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NFI EXAM REVIEW QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS
Combustion Requirements (3) - ANSWER Air, Fuel, Heat
Complete Combustion Produces (4) - ANSWER Water
vapor, carbon dioxide, heat, and non combustible ashes
incomplete combustion produces (3) - ANSWER carbon
monoxide, hydrocarbons, and other gases
rate at which fuel burns is controlled by - ANSWER the
amount of available air
air to fuel ratio is a - ANSWER critical factor in obtaining
optimum fuel combustion
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BTU - ANSWER British Thermal Unit, The amount of
energy needed to heat one pound of water one degree
Fahrenheit
wood ignites at - ANSWER 450-550 F
natural gas ignites at - ANSWER 1,150 F
propane ignites at - ANSWER 920-1120 F
electric spark temp - ANSWER 1,700 F
hot surface igniter temp - ANSWER 2,400 F
butane lighter temp - ANSWER 3,200 F
stick match temp - ANSWER 3,000 F
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cigarette temp - ANSWER 500-800 F
For complete combustion: air is ______ % oxygen +
_____ % nitrogen - ANSWER 20 : 80
for complete combustion, __(QTY)__ molecules of
__(PART)___ need to be mixed with ___(QTY)__ molecule
of _____(PART)____ in the presence of __(PART)__ -
ANSWER 2 oxygen : 1 fuel : heat
When complete combustion happens __(4 things)___ are
released - ANSWER heat, carbon dioxide (C02), water
vapor (H20), and nitrogen (N)
Carbon monoxide is dangerous because (other than
senseless) - ANSWER it mixes with blood and reduces
oxygen carrying capacity
Aldehydes - ANSWER chemical compounds that have a
strong pungent odor
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Carbon monoxide is ________ when aldehydes are
present - ANSWER present
Aldehydes result from - ANSWER flame impingement and
through the presence of contaminated air
Efficiency formula - ANSWER Heat output divided by heat
input (percentage of heat transferred to room)
3 Ts of efficiency - ANSWER Temperature, turbulence,
time
Temperature (efficiency) - ANSWER minimum ignition
temp
Turbulence (efficiency) - ANSWER fuel must collide with
oxygen molecules (refers to the degree of fuel and air
mixing that occurs in combustion zone)
NFI EXAM REVIEW QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS
Combustion Requirements (3) - ANSWER Air, Fuel, Heat
Complete Combustion Produces (4) - ANSWER Water
vapor, carbon dioxide, heat, and non combustible ashes
incomplete combustion produces (3) - ANSWER carbon
monoxide, hydrocarbons, and other gases
rate at which fuel burns is controlled by - ANSWER the
amount of available air
air to fuel ratio is a - ANSWER critical factor in obtaining
optimum fuel combustion
,2|Page
BTU - ANSWER British Thermal Unit, The amount of
energy needed to heat one pound of water one degree
Fahrenheit
wood ignites at - ANSWER 450-550 F
natural gas ignites at - ANSWER 1,150 F
propane ignites at - ANSWER 920-1120 F
electric spark temp - ANSWER 1,700 F
hot surface igniter temp - ANSWER 2,400 F
butane lighter temp - ANSWER 3,200 F
stick match temp - ANSWER 3,000 F
,3|Page
cigarette temp - ANSWER 500-800 F
For complete combustion: air is ______ % oxygen +
_____ % nitrogen - ANSWER 20 : 80
for complete combustion, __(QTY)__ molecules of
__(PART)___ need to be mixed with ___(QTY)__ molecule
of _____(PART)____ in the presence of __(PART)__ -
ANSWER 2 oxygen : 1 fuel : heat
When complete combustion happens __(4 things)___ are
released - ANSWER heat, carbon dioxide (C02), water
vapor (H20), and nitrogen (N)
Carbon monoxide is dangerous because (other than
senseless) - ANSWER it mixes with blood and reduces
oxygen carrying capacity
Aldehydes - ANSWER chemical compounds that have a
strong pungent odor
, 4|Page
Carbon monoxide is ________ when aldehydes are
present - ANSWER present
Aldehydes result from - ANSWER flame impingement and
through the presence of contaminated air
Efficiency formula - ANSWER Heat output divided by heat
input (percentage of heat transferred to room)
3 Ts of efficiency - ANSWER Temperature, turbulence,
time
Temperature (efficiency) - ANSWER minimum ignition
temp
Turbulence (efficiency) - ANSWER fuel must collide with
oxygen molecules (refers to the degree of fuel and air
mixing that occurs in combustion zone)
