Fire Safety Fire Behavior and Combustion Science 1 — Questions and Answers
Question 1: What three elements make up the fire triangle?
- Fuel, oxygen, and heat (Correct answer)
- Fuel, nitrogen, and ignition
- Carbon, oxygen, and spark
- Heat, pressure, and combustion
Correct answer: Fuel, oxygen, and heat
The fire triangle consists of fuel, oxygen, and heat — all three must be present simultaneously for fire to exist and sustain itself.
Question 2: Which class of fire involves ordinary combustibles such as wood, paper, and cloth?
- Class B
- Class C
- Class A (Correct answer)
- Class D
Correct answer: Class A
Class A fires involve ordinary solid combustibles like wood, paper, cloth, and most plastics, and are the most common type found in homes and offices.
Question 3: What is the autoignition temperature of a material?
- The temperature at which it melts and releases gases
- The temperature at which its vapors ignite with a spark
- The minimum temperature at which it will ignite without any external ignition source (Correct answer)
- The temperature at which a fire extinguisher becomes ineffective
Correct answer: The minimum temperature at which it will ignite without any external ignition source
Autoignition temperature is the minimum temperature at which a material spontaneously ignites without any external spark or flame present.
Question 4: What is flashover in the context of fire development?
- When fire moves from one room to another through a doorway
- The sudden, simultaneous ignition of all combustible materials in a room (Correct answer)
- When a fire's fuel supply is completely exhausted
- The point at which a sprinkler system activates
Correct answer: The sudden, simultaneous ignition of all combustible materials in a room
Flashover occurs when all combustibles in a room reach their ignition temperature simultaneously, resulting in near-instantaneous full-room fire involvement.
Question 5: Which combustion gas is responsible for the majority of fire-related fatalities in the United States?
- Carbon dioxide (CO2)
- Hydrogen cyanide
- Carbon monoxide (CO) (Correct answer)
- Nitrogen dioxide
Correct answer: Carbon monoxide (CO)
Carbon monoxide is the leading cause of fire deaths because it is colorless, odorless, and rapidly incapacitates victims before they can escape.
Question 6: How does the 'fire tetrahedron' differ from the older 'fire triangle' model?
- It adds pressure as a fourth element
- It adds the uninhibited chemical chain reaction as a fourth element (Correct answer)
- It replaces heat with radiation
- It includes smoke as a fourth required element
Correct answer: It adds the uninhibited chemical chain reaction as a fourth element
The fire tetrahedron adds the uninhibited chemical chain reaction as a fourth element, explaining how chemical suppression agents extinguish fires without removing heat, fuel, or oxygen.
Question 7: Which class of fire involves flammable liquids such as gasoline and oil?
- Class A
- Class B (Correct answer)
- Class C
- Class K
Correct answer: Class B
Class B fires involve flammable and combustible liquids (gasoline, oil, paint) and flammable gases, and require smothering or chemical suppression rather than water.
Fire Safety Fire Behavior and Combustion Science 1
What three elements make up the fire triangle?