protective device and the VFD
- To limit the energy available at the location of a short circuit
What four conditions can present issues for VFDs?
- No Flow conditions
- High speed response
- Full load conditions
- Equipment speed limitations
What is main difference between the motors of a VFD and an ECM?
The ECM is a DC motor whereas the VFD is an AC motor.
What type of current and how many phase is an ECM?
The power produced is 3 phase DC output
What is the most common use of EC motors in the gas fitting world?
Fans: air-handlers, ventilation fans, furnace fans
How does an ECM achieve commutation?
Electronically, with onboard electronics
Where are the permanent magnets located in an ECM?
In the rotor
What, commonly, can cause a power surge?
A Lightning Strike, High power draws, Tripped breakers
What is the definition of insufficient voltage?
The decrease of electrical power to 90% of normal for 1 minute or more
What is the most common cause of insufficient voltage?
An overloaded system
What is a short circuit?
A low resistance connection between two conductors supplying electrical power to any circuit
What could cause a short circuit?
Damaged insulation, a loose wire, faulty appliance wiring
What device is used to break the circuit when it detects and electric arc in the circuit?
An Arc Fault Circuit Interrupter (AFCI)
What could be a reason for a fuse to blow?
An overloaded circuit, a short circuit, a ground fault, an arc fault
What could be a consequence of corrosion on our electrical connection?
- Loss of material leading to loss of function
- Introduction of additional resistance leading to added heat and eventual failure
Which type of wire is the least resistant to corrosion?
Aluminum
What is the consequence of switching the neutral wire instead of the hot wire on an appliance disconnect switch?
The appliance will always be live, even when the switch is open. Leading to a risk of electrical shock for the technician
To protect against a low water condition how many fuel cutoff devices are required on an automatically fired steam boiler?
2
Beside shutting off the burner, what is another function of a low water cut-off device on a steam boiler?
Energize feed pump
What is done to change the operating level of an external float style LWCO device
Change the installation piping
What is the purpose of a steam trap?
It prevents steam from entering the condensate return piping
At what point does the thermostatic steam trap open?
When the condensate temperature drops below saturated steam temperature
What does the thermodynamic steam trap operate on the basis of?
Bernoulli’s principle
The thermodynamic steam trap will work on lower pressure systems.
TRUE / FALSE
What is an arc flash?
The light and heat created from an arc fault explosion
What is an arc blast?
The pressure wave created after an arc fault
What is the major cause of an arc flash?
Voltage transients
Referring to the figure below, what is arc flash boundary 1 referred to as?
Arc flash protection boundary
Referring to the figure below, what is arc flash boundary 2 referred to as?
Arc flash limited approach boundary
Referring to the figure below, what is arc flash boundary 3 referred to as?
Arc flash restricted boundary
Referring to the figure below, what is arc flash boundary 4 referred to as?
Arc flash prohibited boundary
What is defined as an arc flash protection boundary?
The calculated safe working distance from electrical equipment which would not expose the employee to the hazards associated with an electrical arc flash.
What is defined as an arc flash limited approach boundary?
The minimum permitted distance that unqualified and unprotected personnel may approach a live component.
What is defined as an arc flash prohibited boundary?
The boundary where no electrical worker is permitted unless proper procedures, PPE, training, energized work permits, and risk assessment are all in place.
What is defined as an arc flash restricted approach boundary?
The minimum permitted distance where personnel need to have been trained in shock protection techniques, be wearing the correct PPE, and have a written and approved plan for any work in the zone.
Referring to the DFMA Wiring Diagram, the DFMA supply fan isn’t running and you take the following readings with your multimeter:
- 120 Volts across terminals 1 and 2
- 0 Volts across terminals 1 and 12
- 120 Volts across terminals 12 and 13
What is the conclusion that you come as to why the DFMA supply fan is not running?
The inlet damper limit switch is open. Possible causes: the damper is not fully opening; the damper motor is not working; the damper linkages are disconnected; or the damper limit switch is not working.
Referring to the DFMA Wiring Diagram, the DFMA burner is not firing. You take the following readings with your multimeter:
- 120 Volts across terminals 1 and 2
- 0 Volts across terminals 13 and 16
- 120 Volts across terminals 16 and 18
- 0 volts across terminals 19 and 20
- 0 volts at #7 terminal on the Fireye flame relay
What is the conclusion that you come as to why the burner is not firing?
The burner start contact is open. Could be a faulty relay (not energizing) or the start button has not been pressed.
Referring to the DFMA Wiring Diagram, the DFMA burner is not firing. You take the following readings with your multimeter:
- 120 Volts across terminals 1 and 2
- 0 Volts across terminals 13 and 16
- 0 Volts across terminals 16 and 18
- 120 volts across terminals 20 and 21
- 120 volts from terminals 20 to 2
- 0 volts from terminals 21 to 2
What is the conclusion that you come as to why the burner is not firing?
High airflow switch is open. Causes could be: fan speed too high (sheaves not set correctly - too much velocity across the profile plates), improperly adjusted profile plates (too much velocity), failed switch, sensing tubing disconnected.
Referring to the DFMA wiring Diagram, the DFMA burner is not firing. You take the following readings with your multimeter:
- 120 Volts across terminals 1 and 2
- 120 Volts across terminals 18 and 22
- 0 volts across terminals 20 and 21
- 120 volts from terminals 20 to 2
- 120 volts from terminals 21 to 2
- 0 volts at #7 terminal on the Fireye flame relay
What is the conclusion that you come as to why the burner is not firing?
Low airflow switch is open. Possible causes: the inlet supply filters are plugged, faulty air switch, a service door is open, fan speed too low (sheaves not set correctly - too little velocity), sensing tubing disconnected.
Referring to the DFMA wiring Diagram, the DFMA outlet temperature is too low. You take the following readings with your multimeter:
- 120 Volts across terminals 1 and 2
- 0 Volts across terminals 18 and 22
- 120 volts at #7 terminal on the Fireye flame relay
- 120 volts across terminal 30 to 2
- 24 volts across terminals 34 and 35
- 0 volts across terminals 36 and 37
What is the conclusion that you come as to why the burner is not firing?
Burner modulation 0-10 Volt system has no voltage. This means the burner is stuck in low fire and can’t modulate/ramp up to high fire.
Referring to the figure below, the loop current is measured at 29 mA. What are the possible causes of the excess load on the loop?
Miswiring, ground loop, a problem with the transmitter
Referring to the figure below, what is the minimum power supply required for the 4-20 mA loop?
25 Volts
If two points in a 4-20 mA loop are grounded it can create an alternate pathway for the loop current to flow through.
TRUE / FALSE
True
Referring to the figure below, what should the resistance value be of the shunt resister given the following information?
- Source volts: 26
- Source current: 125
- Loop current: 20 mA max
125-20 = 105
26÷105= .2476 x 100 is 247.6 ohms
248 Ohms
In computer networking, what Does LAN stand for?
Local Area Network
In Computer networking, what does WAN stand for?
Wide Area Network
In computer networking, what is a LAN?
A group of computer devices connected with each other in a small place such as a home, school, campus, hospital, or a factory
In computer networking, what is a WAN?
A long-distance network that covers a country, continent, or the whole world
In computer networking, what is a MAN?
A larger networking area connecting Local Area Networks to a larger network of computers
In computer networking, what is the purpose of a firewall?
stops attacks from WAN to LAN
Even though it is old technology, what type of serial interface connection is still commonly used with industrial machines?
RS232
What type of ethernet connector is used in corrosive environments or when washdowns are needed?
M8 or M12 connectors
What four factors affect the flow of gas through a piping system?
Type of gas, diameter of pipe, length of pipe, pressure drop
What factor determines which of the two formulas are used to develop the code tables?
System Pressure
Pipe sizing tables in the B149.1 used to size low pressure piping systems make an allowance for a reasonable number of fittings. How is this accomplished?
By adding a hidden 20% to the displayed code zone lengths (as noted in the formula in the code book)
Plastic pipe is approved for use in a liquid propane system.
TRUE / FALSE
FALSE (B149.1.20, 6.2.16)
In what two ways can the volume of gas required for an appliance be determined?
The appliance rating plate, or the appliance manufacturer when the rating is not shown on the appliance (B149.1.20, 6.4.2)
What shall not be done if piping or tubing is located in an area where a corrosive chemical is used?
