Weidou Intelligent Technology professionally supplies German Maurer infrared pyrometers. Welcome to inquire by phone.

Germany Dr. Georg Maurer GmbH was founded in 1945, and is a world-renowned expert in the development and production of infrared thermometers. It is used for various monitoring and control functions, such as coating, drying, welding, hardening, welding, sintering, casting, and temperature profile measurement, mainly used in continuous casting plants, pipe welding plants, industrial furnaces, and industries such as plastics, glass, textiles, paper, and steel.

Brand keywords: Dr.Georg, Dr.Maurer, Georg Maurer, German Maurer, MAURER gmbh, MAURER sensor, MAURER temperature sensor, MAURER sensor, MAURER infrared, MAURER infrared, Maurer infrared pyrometer

Infrared pyrometer

     Non-contact temperature measurement using an infrared pyrometer has many advantages. Its application range extends from small or hard-to-reach objects to corrosive chemicals and sensitive surfaces. This article will discuss these advantages, explain the decisive factors for correctly selecting an infrared pyrometer, and clarify its scope of application.   Due to the motion of atoms and molecules, every object radiates electromagnetic waves. The most important wavelength or spectral range for non-contact temperature measurement is from 0.2 to 2.0μm. Natural radiation within this range is referred to as thermal radiation or infrared.  
Test instruments that perform temperature measurement based on infrared radiation emitted by the measured object are called radiation thermometers, radiation pyrometers, or infrared thermometers according to the German industrial standard DIN16160. These names also apply to instruments that perform temperature measurement using visible colored rays radiated by the measured body, as well as instruments that derive temperature from the relative spectral radiation density.

 
One, Advantages of temperature measurement with infrared thermometers  
    Non-contact temperature measurement, performed by receiving infrared radiation emitted from the target object, offers many advantages. This allows temperature measurement of objects that are difficult to access or in motion without any issues, such as materials with poor heat transfer performance or very small thermal capacity. The very short response time of infrared pyrometers enables rapid implementation of effective control loops. Pyrometers do not have wearing parts, thus eliminating the recurring costs associated with using contact thermometers. Especially for very small measured objects, contact measurement can produce significant measurement errors due to the thermal conductivity of the object. In such cases, pyrometers can be used without hesitation, including for corrosive chemicals or sensitive surfaces, such as on paint, paper, and plastic films. Remote measurement allows operation from a distance away from hazardous areas, ensuring operator safety.

 
Two, Principle and construction of infrared pyrometers 
     The infrared radiation received from the measured object is focused by a lens through a filter onto a detector. The detector integrates the radiation density of the measured object to generate a current or voltage signal proportional to the temperature. In the subsequently connected electrical components, this temperature signal is linearized, corrected for emissivity, and converted into a standard output signal.  
In principle, there are two types of pyrometers: portable and fixed. Therefore, when selecting a suitable infrared pyrometer for different measurement points, the following characteristics are primary:  
 1, Aiming device  
     The aiming device serves the purpose of making the measurement area or point indicated by the pyrometer visible. For large measured objects, an aiming device is often unnecessary. For small measured objects and longer measurement distances, an aiming device in the form of a transmissive lens with scale markings on the instrument panel or a laser pointer is recommended.  
 2, Lens  
     The lens determines the measurement spot of the pyrometer. For large objects, a pyrometer with a fixed focal length is generally sufficient. However, when the measurement distance deviates from the focal point, the image at the edge of the measurement spot will become unclear. For this reason, a zoom lens is preferable. Within the given zoom range, the pyrometer can adjust the measurement distance. High-end pyrometers come with interchangeable zoom lenses; near and far lenses can be replaced without recalibration.  
 3, Sensor, i.e., spectral receiver  
     Temperature is inversely proportional to wavelength. At low object temperatures, sensors sensitive to the long-wave spectral region (thermopile sensors or thermocouple sensors) are suitable. At high temperatures, photoelectric sensors sensitive to short waves, composed of germanium, silicon, indium-gallium, etc., are used.  
When selecting spectral sensitivity, the absorption spectral bands of hydrogen and carbon dioxide must also be considered. Within a certain wavelength range, known as the "atmospheric window," H2 and CO2 are almost transparent to infrared radiation. Therefore, the spectral sensitivity of the pyrometer must fall within this range to exclude the influence of changes in atmospheric concentration. When measuring thin films or glass, it must also be taken into account that these materials are not easily penetrated at certain wavelengths. To avoid measurement errors caused by background light, use appropriate sensors that only receive surface temperature. Metals have this physical property: emissivity increases as wavelength decreases. Empirically speaking, for measuring metal temperatures, the shortest measurement wavelength is generally selected.  

