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WorksheetsTypes of Family Gases and Their Characteristics
Total questions: 46
Worksheet time: 23mins
What are the three types of family gases ?
First, second, and third family gases
Primary, secondary, and tertiary gases
Alpha, beta, and gamma gases
Initial, middle, and final gases
What does The Gas Regulations (GSIUR) Regulation 26(9) state regarding an operative who works on a gas appliance?
The effectiveness of any flue;
The supply of combustion air;
Its operating pressure or heat input, or where necessary, both;
Its combustion performance;
Why is an odourant added to natural gas and LPG?
To improve combustion efficiency
To help identify the presence of gas in the air
To increase the energy content
To reduce the cost of gas
Which chemical was originally used to add odour to gas?
Diethyl sulphide
Ethyl mercaptan
Tetrahydrothiophene
Methane
What are the more commonly used chemicals now for adding odour to gas?
Methane and propane
Diethyl sulphide and ethyl mercaptan
Carbon dioxide and nitrogen
Hydrogen and oxygen
How much odourant is typically used to give gas a recognisable smell?
A large amount
A moderate amount
A tiny amount
None
What does the toxicity of a gas imply?
It is flammable.
It is non-reactive.
It is poisonous and can cause death if inhaled.
It is odorless.
What was Town Gas (Family 1) originally processed from?
Natural gas
Coal
LPG
Oil
What harmful substance does Town Gas produce in its natural state?
Carbon Dioxide
Methane
Carbon Monoxide
Nitrogen
Which family of gases does not contain Carbon Monoxide and is non-toxic?
Family 1
Family 2
Family 3
Family 4
What can occur if incomplete combustion happens during the burning of natural gas?
Water is produced.
Carbon Monoxide is produced.
Oxygen is produced.
Methane is produced.
What is the calorific value (CV) of gas in the UK measured in?
Kilojoules per cubic metre
Megajoules per cubic metre
Calories per litre
Watts per cubic metre
What does the calorific value (CV) indicate when gas burns?
The color of the flame
The amount of gas used
The heating power released
The speed of combustion
What is the approximate calorific value (CV) of gas in the UK?
25.0 MJ/m³
38.5 MJ/m³
45.0 MJ/m³
50.0 MJ/m³
What does the gross-calorific value include during the combustion process?
Only the heat from the gas
Heat excluding water vapor
Heat including water vapor
Only the energy from the flame
What is the specific gravity of natural gas?
0.58
1.00
1.50
0.75
Compared to air, how does the specific gravity of LPG gases affect their behavior?
They rise above air.
They fall to a low level.
They remain at the same level as air.
They evaporate quickly.
What is the specific gravity of propane compared to air?
0.58
1.00
1.50
0.75
What is the specific gravity of propane compared to air?
0.58
1.5
2
1
Which gas has the highest gross calorific value?
Natural gas
Propane
Butane
Air
What is the air-gas ratio for natural gas?
9.8 : 1
23.8 : 1
30.9 : 1
5 : 1
Which gas has the lowest ignition temperature?
Natural gas
Propane
Butane
Air
What is the flame speed of butane?
0.36 m/s
0.46 m/s
0.38 m/s
0.50 m/s
What is the effect of the air-gas mixture traveling too fast as a result of excess pressure?
The flame will lift off the burner.
The flame will extinguish.
The flame will become brighter.
The flame will change color.
What happens if the flame speed is too slow?
The flame could light back along the mixing tube.
The flame will lift off the burner.
The flame will become unstable.
The flame will extinguish.
What does the Wobbe number indicate?
The color of the flame
The heat output from a burner when a specific gas is used
The size of the gas tank
The type of gas used
What determines the amount of heat released at a burner?
The color of the gas
The type of burner used
The calorific value (CV) of the gas
The temperature of the room
What factors affect the rate at which gas is burned?
The color of the gas
The size of the burner injector, gas pressure, and relative weight
The type of gas used
The temperature of the burner
What two sets of information does the Wobbe number link together?
Calorific value and specific gravity
Injector size and gas pressure
Temperature and pressure
Volume and density
How is the Wobbe number calculated?
CV divided by SG
CV multiplied by SG
CV divided by the square root of SG
CV multiplied by the square root of SG
What is the Wobbe number for natural gas given a calorific value of 38.5 MJ/m³ and a specific gravity of 0.58?
45.00
50.55
55.00
60.55
Formula for Wobbe number: Wobbe number = CV / √SG
Wobbe number = CV * SG
Wobbe number = CV / SG
Wobbe number = CV * √SG
Wobbe number = CV / √SG
What is the Wobbe number range for Family 1 gases?
23–29
47–54
72–87
30–40
Which type of gas is associated with a Wobbe number range of 47–54?
Town Gas (manufactured)
Natural
LPG
Biogas
What gas type corresponds to Family 3?
Town Gas (manufactured)
Natural
LPG
Hydrogen
How many different families of gases are mentioned in the document?
1
2
3
4
Where would an operative find their mandatory duties regarding correct combustion when working on gas appliances?
In the appliance manual
In the safety regulations handbook
In the manufacturer's guidelines
In the operative's training manual
What is the specific gravity (SG) of methane?
0.55
0.65
0.75
0.85
When would CO be present in the products of combustion?
When combustion is complete
When there is excess oxygen
When combustion is incomplete
When there is no fuel
State the families of gas and their respective numbers.
Family 1, 2, 3
Group A, B, C
Type X, Y, Z
Class I, II, III
Work out the Wobbe number for a natural gas appliance with a CV of 39 MJ/m³.
45
50
55
60
In which regulation can an operative find their mandatory duties regarding correct combustion when working on gas appliances?
Regulation 26(9)
Regulation 15(4)
Regulation 30(2)
Regulation 12(7)
What is the specific gravity (SG) of Methane?
0.58
0.75
0.62
0.80
When would CO be present during combustion?
Incomplete combustion
Complete combustion
Rapid combustion
Slow combustion
Which of the following is not a family of gas mentioned in the document?
Natural gas Family 2
LPG Family 3
Hydrogen gas Family 4
Town/manufactured gas Family 1
What is the Wobbe number for a natural gas appliance with a CV of 39 MJ/m³?
51.21
45.00
60.15
55.30
