Temperature Sensor Selection Guide and Chart
Each type of temperature sensor has a particular set of conditions for which it is best suited with many of these conditions overlapping between sensors, and this makes temperature sensor selection as much an art as it is a science.
Many factors must be considered when selecting the type of temperature device to be used in a specific application, including:
- Temperature range,
- Response time,
The temperature sensor selection chart below gives a guide to the pros and cons of RTDs, Thermocouples and Thermistors; the three most commonly encountered temperature measurment devices in the process industry.
If after studying our temperature sensor selection chart above, and reading the sensor selection summary below you are still unsure then contact a reputable temperature sensor supplier. Suppliers that sell thermocouples, RTDs and thermistors are good sources of information when deciding which type of measuring device to use.
Temperature Sensor Selection Summary
Thermocouples can be used to measure temperatures as high as 1700°C (3100°F).
They generally cost less than RTD's and Thermistors.
Thermocouples can be made smaller in size (down to approximately .020" dia) to allow for faster response to temperature.
They are also more durable than RTD’s and thermistors, and therefore can be used in high vibration and shock applications.
However - thermocouples are less stable than RTD’s when exposed to moderate or high temperature conditions.
Read more about the different types of thermocouples.
Resistance Temperature Detectors (RTD's)
Resistance Temperature Detectors offer better accuracy and a more linear response than thermocouples.
RTD's are more stable than thermocouples and have a wider temperature range than thermistors.
However, RTD's have a longer response time and lower sensitivity.
Read more about the different types of RTD.
Thermistors have a fast response time and are inexpensive, but they are quite fragile and have a much narrower measurement range than other sensor technologies.
The following pages on Control and Instrumentation.com give more detail on the more common temperature sensors:
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For those who want to read further about the theory and practice of measuring temperature, and broaden their understanding of the differing types of temperature instrumentation, then the following books from Amazon will be of interest: