FIRE SAFETY — Choose the correct extinguisher for Class B (petroleum/flammable liquid) fires. Question: Which type of fire extinguisher is most appropriate for a petroleum (flammable liquid) fire under standard safety practice?

Introduction / Context:
Fires are classified by fuel: Class A (ordinary combustibles), Class B (flammable liquids such as petrol, diesel, solvents), Class C (gases), electrical fires, etc. Choosing the correct extinguisher prevents spread and avoids dangerous reactions. Petroleum fires are a classic Class B scenario.

Given Data / Assumptions:

• The fuel is a flammable liquid (petroleum).
• We are selecting the most appropriate, commonly recommended extinguisher type for such fires.
• “Foam type” refers to aqueous film-forming foam (AFFF) or similar.

Concept / Approach:
Class B fires require agents that smother the fuel surface and prevent re-ignition by separating fuel from oxygen and suppressing vapors. Foam extinguishers blanket the liquid, forming a film that inhibits vapor release. Dry chemical powder can also work by interrupting the chain reaction, and CO₂ can displace oxygen; however, foam is especially suited to open-surface flammable liquids and is widely taught as the primary choice for petroleum spills.

Step-by-Step Solution:
Identify class: petroleum → Class B.Match agent: select a surface-smothering agent → foam (AFFF).Eliminate agents unsuitable or risky for liquids: water jets can spread fuel.Confirm that standard fire-safety curricula emphasize foam for petroleum spills.

Verification / Alternative check:
Training manuals list foam/AFFF and dry chemical as acceptable for Class B. In many exams, “foam” is the canonical answer for petroleum fires because of blanket effect and vapor suppression.

Why Other Options Are Wrong:
A) Dry powder works but the best-fit for liquid-surface smothering is foam.B) Water jet can spread the fuel and intensify the fire.C) Soda–acid is an older water-based type, not ideal for flammable liquids.E) CO₂ can help in confined spaces but may not prevent re-ignition on open pools.

Common Pitfalls:
Using water on hydrocarbon fires or confusing electrical/metal fires with liquid fires. Always classify fuel first, then choose the agent.

Final Answer:
Foam type (AFFF/foam)