NFI FINAL EXAM 2025-2026 PREP
QUESTIONS AND ANSWERS GRADED A+
LATEST
For complete combustion: air is ______ % oxygen + _____ % nitrogen
20 : 80
For complete combustion, __(QTY)__ molecules of __(PART)___ need to be
mixed with ___(QTY)__ molecule of _____(PART)____ in the presence of
__(PART)__
2 oxygen : 1 fuel : heat
When complete combustion happens __(4 things)___ are released
heat, carbon dioxide (C02), water vapor (H20), and nitrogen (N)
Carbon monoxide is dangerous because (other than senseless)
it mixes with blood and reduces oxygen carrying capacity
,Aldehydes
chemical compounds that have a strong pungent odor
Carbon monoxide is ________ when aldehydes are present
present
Aldehydes result from
flame impingement and through the presence of contaminated air
Efficiency formula
Heat output divided by heat input (percentage of heat transferred to room)
Combustion Requirements (3)
Air, Fuel, Heat
Complete Combustion Produces (4)
Water vapor, carbon dioxide, heat, and non combustible ashes
,incomplete combustion produces (3)
carbon monoxide, hydrocarbons, and other gases
rate at which fuel burns is controlled by
the amount of available air
air to fuel ratio is a
critical factor in obtaining optimum fuel combustion
BTU
British Thermal Unit, The amount of energy needed to heat one pound of water
one degree Fahrenheit
wood ignites at
450-550 F
natural gas ignites at
, 1,150 F
propane ignites at
920-1120 F
electric spark temp
1,700 F
hot surface igniter temp
2,400 F
butane lighter temp
3,200 F
stick match temp
3,000 F
QUESTIONS AND ANSWERS GRADED A+
LATEST
For complete combustion: air is ______ % oxygen + _____ % nitrogen
20 : 80
For complete combustion, __(QTY)__ molecules of __(PART)___ need to be
mixed with ___(QTY)__ molecule of _____(PART)____ in the presence of
__(PART)__
2 oxygen : 1 fuel : heat
When complete combustion happens __(4 things)___ are released
heat, carbon dioxide (C02), water vapor (H20), and nitrogen (N)
Carbon monoxide is dangerous because (other than senseless)
it mixes with blood and reduces oxygen carrying capacity
,Aldehydes
chemical compounds that have a strong pungent odor
Carbon monoxide is ________ when aldehydes are present
present
Aldehydes result from
flame impingement and through the presence of contaminated air
Efficiency formula
Heat output divided by heat input (percentage of heat transferred to room)
Combustion Requirements (3)
Air, Fuel, Heat
Complete Combustion Produces (4)
Water vapor, carbon dioxide, heat, and non combustible ashes
,incomplete combustion produces (3)
carbon monoxide, hydrocarbons, and other gases
rate at which fuel burns is controlled by
the amount of available air
air to fuel ratio is a
critical factor in obtaining optimum fuel combustion
BTU
British Thermal Unit, The amount of energy needed to heat one pound of water
one degree Fahrenheit
wood ignites at
450-550 F
natural gas ignites at
, 1,150 F
propane ignites at
920-1120 F
electric spark temp
1,700 F
hot surface igniter temp
2,400 F
butane lighter temp
3,200 F
stick match temp
3,000 F
