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

Unit Definition (ounce [US, liquid])
The ounce [US, liquid] is a traditional unit of liquid volume, also called the fluid ounce to avoid confusion with the weight ounce. In the U. S. customary system there are 16 fluid ounces in a pint, so each fluid ounce represents 1.804 687 cubic inches or 29.573 531 milliliters. A U.S. fluid ounce of water weighs just a bit more than one ounce avoirdupois.

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.