The volume of stored material in the tank can be measured in different ways. Main techniques used to measure the volume is same as the Level measurement techniques like Ultrasonic, Radar, Using differential pressure transmitter.
Actually, here we are measuring the level of the material in a reservoir, which can be used to calculate the volume of the material.
For this, any of the level measurement technique can be used. Volume measurement is depended on the shape and the size of the tank. If the vessel has a constant cross-sectional area throughout its working height (e.g. a vertical cylinder), then the material height will directly correspond to stored material volume.
Volume measure for different shapes are discussed below:
For vertical section cyclinder:
V = π r² h
For horizontal section cylinder:
V = L [ (h-r) √(2hr - h²) + r² sin−1 ((h-r)/r) + ((π r²)/2)
For a sphere:
V = π h² (r - h/3)
The volume measurement will be done in the microprocessor attached to the transmitter using the level value, algorithm for this will be already written in the microprocessor.