Per gallon of water used to suppress a fire, without being converted to steam, the added floor weight is closest to which value?

Per gallon of water used to suppress a fire, without being converted to steam, the added floor weight is closest to which value?

• A. 5 pounds
• B. 6.5 pounds
• C. 7.7 pounds
• D. 8.33 pounds

Answer: (D)

The key idea is that the weight added to the floor equals the weight of the water that remains on the floor. A US gallon of water weighs about 8.33 pounds. This comes from water’s density (roughly 62.4 pounds per cubic foot) times the volume of a gallon (0.1337 cubic feet), giving about 8.34 pounds per gallon. If the water stays liquid and isn’t converted to steam, each gallon adds roughly 8.33 pounds of floor load. The other numbers are simply lighter estimates and don’t match the actual weight of a gallon of water.

The key idea is that the weight added to the floor equals the weight of the water that remains on the floor. A US gallon of water weighs about 8.33 pounds. This comes from water’s density (roughly 62.4 pounds per cubic foot) times the volume of a gallon (0.1337 cubic feet), giving about 8.34 pounds per gallon. If the water stays liquid and isn’t converted to steam, each gallon adds roughly 8.33 pounds of floor load. The other numbers are simply lighter estimates and don’t match the actual weight of a gallon of water.