Selecting the Right Stem Length

We often get questions regarding the selection of the right stem length for temperature instruments used in industrial processes. For accurate temperature readings, the length of the sensor must be fully immersed into the process equipment. Tel-Tru bimetal thermometers have a groove that indicates the minimum depth that the thermometer stem needs to be inserted.

Stem lengths for thermometers with threaded connections are measured from the top of the thread to the tip of the stem. Non-threaded thermometers are measured from the back of the case to the tip of the stem.

Tel-Tru thermometer stems should never be modified. The bimetal coil assembly is in the lower 2” of the stem, and if it is damaged, the thermometer is rendered unusable.

Tel-Tru can manufacture custom stem lengths from 2.5″ to 120″ for bimetal thermometers, depending on the model.

We highly recommend the use of a thermowell in applications with flow or pressurization.

If you need help deciding which stem length is best for your industrial or sanitary application, feel free to contact us.
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