Industrial temperature measurement
Temperature is one of the most important process variables in industrial manufacturing. Two widely used measurement technologies are RTDs and thermocouples, and choosing between them requires understanding temperature range, accuracy, response time, installation and process environment. EECG's temperature portfolio includes RTDs, thermocouples, temperature gauges and pressure gauges.
What is an RTD?
RTD stands for Resistance Temperature Detector. An RTD measures temperature based on the predictable change in electrical resistance of its sensing element as temperature changes, and is commonly considered where stable and accurate measurement is required.
What is a thermocouple?
A thermocouple consists of two dissimilar metals joined at one end. When exposed to a temperature difference it generates a voltage that can be measured and converted into temperature. Thermocouples are widely used for industrial temperature measurement.
RTD vs thermocouple
| Feature | RTD | Thermocouple |
|---|---|---|
| Measurement principle | Resistance change | Thermoelectric voltage |
| Accuracy | Generally high | Application dependent |
| Temperature range | Application dependent | Often very wide |
| Response | Application dependent | Often fast |
| Construction | Resistance element | Two dissimilar metals |
| Typical applications | Process measurement | High-temperature and general industrial measurement |
The exact performance depends on the sensor construction and application.
When should you choose an RTD?
- Measurement accuracy is important
- Stable readings are required
- The temperature range is compatible
- Process monitoring requires reliable repeatability
When should you choose a thermocouple?
- Higher temperatures are involved
- Fast response is important
- The application suits thermocouple technology
- Rugged industrial measurement is required
Temperature transmitters
A temperature transmitter converts the sensor signal into a standard industrial output, helping integrate RTDs and thermocouples with PLC, DCS, SCADA and other industrial monitoring systems. EECG's instrumentation portfolio includes temperature transmitters as well as RTDs and thermocouples.
Applications by industry
Steel plants
Furnaces, process equipment, cooling systems, utilities and manufacturing lines. Sensor construction and protection should match the operating environment.
Power plants
Steam systems, boilers, turbines, feedwater, cooling systems and auxiliary equipment.
Cement plants
Kilns, furnaces, process equipment, material handling and utilities.
Chemical plants
Temperature can affect reaction conditions and product quality, so sensor material, process connection and protective construction must suit the chemical environment.
Heavy-duty temperature measurement
Industrial environments can expose sensors to high temperature, vibration, dust, pressure and corrosive conditions, so heavy-duty temperature instruments are often required. EECG's portfolio includes heavy-duty thermometers alongside RTDs and thermocouples.
Conclusion
An RTD may be preferred where stable and accurate measurement is required within its suitable range, while thermocouples suit demanding high-temperature applications. The right choice depends on temperature range, accuracy, response time, process conditions, installation and maintenance requirements.
Need help specifying instruments, valves or a maintenance contract for your plant? Our engineers can review your process conditions.
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