Industrial-Commercial RTD & Thermistor Information
The Importance of Calibration
Thermalogic offers a temperature sensor calibration service to certify minimum accuracy and/or offer convenience in establishing readout formulas used with customer instruments and controls.
Resistance at one, three, or more temperatures can be calibrated for submitted sensors and reported on a certificate to be used for instrument setup or firmware development.
The practical range for sensor calibration is 0°C to 100°C and resistance calibration accuracy is +/- 0.01% of value at specified temperatures +/- 0.05°C, traceable to NIST standards, using liquid bath or dry block methods as appropriate.
The most accurate results will obtain from performing calibrations as closely as possible over the same temperature range to be encountered in the sensor application environment.
In understanding the limits of calibration, is it important to remember the temperature instrumentation and controls often provided more precision than accuracy in customer readout display. A readout to 0.01°C, for instance, will almost never represent actual temperatures to this accuracy and can be misleading unless used simply for trend indication.
Results, reported as resistance values at calibration temperatures, will usually be ultimately used in the Steinhart-Hart formula, for thermistors; or the Callendar-Van Dusen formula, for RTD’s, by customer instruments or controls. As a convenience, the appropriate coefficients for these methods will be provided as part of the calibration report.