Calibration of tanks and containers Tanks are often used as measuring equipment for trade in, for example, petroleum products. However, reliance on the nominal volume of a tank (e.g. as derived from a drawing) can result in an error of one percent or even more. An error of one percent in Sweden’s annual import of petroleum products is equivalent to 300 000 m3. In order to reduce this error, we need to know the effective area of tanks more accurately.
Calibrating tanks is a good start. Although this is most critical for large tanks (the largest that we have calibrated has a volume of 150 000 m3) that are used for what is known as ‘custody transfer’, we also calibrate very small tanks or vessels, right down to pipette volumes.
The commonest shape of a tank used for measurement purposes is that of a vertical cylinder, but we often calibrate considerably more complex shapes.
Most of our tank calibration work is performed in Sweden. However, we also make measurements at short notice throughout Europe, and have on a number of occasions been involved in projects in other parts of the world, such as the Middle East or Asia.
Deciding on the required accuracy level
Calibrations can be performed with various specified accuracy levels, as most appropriate to the particular requirements.
The volumes of most tanks are determined geometrically when they are empty. Smaller tanks can be calibrated volumetrically, by filling the tank with liquid via a calibrated meter.
Not just calibration
These calibrations provide a large quantity of geometrical information that can be useful for other purposes, such as site or general arrangement drawings, deformation or settlement measurements.
RISE is also involved in international standardisation work.