The barrel

One non-SI unit that won't fall into disuse

On reading the letter by M. Escudier in the January issue of this periodical I have to protest on behalf of the petroleum engineers that one non-SI unit is not going to fall into disuse: the barrel, equivalent to 0.159 cubic metres. It applies to OPEC, Brent, West Texas Intermediate and all of the benchmark prices. That students and those already professionally trained should be familiar with the conversion factor and accept the inevitability of retention of the barrel as a unit of quantity of oil is important.

J.C. Jones, Aberdeen

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