Which term describes the gap used to estimate remaining cargo in a tank by measuring the surface of liquid?

Which term describes the gap used to estimate remaining cargo in a tank by measuring the surface of liquid?

• A. Total tank volume
• B. Tank pressure
• C. Ullage
• D. Cargo weight

Answer: (C)

Ullage is the space above the liquid in a tank. Measuring this gap—how far the liquid surface is from the tank top—lets you estimate how much cargo remains because tanks are calibrated to convert that height into a volume (and then into mass if density is needed). A small gap means most of the tank is filled; a large gap means it’s mostly empty. The other terms don’t describe this space: the total tank volume is the tank’s full capacity, tank pressure isn’t a direct measure of remaining cargo, and cargo weight is the mass of what’s aboard, not the empty space used to gauge quantity.

Ullage is the space above the liquid in a tank. Measuring this gap—how far the liquid surface is from the tank top—lets you estimate how much cargo remains because tanks are calibrated to convert that height into a volume (and then into mass if density is needed). A small gap means most of the tank is filled; a large gap means it’s mostly empty. The other terms don’t describe this space: the total tank volume is the tank’s full capacity, tank pressure isn’t a direct measure of remaining cargo, and cargo weight is the mass of what’s aboard, not the empty space used to gauge quantity.