NFSI Firefighting Knowledge 2 — Questions and Answers
Question 1: What does the term 'flashover' describe in firefighting?
- A backdraft explosion caused by oxygen introduction
- The simultaneous ignition of all combustible materials in a compartment (Correct answer)
- A rapid fire spread along a ceiling due to smoke layer
- The point at which suppression foam activates automatically
Correct answer: The simultaneous ignition of all combustible materials in a compartment
Flashover occurs when all combustible surfaces in a room reach their ignition temperature simultaneously, causing near-instant full-room involvement.
Question 2: Which hose line size is most commonly used for interior structural firefighting attack lines?
- 1-inch booster line
- 1¾-inch hose (Correct answer)
- 2½-inch hose
- 3-inch supply line
Correct answer: 1¾-inch hose
The 1¾-inch attack hose balances flow rate and maneuverability, making it the standard choice for interior structural firefighting.
Question 3: What is the primary purpose of a positive pressure ventilation (PPV) fan?
- To cool the fire compartment before entry
- To push fresh air into a structure to clear smoke (Correct answer)
- To increase oxygen supply to help firefighters breathe
- To create a negative pressure zone around the fire
Correct answer: To push fresh air into a structure to clear smoke
PPV fans are positioned at an entry point to push fresh air through the structure, driving smoke and hot gases out of exhaust openings.
Question 4: In the context of wildland firefighting, what does 'spotting' refer to?
- Identifying the fire's point of origin
- Embers carried by wind that start new fires ahead of the main fire (Correct answer)
- A lookout firefighter watching for hazards
- The practice of marking trees for safety zones
Correct answer: Embers carried by wind that start new fires ahead of the main fire
Spotting occurs when burning embers are lofted by fire-generated wind and land beyond the main fire perimeter, igniting new fires.
Question 5: What is the recommended action when a firefighter encounters a closed door that is hot to the touch during a structure search?
- Open it quickly to perform a rapid rescue scan
- Do not open it — the fire is likely directly behind the door (Correct answer)
- Use a halligan to force it open immediately
- Open it slowly at the top first to test for fire
Correct answer: Do not open it — the fire is likely directly behind the door
A hot door indicates fire conditions on the other side; opening it could cause rapid fire spread, flashover, or backdraft.
Question 6: What type of extinguisher agent is most appropriate for a Class D metal fire?
- Carbon dioxide (CO2)
- Dry chemical powder
- Dry sand or specialized dry powder agent (Correct answer)
- Aqueous film-forming foam (AFFF)
Correct answer: Dry sand or specialized dry powder agent
Class D fires involve combustible metals like magnesium or sodium, which react violently with water and CO2; only dry sand or specialized dry powder agents are safe.
Question 7: During a mayday transmission, what does the acronym LUNAR stand for?
- Location, Unit, Name, Assignment, Resources needed (Correct answer)
- Last known position, Unit, Number of victims, Air supply, Radio channel
- Location, Unit, Name, Air supply, Resources needed
- Level, Unit, Name, Assignment, Radio channel
Correct answer: Location, Unit, Name, Assignment, Resources needed
LUNAR (Location, Unit, Name, Assignment, Resources needed) is the standard format for a firefighter mayday call to transmit critical information quickly.
NFSI Firefighting Knowledge 2
What does the term 'flashover' describe in firefighting?