It must not be concealed (B149.1.20, 6.7.3)
In British Columbia, piping of NPS 2 ½” and over shall have welded pipe joints.
TRUE / FALSE
FALSE. BC Gas Safety Regulations - 2.3 Clause 6.9.2 of CSA B149.1-20 is repealed and the following substituted: 6.9.2 Piping of NPS 2-1/2 to 4 shall be either press-connect fittings certified to CSA 6.32(ANSI LC-4) or welded pipe joints. Piping greater than NPS 4 shall be welded pipe joints.
If a gas piping system requires welding, who can perform this welding?
Welding of gas piping systems shall be performed in accordance with a procedure and by an operator registered under the applicable provincial or territorial legislation.
(B149.1.20, 6.9.3).
When can piping or tubing enter a building below grade?
Only when permitted by the Authority Having Jurisdiction (good luck) (B149.1.20, 6.15.8)
What are the three ways that piping or tubing can be identified by in a care, detention occupancy, commercial, industrial or assembly building?
The entire piping or tubing system shall be painted yellow, The piping or tubing system shall be provided with yellow banding that has a minimum width of 1” and is marked at intervals not exceeding 20’, or the piping or tubing system shall be labelled “GAS” or “PROPANE” utilizing yellow label s or markings.
(B149.1.20, 7.17.1)
Can a quick disconnect device be used instead of a manual shut off valve?
NO (B149.1.20, 6.18.7)
In order to increase regulator accuracy, the pitot tube senses pressure at what point?
Lowest outlet pressure point
Which regulator will have the least amount of droop under flow conditions?
A pilot operated regulator
Critical flow in a regulator occurs when the velocity of the gas reaches what threshold?
Sonic Velocity
What does a double-ported balance regulator use to sense downstream pressure?
A downstream sense line
Where is the sense line connected on a proportional regulator?
To the top of the diaphragm
When zero governor regulators are used for burners that are to be operated under positive or negative combustion chamber conditions, how can the combustion chamber pressure be counterbalanced?Connecting a pressure reference line from the combustion chamber to the top diaphragm chamber of the zero governor
Connecting a pressure reference line from the combustion chamber to the top diaphragm chamber of the zero governor
What type of regulator is pictured below?
Double-ported balanced regulator
In the above image what is the purpose of connecting the sense line?
To sense outlet pressure
In the above image at what point is the sense line connected to the main supply piping?
Downstream to the top of the piping
What type of regulator is pictured below?
Atmospheric regulator
What type of regulator is pictured below?
Pilot operated regulator
What would happen if the regulator shown below was installed backwards?
It will pass no flow
What would happen if the above regulator was installed upside down?
It would provide lower downstream pressure
When selecting a regulator for a gas piping system, what regulator inlet pressure should you assume there to be when the system is under no flow?
Static pressure (system setting)
For a direct-operated regulator, what amount of droop can be expected?
10-20%, but by code should be no more than 10%
When you need extreme accuracy in high-pressure gas system applications, what type of regulator is best suited for this application?
Pilot-operated
If two or more available regulator springs have published pressure ranges that include the desired pressure setting, for more accuracy you would select the spring with the lower pressure range.
TRUE / FALSE
t
What factors make it beneficial to select a regulator orifice size in the smallest diameter that will handle the desired flow?
Avoids instability and premature wear, Allows for smaller relief valves, Reduces lockup pressure
What is used to determine the required flow of relief valves for a gas system?
The wide-open flow rates of the upstream regulator
What is the maximum droop allowed from a regulator in a gas piping system?
0.1
Why do air requirements differ for appliances with and without draft control?
Units with draft control require dilution air
An atmospheric gas appliance has an input of 390 Mbh and is equipped with a draft hood. It is to be installed in a building that complies with code clause 8.2.1. A or B. What size duct is required to provide air to this appliance?
9”
A furnace room complies with code clause 8.2.1. (a) or (b). It contains a 260 Mbh furnace without draft control and a 120 Mbh hot water heater with a draft hood.
Size the combustion air duct based on a length of 21’
7”
A boiler room contains the following five pieces of equipment:
- one 3500 Mbh boiler with draft control
- two 450 Mbh hot water heaters with draft hoods
- two 750 Mbh duct heaters without draft control.
Calculate the required free area of the combustion air duct.
436 in2
The following gas appliances are installed in a mechanical room:
- one 1400 Mbh steam boiler with a barometric damper
- one 550 Mbh hot water heater with draft hood
- two 600 Mbh direct fired make-up air units
Select a square grill for the combustion air opening in the boiler room wall that will meet the minimum requirements of the B149.1 gas code (grills rated at 67% free area).
18” x 18” (314.507 in2)
The air supply to a 20,000 Mbh boiler, using a force draft burner, is provided by mechanical means through a horizontal duct 42 feet in length. What is the quantity of air required to be supplied to the boiler?
600,000 ft3 (30 ft3 for every 1,000 btu/h)
A 2,752 Mbh forced draft natural gas boiler is operating in a mechanical room, excess air set at 40%. What is the required free area for the combustion air duct?
92 in2
A structure is equipped with a boiler rated at 5,300 MBH and a hot water tank rated at 400,000 Btu/h. Both pieces of equipment are equipped with draft controls and the air supply is ducted from outdoors. What is the size of the free ventilation air opening?
47.9 in2
A structure is equipped with a boiler rated at 750 kW and a barometric draft control. What is the free area of the combustion air supply opening in mm?
162,750 mm2
A structure has a mechanical room into which air must be ducted from outdoors. It contains the following appliances:
- One boiler rated at 3,000 MBH, equipped with a barometric damper
- Two duct heaters without draft controls rated at 950,000 Btu/h each
- Two hot water tanks rated at 250,000 Btu/h each. Both tanks are equipped with draft hoods
What is the free area of the combustion air supply opening?
385 in2
A structure is equipped with appliances rated at 1,900 MBH. None of the appliances is equipped with draft control devices and the air supply is ducted from outdoors. What is the free area of the ventilation air opening?
10 in2
A structure has a mechanical room into which air must be ducted from outdoors. It contains the following appliances:
- One boiler with no draft control rated at 500 kW
- One boiler with draft control rated at 4,000 MBH
- One duct heater with no draft control rated at 125 kW
- One hot water heater with a draft hood rated at 800,000 Btu/h
What is the free area of the combustion air supply opening?
485.37 in2
A mechanical room is equipped with gas appliances with a total input of 3,200 Mbh. All appliances are equipped with draft control devices. The louvre specified for the combustion air opening has a free area of 70%. What is the size of the opening required to fit the louvre?
428.58 in2
What is the minimum opening size on a screen used on a combustion air-supply opening?
1/4”
On a combustion air louvre with dampers the dampers must be controlled in what way?
Automatically
What interlock is required for an automatically adjustable combustion air louvre?
Normally Open contact interlocked with burner control
What two fan styles are commonly used for mechanical air supply systems?
Axial and Centrifugal
When air is provided by mechanical means what type of switch must be used?
The code does not specify the type. Air proving switch (sail or differential)
What three factors would lead you to want to pre heat combustion air?
Prevent the freezing of pipes, prevent thermal shock of the boiler, maintain appliance efficiency
What do ICI Appliance manufacturers do for high altitude installations? (above 4500 feet)
Increase blower motor horse power
What is the relationship between static pressure and air flow?
As static pressure goes up air flow goes down
What three factors have the greatest affect the static pressure in ducting?
Cross sectional area, length, number of fittings
What is the static pressure ranges of the following combustion supply-air ducting systems?
a. Low Pressure:
b. Medium Pressure:
c. High Pressure:
a. less that 3” w.c.
b. 3” to 6” w.c.
c. 6” to 10” w.c.
When is an overpressure protection device required by code?
When the inlet pressure to a main pressure regulator exceeds the pressure rating of any downstream component or accessory
What method of overpressure protection will interrupt flow of gas in the event of an over pressurization?
Automatic shut-off system
Which type of over pressure protection system must be manually reset after it has been activated?
Automatic shut-off
Referring to the figure below, if the main diaphragm ruptures, what is the likely result?
The relief valve will provide reduced flow rates
Referring to the figure below, this is an example of which type of over-pressure protection?
Pressure relief
Referring to the figure below, what method of overpressure protection is represented?
