Method for calibrating the zero point in a gas analyzer
AssigneeInstrumentarium Corp.
InventorsTimo Merilainen, Borje Rantala, Kurt Weckstrom, Kai Karlsson
Life of this patent
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Abstract
A method for calibrating a gas analyzer (1). A gas analyzer is calibrated by measuring the zero level of the analyzer (1). The level of the analyzer is measured, after a preceding reset, whenever a temperature variation (.DELTA.T) of an infrared sensor (14) included in the analyzer (1) or of a component thermally connected in a highly conductive manner thereto exceeds a predetermined threshold value (A), or the temperature variation rate (D) of the infrared sensor (14) of the analyzer (1) or of a component thermally connected in a highly conductive manner thereto exceeds a predetermined limit valve.
Claims22
A method for calibrating the zero point of a gas analyzer having an infrared sensor, said method comprising the steps of:
- sequentially measuring a phenomenon indicative of temperature conditions in the gas analyzer capable of causing alteration of the zero point;
- determining whether or not the amount of change of the measured phenomenon exceeds a threshold amount of change value and whether or not the rate of change of the measured phenomenon exceeds a threshold rate of change value;
- and
- carrying out a calibration of the zero point of the gas analyzer when one of the threshold values is exceeded, the time at which the calibration of the zero point is carried out being as follows:
- at the end of a minimum time period from a predetermined timing point if the threshold value is exceeded in the minimum time period;
- at the time when the threshold value is exceeded when same occurs after the end of the minimum time period and before a preselected maximum time from a predetermined starting point;
- or at the preselected maximum time from the predetermined starting point in the event the threshold value has not been exceeded before the maximum time.
A method for calibrating the zero point of a respiratory gas analyzer having an infrared sensor, said method comprising the steps of:
- sequentially measuring the temperature of the infrared sensor;
- determining whether or not the amount of change of the temperature exceeds a temperature amount of change threshold value and whether or not the rate of change of the temperature exceeds a temperature rate of change threshold value;
- and
- carrying out a calibration of the zero point of gas analyzer when one of the threshold values is exceeded, the time at which the calibration of the zero point is carried out being as follows:
- at the end of a minimum time period from a predetermined timing point if the threshold value is exceeded in the minimum time period;
- at the time when the threshold value is exceeded when same occurs after the end of the minimum time period and before a preselected maximum time from a predetermined starting point;
- or at the preselected maximum time from the predetermined starting point in the event the threshold value has not been exceeded before the maximum time.
Dependencies are inferred from the claim text.