Both RTDs (Resistance Temperature Detectors) and thermocouples are sensors that are used to measure temperature, however, there are some important differences between both of these. There are different specific criteria as for their performance which will help us determine which one of them is best suited for an industrial process that we are looking to install one for as follows:
- Cost Considerations: For temperatures above 600 degree centigrade RTDs are more expensive than thermocouples. For temperature measurements of the same style and order, an RTD will cost you nearly 2 or 3 times the cost of a thermocouple. Although you can expect to make some savings on RTD installation because of the use of copper wiring at lower temperatures, it is not enough considering the higher cost of the RTD device itself.
- Temperature Range: For measuring the higher temperatures up to 1800°C , thermocouples are considered to be the best and more reliable than most RTDs which cannot operate efficiently at temperatures lesser than 400°C.
- Sensitivity: Although both RTDs and thermocouples are known to quickly respond to any minute changes in temperature, grounded thermocouples are more sensitive and respond at least 3 times faster than a RTD such as PT100. An exposed-tip thermocouple is considered to be the most sensitive and fastest.
- Accuracy: For better accuracy, you should opt for an RTD over a thermocouple for temperatures measurements below 400°C. Typically most RTDs have a better accuracy of about 0.10C in contrast to the thermocouples which are less accurate (1°C). However, some advanced thermocouples are designed to match the accuracy that an RTD can provide. The accuracy of the sensor depends on various factors such as linearity, stability, and repeatability.
- Linearity: All RTDs have a linear temperature-resistance relation to operate efficiently in a given sensor range, but you can see an ‘S’ type plot in a thermocouple.
- Stability: The readings from an RTD probe generally remain more stable and repeatable over a prolonged period of time, but thermocouple readings have a tendency to drift because of the sensor likely to have oxidative changes overtime. Thus, RTDs remain mostly stable and are considered to be a better choice for long term use.
We can easily conclude here that if you are looking for an economical temperature sensor, you can opt for a thermocouple because they are cheaper and easier to manufacture rather than an RTD. You can expect to make significant cost savings by selecting a thermocouple for your process especially in case you need a good number of temperature probes for your process.
On the other hand, if you are looking for a more accurate and reliable temperature sensor, you should opt for an RTD for your process. Not to forget the only constraint with an RTD is the limited temperature range that they can operate optimally.
Heatcon Sensors – The Leading Manufacturer of All Types of High-Quality, Reliable, and Accurate RTDs & Thermocouples!
If you are still unable to make a decision regarding which sensor type will be best suited for your industrial process, you can contact the experts at Heatcon Sensors who have great experience in designing, customizing, and manufacturing all types of high quality temperature sensors for various and sundry industrial processes.