What's the best choice for your industrial temperature sensing requirement, a thermocouple or RTD? In industrial installations, both types of sensor can be specified with similar mounting accessories, dimensional specifications, and instrument interfaces. However, there are three criteria you need to consider before choosing between an RTD or thermocouple probe.
First, what is the temperature range you are trying to monitor?
Generally, if the temperature exceeds five hundred degrees Celsius (500 deg C), thermocouples are for you. RTD's are best between -200 and 500 °C, while thermocouples have a range of -180 to 2,320 °C. For anything above 500 Celsius, you should select the appropriate thermocouple calibration for the sensing range you're working in.Second, what type of sensor accuracy do you need?
RTDs are more accurate temperature sensors, offer highly repeatable readings, drift less over time, and are suitable for high precision requirements. Thermocouples are generally less accurate and are subject to drift. Typical thermocouple accuracy is 2 deg. C.Third, how about the budget you're working under?
Thermocouples can be up to three times less expensive than RTD probes, making thermocouples a good choice if high accuracy and repeatability are not critical. One caveat though. Make sure you consider any additional cost incurred with long runs of thermocouple extension wire. For installations requiring dozens or even hundreds of temperature sensors, the significant difference in basic sensor cost is an important consideration.These three criteria are VERY basic, and intended just to point you in the right direction. There are many other differences between thermocouples and RTDs that need to be understood before application. Consult a temperature sensor expert prior to installing or specifying a thermocouple or RTD wherever or whenever failure can cause harm.
