A floating roof is a type of roof system used in some types of liquid storage tanks. The roof floats on top of the surface of the liquid and raises or lowers as the liquid does. Because liquid storage tanks tend to be cylindrical in shape, in order to find the volume of your floating roof system you need to find two pieces of information: the height at which the floating roof is sitting and the radius of the tank.
Things You'll Need
 Tape Measure

Find your floating roof storage tank's circumference in inches. Take a tape measure and wrap it around the entire tank and record the measurement. Divide this number by 3.14 or "Pi." Take the number you get and divide it by 2 to find the radius of the tank.

Find the height at which your floating roof is sitting at, in inches. Measure from the floating roof to the bottom of the storage tank.

Multiply the radius by itself. This is also called "squaring" the radius.

Multiply this number by the height of your floating roof. Multiply this number by 3.14 to find the volume of your floating roof liquid storage system.