Patent ID: 7398160

Claim:
A gas meter that determines one or more properties of a gas mixture, using an inferential algorithm, comprising: a gas sensor module having: a pressure regulator for receiving the gas mixture and for regulating the pressure of the gas mixture; a test chamber for receiving an amount of pressure-regulated gas mixture, for testing the gas to provide a waveform output signal from which the speed of sound in the gas mixture can be derived, and for providing an output signal representing the carbon dioxide concentration of the gas mixture; a temperature sensor for providing a signal representing the temperature of the gas mixture in the test chamber; a pressure sensor for providing a signal representing the pressure of the gas in the test chamber; and a release valve for controlling the release of the gas from test chamber; wherein the pressure regulator is controllable to provide two pressure states of the gas in the test chamber; wherein the test chamber has a speed of sound sensing channel for containing a first portion of the gas mixture during speed of sound testing, a carbon dioxide sensing subchamber for containing a second portion of the gas mixture during carbon dioxide measurement, and a closed internal conduit that provides a defined linear passageway between the speed of sound sensing channel and the carbon dioxide sensing subchamber, such that the first portion and second portion are in fluid communication via the conduit; a pre-processing module for receiving the output signals from the sensor module signals and for providing data representing each of these signals; thereby providing temperature data, pressure data, speed of sound data, and carbon dioxide data; and a processing module for using the speed of sound data to calculate the speed of sound in the gas, and to use the temperature, pressure, carbon dioxide, and speed of sound data at two states of the gas to inferentially determine at least one property of the gas mixture.