Equipment
Choosing and caring for sensors, loggers, baths, blocks and references.
How to choose a temperature data logger for mapping and monitoring
Match resolution and accuracy to the acceptance criteria, check what calibration is offered, then weigh memory, battery, export and response time.
Pt100 tolerance classes explained (IEC 60751)
Classes AA, A, B and C widen with temperature: Class A is ±0.15 °C at 0 °C but ±0.55 °C at 200 °C. A tolerance class is not a measurement uncertainty.
Thermocouple types and tolerance classes (IEC 60584)
Types K, J, T, N and E each have a defined EMF curve and tolerance classes 1, 2 and 3. The tolerance applies to new wire, not to a year-old thermocouple.
Thermistors: high sensitivity over a narrow range
NTC thermistors give high resolution and stability near ambient, which is why precision loggers use them. Non-linearity means several points and a fit.
Characterising a dry-block calibrator
Before using a dry block for calibration, measure its axial and radial gradients, stability, loading effect and insert wear — then repeat periodically.
Choosing a liquid calibration bath and its fluid
The fluid sets the range, stirring sets uniformity, depth sets immersion. Ethanol, water, oil and salt each own a range; safety decides the overlaps.
Readouts and bridges for reference thermometers
A reference PRT is only as good as the instrument reading it. Resolution, linearity, measurement current and calibration of the readout all enter the budget.
Ice point, triple point of water and other fixed points
Fixed points realise defined temperatures without a calibrated reference. The ice point, at 0 °C to about ±0.002 °C, is within reach of any laboratory.
Infrared thermometers: what they measure and when to trust them
An IR thermometer measures radiance, not temperature. Emissivity, distance and reflected background all move the reading, which makes it a screening tool.
Maintaining calibration equipment between calibrations
References drift, baths contaminate, inserts wear, batteries die. Maintenance and intermediate checks find those before the next calibration does.