WorksheetsCharacteristics of combustion
Total questions: 22
Worksheet time: 40mins
what is the most common cause of incomplete combustion of an open flued appliance
the primary ports become blocked with a build up of lint, fibres
the secondary ports become blocked due to lint, fibres etc
the burner injector becomes enlarged
the burner is damaged due to corrosion or heat stress
An obvious sign of incomplete combustion of an open flued central heating boiler is
explosive ignition
yellow flames at the burner
carbon monoxide alarm activating
signs of spillage at the draught diverter
The process of stoichiometric combustion is shown in which following chemical equation
CH4+2O2 = CO2+2H2O
2CH4+3O2 = 2CO+4H2O
CH4+O2 = C+2H2O
2CH4+5O2=2CO2 +4H2O
In reality oxygen is not supplied neat, but is supplied by the provision of air. Air is generally taken to consist of
20% Nitrogen and 80% oxygen.
20.9% Oxygen and 79.1% Nitrogen
20.9% Nitrogen and 79.1% Oxygen
20% Oxygen and 80% Nitrogen
Battery and mains powered carbon monoxide detectors are now manufactured to which standard
BS 7860
BS 5440-1
BS EN 50291
BS 5440-2
If CO poisoning is suspected, any person affected must be
Given medical advice over the phone
removed from any room containing a gas appliance and relocated to another room
advised that gas appliances should be serviced immediately
removed from the area and relocated to the open air immediately
what level of CO could cause a carbon monoxide alarm to go off within 3 minutes
35 ppm
50ppm
100ppm
300ppm
What type of sensors are fitted within a typical flue gas analyser?
carbon dioxide and oxygen
carbon monoxide
oxygen
carbon monoxide and oxygen
Which of the following is likely to cause vitiation of a room sealed balanced, fanned draught combi boiler?
Room air supply is contaminated
incorrectly assembled flue
partially blocked injectors
fan failure
when sufficient oxygen is mixed with gas and complete combustion occurs the main constituents produced are
carbon monoxide and hydrogen
carbon dioxide, carbon monoxide and hydrogen
carbon dioxide and water vapour
carbon monoxide and water vapour
The main symptoms of carbon monoxide poisoning are
headaches , nausea
backaches headaches
nausea backaches
tiredness, thirst
The critical percentage level of carbon monoxide that causes vitiation affecting the combustion process is
1.5% - 2%
1% - 1.5%
0.5% - 1%
0% - 0.5%
when using a flue gas analyser an oxygen reading is used to calculate the CO2%, this is required to be taken in
outdoor air of more than 25%
Indoor air of 20.9%
Outdoor air of 20.9%
Indoor air of more than 25%
Which of the following is UNLIKELY to be a potential source of carbon monoxide generation
a fuel burning appliance in a dwelling
A electric fire
vehicles or generators in an attached building
an engine on a boat
for the complete combustion of natural gas there must be an air to gas ratio of what?
15:1
7:1
10:1
20:1
What effects could a damaged, defective or poorly fitting case seal have on a fan assisted room sealed boiler
affect the combustion
allow products of combustion to enter the property
result in the boiler being classified as immediately dangerous
all of the above
what constituents make up natural gas? (module 3 page.3)
methane, ethane, propane, butane, nitrogen, carbon dioxide
methane, ethane, propane, hydrogen, nitrogen, carbon dioxide
methane, ethane, propane, butane, nitrogen, carbon monoxide
methane, ethane, propane, butane, nitrogen, oxygen
What are the explosive limited of natural gas and LPG (Gas to air ration)
5-10%
5-15%
10-20%
0.5%
What is the ignition temperature of Natural Gas?
650-680 degrees C
230-340 degrees C
482-632 degrees C
912 - 1052 degrees C
What is the flame speed of Natural Gas? (Module 3 page 5)
0.56 m/sec
0.36 m/sec
0.76 m/sec
0.26 m/sec
What is the specific density of Natural gas compared to air (module 3 page 5)
0.6
0.7
2.1
8.9
What is the substance added to natural gas to make it smell?
sulphur dioxide
ethanethoil mercaptan
butane ethanol
hydrogen sulphide
