Level 1 Class B Review Quiz

Question 1

State the chemical abbreviations for propane and natural gas.

Answer 1

Propane: C3H8, Natural Gas: CH4

Question 2

State the ignition temperatures of propane and natural gas.

Answer 2

Propane: 920o to 1020oF, Natural Gas: 1100o to 1300oF

Question 3

List the specific gravities for natural gas, propane vapour, and liquid propane.

Answer 3

Natural Gas: 0.6, Propane vapour: 1.5, Propane liquid: 0.51

Question 4

What are the limits of flammability for natural gas and propane?

Answer 4

Natural Gas: 4 to 14%, Propane: 2.4 to 9.5%

Question 5

What are the maximum flame temperatures that can be achieved with propane and with natural gas when mixed with air?

Answer 5

CH4:3500oF, C3H8: 3600oF

Question 6

What are the boiling temperatures of propane and natural gas at sea level?

Answer 6

Propane: -44oF, Natural Gas: -258oF

Question 7

What are the flame speeds of natural gas and propane?

Answer 7

25”/sec., 32”/sec. (tube method)

Question 8

Define the term Btu.

Answer 8

British thermal unit. The amount of energy acquired or liberated when changing the temperature of 1 lb. of water 1oF

Question 9

What is the energy content of 1 cubic foot of propane and 1 cubic foot of natural gas?

Answer 9

C3H8:2500 Btu/ft3, CH4:1000 Btu/ft3

Question 10

List the products of complete combustion of natural gas and propane.

Answer 10

CO2 + H2O + N2

Question 11

What are the expansion ratios from liquid to vapour for natural gas and propane?

Answer 11

CH4: 1:600, C3H8: 1:270

Question 12

What are the percentages of nitrogen and oxygen found in air?

Answer 12

O2 = 20%, N2 = 80%

Question 13

What is the air/gas ratio required to achieve complete combustion of natural gas and propane?

Answer 13

CH4: 10:1, C3H8: 25:1

Question 14

What is the ratio of air to Btu content required to complete combustion of all hydrocarbon gases?

Answer 14

10ft3/1000Btu

Question 15

How many Btu equal one kilowatt?

Answer 15

3413 Btu/Kw

Question 16

Explain the term primary air, with reference to an atmospheric burner.

Answer 16

The air entrained and mixed prior to combustion

Question 17

What is the term used to describe the additional air supplied to the combustion chamber of a gas appliance to ensure complete combustion?

Answer 17

Excess Air

Question 18

What is the purpose of dilution air?

Answer 18

To reduce the velocity of the flue gasses

Question 19

A gas appliance is considered to be high input when it exceeds what input?

Answer 19

400,000 Btu/hr., aka. 400MBH

Question 20

What are the pressure limitations of a Class “B” license?

Answer 20

No pressure limitations however Safety Standards Act is limited to 700Kpa (100Psi)

Question 21

pipe sizing

Answer 21

Question 22

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?

Answer 22

Question 23

Calculate the correction factor required when converting gas at 40 degrees F. to standard gas temperature conditions.

Answer 23

Question 24

Calculate the correction factor required when converting gas under a pressure of
134.5 kPa absolute to standard gas pressure conditions.

Answer 24

Question 25

100 cubic meters of gas is pressurized at 50 psig. Calculate the new volume if the gas is released to atmosphere at sea level.

Answer 25

a

Question 26

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.

Answer 26

Question 27

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.

Answer 27

Question 28

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.

Answer 28

Question 29

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

Answer 29

Question 30

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?

Answer 30

Question 31

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

Answer 31

Question 32

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

Answer 32

Question 33

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

Answer 33

Burners are not capable of perfectly mixing air and fuel

Question 34

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

Answer 34

To ensure complete combustion occurs

Question 35

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

Answer 35

10 ft3 to 1000 Btu

Question 36

What is a colourless, odourless, tasteless, and potentially lethal by-product of incomplete combustion? Oxygen Carbon monoxide Nitrogen Aldehydes

Answer 36

Carbon monoxide

Question 37

What is a colourless, acrid smelling toxic by-product of incomplete combustion? Oxygen Carbon monoxide Nitrogen Aldehydes

Answer 37

Aldehydes

Question 38

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

Answer 38

Flame temperature dropping below 1,200°F

Question 39

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

Answer 39

upstream of the draft control device

Question 40

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

Answer 40

Both have the same air requirements, but propane has higher CO2

Question 41

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

Answer 41

none is required

Question 42

What percentage of excess air will produce equal percentages of O2 and CO2 in the flue products? 25% 33% 50% 100%

Answer 42

50%

Question 43

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

Answer 43

cracked heat exchanger

Question 44

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

Answer 44

same as ambient

Question 45

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

Answer 45

1,000 ft3

Question 46

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

Answer 46

3,600 ft3

Question 47

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

Answer 47

30 Imperial gallons

Question 48

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%

Answer 48

4.1 %

Question 49

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%

Answer 49

8.85 %

Question 50

What is absolute zero equal to in: Degrees F? Degrees C?

Answer 50

Degrees F: -460 F, Degrees C: -273 F

Question 51

Convert 30 degrees Fahrenheit to Celsius

Answer 51

30 – 32 / 1.8 = -1.1 C

Question 52

Convert 30 degrees Celsius to Fahrenheit

Answer 52

30 X 1.8 + 32 = 86 F

Question 53

Define sensible heat

Answer 53

Heat that can be measured

Question 54

Define latent heat

Answer 54

Heat energy required or liberated during a change of state

Question 55

State the number of BTU’s required to change 1 lb. of 32oF ice to 32oF water.

Answer 55

144 BTU

Question 56

State the number of BTU’s required to change 1 lb. of 212oF water to 212oF steam

Answer 56

970.4 BTU

Question 57

State the specific heat of water

Answer 57

1

Question 58

State the specific heat of steam

Answer 58

0.48 (ice: 0.53)

Question 59

What is the formula to find the efficiency of a gas fired appliance?

Answer 59

Output/Input

Question 60

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

Answer 60

Units with draft control require dilution air

Question 61

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

Answer 61

1000 Mbh appliance with a draft hood and atmospheric burner

Question 62

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

Answer 62

8 inch

Question 63

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

Answer 63

7 Inch

Question 64

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

Answer 64

343 in2

Question 65

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"

Answer 65

15" ´ 20”

Question 66

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

Answer 66

30 ft3 for each 1,000 Btu/h