Ullage is defined as the distance from liquid surface to the top of the tank.

• A. Distance from tank bottom to liquid
• B. Distance from liquid surface to top of tank
• C. Total tank volume
• D. Weight of cargo

Answer: (B)

Ullage is the empty space in a tank—the vertical distance from the surface of the liquid up to the top interior of the tank. This headspace matters because it helps determine how much liquid remains, how much vapor space there is for safe venting, and how cargo volume is calculated during loading and unloading. So the measure defined as the distance from the liquid surface to the top of the tank is the ullage.

The other options describe something different: the distance from the bottom of the tank to the liquid is the liquid depth, not the empty space; the total tank volume is the tank’s capacity, not how much space is left; and the weight of the cargo is a mass measurement, not a spatial one.