I have a question regarding thermocouples
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Question: Some people say that thermocouples are mostly used for high-temperature measurements. So, at 0 degrees Celsius, or for example at -40 degrees Celsius, can a certain type of thermocouple still be used? But most people say that negative temperatures are mostly measured using thermal resistors. Is this how we actually use it? I see that some types of thermocouples can measure temperatures below 0 degrees, but I also noticed that the manufacturers of these thermocouples state that their temperature measurement range is generally above 0 degrees Celsius. Please ask a professional engineer to answer. Thank you.
This one? I’m not a professional engineer, so I won’t answer.
K, E, J, and T type thermocouples, as well as resistive elements, can all be used to measure temperatures below zero; you can take a look at the calibration tables for thermocouples and thermal resistors
Below 300 degrees, thermal resistors are generally used as they offer higher precision. Your requirements aren’t high, so it’s fine.
In a regular factory, how low can it get in degrees Celsius? It can’t be that low, so any type of thermistor will do. Thermocouples are indeed used in high-temperature environments, such as temperatures over 1000°C; that’s what I’ve seen so far. Thermistors are used for low temperatures, while thermocouples are used for high temperatures
This post was last edited by huazh on 2017-2-27 10:59. Thank you to everyone who provided answers above. It’s like this: I’m writing a program for an instrument that uses thermocouples to measure temperature. Do I need to include the scale values at 0 degrees? If a thermocouple is used to measure high temperatures, then there is no need to include the scale at 0 degrees Celsius in the program. Is this okay? Is it possible to use a thermocouple to measure temperatures below 0 degrees Celsius?
At low temperatures, the measurement accuracy of thermal resistors is higher than that of thermocouples. Due to the poor seismic resistance of thermal resistors, thermocouples should also be chosen in environments with vibrations.
May I ask, what type of thermocouple is commonly used in China for measuring temperatures below 0 degrees? Have you seen or used thermocouples to measure temperatures below 0 degrees Celsius?
It’s a matter of the measurement range. Generally, thermocouples have a relatively high temperature limit, usually above 1000 degrees Celsius; in some cases it is around 800 degrees. The lower temperature limit can be below 0 degrees Celsius; if the actual temperature range is narrow and the upper temperature limit is not very high, it is better to use a thermal resistor, as this relates to the sensitivity of the temperature sensor.
The owner’s questions have left me completely speechless.