What is a Pyrometer? Working Principle Its Types

Precision is an essential quality that is necessary for all scientific and engineering processes conducted in many industries. In which, temperature measurement is one of the critical parameters and a high degree of precision is required. While measuring the temperature, it is important for maintaining and understanding a test sample’s properties. There are a variety of methods available for the measurement of high temperatures such as thermometers, temperature gauges, and many more. However, when the heat rises in intensity, such as in kilns and furnaces, thermometers are no longer as accurate, necessitating the need for Pyrometers.  

The pyrometer is a very useful tool for measuring extremely high temperatures from a distance. It works by detecting the heat/radiation emitted by the hot object and uses this to calculate the temperature. This is extremely useful in situations where it would be dangerous or difficult to get close to the object, or if the object is too hot to touch. Let’s discuss more about what it is, and its various types through this article.   

What is a Pyrometer?  

A pyrometer is a device that is used to measure a high degree of temperature without being in contact. It uses heat/radiation from the object’s body to measure the temperature. Thus, they are more advantageous in the cases where the temperature needs to be measured without touching the material or sample.   

Pyrometers have come a long way since their inception. They were created to measure the surface temperatures of aerospace components that couldn’t be touched. Today, pyrometers are mostly automatic and digital-based. However, there are still a few different types of equipment and techniques that can be used to measure surface temperatures.  

Working Principle of Pyrometers  

The basic working principle of pyrometers is measuring the temperature of an object without making physical contact with it. It does this by detecting the heat/radiation emitted from the object. The pyrometer has two main components: an optical system and detectors. The optical system is used to focus the radiation onto the detectors, which record the temperature level depending upon the intensity of radiation emitted.  

When using a pyrometer to take the surface temperature of an object, the optical system captures the energy emitted from the object. The radiation is then sent to the detector, which is very sensitive to the waves of radiation. The output of the detector refers to the temperature level of the object due to the radiation. Note that the temperature of the detector analysed by using the level of radiation is directly proportional to the object’s temperature.  

The radiation emitted from every targeted object with its actual temperature goes beyond the absolute temperature. This emitted radiation is referred to as Infrared, which is above the visible red light in the electromagnetic spectrum. The radiated energy is used for detecting the temperature of the object and it is converted into electrical signals with the help of a detector.  

Types of Pyrometers  

Pyrometers are classified into two types: –  

  • Optical Pyrometers  

The optical pyrometers are specifically designed to detect thermal radiation in the visible spectrum. Any object whose temperature is absolute 0 will emit or generate radiation. The emission depends on the temperature of the object. The optical lens captures the radiation from the source and helps in focusing thermal radiation on the lamp. Optical pyrometers provide a visual comparison between a calibrated light source and the targeted object’s surface. There may be three possibilities-  

  1. When the filament is “DARK”, then the source object is hotter than the reference temperature.  
  2. When the filament temperature is hotter than the source temperature it reflects “BRIGHT” in color.   
  3.  When the temperature of the filament and the object’s surface is equal, the thermal radiation intensity caused by the filament merges into the targeted object’s surface and becomes invisible.  

At this time, the current passing through the filament is converted into a temperature level.  

  • Infrared/ Radiation Pyrometers  

These pyrometers are designed to detect thermal radiation in the infrared region. The radiation is usually at a distance of 2-14um. Furthermore, they are made up of pyroelectric materials like polyvinylidene fluoride (PVDF), triglycine sulphate (TGS), and lithium tantalate (LiTaO3). It directly measures the temperature of a targeted object from the emitted radiation that is directed to a thermocouple to convert into electrical signals.  

If you are looking for a company that offers a wide range of pyrometers suited to all types of industrial processes, then Tempsens covers everything. They offer varieties of pyrometers with different sensors and filters used for specific applications in Industrial and R&D. With a focus on manufacturing and supply of high-quality thermal engineering products, they have a global network of distributors spread across 20 countries.