Question 1272 Deck General

The correct answer is B) an above-deck datum, usually the top of the ullage hole. Ullage measurements are taken from the top of the liquid to an above-deck datum, typically the top of the ullage hole. This is because the ullage hole provides a consistent and accessible reference point from which to measure the depth of the liquid in the tank. The base of the expansion trunk (A), the base of the ullage port (C), and a line scribed within the ullage port (D) are not the standard reference points used for ullage measurements.