FE Fire Extinguisher Types & Classification 3

Question 1

A Class D extinguisher agent must be matched to the specific metal fuel because:

Accepted Answer

Different combustible metals require different compatible agents to avoid violent reactions

Answer

Using an incompatible Class D agent on a specific metal can cause violent reactions, so agent selection must match the metal involved.

Question 2

The 'B' numerical rating on a Class B extinguisher (e.g., 10-B) represents:

Accepted Answer

The approximate square footage of flammable liquid fire it can extinguish

Answer

The numerical B rating approximates the square footage of a flammable liquid fire in a one-foot-deep pan that the unit can extinguish.

Question 3

Which extinguisher agent works by forming a vapor-suppressing aqueous film over flammable liquid surfaces?

Accepted Answer

Aqueous Film-Forming Foam (AFFF)

Answer

AFFF creates an aqueous film that spreads across flammable liquid surfaces, cutting off oxygen and suppressing vapors.

Question 4

When an extinguisher carries a Class C rating only (no A or B), what does this mean operationally?

Accepted Answer

The agent is non-conductive but the unit has not been rated for fuel or combustible fires

Answer

A stand-alone Class C rating means the agent won't conduct electricity, but the unit lacks sufficient agent to earn A or B ratings.

Question 5

Multipurpose dry chemical (ABC) extinguishers use which primary agent?

Accepted Answer

Monoammonium phosphate

Answer

Monoammonium phosphate is the agent in multipurpose ABC dry chemical extinguishers because it is effective on Class A, B, and C fires.

(FE) Certified Portable Fire Extinguisher Technician Practice Test