FST Fire Extinguishers 3 — Questions and Answers
Question 1: How frequently must a hydrostatic test be performed on a stored-pressure dry chemical extinguisher?
- Every 3 years
- Every 5 years
- Every 6 years
- Every 12 years (Correct answer)
Correct answer: Every 12 years
Stored-pressure dry chemical extinguishers require hydrostatic testing every 12 years per NFPA 10.
Question 2: An extinguisher with a '2-A:10-B:C' rating means it is rated for:
- Two separate Class A fires, ten Class B fires, and one Class C fire
- Twice the Class A capacity of a 1-A unit, ten square feet of Class B fire, and Class C hazards
- 2 gallons of water equivalent for Class A, 10 square feet of flammable liquid for Class B, and electrical fires (Correct answer)
- Class A fires up to 2 acres, Class B fires up to 10 gallons, and Class C fires
Correct answer: 2 gallons of water equivalent for Class A, 10 square feet of flammable liquid for Class B, and electrical fires
The '2-A' means the extinguisher has the Class A firefighting equivalent of 2.5 gallons of water; '10-B' means it can extinguish 10 square feet of Class B fire; 'C' indicates it is safe for use on electrical fires.
Question 3: What is the maximum floor area that a single 2-A rated extinguisher can protect?
- 1,500 sq ft
- 3,000 sq ft
- 6,000 sq ft
- 11,250 sq ft (Correct answer)
Correct answer: 11,250 sq ft
Under NFPA 10, a 2-A extinguisher protects up to 6,000 square feet under light hazard occupancy, but one 'A' unit covers 3,000 sq ft up to a maximum of 11,250 sq ft per extinguisher.
Question 4: Which condition would require a fire extinguisher to be immediately removed from service?
- A pressure gauge reading at the low end of the green zone
- A missing pull pin with the tamper seal intact
- A broken tamper seal with the pull pin still in place (Correct answer)
- A label that is slightly faded but still readable
Correct answer: A broken tamper seal with the pull pin still in place
A broken tamper seal indicates the extinguisher may have been used or tampered with, requiring immediate removal for inspection and possible recharging.
Question 5: For a high-hazard occupancy, what is the maximum travel distance to a Class B fire extinguisher?
- 30 feet (Correct answer)
- 50 feet
- 75 feet
- 100 feet
Correct answer: 30 feet
NFPA 10 requires a maximum travel distance of 30 feet to Class B extinguishers in high-hazard occupancies.
Question 6: A carbon dioxide (CO2) extinguisher is most effective against which type of fire scenario?
- Outdoor Class A fires in windy conditions
- Deep-seated smoldering fires in upholstered furniture
- Small Class B and C fires in enclosed spaces (Correct answer)
- Large warehouse fires involving ordinary combustibles
Correct answer: Small Class B and C fires in enclosed spaces
CO2 extinguishers work by displacing oxygen and are most effective on small flammable liquid (B) and electrical (C) fires, particularly in enclosed areas where the gas can concentrate.
Question 7: When mounting a fire extinguisher, NFPA 10 requires that extinguishers weighing 40 lbs or less have their handles no higher than:
- 3.5 feet from the floor
- 4 feet from the floor
- 5 feet from the floor (Correct answer)
- 6 feet from the floor
Correct answer: 5 feet from the floor
NFPA 10 specifies that extinguishers with a gross weight not exceeding 40 lbs shall be installed so the handle is no higher than 5 feet above the floor.
FST Fire Extinguishers 3
How frequently must a hydrostatic test be performed on a stored-pressure dry chemical extinguisher?