PETROLEUM TRANSPORTATION: BARRELS, GALLONS, LITERS, AND TONNES (METRIC)

August 10, 2022

In the past, commodities—both dry goods and liquids were sold according to their volume. Different sizes of watertight wooden barrels—sides are curved, to make the middle wider than the top and bottom ends—had used to transport liquid goods—alcoholic drinks, fish, etc.

Wooden barrels were widely available; so, they became the first choice for the transportation of crude oil and refined petroleum products (e.g., kerosine). Barrels of different sizes were used to move oil. Evaporation and leaks caused barrels’ oil levels to drop, during transportation to the refinery.

42-gallon barrels became the best choice for the transportation of oil. (1 US gallon (gal) = 3.785 liters (L); 42 US gallons = 158.97 liters). Oil producers officially agreed to use the 42-gallon oil barrel as the standard barrel to transport oil. A barrel is a standard unit of measure of volume for liquids, in the oil industry. Although tankers and pipelines move petroleum, and physical barrels are rarely used, US barrel (42 US gallons) is still an official standard, today.

How much mass fits in a 42-gallon barrel of oil? The mass depends on the density of the liquid. Density is the mass per unit volume. Specific gravity—is the ratio of the mass of a volume of liquid at a specific temperature to the mass of the same volume of water at that temperature. In other words, specific gravity is a factor. It tells us how much heavier or lighter a substance is than water. The density of water is 1 kg/L. Therefore, if the density of oil is expressed in kg/L, the oil’s density equals the specific gravity. Different crude oils can have different densities. For example, If the density of crude oil is 0.973 kg/L then the approximate weight of the barrel of crude oil will be 155 kg or 0.155 t.

 

REFERENCES

• EPA ExpoBox Unit Conversion Table
• History of the 42-Gallon Oil Barrel
• Fact #676: May 23, 2011 U.S. Refiners Produce about 19 Gallons of Gasoline from a Barrel of Oil