Why is BBL doubled?

The first "b" in "bbl" may have been doubled originally to indicate the plural (1 bl, 2 bbl), or possibly it was doubled to eliminate any confusion with bl as a symbol for the bale. Some sources assert that "bbl" originated as a symbol for "blue barrels" delivered by Standard Oil in its early days.

What does Mbbl stand for?

But due to tradition, the Mbbl acronym is used today meaning "one thousand bbl", as a heritage of the roman number "M" for Latin "mille" meaning "one thousand". On the other hand, there are efforts to avoid this ambiguity, and most of the barrel dealers today prefer to use kbbl, instead of Mbbl, mbbl, MMbbl or mmbbl.

What is the difference between a barrel and a drum?

In many connections the term drum is used almost interchangeably with barrel . Since medieval times the term barrel as a unit of measure has had various meanings throughout Europe, ranging from about 100 litres to about 1,000 litres.