NFST NFST Fire Behavior and Science 1 — Questions and Answers
Question 1: What is the minimum oxygen concentration required to sustain flaming combustion?
- 12%
- 16% (Correct answer)
- 21%
- 25%
Correct answer: 16%
Flaming combustion generally requires at least 16% oxygen concentration to sustain itself.
Question 2: Which of the following best describes 'flashover' in a structure fire?
- When the first window breaks from heat
- When all combustible surfaces in a room ignite nearly simultaneously (Correct answer)
- When a backdraft explosion occurs
- When a fire jumps from one building to another
Correct answer: When all combustible surfaces in a room ignite nearly simultaneously
Flashover occurs when all combustible surfaces in a compartment reach ignition temperature and burst into flame almost simultaneously.
Question 3: The three components of the fire triangle are fuel, heat, and which third element?
- Carbon dioxide
- Nitrogen
- Oxygen (Correct answer)
- Hydrogen
Correct answer: Oxygen
The fire triangle consists of fuel, heat, and oxygen — remove any one and the fire will extinguish.
Question 4: What type of heat transfer occurs when heat moves through direct contact between objects?
- Convection
- Radiation
- Conduction (Correct answer)
- Combustion
Correct answer: Conduction
Conduction is heat transfer through direct physical contact between materials.
Question 5: Which class of fire involves energized electrical equipment?
- Class A
- Class B
- Class C (Correct answer)
- Class D
Correct answer: Class C
Class C fires involve energized electrical equipment and require non-conductive extinguishing agents.
Question 6: Backdraft is most likely to occur when a fire in a closed compartment receives a sudden influx of what?
- Water
- Oxygen (Correct answer)
- Carbon dioxide
- Foam
Correct answer: Oxygen
Backdraft happens when a smoldering, oxygen-starved fire suddenly receives a fresh supply of oxygen, causing a rapid explosion.
NFST NFST Fire Behavior and Science 1
What is the minimum oxygen concentration required to sustain flaming combustion?