Patent ID: 6742382
Filing Date: 2004-06-01
Classification: G01N,Y10T

Abstract:
A method for operating an instrument for detecting a combustible gas comprising a sensor including a heated surface on which the combustible gas reacts to cause a variation in an electrical parameter output, an electrical power supply for the instrument including a connection for heating the heated surface, a measuring unit for measuring gas concentration based on readings from the sensor and an output display for indicating the presence of a combustible gas, comprising the steps of:providing means for actuating the power supply based on the electrical parameter measured by the measuring unit; determining a first operating temperature T2 for the heated surface at which reaction of all types of combustible gas including methane takes place; in the absence of a combustible gas, operating the instrument with the heated surface at a second operating temperature T1 at which combustible gas reacts on the heated surface and which is less than T2; and determining, with the measuring unit, changes in the electrical parameter output of the sensor, and further supplying power to the sensor such that: when the sensor output is less than a predetermined threshold value, continuing to operate the sensor at temperature T1, and when the sensor output is at least equal to the threshold value indicating the presence of a combustible gas, increasing the temperature of the heated surface to T2, and operating at T2 during any time period when the electrical parameter is above the threshold value.