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Pyrometer is any non-contacting device that intercepts and measures thermal radiation
Thermal radiation

Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the object's temperature. Infrared radiation from a common household radiator or electric heater is an example of thermal radiation, as is the light emitted by a glowing incandescent light bulb....
. This measure is used to determine temperature, often of the object's surface.

The word pyrometer comes from the Greek
Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
 word for fire, "p??", and meter, meaning to measure. Pyrometer was originally coined to denote a device capable of measuring temperatures of objects above incandescence
Incandescence

Incandescence is the emission of light from a hot body due to its temperature. The term derives from the verb incandesce, to grow white....
 (i.e. objects bright to the human eye).

rometer has an optical system and detector.






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Pyrometer is any non-contacting device that intercepts and measures thermal radiation
Thermal radiation

Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the object's temperature. Infrared radiation from a common household radiator or electric heater is an example of thermal radiation, as is the light emitted by a glowing incandescent light bulb....
. This measure is used to determine temperature, often of the object's surface.

The word pyrometer comes from the Greek
Greek language

Greek is an Indo-European languages native to the southern Balkan peninsula, the language of the Greek people. It forms an independent branch within Indo-European....
 word for fire, "p??", and meter, meaning to measure. Pyrometer was originally coined to denote a device capable of measuring temperatures of objects above incandescence
Incandescence

Incandescence is the emission of light from a hot body due to its temperature. The term derives from the verb incandesce, to grow white....
 (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
Thermal radiation

Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the object's temperature. Infrared radiation from a common household radiator or electric heater is an example of thermal radiation, as is the light emitted by a glowing incandescent light bulb....
 onto the detector. The output signal of the detector (Temperature T) is related to the thermal radiation
Thermal radiation

Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the object's temperature. Infrared radiation from a common household radiator or electric heater is an example of thermal radiation, as is the light emitted by a glowing incandescent light bulb....
 or irradiance
Irradiance

Irradiance, radiant emittance, and radiant exitance are radiometry terms for the power of electromagnetic radiation at a surface, per unit area....
 j* of the target object through the Stefan–Boltzmann law, the constant of proportionality s, called the Stefan-Boltzmann constant
Stefan-Boltzmann constant

The Stefan?Boltzmann constant , a physical constant denoted by the Sigma, is the constant of proportionality in the Stefan?Boltzmann law: the total energy radiated per unit surface area of a black body in unit time is proportional to the fourth power of the thermodynamic temperature....
 and the emissivity
Emissivity

The emissivity of a material is the ratio of energy Radiation by a particular material to energy radiated by a black body at the same temperature....
 e of the object.

This output is used to infer the object's temperature. Thus, there is no need for direct contact between the pyrometer and the object, as there is with thermocouple
Thermocouple

A thermocouple is a junction between two different metals that produces a voltage related to a temperature difference. Thermocouples are a widely used type of list of temperature sensors and can also be used to convert heat into electric power....
 and Resistance temperature detector (RTDs).

Applications

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
Metallurgy

Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic Chemical element, their intermetallics, and their mixtures, which are called alloys....
 furnace
Furnace

File:Piec krepa.JPGA furnace is a device used for heating. The name derives from Latin fornax, oven. The earliest furnace was excavated at Balakot, a site of the Indus Valley Civilization, dating back to its mature phase ....
 operations. Reliable and continuous measurement of the melt temperature is essential for effective control of the operation. Smelting rates can be maximized, slag
Slag

Slag is a partially vitreous by-product of smelting ore to purify metals. They can be considered to be a mixture of metal oxides; however, they can contain metal sulfides and metal atoms in the elemental form....
 can be produced at the optimum temperature, fuel consumption is minimized and refractory life may also be lengthened. Thermocouples
Thermocouple

A thermocouple is a junction between two different metals that produces a voltage related to a temperature difference. Thermocouples are a widely used type of list of temperature sensors and can also be used to convert heat into electric power....
 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.

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See also

  • Infrared thermometer
    Infrared thermometer

    Infrared thermometers measure temperature using blackbody radiation emitted from objects. They are sometimes called laser thermometers if a laser is used to help aim the thermometer, or non-contact thermometers to describe the device?s ability to measure temperature from a distance....
  • Thermal radiation
    Thermal radiation

    Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the object's temperature. Infrared radiation from a common household radiator or electric heater is an example of thermal radiation, as is the light emitted by a glowing incandescent light bulb....
  • Thin filament pyrometry
    Thin filament pyrometry

    Thin Filament Pyrometry is an optical method used to measure temperatures. It involves the placement of a thin filament in a hot gas stream. Radiative emissions from the filament can be correlated with filament temperature....