NFI FINAL EXAM PREP QUESTIONS AND ANSWERS GRADED A+ LATEST

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