Pyrometer - what is it? Non-contact pyrometer

Recently, the device, called the "pyrometer", has been widely used. What is this device and what is its essence? Its purpose is to measure the temperature of an object at a certain distance from it.

With the help of pyrometers it is possible to obtain in a safe way indicators of the temperature of hard-to-reach or hot objects, therefore they are indispensable helpers in any industrial production. After all, there are often situations where it is simply impossible to approach the object of measurement, or it poses a danger to human health.

A bit of history

The first pyrometer (what is this device, read below) was invented by the Dutch physicist Peter van Mushenbrookt. These devices could only measure the temperature of bodies visually. The main calculations were made from processing data on the color change and brightness of the incandescent object. Of course, these figures were not accurate enough. At the present time, the functionality of such devices has significantly expanded, it allowed to measure the temperature of not only heated objects, but also those objects in which this figure does not exceed 0 degrees. For example, the Optris infrared pyrometer measures temperatures in the range of -32 to ⁺ 900 ^° C.

The perfection of these instruments began in the 60s of the XIX century. The given branch successfully develops and now. Thanks to active development, it became possible to produce industrial pyrometers, which were equipped with high technical characteristics. At the same time with the development of nanotechnology, the size of the devices became smaller every year, which made their use as convenient as possible.

The first portable model of the pyrometer was developed in 1967 by the leading American company Wahl. It served as a prototype of modern infrared devices. The introduction of new technologies and developments allowed to improve the work of the pyrometer. Its main principle was based on the determination of the thermal energy that the object radiated. With the wide introduction of these devices, it became possible to measure remotely the temperature of both liquid and solid bodies.

The thermometer-pyrometer is classified today according to several important parameters. Let's look at them in detail.

Main features

By this criterion, three main types can be distinguished:

• Brightness. The temperature of the heated object is determined by comparing its color and the shade of the reference thread.
• Radiation. Such pyrometers determine the temperature of the object according to the power of its thermal radiation.
• Color. This version of the device evaluates the temperature of the object based on the color reflection of its surface in various spectra.

Temperature range

In order to obtain accurate temperatures, it is necessary to select the correct pyrometer. What does this mean? This device has two types of modifications:

• Low-temperature. Pyrometers of this type are capable of measuring only the negative temperatures of objects.
• High-temperature. These devices only evaluate the heated objects. Therefore, one of the most important parameters for such devices is the limiting measurement temperature.

Execution type

A non-contact pyrometer is also classified according to the type of destination:

1. Portable models are a pocket type of these devices. Such devices are indispensable when, when measuring the temperature of an object, it is impossible to approach it sufficiently. Pyrometers of this kind are equipped with a small screen that allows you to display text and graphic information.
2. Stationary devices. Stationary type pyrometers are used for high-precision measurements. Such devices are in demand by large industrial enterprises, where constant monitoring of the temperature indexes of production is required.

Recommendation: It is advisable to pay attention to pyrometers infrared for employees who make temperature measurements very often, before buying the device. It does not hurt to compare the main characteristics and cost of several samples available on the market. Below is a brief description of four types of infrared pyrometers.

Monochrome models

Infrared (one-color) pyrometer is designed to measure a single wave of thermal energy. These models are inexpensive, they are an ideal portable option. The principle of their work is very simple: just point the pyrometer at the object and press the corresponding button. Their undisputed advantage is the ability to conduct temperature measurements from any distance.

These instruments have a limitation in measuring the diameter of the spot, and are also very sensitive to environmental contamination. It is these shortcomings that significantly reduce the scope of their application, for example, in a smoky or very humid room, a single-color pyrometer will not work correctly.

Infrared thermocouples

One of the simplified versions of infrared pyrometers is a thermocouple. The main feature of this device is the absence of complex electronics, which is used to amplify the received signal. This is what became its undeniable merit, which provided a unique opportunity for the application of this device. The principle of operation of the thermocouple is quite simple: the resulting radiation is converted into a thermocouple nonlinear signal.

Benefits:

• low cost;
• Good compatibility with measuring instruments;
• The maximum temperature is higher than that of other models.

Also worth paying attention to the shortcomings. In principle, there are only two of them:

• Error more than 2%;
• Wide spectral range.

Two-color pyrometer - what is it?

This device appeared relatively recently. This is a more advanced model that measures the value of two or more radiated waves. The advantage of a two-color pyrometer, which significantly differs it from traditional infrared devices, is the ability to work in different color spectra. These indicators allow using this device in polluted places, since it is not affected by the presence of foreign substances, such as smoke, gas, steam and others. Also, this pyrometer is indispensable in working with the indicators of blackness, it will accurately determine the temperature of the solid metal, which turns into a liquid state.

Fiber optic pyrometers

The principle of operation of these devices is identical to traditional pyrometers. The difference is only in the presence of a fiber optic cable, through which the light flux is transported. The advantage of this configuration is that the cord can be arbitrarily bent. This makes it possible to measure the temperature in the most inaccessible places.

Fiber-optic pyrometers are widely used in places with a high electromagnetic field, where traditional models are completely powerless. Such devices are equipped with a fixed focus. It allows you to measure the radiation of thermal energy with a minimum spot diameter of 0.1 mm. However, such a focus sets the limits in the distance: for accurate measurement it is necessary to strictly follow the distance specified in the instruction.

Laser Pyrometer

In order to measure at a great distance, the manufacturers installed laser sights on pyrometers . They come in several forms.

1. A laser device with one beam makes it possible to aim the pyrometer only at the center of the spot of thermal energy. Depending on the models of these instruments, the sensitivity zone can have an error of 1-2 cm. Such a defect is most often found in inexpensive devices.
2. Pyrometer laser with a double beam allows you to determine the size and location of the measured object. Use near is not recommended, since the indicators are often overestimated.
3. Circular sights are the most accurate instruments, effectively working at different distances and with any dimensions of the spot being measured.

Instructions

When purchasing this device, it is necessary to check if there is an instruction manual. Pyrometer is a complex device, so it will be difficult to understand the functions independently. The instructions describe important points that are necessary for proper operation. Here are some of them:

• Output types and software;
• Data on errors;
• Index of inertia;
• Type of focus;
• Temperature regime;
• Spectral range;
• Coefficient of radiation, etc.

Application of pyrometers

Infrared pyrometers are widely used in various industries:

• In thermal power engineering - when it is impossible to approach a heated object;
• In the electric power industry - pyrometers are used for continuous monitoring of objects and ensuring fire safety during their operation;
• In various laboratory studies - if there is no possibility to touch the object under study, or when the measurement of its temperature can not be performed in the usual way;
• In construction - pyrometers are used to determine the places of heat loss in houses and buildings for residential and industrial use, as well as on heating mains in order to quickly detect breakthroughs.