A pyrometer is a device that is used for non-contact temperature measurement. Accurate, non-contact temperature measurement is essential in all types of industries and industrial processes for melting, heating, drying, forming or heat-treating materials.
Pyrometers work by detecting infrared (IR) radiation. A pyrometer is an optical device that uses a lens to focus the IR radiation onto a detector, which converts the IR radiation into an electrical signal. The temperature of the object can then be calculated from the strength of the IR radiation that is detected.
What Is IR Radiation?
IR radiation refers to a specific part of the electromagnetic spectrum that is not visible to the naked eye. All objects with a temperature, including cold objects, emit IR radiation, but as an object’s temperature increases, so does the amount of IR radiation that it emits, so it is often referred to as “heat radiation”.
The diagram above shows that the IR spectrum covers the wavelength of 0.7µm to 1000 µm. Generally, pyrometers operate in wavelengths from 0.38 µm to 14 µm. The exact wavelength will depend on the type of pyrometer and the specific application it is used for.
How Does a Pyrometer Determine a Temperature from IR?
To measure temperature with a pyrometer, the device must first be calibrated to a known temperature. This is typically done using a blackbody calibration source, a device that emits a known amount of IR radiation at specific temperatures.
The pyrometer uses a detector to measure the amount of IR radiation emitted by the object. The detector converts the IR radiation into an electrical signal, which is then processed by the pyrometer’s electronics to calculate the temperature of the object.
The temperature calculation is based on the principle that the amount of IR radiation emitted by an object is directly proportional to its temperature. Therefore, the more IR radiation that the pyrometer detects, the higher the object’s temperature. The pyrometer can then display the temperature of the object on its screen or output the temperature to a computer or other device.
Explore Our Range of Impac Pyrometers at LIMAB UK
What Can Interfere with the Accuracy of a Pyrometer?
It’s important to be aware of possible sources of interference that might cause a temperature reading error when using a pyrometer, for example:
- Other sources of IR radiation: IR radiation from another hot object nearby could influence the measurement if it can be picked up by the pyrometer’s field of view.
- Transparent materials: If a transparent material is being measured, hot objects behind the measured object might cause interference.
- Dust, steam, vapour, smoke, etc.: These can all attenuate IR radiation, leading to inaccurate measurements.
- Field of view errors: The spot has to fit the size of the object if a single-colour pyrometer is being used.
- Electromagnetic interference: Strong electromagnetic fields can interfere with a pyrometer’s electronics.
With careful consideration and the correct selection of the pyrometer, most of these potential sources of interference can be avoided. Please speak with a product specialist for advice.
Learn More about Pyrometers
In summary, pyrometers work by measuring IR radiation and are useful in a wide range of industries and working conditions. Learn more about pyrometers by using the links below:
- Learn what a pyrometer is
- Learn more about the advantages of pyrometers compared to contact thermometers
- Learn more about the different types of pyrometer
- Learn more about what information you need to select the correct pyrometer
- Learn more about spot size when selecting a pyrometer
Visit our temperature measurement and thermal processing page to learn more about LIMAB UK’s temperature measurement products, including pyrometers. To speak to a product specialist to find out how a pyrometer could benefit your company, call +44 (0)1823 668633.
