Method and system for testing the accuracy of a thermocouple probe used to measure the temperature of molten steel
AssigneeVesuvius Crucible Company
InventorsJohn D. Usher, Todd A. Kirkpatrick
Life of this patent
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Abstract
A method and system for testing the accuracy of a thermocouple probe exposed to a medium having a temperature of between about 2200.degree. F. and 3400.degree. F. is provided that includes the step of measuring the rate of change of the temperature readings of the probe after a temperature of at least 2000.degree. F. is read, and comparing the measured rate of change with a standard rate of change obtained from a properly operating probe. Both the method and the system are advantageously capable of determining whether the temperature readings of a thermocouple in use in a steel production plant are accurate without the need for comparative readings from other thermocouple probes.
Claims20
A method for testing the accuracy of a temperature probe exposed to a medium having a temperature of between about 2200.degree. F. and 3400.degree. F., comprising the steps of
- measuring the rate of change of the temperature readings of the probe after a temperature of at least 2000.degree. F. is read,
- comparing the measured rate of change with a standard rate of change obtained from a properly operating probe, and
- declaring the temperature probe to be inaccurate whenever the rate of change deviates significantly from the standard rate of change.
A method for testing the accuracy of a thermocouple probe exposed to liquid metal having a temperature of between about 2200.degree. F. and 3400.degree. F., comprising the steps of:
- measuring the rate of change of the temperature readings of the probe after a temperature of at least 2000.degree. F. is read, and
- comparing the measured rate of change with a standard rate of change obtained from a properly operating probe.
A system for testing the accuracy of a temperature probe exposed to a medium having a temperature of between about 2200.degree. F. and 3400.degree. F., comprising:
- a temperature probe, and
- means for measuring the rate of change of temperature readings of the probe after said probe reads a temperature of at least 2000.degree. F.;
- comparing the measured rate of change with a standard rate of change obtained from a properly operating probe, wherein the rate of change is determined by periodically computing a value of .tau. from the following expression:
- .tau.=t/(ln((T.sub.1 -T.sub.0)/(T.sub.1 -T)))
- where T equals the temperature displayed by the probe t seconds after displaying a temperature of T.sub.0 when immersed in a medium of a temperature T.sub.1 ;
- and
- declaring the temperature probe to be inaccurate whenever the rate of change deviates significantly from the standard rate of change.
Dependencies are inferred from the claim text.