Glossary · Sensors and measurement
Pyrometer
Also known as: Infrared thermometer, Radiation thermometer
German: Pyrometer
In temperature measurement, a pyrometer is a non-contact instrument that determines the surface temperature of an object from the thermal radiation it emits, usually in the infrared range.
- Sensors
In one sentence
A pyrometer measures surface temperature without contact from the thermal radiation an object emits, usually in the infrared range.
Example
A pyrometer measures the temperature of steel billets leaving the furnace, where contact sensors would not survive.
How it applies
- Engineering: Pyrometers suit moving, very hot or inaccessible objects. The emissivity of the surface must be known or compensated; shiny metals are difficult. The spot size depends on distance and optics.
- Installation: Dust, steam, windows and ambient radiation between pyrometer and object influence the reading. Air purge units protect the optics.
- Commissioning: Set emissivity and check the reading against a reference, for example a contact measurement at a known condition.
- Documentation: Record the emissivity setting and the measuring spot position. Changed surface conditions, such as oxidation or coating, change the reading, and operators should know this.
Pyrometer vs. contact thermometer
A pyrometer measures surface temperature without contact and responds fast. A Thermocouple or Resistance temperature detector (RTD) measures the temperature at the sensor tip, which requires contact but is independent of emissivity.