Two methods for measuring the tank level are recognized:
– A volume-based tank gauging system, with quantity assessment based on level and temperature measurement
– A mass-based tank gauging system, with quantity assessment based on measurement of the hydrostatic pressure of the liquid column.
The petrochemical industry generally uses static volumetric assessments of the tank content. This involves level, temperature and pressure measurements. There are different ways of measuring the liquid level and other properties of the liquid. Whatever method is used, a high degree of reliability and accuracy is vital when the data is used for inventory control or custody transfer purposes.
A tank gauging system is much more than just the instruments on the tank, however. Tank gauging requires large field bus networks to enable reliable data communication – wired or wireless. Tank gauging systems must also be able to calculate product volumes and mass according to industry standards. The tank gauging system performs many different functions, from operator interface, batch handling and reporting, to alarm functions, connectivity to host systems and much more.