During a fire, to maximize efficient use of water when cooling flammable gas storage tanks, fire streams should be directed:

During a fire, to maximize efficient use of water when cooling flammable gas storage tanks, fire streams should be directed:

• A. Around the tank base.
• B. Above the level of the contained liquid.
• C. Below the level of the contained liquid.
• D. Into the involved tank.

Answer: (B)

When fighting a fire in a tank that contains a flammable liquid or gas, the priority is to keep heat from reaching the contents by cooling the exterior of the tank. Spraying water on the outside above the liquid level is most effective because it absorbs heat before it can transfer into the liquid, slowing vaporization and reducing the risk of a pressure-related failure like a BLEVE. The water on the upper exterior creates a cooling barrier where the shell is most stressed by radiant and convective heat, helping to protect the contents without introducing water into the tank. Directing water around the base is less efficient at cooling the critical upper areas and can still allow heat to penetrate the shell. Directing water below the liquid level risks water entering the liquid, which can promote vaporization and increase internal pressure. Pouring water into the tank is unsafe and wastes cooling potential.

When fighting a fire in a tank that contains a flammable liquid or gas, the priority is to keep heat from reaching the contents by cooling the exterior of the tank. Spraying water on the outside above the liquid level is most effective because it absorbs heat before it can transfer into the liquid, slowing vaporization and reducing the risk of a pressure-related failure like a BLEVE. The water on the upper exterior creates a cooling barrier where the shell is most stressed by radiant and convective heat, helping to protect the contents without introducing water into the tank.

Directing water around the base is less efficient at cooling the critical upper areas and can still allow heat to penetrate the shell. Directing water below the liquid level risks water entering the liquid, which can promote vaporization and increase internal pressure. Pouring water into the tank is unsafe and wastes cooling potential.