Temperature calibration in practice
Bench-level technique for PRTs, thermocouples and loggers: sources, immersion, self-heating, hysteresis, references and the ice point.
11 articles · about 37 min · for Laboratory technicians and engineers performing or specifying temperature calibrations.
- 01CalibrationHow to calibrate a Pt100Calibration by comparison against a reference thermometer, and the factors that decide the uncertainty.4 min
- 02CalibrationChoosing calibration pointsCalibrate where you measure. Points should bracket the use range and include any temperature where a decision is made.3 min
- 03CalibrationLiquid bath versus dry-block calibratorWith the same reference and the same repeatability, a stirred bath gives U = 0.038 °C and a dry block 0.139 °C, where the source becomes the largest term.3 min
- 04CalibrationImmersion depth and stem conductionA probe conducts heat along its stem. Insufficient immersion makes the sensor read closer to room temperature than to the medium.3 min
- 05CalibrationSelf-heating in resistance thermometersThe measuring current warms the element above its surroundings: under a millikelvin in a stirred bath, tens in still air. Calibrate in the medium you use.4 min
- 06CalibrationHysteresis in temperature sensorsA sensor can read differently at the same temperature depending on where it came from. Calibrations that only approach from one direction hide it.3 min
- 07CalibrationSelecting a reference thermometerPick a reference for stability first and certificate uncertainty second: one that drifts between its own calibrations is worse than a larger honest number.4 min
- 08CalibrationThe ice-point checkA properly made ice bath gives 0 °C to within a few millikelvin — a cheap, repeatable way to watch a PRT for drift between calibrations.3 min
- 09UncertaintyThe reference thermometer's contribution to uncertaintyThe reference contributes its certificate uncertainty, drift since calibration, and any interpolation or self-heating effect. Together they set the floor.3 min
- 10CalibrationData logger calibration: how temperature loggers are calibratedA logger is calibrated as a whole system, sensor and electronics and firmware together, in a chamber, at the temperatures you actually use it at.3 min
- 11CalibrationHow thermocouples are calibratedComparison against a reference in a bath or furnace, with the reference junction realised. Ignore it on a type K at 420 °C and you read 398 °C.4 min
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