Precision in temperature measurement plays an integral role in the efficiency, quality, and safety of many industrial processes. The decision between the pyrometer vs thermocouple is not a question of declaring one technology “better” than the other; rather, it is a question of being able to identify which measurement principle will yield optimal results for your specific plant and process characteristics. To support you with making informed decisions about the use of these two technologies within your industrial operations, we have prepared this definitive guide.
What is a Pyrometer?
A pyrometer is a device used to measure temperature without any physical contact with the object being measured by reading the amount of infrared radiation emitted by it. Since all materials emit infrared energy that is proportional to their temperature, surface temperatures can be measured accurately using a pyrometer even when there is no direct contact between the pyrometer and the surface being measured. The pyrometer uses an optical system to collect thermal radiation and provide an accurate measurement of temperature ranging from 210 to 3000°C. Therefore, a pyrometer’s non-contact technology offers great value in situations where other temperature measurement devices would be unable to operate due to movement of the object being measured, limited access to the object being measured, and/or extremely high temperatures where contamination may occur from using a contact measurement device.
Advantages of Pyrometer
- No physical contact with equipment means less chance for equipment to wear out or become contaminated when dealing with molten metals.
- Rapid response speeds can measure heat flux for quenching operations within 2ms, providing an accurate representation of temperature shifts during material phase transitions.
- Ability to measure up to 2500C provides additional capabilities not available with traditional thermocouples.
- Ability to measure the temperature of a moving object provides real-time monitoring of steel strip temperatures in rolling mill operations.
- Continuous casting and induction heating processes will not have their product integrity compromised.
- Increased operator safety with the ability to accurately measure hazardous materials from safe distances.
- Small spot size capability to provide localized precise temperature measurements as small as 0.5 mm.
- Electromagnetic interference immunity (EMI) with an additional advantage of fiber optic variants such as the A450+FOPL.
- There will be no heat sink effect, which will protect against thermal distortion on fragile measurements.
- This product will require less maintenance due to the elimination of consumable sensor components in demanding environments.
Is a Thermocouple a Heat Sensor?
A thermocouple is a contact-based temperature sensor comprising two dissimilar metal wires joined at one end, generating a voltage proportional to temperature through the Seebeck effect. This proven technology has served industries reliably for decades. Tempsens manufactures comprehensive thermocouple ranges in all types including mineral insulated construction for temperatures from -200°C to 2320°C.
Advantages of Thermocouples
- Provides accurate measurements for a small amount of money
- Temperature range from cryogenic all the way up to ultra-high temperatures allowing multiple applications
- Ability to accurately measure with direct immersion in all heating media (furnace gases), etc.
- Rugged construction can withstand pulling, vibration, and harsh environmental conditions
- Transmitting signals over great distances only requires compensating cables
- Continuous track record of reliability built from years of successful applications in steel manufacturing around the world.
- Customized design capabilities that allow for lengths of up to 40 meters on a case-by-case basis depending on application.
- Ability to operate without the need for any electrical power source by producing measurement signals via a self-sustaining power supply.
- Limited compatibility with protection tubes; however, available tubes can withstand different types of chemical environments.
- Step-by-step stability in the long term, maintaining calibration accuracy through the entire service life of the equipment.
Difference between Pyrometer vs Thermocouple
| Parameter | Pyrometer | Thermocouple |
| Measurement Principle | Non-contact infrared radiation detection | Contact-based Seebeck effect voltage generation |
| Temperature Range | 210°C to 3000°C (Tempsens models) | -200°C to 2320°C depending on type |
| Response Time | 2ms to instantaneous | Seconds to minutes depending on mass |
| Target Application | Moving objects, inaccessible locations | Immersion in process media, fixed installations |
| Installation | Remote mounting, line-of-sight required | Direct contact with measurement point |
| Maintenance | Minimal, optical cleaning required | Periodic replacement due to degradation |
| Accuracy Impact | Emissivity compensation needed | Junction condition and reference temperature |
| Cost | Higher initial investment | Lower initial cost, higher lifecycle costs |
| Environmental Suitability | Electromagnetic interference immune (fiber optic) | Susceptible to EMI in induction applications |
| Best For | Continuous casting, TMT quenching, rolling mills | Coke ovens, blast furnaces, annealing processes |
Conclusion
The microwave furnace principle is based on dielectric heating. A microwave furnace uses magnetrons to emit electromagnetic waves to the furnace chamber at a frequency of 2.45 Gigahertz. The microwaves penetrate the dielectric materials in the chamber and excite the polar molecules to oscillate rapidly, producing heat through friction. This heating method is known as volumetric heating because it heats the entire part of the piece rather than just being in contact with the heating element. Hence, the speed of heating, the energy efficiency of heating, and the ability to achieve uniform temperature distribution throughout the sample are much higher than with a conventional heating method and there is no need for the piece being heated to be in contact with the heating element. pyrometer vs thermocouple technologies serve as companion technologies for development of a comprehensive temperature control strategy. The differences between the two types of sensors need to be understood in order to make a correct decision regarding your optimal sensor selection for your industry. Tempsens provides thermocouple and pyrometer technologies engineered to a standard of quality that meets or exceeds all international standards for industrial applications. Our mineral insulated thermocouples provide the necessary durability when used in blast furnace hearths, while our non-contact pyrometers provide highly precise temperature measurements during ladle preheating and induction heating operations.
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FAQ
What is the difference between thermocouple and pyrometer?
A thermocouple uses voltage generation from two dissimilar metals to measure temperature via physical contact, while a pyrometer uses non-contact infrared radiation detection to measure temperature. While thermocouples are ideal for fixed installations or in applications involving immersion into liquids, pyrometers are suitable for measuring the temperatures of moving objects and for measuring the temperatures of very hot objects that cannot be accessed.
What are the advantages of using a pyrometer?
Pyrometers use non-contact methods of measurement eliminating contamination risks with their usage. They have short response times on dynamic processes of 2ms. They function at very high temperatures (up to 3000°C), and can measure moving targets, particularly in rolling mills. Pyrometers are completely insulated against EMI (electromagnetic interference) if configured using a fibre optic configuration.
Is a thermocouple better than a pyrometer?
There is no definitive ‘better’ option; the choice will depend on the demands of the application. Thermocouples are ideal for cases where direct contact with the material being measured is possible, in low-cost installations and environments where the contact measurement method is acceptable. Pyrometers are more effective on objects that move, are out of reach, require high-temperature readings that cannot be performed using thermodynamic sensors, or when there is no disruption caused to the material being measured.
