Q1: Large scale fire on fuel gas line is normally extinguished by

ANS:D - nitrogen

Certainly! When dealing with large-scale fires on fuel gas lines, it's crucial to understand the properties of the extinguishing agents and their effectiveness in combating such fires. Let's delve into a detailed explanation:

1. Water: While water is commonly used as a firefighting agent, it may not be the best choice for fuel gas fires. Water can potentially spread the fire by dispersing the flammable liquid or vapor, leading to an increased risk of explosion. Additionally, water may not effectively penetrate the fuel surface to extinguish the fire thoroughly.
2. Steam: Steam can be generated by applying water to the fire, but its effectiveness in extinguishing fuel gas fires is limited. While steam can displace oxygen and cool the fuel surface, it may not rapidly smother the fire or prevent reignition, especially in large-scale fires.
3. Foam: Foam is often the preferred choice for extinguishing large-scale fuel fires, including those involving fuel gas lines. Foam works by forming a blanket over the fuel surface, cutting off the oxygen supply to the fire and suppressing flammable vapors. It also provides cooling properties, reducing the temperature of the fuel surface and minimizing the risk of reignition.
4. Nitrogen: Nitrogen is an inert gas that can be used to displace oxygen and smother the fire. However, its effectiveness in extinguishing fuel gas fires may be limited compared to foam. Nitrogen systems are more commonly used in situations where other agents may not be suitable or where there is a risk of oxygen-sensitive materials being damaged by traditional firefighting methods.

In summary, while water, steam, and nitrogen can have some firefighting applications, foam is generally considered the most effective agent for extinguishing large-scale fires on fuel gas lines. Foam's ability to form a blanket over the fuel surface, suppress flammable vapors, and provide cooling makes it a valuable tool in firefighting operations.