Upstream monitor system
Referring to the figure below, how can we easily change which regulator is the worker and which is the monitor?
Switch the set points on the regulators
A separate line relief valve shall be installed where in relationship to the regulator?
As close as possible downstream from the regulator
What is the purpose of tertiary air in the combustion process?
To add air to control emissions and flame shape
What type of heat transfer does an infrared burner utilize?
Direct radiation
What type of heat transfer does a low temperature indirect heating burner use?
It uses a fan to transport the heated air to the work
What type of heat transfer does a direct-fired burner use?
It uses a mix of radiation and hot gas convection
What type of heat transfer does a high temperature indirect-heated burner utilize?
Tubes or enclosed walls are heated and radiate heat to the work
Identify the type of flame represented in the following image:
Figure 1 type A
Identify the type of flame represented in the following image:
Figure 2 type C
Identify the type of flame represented in the following image:
Figure 3 type E
Identify the type of flame represented in the following image:
Figure 4 type F
Identify the type of flame represented in the following image:
Figure 5 type H
A propane fired boiler has a low-fire input of 1,700,000 BTUH and a high-fire input of 22,100,000 BTUH. What is its turndown ratio?
0.5423611111111111
What ratio of air/natural gas are most premix burners limited to for acceptable, normal operation?
0.41736111111111107
What are three characteristics of a nozzle mix burner?
- Its ability to operate over a wide range of air/gas ratios
- To control the mixing of the gas and air without sacrificing clean combustion or flame stability
- To allow the ability to vary the flame shape
What methods can be used to atomize oil in an oil fired burner?
- Air atomizing
- Pressure atomizing
- Steam atomizing
How can the flame length of an oil-fired burner be modified?
Changing the oil nozzle spray angle
The main burner flame shall be proven at the furthest point(s) along its base from the source of ignition when the burner flame width is in excess of how many feet?
3 feet
What style of burner is represented by the following image:
a. Gun burner
What style of burner is represented by the following image:
Lance burner
What style of burner is represented by the following image:
Cane burner
What style of burner is represented by the following image:
Immersion burner
What advantage does a direct contact water heater have?
No loss out the stack, no lost condensation, no lost radiant heat.
Describe how an immersion burner works.
A submerged radiant tube heat exchanger is used to heat large volumes of liquid.
Describe how an indirect bath heater works.
It uses two separate, submerged heat exchangers to heat a fluid with one heat exchanger and transfer that heat from the fluid to the second heat exchanger.
What are three of the potential hazards of using a direct fired construction heater?
- Being too close to combustibles can lead to a fire
- The possibility of fire if used in a wood frame structure
- There is the potential for dangerous levels of carbon monoxide
What is a curing oven used for?
Used to generate some form of chemical reactions once a temperature setpoint is reached by a particular substance.
What is a drying oven used for?
It is used to remove moisture from materials.
What is a baking oven used for?
It is used to remove moisture from materials and to generate some form of chemical reactions once a temperature setpoint is reached by a particular substance.
What is the typical temperature range of an industrial furnaces?
750 to 3,275 °F
What is the purpose of a CO2 generator?
To produce carbon dioxide required by plants in commercial green houses.
What is the purpose of an exothermic generator?
To produce cover gasses as a non-oxidizing atmosphere for the heat treating of bright metals.
What is the purpose of an endothermic generator?
To provide a positive pressure in a heat-treating furnace, and a platform on which a carburizing or decarburizing environment can be formulated.
A direct fired make-up air unit is designed for temperatures ranging from -5⁰F to 85⁰F. At what outdoor temperature (within design parameters) will the velocity across the burners be the greatest?
85⁰F
A direct fired makeup air heater has the same function as an RTU.
TRUE / FALSE
What is the main benefit of a DFMAH?
No efficiency lost to a heat exchange
Referring to the B149.1 under what conditions can a DFMAH be used?
A DFMAH shall not be installed unless it is necessary to exhaust air and replace it with preheated air
What must be proved before the DFMAH can start?
Any inlet or discharge air louvres must be proved open through an interlock with the control the exhaust system is operating
What is the purpose of makeup air?
To replace the air exhausted by large exhaust appliances which, when properly designed, installed and maintained ensure a neutral pressure in the building
When a DFMAH is used in a kitchen it must be interlocked with the kitchen exhaust fan so that neither fan can operate without the other operating?
TRUE / FALSE
t
List three things that could affect the external static pressure placed on a DFMAH.
Filters, Grilles, Ductwork
When the DFMAH is in operation the burner is always firing?
TRUE / FALSE
What are the two modes of operation for a spray booth DFMAH?
Spray Mode, Bake Mode
In a DFMAH what is adjusted to control air velocity?
Profile plates
Other than make up air for a kitchen or spray booth list three other applications for DFMAH.
Shaft pressurization (stairwell or elevator), storage garage, mine shaft
What can be the results of an improperly selected, sized and/or installed venting system?
Efficiency loss, Appliance damage, Increased appliance maintenance, damage to breeching & stack, Production downtime, Increased operating costs.
Define forced draft:
A mechanical draft produced by a device upstream from the combustion zone of an appliance
What is the draft source for a natural draft appliance? Explain how this draft source moves the products of combustion through the appliance and the venting.
Gravity is the source. It moves the products of combustion through the appliance and venting because the hot flue gases are lighter and naturally rise (buoyancy).
Define induced draft:
A mechanical draft produced by a device downstream from the combustion zone of an appliance
Describe the three general variations of Burner inlet blowers and the different pressures associated with each.
a. Blowers which operate with enough pressure to overcome the burner alone. The combustion chamber, appliance outlet and venting will all be under negative pressure
b. Blowers which operate with enough pressure to overcome the burner and combustion chamber. The combustion chamber will be under positive pressure, appliance outlet will be neutral or negative and the appliance venting will be under negative pressure
c. Blower which operates with enough pressure to overcome the burner, combustion chamber and part or all of the venting. All parts of the system past the burner are under positive pressure.
What is the pressure upstream of the blower when it is located on the outlet of the appliance?
Negative
What is the pressure downstream of the inducer blower located on the outlet of the appliance?
It will be positive immediately downstream but could be either negative, neutral or positive on the downstream side depending on the blower’s power and the venting system
In a venting or chimney system with mechanical draft what two types of draft can be present and what type of pressure is associated with each?
Forced draft – static pressure in the venting is positive
Induced draft – static pressure is the venting is negative
When a venting system was originally installed as a gravity system where is the best location for the blower to be located? Why?
Forced draft – static pressure in the venting is positive
Induced draft – static pressure is the venting is negative
What must be done when a power venter is used in place of a natural draft venting system.
Gas flow to the main burner must be prevented in the event of power venter failure
When must design registration take place when you are designing or modifying complex, technical, and regulated equipment in BC?
Before the construction and installation of the equipment
When are parallel blade damper used?
For open/closed operation
When are opposed blade dampers used?
For modulating operation
What must be done when an automatic flue damper is installed on an appliance with a continuous pilot?
Must have a fixed minimum opening of 20% of the flue area and be interlocked with the burner control system so the that damper is proved fully open before ignition of main burner and The fuel supply to the appliance will be shut off in the event of failure except where the damper will fail fully open.
What are three common ways to prove draft in an appliance or venting system?
A pressure switch, An integrated proven draft switch, A pressure transducer
What type of boiler is generally considered to be not limited in its energy output and operating pressure?
Water tube boiler
Referring to Figure 1, what type of boiler is shown?
Horizontal Fire tube boiler
Referring to Figure 1, how would this boiler be identified for passes?
2-pass
Referring to Figure 1, what is the first pass that the burner is firing into referred to as?
Morrison tube
What can be done in a firetube boiler to maintain a consistent velocity of the flue products through the boiler?
Decrease the amount of tubes at each consecutive pass
What type of firetube boiler has a reversal chamber surrounded by water?
Wet back
Referring to Figure 2, what is the portion of tubes called in a water tube boiler in which the cooler water flows down to the steam drum?
Downcomers
What type of firetube boiler has a reversal chamber that is not surrounded by water?
Dry back
Referring to Figure 2, what is the portion of tubes called in a water tube boiler in which the hot water flows up the portion of the tubes connected between the lower and upper drums?
Risers
Referring to Figure 3, what is the part of the water tube boiler identified within the red circle?
