DENSITY AND SPECIFIC GRAVITY

Density is define as "mass per unit volume".

FW = 1000 kg per m3 or 1.000 ton/m3
SW = 1025 kg per m3 or 1.025 ton/m3

Density in kg/m3 = 1000 x SG

sample 1:
When double bottom tank is full of fresh water it holds 120 tonnes. Find how many tonnes of oil of relative density 0.84 it will hold.

Relative density = Mass of Oil / Mass of FW
Mass of Oil = Mass of FW x relative density
                    = 120 x 0.84 tonnes
                    = 100.8 tonnes of oil

sample 2:
A tank measures 20m x 24m x 10.5m and contains oil of relative density 0.84. Find the mass of oil it contains when the ullage is 2.5m. Ullage is the distance from the liquid surface in the tank to the top of the tank.

Volume of oil  = L x B x D
                        = 20 x 24 x 8

Density of oil  = SG x 1000
                        = 840 kg/m3 or 0.84 t/m3

Mass of oil      = Volume x density
                         = 20 x 24 x 8 x 0.84
                         = 3225.6 tonnes


Specific Gravity of some liquids
Salt water = 1.025                   Oil fuel = 0.950            Lubricating fuel = 0.900
Fresh water = 1.000                Diesel fuel = 0.900

the mass of each above is 1 ton with various volumes