OBT3 ACTUAL EXAM PAPER 2026 QUESTIONS
WITH SOLUTIONS GRADED A+
◉ Approximately 96% to 99.75% of fuel oil is composed of. Answer:
Hydrogen and carbon
◉ The two general categories of refined fuel oils are. Answer: Distillates
and residuals
◉ True or false: kerosine is classified separately from fuel oil but
considered as fuel oil under the fuel oil code. Answer: True
◉ 0 fuel oil application. Answer: Intended for use in appliances in far
northern regions
◉ 1 fuel oil applications. Answer: Used where #w fuel oil cant be used
satisfactory
◉ #2 fuel oil applications. Answer: Used in most domestic type burners
◉ #4 fuel oil applications. Answer: Industrial type fuel for burners not
equipped with preheaters
,◉ #5 fuel oil applications. Answer: Useed in burners equipped with pre-
heaters requiring greater fluidity of #6 six
◉ #6 fuel oil. Answer: Only be employed in burner equipped with pre
heaters
◉ Degrees of API gravity is a measurement scale of a fuel oil's. Answer:
Density or weight
◉ #2 fuel oil has a API gravity range of. Answer: 30-36
◉ The commonly excepted heat value of number 2 fuel oil
is__________ BTU/us gallon. Answer: 140 000
◉ If the input reading of an appliance is 91,000 BTU the correct nozzle
size would be. Answer: 0.65
◉ Viscosity is a measure of a fluids. Answer: Resistance to flow
◉ A fuel oil's viscosity_____________ (increases or decreases) as the
temperature of fuel oil decreases. Answer: Increases
◉ The distillation characteristics of a fuel oil indicates it's. Answer:
Volatility and ability to vaporize
,◉ T or f. Liquid fuel oil will burn. Answer: False
◉ Flashpoint is defined as the lowest temperature and which a few oil
will. Answer: Vapours will first ignite when exposed to a flame
◉ Fire point is defined as the lowest temperature at which fuel oil will.
Answer: There are sufficient vapours generated by the heated oil
◉ Poor point is defined as the lowest temperature at which fuel oil will.
Answer: No longer flow
◉ Cloud point is defined as the lowest temperature At which fuel oil
will. Answer: Wax crystals begin to form
◉ Sulphur is a. Answer: Corrosive chemical compound found in minor
amounts in few oil
◉ Name two reasons that water is found in a fuel oil storage tanks.
Answer: 1) water is heavier than oil
2) it's a breeding ground for micro scopic bacterial growth
◉ True or false) colour and odour or reliable indicators of the properties
and qualities of fuel oil. Answer: False
, ◉ The products of a complete combustion of fuel oil and air are.
Answer: Carbon dioxide
◉ The ultimate CO2 from the combustion of number 2 fuel oil and air
is. Answer: 15.3%
◉ Name three undesirable products incomplete incomplete combustion.
Answer: Soot, carbon monoxide, reduced heat
◉ Carbon dioxide and nitrogen are. Answer: Toxic gases
◉ What gas is a inert and passes through the combustion reaction
without significant effect except for absorbing heat. Answer: Nitrogen
◉ Describe the symptoms of carbon monoxide poisoning. Answer:
Headaches, dizziness, nausea without fever
◉ (True or false) the appearance of a few oil flame specifically it's
colour insert production, is the best indicator of the quality of the
combustion process. Answer: False
◉ Name the two ways of preparing feel oil for combustion. Answer:
Vaporization and atomization
WITH SOLUTIONS GRADED A+
◉ Approximately 96% to 99.75% of fuel oil is composed of. Answer:
Hydrogen and carbon
◉ The two general categories of refined fuel oils are. Answer: Distillates
and residuals
◉ True or false: kerosine is classified separately from fuel oil but
considered as fuel oil under the fuel oil code. Answer: True
◉ 0 fuel oil application. Answer: Intended for use in appliances in far
northern regions
◉ 1 fuel oil applications. Answer: Used where #w fuel oil cant be used
satisfactory
◉ #2 fuel oil applications. Answer: Used in most domestic type burners
◉ #4 fuel oil applications. Answer: Industrial type fuel for burners not
equipped with preheaters
,◉ #5 fuel oil applications. Answer: Useed in burners equipped with pre-
heaters requiring greater fluidity of #6 six
◉ #6 fuel oil. Answer: Only be employed in burner equipped with pre
heaters
◉ Degrees of API gravity is a measurement scale of a fuel oil's. Answer:
Density or weight
◉ #2 fuel oil has a API gravity range of. Answer: 30-36
◉ The commonly excepted heat value of number 2 fuel oil
is__________ BTU/us gallon. Answer: 140 000
◉ If the input reading of an appliance is 91,000 BTU the correct nozzle
size would be. Answer: 0.65
◉ Viscosity is a measure of a fluids. Answer: Resistance to flow
◉ A fuel oil's viscosity_____________ (increases or decreases) as the
temperature of fuel oil decreases. Answer: Increases
◉ The distillation characteristics of a fuel oil indicates it's. Answer:
Volatility and ability to vaporize
,◉ T or f. Liquid fuel oil will burn. Answer: False
◉ Flashpoint is defined as the lowest temperature and which a few oil
will. Answer: Vapours will first ignite when exposed to a flame
◉ Fire point is defined as the lowest temperature at which fuel oil will.
Answer: There are sufficient vapours generated by the heated oil
◉ Poor point is defined as the lowest temperature at which fuel oil will.
Answer: No longer flow
◉ Cloud point is defined as the lowest temperature At which fuel oil
will. Answer: Wax crystals begin to form
◉ Sulphur is a. Answer: Corrosive chemical compound found in minor
amounts in few oil
◉ Name two reasons that water is found in a fuel oil storage tanks.
Answer: 1) water is heavier than oil
2) it's a breeding ground for micro scopic bacterial growth
◉ True or false) colour and odour or reliable indicators of the properties
and qualities of fuel oil. Answer: False
, ◉ The products of a complete combustion of fuel oil and air are.
Answer: Carbon dioxide
◉ The ultimate CO2 from the combustion of number 2 fuel oil and air
is. Answer: 15.3%
◉ Name three undesirable products incomplete incomplete combustion.
Answer: Soot, carbon monoxide, reduced heat
◉ Carbon dioxide and nitrogen are. Answer: Toxic gases
◉ What gas is a inert and passes through the combustion reaction
without significant effect except for absorbing heat. Answer: Nitrogen
◉ Describe the symptoms of carbon monoxide poisoning. Answer:
Headaches, dizziness, nausea without fever
◉ (True or false) the appearance of a few oil flame specifically it's
colour insert production, is the best indicator of the quality of the
combustion process. Answer: False
◉ Name the two ways of preparing feel oil for combustion. Answer:
Vaporization and atomization