Three, Development trends of infrared pyrometers  
     As in many sensing technology fields, the development trend of pyrometers is towards smaller, compact designs. A round housing with a central thread is ideal for installation on machinery and equipment. This trend is realized through the continuous miniaturization of electrical components and high-level integration, allowing increasingly smaller and more refined electrical components to be condensed into ever-smaller spaces. Compared to past analog technology, the application of microcontrollers has improved the precision of detector signal linearization, thereby increasing the accuracy of the instrument.  
The market demands fast, cost-effective reception of measurement values, capable of directly outputting a linear current/voltage signal proportional to temperature. Processing of measurement values, such as smoothing functions, storage of specific values, or limit contacts, is placed on intelligent displays, controllers, or SPS (programmable logic controllers). Emissivity adjustment via external cables can be performed outside hazardous areas, even while the machine is running, and can also be adjusted by the SPS.   Through the use of microcontrollers, data bus interfaces can now be implemented without problem, although network connectivity has not yet been fully realized. For further signal processing, traditional standard analog signals are still used. In the detector section, new materials used for photoelectric sensors have demonstrated improved sensitivity and even higher resolution. In thermopile sensors, new sensors require shorter adjustment times. The advanced development of pyrometers with aiming devices includes interchangeable zoom lenses that can be replaced without recalibration, allowing the same base instrument to be used for different measurement positions, thus saving on warehouse management costs.  

Four, Main criteria for selecting a pyrometer 
    The application of pyrometers is primarily determined by the measuring range. Both the measurement voltage and the starting value of the measuring range must comply with the requirements of the measurement task. The larger the selected measurement voltage, the lower the resolution, and thus the poorer the accuracy. This is particularly true at low starting values of the measuring temperature; selecting a large measurement voltage will reduce accuracy by a factor of two. Therefore, it is recommended to select the smallest possible measurement voltage. 
The starting value of the measuring range determines the spectral sensitivity and, consequently, the type of detector. Measurement errors caused by incorrect emissivity adjustment are significantly smaller for short-wave sensors than for long-wave sensors. Therefore, for thermal film sensors (8–14μm) at 800 °C, the measurement error caused by incorrect emissivity adjustment will be five times greater than that of germanium photodiode sensors (1, 1–1, 6μm). The permissible measuring range for germanium photodiode sensors starts from approximately 250 °C. 
    For example, in the ceramic industry or combustion processes in power plants, the measuring range is typically 0–1300 °C. To avoid large errors, pyrometers with short-wave detectors should be selected, even though their upper temperature limit ranges from 250 to 1300 °C. 
Another criterion for selecting a suitable pyrometer is the distance-to-spot ratio. This refers to the ratio between the measuring distance and the diameter of the measuring spot. If the object being measured is small, the measuring distance is large, or so-called "hot spots" are located on a large area, a large distance-to-spot ratio is required. Conversely, for large-area measuring points, a small distance-to-spot ratio is selected because the sensor provides a stable output signal for the average value of the measuring point. 
It must also be determined whether the pyrometer includes a sighting device, as this will increase the cost by 50%. The key factor here is cost consideration. For large-area measurement objects, it is usually unnecessary to integrate a sighting device; instead, an external sighting device can be used for alignment during pyrometer installation. This offers a price advantage, as only one sighting device is needed for multiple measurement points. 
For small measurement objects or long measuring distances, continuous aiming capability is required. With a transparent lens featuring a scale on the instrument panel, the actual size of the measuring spot can be clearly seen. A more affordable option is laser pointing, but it only allows point-by-point measurement. When measuring enclosed furnaces or similar applications, a viewing window is required.  It is therefore necessary to decide whether the pyrometer requires specific functions, such as smoothing, special value storage, limit contact, or a computer interface. To adapt the pyrometer to the surface of the measured object, the ability to adjust emissivity is essential. Other functions can be implemented cost-effectively by connecting recorders, controllers, or programmable logic controllers (PLCs).  Furthermore, for certain applications, the physical structure is also a deciding factor. In higher ambient temperatures, the pyrometer head contains only the optical components, while the electronic components are connected via fiber optic cable and placed away from high-temperature areas. The advantage is that cooling devices can be saved. 
    The first consideration is the pyrometer model: is it a spectral pyrometer or a ratio (two-color) pyrometer? Spectral pyrometers receive radiation density at a single wavelength. In contrast, ratio pyrometers use dual sensors (two individual sensors) to measure radiation density at two different wavelengths. The ratio of these two detector signals represents the temperature proportionality. Due to intermediate media such as steam or dust within the pyrometer's radiation path, or variations in emissivity, these two channels do not show signal fluctuations within a certain range. However, monochromatic spectral pyrometers will immediately display such fluctuations. Therefore, ratio pyrometers are preferred for converter furnaces or in metal manufacturing and processing industries where radiation interference is severe. 

