Convert from keel [coal] to dan [China]

Unit Definition (keel [coal])
The keel is a traditional British unit of weight for coal. After considerable variation, the keel of coal was standardized in 1695 as 21.2 long tons, or 47 488 pounds (21.5402 metric tons). This is the approximate weight of coal carried at that time by barges on the river Tyne in northern England; the barges were also called keels, from the Dutch word kiel for such a ship.

Unit Definition (dan [China])
The dan [China] is a traditional Chinese weight unit, previously spelled tan in many English works. During the European colonial era the unit was equal to 100 catties or 133.333 pounds. In modern China the dan is equal to 100 jin, which is exactly 50 kilograms (110.231 pounds). The dan is the Chinese equivalent of the European quintal or hundredweight.