How to Calibrate a Bimetal Thermometer

General information

• For accurate reading, the thermometer must be immersed past the sensing portion of the stem. On Tel-Tru bimetal thermometers this is indicated by a line on the lower portion of the stem. Check the specifications to verify the immersion depth from other manufacturers. A master thermometer should also be immersed to the same depth.
• Any severe shock to the thermometer, dropping, bending of the stem or head, etc., can possibly impair its accuracy, requiring a calibration.
• Calibration in commercial environments is generally done with a Dry Block Calibrator such as the Tel-Tru Check-Set for convenience and traceability, but the ice bath or boiling water methods can be used as well.

Calibrating instructions

• Compare temperatures of the thermometer and testing device. If the thermometer in test doesn't match the calibrator temperature or master thermometer, it will need to be adjusted.
• Adjustment methods vary somewhat with manufacturer. Below are diagrams showing how to adjust various models of Tel-Tru thermometers.

Calibrating Tel-Tru Industrial Bimetal Thermometers

Calibrating Tel-Tru Pocket, Laboratory Testing, Spot Checking and Meat Thermometers

• Models with the recalibration feature have a threadless friction hex nut and calibration can be reset by carefully holding the thermometer head and turning the hex nut with a wrench (see Figure D).

If you have any questions, please feel free to contact us.
A printable PDF version of this material is also available, click here.