FST Fire Extinguishers 4 — Questions and Answers
Question 1: During an annual maintenance inspection, a technician finds that a dry chemical extinguisher has caked or hardened agent inside. What is the required action?
- Shake the extinguisher vigorously to break up the agent and return it to service
- Recharge only the portion of agent that has hardened
- Remove from service, empty, clean, and recharge with new agent (Correct answer)
- Tag it for the next scheduled 6-year maintenance and return to service
Correct answer: Remove from service, empty, clean, and recharge with new agent
Caked or hardened agent must be replaced; the extinguisher must be emptied, internally cleaned, and recharged with fresh agent to ensure proper discharge.
Question 2: What does the letter 'D' classification on a fire extinguisher indicate?
- The extinguisher is rated for use on dry wood fires
- The extinguisher is designed for combustible metal fires (Correct answer)
- The extinguisher has been approved for deep-fat fryer use
- The extinguisher uses a dry chemical agent only
Correct answer: The extinguisher is designed for combustible metal fires
Class D extinguishers are specifically designed for combustible metal fires such as magnesium, titanium, zirconium, sodium, and potassium.
Question 3: A 6-year maintenance on a stored-pressure dry chemical extinguisher requires the technician to:
- Replace the cylinder and all internal components
- Empty the extinguisher, inspect internally, and replace agent and expellant gas (Correct answer)
- Perform a hydrostatic test and replace the pressure gauge
- Visually inspect the exterior and verify the gauge is in the green zone
Correct answer: Empty the extinguisher, inspect internally, and replace agent and expellant gas
The 6-year maintenance requires complete emptying, internal examination, replacement of all dry chemical agent, and recharging with new expellant gas.
Question 4: Which type of extinguisher requires a hydrostatic test every 5 years?
- Stored-pressure water extinguishers (Correct answer)
- Stored-pressure dry chemical extinguishers
- Halon extinguishers
- CO2 extinguishers
Correct answer: Stored-pressure water extinguishers
Stored-pressure water, loaded stream, and AFFF (foam) extinguishers require hydrostatic testing every 5 years per NFPA 10.
Question 5: When using the PASS technique to operate a fire extinguisher, what does the second 'S' stand for?
- Squeeze the handle
- Sweep side to side at the base of the fire (Correct answer)
- Stand back from the fire
- Signal for help before approaching
Correct answer: Sweep side to side at the base of the fire
In the PASS acronym, the second S stands for Sweep — moving the nozzle from side to side at the base of the flames.
Question 6: What is the primary hazard of using a CO2 extinguisher in a small, confined space?
- The dry ice particles can damage electrical equipment permanently
- The discharge may spread the fire to adjacent areas
- Oxygen displacement can create an immediately dangerous atmosphere for occupants (Correct answer)
- The cold discharge can cause the fire to reignite after use
Correct answer: Oxygen displacement can create an immediately dangerous atmosphere for occupants
CO2 extinguishes fire by displacing oxygen; in a confined space, this can reduce oxygen to levels immediately dangerous to life and health (IDLH) for any occupants.
Question 7: A fire extinguisher service technician discovers an extinguisher that has a manufacture date of 12 years ago and has never been hydrostatically tested. What is the correct action?
- Perform an immediate hydrostatic test and return to service if it passes (Correct answer)
- Condemn and destroy the extinguisher — it is past all service life
- Tag the unit for hydrostatic testing at the next scheduled annual inspection
- Perform a 6-year maintenance and defer the hydrostatic test one year
Correct answer: Perform an immediate hydrostatic test and return to service if it passes
The extinguisher is overdue for its hydrostatic test; it must be removed from service immediately and hydrostatically tested before it can be returned to service.
FST Fire Extinguishers 4
During an annual maintenance inspection, a technician finds that a dry chemical extinguisher has caked or hardened agent inside.
What is the required action?