Abstract: A process for determining the phase portion of a medium in open and closed pipes, especially for use in connection with a process for determining the volume flow, with the help of at least three condenser plates extending basically over the entire height of the pipe and with the help of a control and evaluation circuit, in which at least one of the condenser plates has an alternating voltage applied to it by the control and evaluation circuit and the current flowing between the condenser plate with the voltage appled to it and at least one other condenser plate is recorded by the control and evaluation circuit. The process is designed so that the current between at least two condenser plates is recorded by the control and evaluation circuit from two different groups of condenser plates separated by the vertical line of the pipe.