Process water analyzer

Abstract

The invention relates to a process water analyzer (10) for automatically analyzing a parameter of a water sample, comprising: a process liquid storage tank (70, 72) having a process liquid (70 ', 72') wherein a process liquid storage volume (V70, V72) in the storage tank (70, 72) defines a storage liquid level (I70, I72) at a storage liquid level height (h70, h72); a metering chamber (30) fluidly connected to the process liquid storage tank (70, 72) and fluidly positioned downstream of the process liquid storage tank (70, 72); a positive displacement metering pump (20) fluidly connected to the top of the metering chamber (30), a metering pump (20) for sucking the process liquid (70 ', 72') into the metering chamber (30), an air cushion (27) being always vertically arranged between the metering pump (20) and the liquid column upper level (I) of the process liquid column (Ic70, Ic72), and having an effective vertical liquid column length (c70, c72) between the storage liquid level (I70, I72) and the liquid column upper level (I); a gas pressure sensor (60) for sensing the gas pressure (P) of the gas cushion (27); and a liquid storage volume control unit (100) that calculates an actual process liquid storage volume (V70, V72) based on the gas pressure (P) provided by the gas pressure sensor (60) and the known vertical height (h) of the liquid column upper liquid level (I). This arrangement enables the liquid level sensor of the process liquid storage tank (s) to become redundant.

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