Unfortunately, there are several units called barrel; the summary of the Wikipeda article says (emphasis added): A barrel is one of several units of volume, with dry barrels, fluid barrels (UK beer barrel, U.S. beer barrel), oil barrel, etc. The volume of some barrel units is double others, with various volumes in the range of about 100-200 litres (22-44 imp gal; 26-53 USgal).
For more details: http://en.wikipedia.org/wiki/Barrel_(unit)
This is one important reasons for using the metric system - standardization.
1 Barrel is 115.6 liters.
1 Barrel = 42 US gallons = 158,99 liter 60.000 barrel = 2.520.000 US gallons = 9.539.400 liter
129 (grams per liter) = 129,000,000 micrograms per liter.
21/1.5 = 14
159 liters per barrel.
159 litres per barrel.
There are 1000mL per liter.
1000cc per liter.
22.8 kilometers per liter
There are 1,000 milliliters per liter.
98 kilometers per liter
multiply kilometers per liter by .425144 to get gallons per mile
A barrel usually contains up to 42 gallons of jet fuel. The barrels are priced per barrel or per gallon.