Sensirion Ag

Thomas Huber

Mark Hornung

Andreas Rüegg

Remo Fürst

Philipp Reibisch

A mass flow controller () comprises a fluid inlet () and at least one first flow meter () to measure a first flow rate (F) and to output a first flow signal (FS); at least one second flow meter () to measure a second flow (F) rate and to output a second flow signal (FS); a control device () connected to said first and second flow meters () and configured and arranged to generate a control signal (C); and at least one control valve () connected to said control device () to control a total flow rate (F) through the mass flow controller () in response to the control signal (C). The control signal (C) is generated as a function of both the first and second flow signals (FS,FS) such that the mass flow controller's () sensitivity to perturbations of said inlet pressure is minimized.

Inlet pressure perturbation insensitive mass flow controller

A method for determining a fluid composition parameter, e.g., a fluid identifier, a mixing ratio or a parameter describing heat transfer properties, of an unknown fluid in a mass flow controller is disclosed. A control valve of the mass flow controller is set so as to establish a constant flow, preferably zero flow, through the mass flow controller. A heating element of the flow sensor is heated, and at least one temperature value is measured with temperature sensors arranged on both sides of the heater while the fluid contacts the flow sensor. First calibration data (LUT) are retrieved. The first calibration data have, as input values, temperature values measured with the flow sensor at the previously established constant flow and have, as output values, values of the fluid composition parameter. The first calibration data are used to determine the fluid composition parameter from the measured temperature value.

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Stäfa, Switzerland

Thomas Huber