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Thermocouple reading deviation

We recently purchased the DT80-4 to work in low temperature to read T type thermocouple probes. It is connected with 2 thermocouples on the main module and 40 thermocouples on the CEM20 module. The main and extension module are both working in about -20C environment and 40% relative humidity. To calibration the thermocouples, we use glycol to simulate the low temperature situation. When we put some of the thermocouple probes into glycol at temperature below 0C, the other ones which are at room temperature have lower readings simultaneously which is approximately 2C lower. And also the probes in glycol reads 4-5C lower temperature than our standard thermometer. Do you have an idea what went wrong? Thanks for the help!

We recently purchased the DT80-4 to work in low temperature to read T type thermocouple probes. It is connected with 2 thermocouples on the main module and 40 thermocouples on the CEM20 module. The main and extension module are both working in about -20C environment and 40% relative humidity. To calibration the thermocouples, we use glycol to simulate the low temperature situation. When we put some of the thermocouple probes into glycol at temperature below 0C, the other ones which are at room temperature have lower readings simultaneously which is approximately 2C lower. And also the probes in glycol reads 4-5C lower temperature than our standard thermometer. Do you have an idea what went wrong? Thanks for the help!

Hi Fiona,

The 2-degree and 5-degree difference in thermocouple reading is equal to 0.08 mV and 0.2 mV. That signal may come from any external interference, may I know how long is the thermocouple wire? And how did you lay the wire from the logger to the glycol bath?

The best would be to add a shield as well as twist the wire to address the interference.

Best regards,
dataTaker Expert

Hi Fiona, The 2-degree and 5-degree difference in thermocouple reading is equal to 0.08 mV and 0.2 mV. That signal may come from any external interference, may I know how long is the thermocouple wire? And how did you lay the wire from the logger to the glycol bath? The best would be to add a shield as well as twist the wire to address the interference. Best regards, dataTaker Expert
edited Jul 27 at 2:46 am
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