Granville-phillips Company

Charles F Morrison Jr

A 'pressure' gauge which measures density of a gas in a vacuum system is temperature-compensated to give more accurate pressure readings by taking into account the actual gas temperature in the gauge as well as the temperature of the gas during calibration of the gauge. The calibration is for gauge output current versus measured gas pressures; during calibration, the gas temperature is also measured. During pressure measurement gas temperature is measured in the gauge and a microcomputer is used for computations and for lookup of calibration pressure values which nominally corespond to gauge output current values. The output current is first compensated for temperature correction by multiplying it by the actual absolute gas temperature and dividing the product by the absolute calibration gas temperature. This new temperature-compensated output current is used by the microprocessor to access the stored calibration data and to provide a temperature-compensated pressure value.

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Boulder, CO, United States of America

Charles F Morrison Jr