Preparation of Tank Capacity Tables

Capacity tables should be set out to show litres at intervals of 5 cm in dip with proportional part tables for intermediate dips in millimetres.

Computation of Capacities

Open capacity in litres per centimetres = (C² X 10) / 4Π = 0.795778 X C².

When the tank is tilted by an angle Ø,
the open capacity in litre per cm = 0.795778 X C² X sec Ø
(C = internal circumference of the tank in metres and Π = 3.14158

Calculating Internal Circumference

Internal Circumference of a tank may be calculated by measuring internal diameters at different heights or by obtaining the external circumference by strapping method and applying following corrections:

1.  Temperature correction

The measuring tape is calibrated at 20°C but the reference temperature for tank calibration is 15° C. So, the external circumference in metre will have to be multiplied by correction factor of 0.99991

2.  Step-over correction

• By choosing tape courses to avoid obstructions, step-overs can be avoided to a great extent.
• Step-over correction is necessary for all vertical seams.
• Step-over less than 2 mm need not to be included.

3.  Shell Plate Thickness Correction

the correction will be deduction of 2Π X d where d is the thickness of shell-plate.

4.  Correction for Liquid Head and Temperature

Theses effects are eliminated by strapping the tank when it is filled not less than 2/3 rd capacity with the product or water.

Open Capacity Calculation

Table 3/5

This table has been divided into four parts for the sake of space and clarity. Practically, there should be a combined table to include all data in a single sheet.
It is also to be noted carefully that circumference measurement is always in metre and height measurements in cm.

Part I:

* Height of datum plate 16.4 cm

Part II:

Part III:

Part IV:

Bottom Calibration at 0.00 cm: 28230 litre

Total Capacity Calculation

Table 4/5