Convert from ounce [UK, liquid] to drum [metric, petroleum]

Unit Definition (ounce [UK, liquid])
The ounce [UK, liquid] is a traditional unit of liquid volume, also called the fluid ounce to avoid confusion with the weight ounce. In the British Imperial system there are 20 fluid ounces in an imperial pint, so each fluid ounce represents about 1.733 871 cubic inches or 28.413 063 milliliters. A British fluid ounce weighs exactly one ounce at a specified temperature and pressure.

Unit Definition (drum [metric, petroleum])
The drum [metric, petroleum] is a unit of volume sometimes used in the oil trade. In the metric world, drums of 200 liters, 205 liters, and 208 liters are in use as substitutes for the traditional size.