What measurement in a tank is used to estimate remaining cargo?

• A. Distance from liquid surface to top of tank
• B. Ullage is the distance from bottom to liquid
• C. Total tank volume
• D. Temperature of cargo

Answer: (A)

Ullage—the air space between the surface of the cargo and the top of the tank—is the measurement used to estimate remaining cargo. Measuring this gap and using the tank’s calibration lets you translate that space into a remaining liquid volume. The smaller the ullage, the more cargo remains; a larger ullage means less cargo. Other options don’t fit because depth from bottom to liquid tells you how deep the liquid sits but not the standard empty space used for volume estimation; total tank volume is just the tank’s capacity, not a live reading; and temperature affects density, not the direct measure of how much cargo is left.