Mud drum
Referring to Figure 4, what is the part of the water tube boiler identified within the red circle?
Steam drum
Referring to Figure 5, what is the design type called for this water tube boiler?
A type
Referring to Figure 6, what is the design type called for this water tube boiler?
D type
Referring to Figure 7, what is the design type called for this water tube boiler?
O type
What is the input of an 80% efficient steam boiler with an EDR rating of 11,500 ft2?
What is the BHP rating of a hot water boiler with an output rating of 3,400 MBH?
What Btu output would be required from a steam boiler to supply 8300 ft2 of exposed radiation?
The input of a 75% efficient steam boiler is 1,000 MBH. How many pounds of 212°F water could be generated into 212°F Steam in 90 min?
A hot water boiler is 80% efficient and operates at 170°F. How many ft3 of C3H8 would be consumed each hour to heat a building which contains 7100 ft2 of gross EDR?
A propane boiler with an input of 5,000 MBH is 75% efficient. How many ft2 of net EDR will it satisfy when operating with 170 o F water?
A building with a net EDR of 15,500 ft2 is heated with a 100 BHP steam boiler. By what percentage would the boiler have to be over fired in order to satisfy the required output?
If a steam boiler was fired at 140% of its rated output of 60 BHP, how many ft2 of net EDR could the boiler service?
A boiler with rating of 109 BHP is to be fired on CH4 what would you suggest is the input? Assume 75% efficiency.
Modern burner controls do not need to be continuously powered.
What initiates the burner cycle?
The Control Circuit switches being completed
List some of the typical switches that could be found on the limit circuit of a boiler.
Manual switch, operating Aquastat, high limit Aquastat, low water cut-off, thermostat, DDC contacts, Pressuretrol, flow switch, aux-low water cut-off.
What is the purpose of an interlock?
To stop the burner from firing to prevent an appliance from damaging itself if a condition fails to be satisfied.
What must be done when a non-recycling interlock opens?
It must be reset manually
What feature shall be included on a low water cut-off that is an interlock for a water boiler that is located above the hot-water circulating system?
It must have a manual reset feature.
Define Permissive:
Conditions that need to be satisfied before you can start the equipment cycle.
Define Interlock:
Prevents an appliance from damaging itself if a condition fails to be satisfied.
List the common run interlocks:
Combustion Air Proving Switch (CAPS), Mag Starter Aux Switch, Low gas Pressure Switch (LGPS), High Gas Pressure Switch (HGPS), Oil Temp Switch, Low Oil Pressure Switch, Low Atomizing Media Switch
What type of interlock is required when combustion air is supplied by mechanical means?
A combustion air proving switch
What is the “normal” position of a combustion air proving switch?
Open (NO)
What is the purpose of the purge interlock:
To prove adequate air supply before the start of the pre-purge countdown timer and during the purge period.
What is the purpose of a low fire start interlock?
To prove combustion air damper and fuel valve are in low fire position before ignition.
How many air changes of the combustion zone and flue passages must take place during the pre-purge period prior to the ignition cycle?
4
When shall a proven low fire start be required?
On a variable input appliance that has an input in excess of 1,000,000 BTUH, unless otherwise approved.
List 4 types of pre-ignition interlocks:
Start interlock, fuel valve switch, proof of closure switch, overtravel proof of closure switch
Define proof of closure switch:
A factory sealed switch incorporated into a safety shut-off valve that includes at least one set of contacts, which close only after the valve port is closed and which open prior to the opening of the valve port.
What type of switch is pictured below?
Over Travel Proof of Closure Switch
For a PID controller, what does the proportional do?
It produces an output value that is proportional to the current error value
For a PID controller, what does the derivative do?
It sums the error over time
For a PID controller, what does the proportional gain do?
It determines the ratio of output response to the error signal
For a PID controller, what does the integral do?
It acts as a brake or dampener on the control effort
Referring to the image below, what must be done to create a proportioning regulator with the use of the regulator shown?
Cross-connect an impulse line from downstream of the combustion air control valve to the top of the regulator diaphragm
When an impulse line is used for a proportional regulator system, what is the minimum pipe diameter the line should be installed from the shaft of the combustion air control valve?
5 Pipe diameters
When an impulse line is used for a proportional regulator system, what is the minimum pipe diameter the line should be installed from any pipe tee or elbow (change in direction)?
3 Pipe diameters
If it is absolutely necessary to locate the connection of an impulse line less than the recommended pipe diameters downstream of the combustion air control valve, how should the hole be drilled in the pipe?
Parallel to the to the shaft of the valve on the side of the pipe
How should a cross-connection impulse line from the combustion air to the regulator be installed?
With no dips in the line to avoid trapping water and pitched towards the combustion air line
Referring to the figure above, what is the purpose of the limiting orifice?
t limits gas flow to the maximum burner rate
Referring to the figure above, how is low fire adjusted and set?
By adjusting the spring in the regulator
Referring to the figure above, what can be done to correct the regulator action affected from variable combustion chamber pressures or any combustion chamber pressures higher or lower than the room pressure adjacent to the regulator?
An impulse line can be cross-connected from the combustion chamber to the air/gas ratio regulator
For nozzle mix burners, when is a cross-connected impulse line from the regulator’s vent to the main combustion air line required?
When the minimum gas inlet pressure exceeds the maximum air pressure by 3.5 or more inches water column
If the minimum gas pressure at the proportional regulator inlet is not more than the maximum air pressure at high fire, what can be done to compensate for this?
Install a two-pipe bleeder and set it so the maximum impulse pressure is 4 iwc less than the gas inlet pressure
Referring to the figure below, what type of actuator is used to drive the vent damper?
Linear
Referring to the figure below, what type of actuator is used to drive the vent damper?
Rotary
When an automatic flue damper used on an appliance equipped with direct-spark ignition falls fully open upon loss of driving medium, the fuel supply to the appliance needs to be shut off.
False
What type of tubing is used to connect a differential pressure transducer used to control a damper actuator to the flue stack probe?
Silicon
What is the typical maximum distance a differential pressure transducer used to control a damper actuator should be connected to the flue stack probe?
6 feet
Referring to the figure below, What should distance ‘A’ be to improve accuracy?
3 times the vent diameter
If a CO sensor is used in a boiler room, how high above the floor should the sensor be mounted?
4 to 6 feet
When CO sensors are installed in an 28,250 ft2 boiler room, a total of how many sensors are required?
4 (7500sqft per)
What Category appliance has nonpositive pressure and a temperature above 140°F (60°C)?
Category I
What Category appliance has positive pressure and a temperature below 140°F (60°C)?
Category IV
What Category appliance has positive pressure and a temperature above 140°F (60°C)?
Category III
What Category appliance requires venting that is made of material that is intended to resist corrosion from condensing?
Category II & IV
What Category appliance has nonpositive pressure and a temperature below 140°F (60°C)?
Category II
What Category appliance requires venting to be sealed and pressure tight?
Category III & IV
What is that maximum temperature of 316L stainless venting?
550°F
What temperature can high temperature silicone go up to?
2000°F
A flue vent can be supported by the appliance it serves.
False
What is the typical grade for horizontal flue venting?
1/4” per foot
How should the flue venting be graded for a condensing type appliance when running the vent horizontally to the outdoors?
Towards the appliance
To maintain the flow of condensate in a condensing appliance’s flue venting, a horizontal change in size of the venting should be done with what type of increaser?
Eccentric type
When changing the size of vertical venting, it should normally be done with what type of increaser?
Concentric type
What is used on flue venting guy wires to allow for vent expansion and contraction without stretching the guy wires?
Spring loaded turnbuckles
From the combustion flow formula identify what each variable represents.
Q = flow rate (cubic feet per hour)
A = area of the orifice (square inches)
K = discharge coefficient of the orifice
∆P = pressure drop across the orifice (inches water column
Sg = specific gravity of the gas
What would be the most reliable source to find the specific gravity of natural gas?
From your natural gas utility
What is the purpose of an Orifice plate?
To measure a general approximation of flow rate
The higher the discharge coefficient of the orifice the less restriction there is to gas flow.
TRUE / FALSE
True
When using an Orifice plate what are three things that could skew the results?
- The location of the pressure taps
- The thickness of a square edge plate
- If the appliance is operating in low fire
What is the minimum diameter gauge allowed to be used for a pressure test on a gas piping system?
