© 2019 Department of Petroleum Resources. All rights reserved Department of Petroleum Resources (DPR) PROCEDURE GUIDE

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4.1     Calculation of Petroleum and Petroleum Products Volume in tank Storage 
4.1.1 Parameters 
4.1.1.1 All volume correction factors are to be obtained from the Petroleum Tables ASTM D 
1250 and API MPMS Chapter 11.1 
4.1.1.2 Tank Dip: This is the height of the column of petroleum and petroleum product in the 
tank as obtained from the gauging exercise. 
4.1.1.3 Volume Correction Factor (VCF):  For Petroleum, this is obtained by first establishing 
the API gravity or Specific gravity of the sample at 60˚F from table 5A or 23A, of the 
measurement tables respectively. The corresponding volume correction factor is 
then obtained by referring the Specific gravity or API gravity at 60/60˚F to table 24A 
or 6A of the measurement tables respectively. However, when using density at 150C, 
volume correction factor shall be determined using table 54A of the measurement 
tables.  
For Petroleum Products, this is obtained by first establishing the density of the 
sample at 59˚F (15OC) from table 53B of the measurement tables. The corresponding 
volume correction factor is then obtained by referring the density at 59˚F to table 
54B of the measurement tables. 
4.1.1.4 Long Tons per Barrel Factor:  This is obtained by referring the API gravity or S.G at 
60/60oF to API MPMS Chapter 11. 
4.1.2   Calculation for Fixed Roof Tank 
The tank dip is referred to the appropriate tank calibration table to obtain the gross quantity 
of oil in barrels at tank temperature. Thereafter the quantities are calculated as follows: 
4.1.2.1 Gross Standard Volume at 60/60ᵒF: This is obtained by multiplying the gross volume 
at tank temperature by the volume correction factor obtained in paragraph 4.1.1.2. 
4.1.2.2 Gross Weight: The gross volume in barrels at 60/60oF is then multiplied by the long 
ton per barrel factor obtained (in 4.1.1.3) to give the equivalent weight in long ton at 
60/60ᵒF. 
4.1.2.3 Quantity of Water and Sediment (BS&W) in Petroleum:  This is obtained by 
multiplying the gross volume of petroleum at 60/60˚F by the BS&W percentage to 
give the volume of water in the petroleum in barrels. Thereafter, multiplying the 
water volume by a factor of 0.15616 yields the equivalent weight of water in long 
tons. 
4.1.2.4 Net volume and Weight of Petroleum in Tank:  The net volume of petroleum in the 
tank is obtained by subtracting the volume of water from the gross volume of 
petroleum while the weight of water is subtracted from the gross weight of 
petroleum in the tank at 60/60˚F to obtain the net weight of petroleum in the tank. 
4.1.3    Calculation for Floating Roof Tanks 
4.1.3.1 The only difference to note when calculating the quantity in a floating roof tank is 
that, correction shall be made for the roof displacement which in turn depends on 
the weight of the roof and specific gravity at tank temperature of the petroleum in 
storage.