AskDefine | Define pyrometer

Dictionary Definition

pyrometer n : a thermometer designed to measure high temperatures

User Contributed Dictionary



  1. A thermometer designed to measure high temperatures.
  2. An instrument for measuring the thermal expansion of solids.

Related terms

Extensive Definition

Pyrometer is any non-contacting device that intercepts and measures thermal radiation. This measure is used to determine temperature, often of the object's surface.
The word pyrometer comes from the Greek word for fire, "πυρ", and meter, meaning to measure. Pyrometer was originally coined to denote a device capable of measuring temperatures of objects above incandescence (i.e. objects bright to the human eye).

Principle of operation

A pyrometer has an optical system and detector. The optical system focuses the thermal radiation onto the detector. The output signal of the detector (Temperature T) is related to the thermal radiation or irradiance j* of the target object through the Stefan–Boltzmann law, the constant of proportionality σ, called the Stefan-Boltzmann constant and the emissivity ε of the object. j^ = \varepsilon\sigma T^
This output is used to infer the objects temperature. Thus, there is no need for direct contact between the pyrometer and the object, as there is with thermocouple and Resistance temperature detector (RTDs).


Pyrometer are suited especially to the measurement of moving objects or any surfaces that can not be reached or can not be touched.

Smelter Industry

Temperature is a fundamental parameter in metallurgical furnace operations. Reliable and continuous measurement of the melt temperature is essential for effective control of the operation. Smelting rates can be maximized, slag can be produced at the optimum temperature, fuel consumption is minimized and refractory life may also be lengthened. Thermocouples used to be the traditional device, but they are unsuitable for continuous measurement because they rapidly dissolve.

Over-the-bath Pyrometer

Continuous pyrometric measurement from above the bath surface is still employed, but is known to give poor results because of emissivity variations, interference by gases and particulate matter in the intervening atmosphere, and dust accumulation on the optics.

Tuyère Pyrometer

The Tuyère Pyrometer is an optical instrument for temperature measurement through the tuyeres which are normally used for feeding air or reactants into the bath of the furnace.
pyrometer in Czech: Pyrometr
pyrometer in German: Pyrometer
pyrometer in Spanish: Pirómetro
pyrometer in French: Pyromètre
pyrometer in Italian: Pirometro
pyrometer in Japanese: パイロメーター
pyrometer in Dutch: Pyrometer
pyrometer in Polish: Pirometr
pyrometer in Portuguese: Pirômetro
pyrometer in Romanian: Pirometru
pyrometer in Russian: Пирометр
pyrometer in Ukrainian: Пірометр
Privacy Policy, About Us, Terms and Conditions, Contact Us
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2
Material from Wikipedia, Wiktionary, Dict
Valid HTML 4.01 Strict, Valid CSS Level 2.1