3 inch (B149.1 - 6.22.2 (b))
Using good engineering practices, what type of fluid should be used to pressurize a piping systems 4 inches and larger that contain a combustible gas?
inert gas (B149.1 6.22.2)
What is the minimum test pressure as per code requirements for 372’ of 8” NPS schedule 80 steel pipe (yellow jacket) installed underground operating at a gas pressure of 40 psig?
100 psig (B149.1
When pressure testing a gas piping system, what is the maximum range the pressure gauge shall exceed the test pressure by?
at least by 15% but not more than 300% (B149.1 6.22.2 (b))
What is the maximum diameter purge point opening when purging NPS 2”?
1/2 inch
What is the maximum pipe size that can be purged using air or fuel gas as the purging agent if the length of the pipe is 45 feet?
2-1/2 inch (B149.1 Table 6.4)
What is the recommended pressure used when purging with nitrogen?
0.5 or 14” w.c.
What is the recommended purge velocity through the piping system?
200 ft/min
What is the reason for purging at the correct velocity through a piping system?
completely scrubs the walls, no stratification, faster than flame speed
Why is purging using an inert gas a requirement when exceeding the pipe lengths for the diameters given in Table 6.4 of the B149.1?
larger volumes of piping cannot withstand an internal explosion from a gas air mixture
What does TOE stand for in a TOE nipple?
Thread One End
During a nitrogen purge, what velocity must be maintained at the purge outlet?
200 ft/sec
When purging outdoors, what is the minimum distance from a building intake allowed?
10 feet
For refractory classification what would be considered a normal fusion temperature for the following refractories:
Normal Refractories
Super Refractories
High Temperature Refractories
- Normal Refractories 1600⁰C
- Super Refractories 2200⁰C
- High Temperature Refractories 1900⁰C
For refractory compounds and materials, what materials classification group do the following fall under:
Silica
Graphite
Lime
- Silica Acid Materials
- Graphite Neutral Materials
- Lime Alkaline Materials
Why do alkaline and acidic refractory material need to be kept apart on installation?
They react with each other under high temperature and form salt
What is the main purpose of refractory material?
To contain the heat generated by the combustion process
Properly selected, mixed and installed what percentage of fuel costs could refractory save.
5% - 7 %
Broadly speaking, what are the two refractory types?
Shaped and Unshaped
Refractory helps shape the burner flame in the combustion chamber?
TRUE / FALSE
t
What is the most important factor that affects the lifespan of refractory?
Refractory Dry-out
What schedule must be followed for curing and dry-out of refractory?
Follow Manufacturer’s Instructions
What can cause horizontal crack formation in refractory?
Thermal cycling, Stress accumulation, creep
Define a Valve Train.
The combination of valves, controls, piping, and tubing of an appliance upstream from the manifold through which gas is supplied to the appliance and by which gas is controlled
Where will you find the minimum standards for the design of fuel trains?
CSA B149.3, specifically annex B
What three factors will determine the number and type of components in the valve train?
The appliance input, type/number of burners and gas pressure.
When gas and another fuel are used in a dual or combination burner, a manual isolation valve shall be provided upstream of the main gas valve train components but downstream of the pilot line connection.
True / False
True (B149.3 6.1)
Where will you find the symbol legend for gas valve train components?
Figure B.1 in CSA B149.3
What types of valve can be used for the manual shut-off of a valve train?
A valve approved for use with gas, and can be a Plug, ball or eccentric type B149.1 6.18.1
What percentage above or below regulator set pressure can we operate at, through the firing range of an appliance?
B149.3 4.4
10% boost (above set point)
10% droop (below set point)
According to the B149.3, at what inlet pressure does a regulator need to be of a lockup style?
0.5 psig (3.5 kPa)
Define Overpressure Protection Device:
A device that under abnormal conditions will act to reduce, restrict, or shut off the supply of gas flowing into a system to prevent gas pressure in that system from exceeding the rated pressure of the system components.
What is the primary automatic valve used to start and stop the flow of gas?
Safety shut-off valve
The downstream safety shutoff valve should be quick-opening, to provide smooth and reliable lighting of the burners.
True / False
False (B149.3 8.1.3 It should be slow-opening)
What is the maximum closing time required for a safety shut-off valve?
1 second
What is incorporated in a safety shut-off valve to make it a proof of closure switch?
An end switch that makes when the valve is in the closed position.
The tightness of a SSOV closure is assumed to be good and does not need to be checked when servicing equipment.
True / False
False
What components are included in a double block and bleed?
A double block and bleed has two SSOV and a vent valve installed between them
Electrically, what type of automatic vent valve shall be used?
Normally open so that it closes when energized.
On a 3” Valve train what size does that valve and vent line pipe need to be?
1 ¼”
How shall the the safety vent valve (SVV) be wired in relation to the safety shut-off valves?
In parallel
What is a valve proving system?
A system that proves the effective closure of safety shut-off valves by detecting leakage. It can consist of a programming unit, a measuring device, valves, and other functional assemblies.
When is an input flow control valve required?
On installations where the firing rate is automatically changed
Where is a test firing valve located?
Downstream of all safety shut-off valves on the valve train and as close to the burner as is practicable.
What is the purpose of the test firing valve?
- The purpose of a test firing valve is to give the Technician the ability to isolate the main burner and test/adjust the other valve train components while energized and live/gasified without firing the main burner.
- The test firing valve is also used for manual control of the first main burner firing during commissioning. It gives the technician the opportunity to observe and listen to light-off under a more manual control.
The test firing valve must not have stops in the OPEN and CLOSED positions?
True / False
False B149.3 6.2(d)
What is a supervisory system?
A burner control system that requires physical presence of an operator for manual starting of the burner cycle
What is the difference between a regular lubricated plug cock and a FM or supervising cock?
The supervising cock incorporates two side outlets which are only open after the main gas passage is completely closed.
What is a common name for a manual reset gas shut-off valve?
A Latch valve
What prevents the electrically powered manual reset gas shut-off valve from being reset or latched when the valve is not energized?
The handle moves freely and will not engage the internal latch mechanism
Referring to Figure 1, before start-up the FM Valve is in the open position to allow gas to the burner. When attempting to open the diaphragm latch valve, why will the valve not engage the latch and open?
The gas pressure is not able to pressurize the diaphragm of the latch valve
Referring to Figure 2, after start-up of the burners (FM valves opened), what keeps the solenoid latch valve energized?
Gas pressure to PS1
Referring to Figure 3, what must be proven before the burner can be lit?
FM valve closed, gas pressure and air pressure
Referring to Figure 3, how does the latch valve stay open when the FM valve is opened to the burner?
The gas bypass and combustion air
Referring to Figure 4, what allows the initial engagement of the latch valve before the FM valve is opened?
Air pressure to PS1 and combustion air to the latch valve
Referring to Figure 4, what allows the engagement of the latch valve after the FM valve is opened?
Gas pressure to PS2 and combustion air to the latch valve
What type of heat is referred to when the transfer of thermal energy from a substance results in a decrease in temperature?
Sensible heat
What type of heat is referred to when energy is absorbed by a substance causing a change in its physical state?
Latent Heat
What three substances are used in an ammonia absorption refrigeration system?
Ammonia, hydrogen, and water
What is the pressure of an ammonia absorption refrigeration system?
200 to 230 Psig
An ammonia/water absorption refrigeration system cannot chill air below freezing due to the system using water (the water will freeze).
TRUE / FALSE
What does lithium bromide act as in a lithium bromide absorption refrigeration system?
Absorbent
What does water act as in a lithium bromide absorption refrigeration system?
Refrigerant
What pressures do lithium bromide absorption chillers operate between?
1 to 10 kPa
What are the characteristics of ammonia used in an absorption refrigeration system?
Colourless and a strong odor
What are the characteristics of lithium bromide used in an absorption refrigeration system?
Reddish in colour and a strong odor
At what level of ammonia concentration (ppm) should personal protective equipment be used if there is a possibility of exposure?
Above 50 ppm
At what level of ammonia concentration (ppm) is the maximum allowable averaged over an eight-hour period?
Above 25 ppm
What are the explosive upper and lower limits of ammonia in air?
15% and 28%
Lithium bromide burns skin on contact.