Five Examples of Infrared Pyrometer Applications 
    The potential applications for different pyrometers are extremely wide. The significant price drop in recent years has opened up more and more application areas, especially in the low-temperature range or as replacements for conventional thermometers. The following examples provide an overview of uses and solutions. 
 1 Concrete Processing Industry 
    In concrete processing, temperature plays a key role in setting time and the resulting strength. Especially for safety-critical concrete, a certain processing temperature must be achieved. Contact probes are quickly damaged mechanically due to the corrosive effect of cement. Pyrometers can directly measure the temperature of the mixing drum or the temperature of the concrete at the outlet. Because ISO9000 quality inspection requirements mandate that temperature be documented together with other production parameters, and due to the dirty industrial environment, very robust, dust-proof and waterproof measurement lenses are required. To protect the pyrometer, suitable accessories such as air purge nozzles, lens protective covers, and insulating tubes are used. 
 2 Paper Industry 
    In paper refining, the paper web runs between a heated metal roll and a calendering roll coated with plastic. If the paper width is less than the roll width, the temperature at the edges of the calendering roll will be significantly higher than in the center. The temperature difference between the center and the edges must not exceed a specified ** temperature, otherwise the plastic coating will be damaged. 
To measure temperature, each stand can be equipped with three fixed pyrometers, or one pyrometer can be moved along the length of the roll using a sighting device. Due to intense local steam, a waterproof pyrometer with an air purge nozzle is required for free blowing of the viewing window. Since temperature processing requires a SPS machine, standard instruments with emissivity correction are sufficient. 
 3 Ceramic Industry 
    For the production of ceramic materials, it is necessary to know the temperature profile during the firing process to achieve consistent product quality and avoid waste. At the same time, to save energy, the temperature must be controlled within minimal limits. Until now, thermometers have been used to measure temperature, but they only measure ambient air temperature. Pyrometers offer the advantage of directly measuring the surface temperature of the object in a very short time, allowing for accurate measurement and control of the firing temperature. 
 4 Metallurgical Industry 
    In the metallurgical industry, infrared temperature measurement is applied in various fields. Examples include diagnosis of inner wall defects in various furnaces, diagnosis of cooling wall damage, and control of process parameters. Infrared temperature measurement allows for accurate monitoring of equipment condition, extending equipment service life, saving energy, reducing costs, and improving product quality. 
    Thus, it is evident that traditional thermometers are becoming obsolete products; they will disappear or become damaged over time, requiring constant replacement. Pyrometers have no wearing parts, so theoretically, their service life is infinite. Therefore, the relatively higher initial investment cost can be recovered in a short period. Pyrometers can be installed on the side or on top to avoid tilted alignment, ensuring the pyrometer does not only capture the edge. Air purge nozzles should not be placed directly on the pyrometer lens. In higher ambient temperatures, an additional cooling device is required. 

Weidou Intelligent Technology professionally supplies German Maurer infrared pyrometers. Welcome to inquire by phone.

Germany Dr. Georg Maurer GmbH was founded in 1945, and is a world-renowned expert in the development and production of infrared thermometers. It is used for various monitoring and control functions, such as coating, drying, welding, hardening, welding, sintering, casting, and temperature profile measurement, mainly used in continuous casting plants, pipe welding plants, industrial furnaces, and industries such as plastics, glass, textiles, paper, and steel.

Brand keywords: Dr.Georg, Dr.Maurer, Georg Maurer, German Maurer, MAURER gmbh, MAURER sensor, MAURER temperature sensor, MAURER sensor, MAURER infrared, MAURER infrared, Maurer infrared pyrometer