US 4,866,640 A · Temperature compensation for pressure gauge

Abstract

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.

Claims16

Dependent claims

An apparatus for determining a temperature-compensated value of a pressure measurement of a gas, comprising:

a gauge means responsive to the density of said gas for connection to a system containing said gas;
said gauge means producing an electrical output signal in response to the density of the gas in the gauge;
a means for storing calibration data of said gas, the calibration data being obtained at a measured calibration gas temperature in the gauge and including data relating said electrical output signal to predetermined values of pressure during calibration;
a temperature measuring means for measuring temperature of gas in the gauge where pressure is to be determined;
a computer means for temperature-compensating said electrical output signal based upon actual measured temperature of the gas in the gauge as measured by said temperature measuring means;
whereby said computer means uses said temperature-compensated electrical output signal to determine a temperature-compensated pressure value of the gas in the gauge.

3 more elements

Dependencies are inferred from the claim text.

Temperature compensation for pressure gauge

Life of this patent

Temperature compensation for pressure gauge

Life of this patent

Abstract

Claims16