TRUE / FALSE
What are the explosive upper and lower limits of lithium-bromide in air?
lithium-bromide is not explosive
What is considered a strong water-lithium bromide solution?
Little to no water in the lithium bromide; is strong in its ability to absorb water
What is considered a weak solution in an ammonia-water system?
A solution of water with little ammonia
What is a good safety practice to have in regards to lithium bromide
- Written safe work procedures
- Exposure control plan
- WHMIS program
What are the four basic components of an absorption refrigeration system?
Generator, condenser, evaporator, absorber
What is the purpose of the generator in an ammonia absorption refrigeration system?
To heat the refrigerant so the ammonia vaporizes and separates from the water solution
What is the purpose of the absorber in an ammonia absorption refrigeration system?
To attract – and absorb – the refrigerant from the evaporator.
What is the purpose of the evaporator in an ammonia absorption refrigeration system?
To mix the liquid refrigerant (ammonia) with pressurized hydrogen atmosphere and causing the ammonia to evaporate.
What is the purpose of the condenser in an ammonia absorption refrigeration system?
To collect and remove heat from the separated ammonia causing it to condense into a liquid.
What happens in a lithium bromide absorption system when you heat the weak lithium bromide solution?
The water will evaporate and rise, and the lithium bromide will sink to the bottom
What two components of an absorption chiller are found in the topmost chamber?
Condenser and generator
What two components of an absorption chiller are found in the bottommost chamber?
Evaporator and absorber
In an absorption chiller, where does the water vapour end up right after it is separated from the lithium bromide?
The condenser section
In an absorption chiller, where does the lithium bromide end up after it is separated from the water?
The absorber section
n an absorption chiller, what happens to the condensed water as it gets sprayed over the surface of the evaporator?
The water evaporates and transfers the thermal energy out of the chilled water line
Approximately what temperature will the chilled water be as it leaves the evaporator?
7°C
In an absorption chiller, what causes the vacuum in the absorber chamber?
The attraction between the water and lithium bromide particles in the absorber
What does a Process Flow Diagram (PFD) illustrate?
Relationships between major components at an industrial plant
A Process Flow Diagram (PFD) can be used to document a process, improve a process, or model a new process.
TRUE / FALSE
t
What is the purpose of a Process Flow Diagram (PFD)?
-To document a process for better understanding, quality control and training of employees
-To help show unnecessary steps, bottlenecks and other inefficiencies
-To standardize a process for optimal efficiency and repeatability
The most common Process Flow Diagram (PFD) symbols come typically from what agency?
ISO
What does a Piping and Instrumentation Diagram (P&ID) illustrate?
The functional relationship of piping, instrumentation and system equipment components
How can a Piping and Instrumentation Diagram (P&ID) be used?
To create and implement philosophies for safety and control
What types of supporting documents are used for a Piping and Instrumentation Diagram (P&ID)?
-Piping Material Specifications (PMS)
-Equipment and Instrumentation Specifications (EIS)
-Functional Requirement Specifications (FRS)
What are the four basic components of an absorption refrigeration system?
Generator, condenser, evaporator, absorber
What is the purpose of the generator in an ammonia absorption refrigeration system?
To heat the refrigerant so the ammonia vaporizes and separates from the water solution
What is the purpose of the absorber in an ammonia absorption refrigeration system?
To attract – and absorb – the refrigerant from the evaporator.
What is the purpose of the evaporator in an ammonia absorption refrigeration system?
To mix the liquid refrigerant (ammonia) with pressurized hydrogen atmosphere and causing the ammonia to evaporate.
What is the purpose of the condenser in an ammonia absorption refrigeration system?
To collect and remove heat from the separated ammonia causing it to condense into a liquid.
What happens in a lithium bromide absorption system when you heat the weak lithium bromide solution?
The water will evaporate and rise, and the lithium bromide will sink to the bottom
What two components of an absorption chiller are found in the topmost chamber?
Condenser and generator
What two components of an absorption chiller are found in the bottommost chamber?
Evaporator and absorber
In an absorption chiller, where does the water vapour end up right after it is separated from the lithium bromide?
The condenser section
In an absorption chiller, where does the lithium bromide end up after it is separated from the water?
The absorber section
n an absorption chiller, what happens to the condensed water as it gets sprayed over the surface of the evaporator?
The water evaporates and transfers the thermal energy out of the chilled water line
Approximately what temperature will the chilled water be as it leaves the evaporator?
7°C
In an absorption chiller, what causes the vacuum in the absorber chamber?
The attraction between the water and lithium bromide particles in the absorber
Referring to Figure 1, what is the type of control system called?
Single-point linkage control
Referring to Figure 2, what is the name of the part of the linkage system located in the red rectangle?
Jack shaft
Referring to Figure 3, what is the type of control system called?
Parallel position control
How is a parallel position control set up for a burner system?
Setting the air and fuel using a laptop and appropriate software using a BACnet system
What are valves that are used to automatically throttle flow are generally referred to as?
Control valves
What is the actuation movement that moves a valve disk up and down?
Linear
What is the actuation movement that turns a valve disc 90°?
Rotary
What type of medium actuates a pneumatic valve?
Air
What type of medium actuates a hydraulic valve?
Mineral oil
If a pneumatic gas valve fails it will fail in the open position.
TRUE / FALSE
False
If a hydraulic gas valve fails it will fail in the closed position.
TRUE / FALSE
True
How many recommended pipe diameter lengths of straight pipe before and after the valve should be installed to lessen the chance of internal flow turbulence in the piping manifolds and control valve?
Four
Referring to Figure 1, what type of control valve is depicted?
Hydraulic
Referring to Figure 2, what type of control valve is depicted?
Mechanical
Referring to Figure 3, what type of control valve is depicted?
Pneumatic
What is the power end of the Honeywell, Series 90 Modutrol used for?
It is used to drive linkages
What is the auxiliary end of the Honeywell, Series 90 Modutrol used for?
It is used to devices like auxiliary switches
In what orientation should motors with crankshafts be installed?
Horizontal
How is strain avoided on the motor and linkage of a fuel/air system?
The drive lever rotational start point is kept off of the shaft centerline
Fixed Stroke Actuators are available in what two opening ranges?
90⁰ or 160⁰
Adjustable stroke model actuators can be field adjusted between what range?
90⁰ - 160⁰
What controls the speed and the amount of rotation of the driven lever pivot point?
It is controlled by the starting position of both levers and the connection distance of the linkage to the lever pivot points
Placing the drive lever closer to the shaft centerline than the driven lever is placed will do what to the rotation of the driven lever?
It will be reduced
Placing the driven lever closer to the shaft centerline than the driver lever is placed will do what to the rotation of the driven lever?
It will be increased
How are precise changes made on the linkage for a fuel valve?
By adjusting the cam spring
The gas butterfly valve is used to control modulation and to stop gas flow?
TRUE / FALSE
FALSE - it is not used to stop the gas
How can high and low fire be adjusted on a gas butterfly valve?
By using the stop screws
Where would you find information for making initial set up adjustments to linkages?
From the equipment manufacturer
What must be done while making any adjustments to linkages?
Combustion analysis must be performed
How do we balance safety and efficiency when adjusting our linkages with the use of a combustion analyzer?
- Adding more oxygen reduces the chance of CO and increases safety.
- Reducing oxygen increases our efficiency but has the potential to increase CO thus being less safe.
- Always prioritize safety.
Which two alternate fuels are commonly uses in Liquid form?
2 heating oil, waste oil
Which alternate fuels are commonly used in gaseous form?
- Biogas (digester gas, landfill gas, biomethane)
- Propane-air mixes
What is the most common secondary fuel source?
2 fuel oil
When used in the same appliance natural gas and fuel oil enter the combustion chamber through the same nozzle or injector.
TRUE / FALSE
A benefit of the day tank in a fuel oil system is that by being in the mechanical room the fuel oil is preheated.
TRUE / FALSE
t
What is done to #2 fuel oil to extend its life when stored?
Fuel stabilizers are added
How often should alternate fuel system be operated?
Every 6 months
On average, how much methane is contained in landfill gas?
50% - 60%
On average, how much methane is contained in digester gas?
60% - 70%
How is landfill and digester gas pressurized for use?
A gas blower is used
Which code is used for the installation and upgrading of digester and landfill gases?
B149.6
Why is it so important, when dealing with bio gasses, to avoid contamination with water?
