Patent ID: 8370089

Claim:
A method for determining (measuring) the level/height of one or more interfaces, h 1 -h x , between two or more fluids/process media (fluid phases) of different density that are contained in a vessel or a tank ( 1 ) the method comprising: determining the position (the level) of the different interfaces in a tank ( 1 ) by measuring the pressure and thus indirectly determining the density of the fluid over the height of the tank positioning a pressure measuring rod ( 2 , 4 ), equipped with pressure sensors ( 3 , 5 ), in and extending over the height of the tank ( 1 ), to determine the position of the different interfaces wherein, there are more pressure sensors and pressure measurements than the number of variables that are to be determined, so that the system is overdefined and thus more robust, determining the interfaces using a mathematical model or algorithm which calculates how the density and hence the pressure vary over the height of the tank as a function of the fluid properties of the respective fluids in the tank, the interface, on the basis of the density being relatively similar within each layer of the respective fluid, being defined as the respective point (level) at which the density changes from one layer to the next in the tank.