Mass flow controller automatic calibration factor correction - by comparing gas wt. lost with wt. from integrated flow using computer

摘要

A flow measurement arrangement for gases and vapours uses generation of automatic correction values for the calibration factor of mass flow controllers used with different gases or vapours whose characteristics vary linearly or otherwise as they condense. The flow through the mass flow controller is integrated by a computer whilst the weight lost by the supplying gas container is measured by the computer. The total flow value is then converted to an equivalent wt. and compared with the measured wt. loss. A resulting difference within permissible tolerance limits is used to form a corrected calibration factor. If the difference exceeds a permitted tolerance threshold a fault is indicated. The computer also generates the flow regulation signal.