Bio gasses contain hydrogen sulfide which when mixed with moisture create sulphuric acid, which is highly corrosive
What three materials are acceptable for the pipe and fittings in a digester gas installation and where can each be used?
Stainless Steel – general piping
Plastic – underground
Copper – vent lines and bleed lines
Why is a flame arrestor required in the valve train of equipment that burns Biogas?
Flashback can be a problem with this equipment because of the changing composition and available supply volume and pressure
Biogas and natural gas can supply the same burner and can be controlled with an automatic switch over.
TRUE / FALSE
t
Why are propane / air mixes commonly used as a secondary fuel source as a back up to natural gas?
They have a similar calorific value as natural gas and can use in the same burners
How does a venturi mixer combined propane and air?
It uses high pressure propane vapour to entrain air directly from the atmosphere using a venturi
How does an Atmospheric Carburetor system work?
It uses a mixing valve and gas booster to pull the propane/air mix
How does a Pressurized Carburetor system work?
It uses a mixing valve and compressed air to push the propane/air
What is the main benefit of a parallel pipe mixer?
It provides very precise control under varying conditions
Calculate the input of a gas appliance that uses .275 imperial gallons of liquid propane in 40 minutes.
Calculate the input of a gas appliance that uses .33 US gallons of liquid propane in 40 minutes.
Calculate the output of a propane appliance that is 75% efficient and uses 20 lbs of liquid propane per hour.
If a propane appliance was firing continuously at 900 mbh how long would 50 imperial gallons of liquid propane last.
If the flow rate of natural gas through an orifice was 1500 cfh, what would the new flow rate be if the fuel was changed to a 50% propane 50% air mix. All other factors remain the same.
A natural gas boiler with an input of 1,200,000 Btuh uses 55 % propane 45 % air mix as an emergency standby.
What would the input be when operating on the standby fuel if all other orifice flow factors remained the same?
How long would 1000 US gallons of liquid propane last if vaporized to supply the new input?
A natural gas boiler is operating under the following conditions:
- Input 15000 mbh - Single burner - Manifold gas pressure 2 psig - Standby fuel 55% propane 45% air mix
a.What is the area of the orifice based on a 0.9 K factor?
b.What is the input when operating on the standby fuel?
c.How many pounds of liquid propane would be required to
supply the boiler for 48 hours when operating on the
standby fuel?
A natural gas boiler with an input of 1,200,000 Btuh uses 55 % propane 45 % air mix as an emergency standby.
What would the input be when operating on the standby fuel if all other orifice flow factors remained the same?
A natural gas boiler with an input of 1,200,000 Btuh uses 55 % propane 45 % air mix as an emergency standby.
How long would 1000 US gallons of liquid propane last if vaporized to supply the new input?
A natural gas boiler is operating under the following conditions:
- Input 15000 mbh - Single burner - Manifold gas pressure 2 psig - Standby fuel 55% propane 45% air mix
a. What is the area of the orifice based on a 0.9 K factor?
A natural gas boiler is operating under the following conditions:
- Input 15000 mbh - Single burner - Manifold gas pressure 2 psig - Standby fuel 55% propane 45% air mix
b. What is the input when operating on the standby fuel?
A natural gas boiler is operating under the following conditions:
- Input 15000 mbh - Single burner - Manifold gas pressure 2 psig - Standby fuel 55% propane 45% air mix
c.How many pounds of liquid propane would be required to
supply the boiler for 48 hours when operating on the
standby fuel?
What is the minimum operating ambient temperature for the control?
-40°C
What is the maximum operating ambient temperature for the control?
140°F
What is the required minimum line voltage supply for the control?
85 Vac
What is the maximum full load amps (FLA) allowed on terminal 4 for the RM7895?
9.8 amps
What is the maximum relative humidity the control is designed to operate?
0.85
What is the maximum continuous vibration the control can be subjected to?
0.5G
Can the control’s wiring subbase be mounted in the horizontal position?
NO
At what amperage must the dedicated earth ground be capable of conducting the current to blow at?
15A
If a Data ControlBus Module is used what type wire should be used?
Twisted pair shielded cable
If the interconnection daisy chain of more than two modules, i.e. Data ControlBud, Modbus, etc., connections are longer than 100 feet, what must be done?
A 13 Vdc full-wave rectified transformer needs to be installed separately to the daisy chain
What size and type of wire should be used for a remote reset module?
22 AWG two-wire twisted pair
How should the signal ground be connected to modules installed in a daisy chain?
Connect the wire’s shield at both ends of the daisy chain
What is the maximum length of wire for a reset module pushbutton?
1000 feet
How many inches below the relay module are needed for the flame amplifier mounting?
2 inches
Define:Primary Controller
Sequences ignition and monitors flame
Define:Programming Controller
A primary control with programmable options like timed pre-purge, timed ignition trials, timed post purge
Define:Intermittent Pilot
Is ignited on a call for heat, stays lit for the run cycle and is extinguished at the end of the cycle
Define:Interrupted Pilot
Is ignited on a call for heat, lights the main burner then is extinguished while the burner continues the run cycle
Define:Pre-purge
A predetermined time that the blower will run pushing air through the combustion chamber and heat exchanger passes prior to any ignition
Define:Safe start check
On a call for heat the controller checks for presence of a flame and integrity of flame amplifier before starting any burner ignition sequencing functions
Define:Trial for ignition
A limited pre-determined time that the flame detector/amplifier must sense the ignition of a burner flame to allow the controller to continue sequencing.
Define:Flame Relay
A relay within the controller that is actuated once a flame is detected.
Define:Run time
The period of time after the main burner is ignited until the call for heat is satisfied.
Define:Flame failure response time
The limited time that the controller has to de-energize the Safety Shut-off Valves in respond to a loss of flame signal.
Define:Recycle
The normal restart of a controller.
Define:Recycling controller
A controller that will respond to a flame failure by attempting to recycle.
Define:Non Recycling Controller
A controller that will require manually resetting in response to a flame failure.
Define:Dynamic Self Check
A detector and amplifier that verifies its operation during a run cycle installed on burners that do not cycle within a 24 hr period.
Define:Safety Shut Down
When a controller is locked out and must be manually reset.
Define:Pilot Trial for ignition
The maximum permitted time that the controller has to establish a pilot flame.
Define:Early Spark termination
Allows the controller to de-energize the ignition transformer before the main burner is actuated.
Define:Main Burner Trial for Ignition
The time that the pilot and main burner overlap before the pilot is de-energized so the controller can monitor the main flame only. (interrupted pilot)
What was the major weakness of early, AC conductivity flame detection systems?
Carbon deposits created by flame impingement could create a “bridge” between the electrodes that had a similar resistance/conductivity as the flame. Thus creating an unsafe situation.
What is the minimum and preferred ratios of ground electrode to flame electrode?
- Minimum 4:1
- Preferred 10:1
Where is the ground electrode usually located?
In the burner head
What is rectification?
The conversion of an alternating current to a direct current
How does a diode work?
It operates like a check valve. It has low resistance in one direction and high resistance in the other
What is identified by the flame safeguard to prove that a flame is present?
The imbalance of current flow. In this way the flame safeguard can distinguish between a short to ground and a flame
What are the three characteristics of a premix pilot?
- Strong
- Stable
- Higher flame propagation
(A raw gas pilot is the opposite of these)
How quickly can a flame rod amplifier detect the loss of flame?
Within microseconds
What must be done when setting a pilot burner/flame rod system?
A pilot turndown test must be performed
On an in-shot burner the flame rod should be position above the burner.
TRUE / FALSE
False
What are the two main advantages of flame rod systems?
- Quick response to flame failure
- Flame rods cannot be bypassed or defeated
Flame rods can be used with fuel oil systems.
TRUE / FALSE
False
Flame rods can be used to supervise pilot only, main flame only or pilot and main flame.
TRUE / FALSE
True
What do you use to clean a flame rod?
A Scotch Brite pad
What part of the flame should the sighting be most concentrated on when sighting an ultraviolet flame detector?
The first third
What part of the flame should the sighting be most concentrated on when sighting an infrared flame detector?
The last third
What part of the flame is visible light most concentrated in?
The middle
Referring to the Figure below, what UV flame scanner position would be the most ideal?
UV scanner #2
Which flame detector is not compatible for supervising oil burners?
