Question 49

The Correct Answer is A **Explanation for A (Shut off the leak):** The primary hazard in a liquefied gas fire caused by escaping gas is the continuous supply of fuel. If the fuel supply is not stopped, the fire cannot be truly extinguished and the risk of explosion (BLEVE - Boiling Liquid Expanding Vapor Explosion) remains high. Therefore, the **first and most critical action** is to isolate the fuel source (shut off the leak), provided it can be done safely without undue risk to personnel. Once the leak is shut off, the fire will cease. **Explanation why other options are incorrect:** * **B) Call the local fire department:** While calling for professional help is essential, it is a preparatory action, not the *first action in extinguishing* the fire. If safe to do so, immediately prioritizing the shutdown of the fuel source is the most effective extinguishing step. * **C) Use a chemical foam fire extinguisher:** Foam is generally ineffective on gas fires. Extinguishing a gas fire with an agent (like dry chemical or CO2) before stopping the leak is extremely dangerous because it creates an unignited cloud of flammable gas, leading to a severe explosion hazard if ignition occurs again. * **D) Sweep flames away with water spray:** Water spray (fog) is used primarily to protect adjacent exposures, cool the tank walls, and control the radiant heat. It is an important defensive action, but it does not extinguish the fire and is secondary to eliminating the fuel source.