Let’s consider the different possible tanks’ shapes:

- Elliptical
- Circular
- Double-D
- Expanded surface

Each of them has a different surface area.

The total volume of the tank is resulting by the product of the bottom ends area by the length.

The above list is in order of growing area and consequently of shorter tank length, naturally different dimensions are available for each shape.

The different points of view are:

**A- TANK STABILITY**

Mostly important in case of high speed and/or rough roads.

In this case it is important to keep the center of gravity as low as possible, therefore the best solution would be n. 1 Elliptical shape.

**B- PRESSURIZED TANK**

Very important for gas transportation and/or vacuum tank.

In this case the only possible shape is n. 2 Circular shape, but this shape also presents the highest center of gravity with possible consequences on the stability of the vehicle.

**C- MAXIMUM CAPACITY OF THE TANK**

This is normally considered by each customer, especially in large construction sites, because it reduces the total number of vehicles required. The best shape in this case is n. 4, which also provides the second best lower center of gravity.

## There is not a preferred shape for the tank, it all depends from which of the above criteria prevails.