Flame rod
Which flame detector is not compatible for supervising natural gas burners?
Photo cell
Which type of flame detector is not light responsive?
Flame rod
Which type of flame detector can be affected by refractory glow?
Infrared
Which type of flame detector can be affected by UV radiation from the ignition spark?
Ultraviolet
What type of test should be performed to ensure the optic flame detector cannot detect ignition spark?
Spark rejection test
What three things can be done to restrict the field of view for an optical flame sensor?
- Adding an orifice to the sighting pipe
- Lengthening the sighting pipe
- Decreasing the diameter of the sighting pipe
Why do UV optical flame sensors use quartz glass to contain the gas and electrodes?
It does not block UV light
When is a self-checking type flame detector required?
When the burner firing cycle can last longer than 24 hours without cycling
What inputs does the flame safeguard primary control receive?
Flame detector, controller, and limits
What outputs does the flame safeguard primary control output?
Burner motor, ignition transformer, pilot valve, main fuel valve
What additional inputs does a flame safeguard programming control receive?
A Flame Safeguard Programming Control (FSG) adds timing capability that enables the control to time the sequence functions like purges and ignition trial periods and adds interlocks to the inputs
The trial for ignition period of a main burner flame from an intermittent or interrupted pilot flame shall not exceed how many seconds?
10 seconds
When combustion air is supplied by mechanical means and the ignition is by means of a direct spark, interrupted pilot or intermittent pilot how many combustion zone/flue passage air changes are required?
4 air changes
All Flame Safeguards must perform what three basic functions?
- Check itself against unsafe failure by checking for a flame-simulating condition before start-up. If a condition is present the burner cannot start.
- Sequence the operation, start, run and shutdown of the burner system
- Supervise the presence of a flame, cutting off the fuel supply if a flame is not present
What are the two trial for ignition settings that are field selectable on a RM7890 Flame Safeguard?
4 or 10 seconds
On a RM7890 what two things will happen if flame is lost during the Main Flame Establishing Period?
The control will lock out and alarm will be triggered
What happens if the RM7890 senses a flame during the standby period?
The control will lock out and present a fault
Referring to the figure below, does the fuel train require an overtravel proof of closure switch?
No - pilot fuel train 7.1.6
At what percentage of input is considered to be maximum for low fire start position when the burner input is in excess of 1,000,000 Btus?
0.4
What is the maximum trial for ignition period of an intermittent or interrupted pilot flame?
10 Seconds
What is the maximum trial-for-ignition period of a main burner flame from an intermittent or interrupted pilot flame?
10 Seconds
When is a pre-purge required for a burner?
When the combustion supply is by mechanical means and an intermittent pilot is used.
When is a proven low fire start required for a gas fired appliance?
When the appliance input is in excess of 1,000 MBH
When a purge timer is used it shall provide a means of adjustment for proper setting in the field?
False
Referring to the Fireye E110 control manual, where would the combustion air switch be wired on the sub-base?
3-P
Referring to the Fireye E110 control manual, what terminals must make to drive the firing rate motor to high fire?
10-X
Referring to the Fireye E110 control manual, which terminals need to be made to to prove low fire start position?
M-D
Referring to the Fireye E110 control manual, which terminals need to be made to start the high fire purge?
D-8
Referring to the Honeywell 7895 control manual, what is the operation sequence of the ignition transformer and pilot system of the 7895A 1048 control?
Interrupted ignition / intermittent pilot
Referring to the Honeywell 7895 control manual, where would the combustion air switch be wired on the sub-base?
37049
Referring to the Honeywell 7895 control manual, what needs to be done to the 7895A control to ensure lockout on failure of the combustion air proving switch (CAPS)?
Remove jumper JR3
Referring to the Honeywell 7895 control manual, what will happen if a jumper is clipped and removed after 200 hours of operation?
It will cause a non-resettable fault 110, and the relay module must then be replaced
If during the run cycle of a 7895 controller, the operating aqua stat’s contacts remain closed and the high limit Aquastat contacts have opened, what is the expected outcome?
The appliance will restart once the high limit is reset
What is the approximate pre-purge time in seconds required for a 78% efficient boiler with an input of 11,456 MBH running at 23% excess air and has a total internal flue volume (including heat exchanger and flue passages) of 133 ft3?
14 seconds
What is the approximate pre-purge time for pre-purge for a 5,000,000 Btu appliance with a forced draft burner that is operating on a 45% propane and 55% air mix, the excess air set at 30%, and the Combustion chamber and flue passages total 50 ft3?
11 seconds
Calculate the approximate pre-purge time for a steam boiler using the following information:
- Rating: 645 Boiler Horsepower
- Efficiency: 81%
- Fuel: CH4
- Calorific value of fuel: 1,099 Btu/ft3
- Excess air: 21%
- Water capacity: 1,242 U.S. gallons
- Shell length: 153 inches
- Internal Diameter: 74 inches
11 seconds
How many air changes of the combustion chamber and flue passages are required for a pre-purge of a gas fired appliance?
4 air changes
How any subcategories of fuel oil are there?
six; #1, #2, #3, #4, #5, #6
Fuel oils #1 and #2 are considered to be what type of fuel oil?
Distillate oils
Fuel oils #3 and #4 are considered to be what type of fuel oil?
Combined distillate and residual oils
Fuel oils #5 and #6 are considered to be what type of fuel oil?
Residual oils
Do distillate oils require preheating before burning?
No
For C15H28 #2 oil, how much cubic feet of air would be required for perfect combustion?
110 ft3
For C15H28 #2 oil, what would be the expected percent of CO2 be when performing a combustion analysis if the excess air is 22%?
0.11789999999999999
For C15H28 #2 oil, what would be the expected percent of O2 be when performing a combustion analysis if the excess air is 22%?
0.0381
What is defined as waste oil?
Any new or used oil that has been mixed with a known hazardous substance
How many Part per million (ppm) of halogen concentration does new oil need to have to be considered waste oil?
1,000 ppm
Waste oil cannot be incinerated in British Columbia.
False
What is one condition that needs to be met to allow used oil to be mixed with fuel oil for use in a used oil furnace?
The mixtures flash point can not be lower than 37.7°C
What type of heater can be used when firing waste oil?
An Environmental Protection Agency approved heater
What methods are used to vaporize liquid propane?
steam, electricity, fuel
What are the different types of fuel vaporizers?
direct-fired, indirect-fired, tank heater
Referring to the figure below, what type of vaporizer is represented?
direct-fired
Referring to the figure below, what type of vaporizer is represented?
indirect-fired
Referring to the figure below, what type of vaporizer is represented?
tank heater
What should be installed on a liquid propane vaporizer system to provide sufficient pressure to the inlet of a vaporizer during conditions of low tank pressure?
liquid pump
Referring to the figure below, what should the optional vapor line regulator be set to?
2 psig lower than the vapor outlet line
On a propane vaporizer system, a separator and/or drip leg should be installed upstream of outlet pressure regulator.
True / False
False
Referring to the figure below, what is the maximum recommended distance the outlet pressure regulator should be from the vaporizer outlet?
24 inches
On a propane vaporizer system, the outlet pressure regulator should be installed at or below the height of the vaporizer outlet.
True / False
False
If plastic pipe is used on the downstream side of the vaporizer, how close to the vaporizer can the connection be to the outlet of the vaporizer before needing to be steel pipe?
10 feet
When a building contains a vaporizer, what way shall the exit doors swing?
outwards
For a propane dispensing system, what shall the fuel dispensing hose be equipped with?
breakaway quick-closing coupling
In accordance with what code shall the install requirements be for the supply piping to a propane dispenser?
B149.1
Where shall a vehicle dispenser system be located?
Outdoors and may be located under an overhead canopy
How far does the discharge from a propane dispenser purging equipment vent pipe need to be installed from a source of ignition?
10 feet
What is the minimum buried depth that posts need to be installed below grade that protect a propane dispenser?
36 inches
A propane dispenser located on an island does not need to be protected by posts as long as the pump and the internal valve are interlocked so that the valve is closed when the pump is not running.
True / False
True
How far away shall a propane dispensing system need to be located from a combustible building?
25 feet
The return lines for a dispensing device that is connected to a liquid space of a propane tank does not require a back check valve as long as a bypass is installed to the vapor side of the tank.
True / False
False
