Pyrometers for non-contact temperature measurement: general information, types, rules of use

In industrial production, situations often arise in which it is necessary to accurately determine the temperature of an object without direct contact with it. Conventional methods do not give the desired result, so scientists have invented various pyrometers to measure temperature using a non-contact method. The devices immediately began to be widely used and became indispensable devices.

General information about the device

A pyrometer is a very simple and easy-to-use device. In order to measure the temperature of a selected object, simply point the device at it. It instantly detects the degree of heating and gives readings.

Advantages and disadvantages

The pyrometer device, like most of the invented devices, has its own advantages and disadvantages. They are determined by the characteristics of the device and the conditions of use.

The benefits include the following:

1. Simplicity of design and small dimensions. Pyrometers are used quite often, so their small size allows them to be carried even in the smallest pocket or special bag.
2. Low cost. The use of a minimum number of parts in the design allows manufacturers to produce devices in large quantities and sell them at a low price.
3. High reliability. The device has good performance, which is indispensable when using it in extreme conditions.
4. Wide measuring range. Most modern pyrometers allow you to determine the temperature of an object in the range from 10 to 800 degrees. In devices produced for specific tasks, this indicator can reach even higher values.

In addition to the positive aspects, there are also negative ones. They must be taken into account when choosing and buying a device.

Among the disadvantages are the following:

1. Dependence of the device on the emissivity of the object. When measuring the temperature, an equally heated shiny and dark object will have different readings.
2. The pyrometer may give incorrect readings due to the surface structure of the test object, its physical condition and the presence of protective coatings.
3. It is possible to correct the indicators and set the error only on the newest devices. Old devices do not have this function.
4. Distance affects measurement accuracy. The larger it is, the higher the probability of giving incorrect indicators.

Applications

Pyrometers are widely used in manufacturing where many heating devices are installed. With their help, the temperature of heating mains, boilers, steam lines and workpieces is checked. Electricians use this device to check the degree of heating of cables, transformers and wire junctions, and metallurgists - furnaces, machine tools, presses.

The pyrometer and the auto repairman did not pass by. They check the heating of the electric motor and other machine parts with them. In the food industry, such devices are used to obtain accurate information about the storage temperature of certain food products.

Non-contact pyrometers are sometimes used for special cases. Among them, the following are worth noting:

1. The need to take a quick measurement (in case of fires and other unforeseen situations).
2. Investigation of objects or parts with low heat capacity.
3. Observe the degree of heating of objects that should not be touched by hands or any devices.
4. Measuring the temperature of a thin surface layer of a product or a very small part of it.
5. Control over the degree of heating of the workpiece in the manufacture of parts of particular importance.
6. Study of objects that run on electrical energy.
7. The need to determine the temperature of a fast moving object.
8. Checking the degree of heating of hard-to-reach units or its individual parts.

Device and principle of operation

A pyrometer refers to devices that allow you to measure the temperature of an object from a distance from it. In most cases, they are made in a shape very similar to a pistol. A small liquid crystal indicator is built into the device, which receives all the information about the measurements, and gives their result.

The main functions of the device include:

• calculation and determination of the maximum as well as the minimum value among several measurements taken;
• sound and visual notification when a preset limit is reached;
• a small amount of built-in memory for storing information about the measurements taken.

Modern devices have a USB output. With its help, you can quickly transfer data to a computer and immediately process it.

The pyrometer consists of the following parts:

• optical instruments;
• mirror;
• viewfinder and its axis;
• measuring device;
• electronic converter;
• sensors;
• frame;
• control buttons.

All of them ensure the normal functioning of the device and the delivery of the most accurate results.

Pyrometer operating principle:

1. Heat waves from the object enter the bell of the device.
2. Through it, they go to the temperature measuring sensor.
3. It converts heat energy into an electrical signal. The power of the latter depends on the degree of heating of the object. The higher it is, the more current is generated at the sensor.
4. Then the signal goes to an electronic converter, where it is processed.
5. The finished result is displayed on the liquid crystal screen.

Types of pyrometers

These devices, indispensable in the industry, are produced according to the needs of a specific production. They are divided into several types:

1. By the principle of operation: optical, infrared. The first are divided into two more types, which are called color (compare the brightness of the object with other regions of the spectrum) and brightness (investigate the degree of radiation coming from the part, with the values ​​of the incandescence threads).
2. By aiming method: with optical and laser guidance.
3. By emissivity: constant and variable.
4. By the method of movement: mobile, stationary.
5. According to the measured indicators: high-temperature (for determining indicators above +400 degrees Celsius) and low-temperature (for measuring up to 30 degrees below zero).

Optical apparatus

This pyrometer is considered one of the most commonly used. It makes measurements in the infrared and visible light range. The device consists of the following parts:

• lens;
• lamp;
• attenuating filter;
• filament;
• rheostat;
• millivoltmeter;
• rheostat lever;
• monochrome filter;
• eyepiece;
• various handles to control the rheostat and the entire device.

The principle of operation of the device is based on a comparison of the degree of brightness of radiation emanating from an object with the same indicator of the filament. The last parameter is determined by the manufacturer and stored in the pyrometer memory.

The optical apparatus operates as follows:

1. The light emanating from the investigated part enters the lens of the device.
2. Through it, it enters the eyepiece.
3. The worker sees the output level of brightness and compares it with that of the temperature lamp. The whole process is carried out in monochromatic light, which is created using a special light filter.
4. The temperature is measured with a millivoltmeter. It has a special marking, which takes into account the degree of filament heating.

Infrared radiometer

This type of pyrometer works on the basis of a radiation method and in a limited range of infrared radiation. For ease of use, the device is equipped with a special laser pointer. It helps to point the device to a specific place on the part and measure its temperature.

An infrared thermometer consists of the following components:

• diaphragm;
• lens;
• copper casing;
• frame;
• lamp;
• light filter;
• eyepiece;
• glow;
• millivoltmeter.

The principle of operation of the device is based on capturing thermal radiation coming from a hot object and focusing with a sensitive element connected to a thermocouple.

The device works in this way:

1. The switched on pyrometer is aimed at the part under study so that it is in the lens and completely covers other objects from human eyes.
2. The eyepiece moves and the maximum image clarity is achieved. In this case, it is important to use a light filter. It will not only allow you to more accurately measure, but also protect your eyes from the harmful effects of bright light.
3. Thermal radiation enters the sensitive element of the device. It is made in the form of a platinum plate.
4. Thermocouples are soldered to it, which heat up depending on the temperature of the object.
5. It is measured and the result is displayed on the device screen.

Terms of use and safety precautions

Before using the pyrometer, you must study its instructions in detail. This will help not only to better understand the principle of operation, but also save you from most of the problems that may arise during operation.

Fundamental rules:

1. The device turns on, and its bell is directed towards the object of research.
2. Measurement limits are determined.
3. The received information is issued.
4. The data is written to the device memory or to any external media.

The device is very simple, and even the person who holds it in his hands for the first time will be able to work with it.

In addition to the rules of use, one should not forget about safety precautions. It is necessary to observe such Precautions when working with the device:

1. It is forbidden to direct the pyrometer into human eyes. The laser beam that emanates from it can cause burns and other damage to the organs of vision.
2. Keep the device out of the reach of children. If this is not done, then the baby may accidentally stumble upon it and use it as a toy. In this case, the slightest negligence can lead to damage of varying severity.
3. Do not place the device on a hot surface.
4. After examining a very hot surface, the contact probe becomes quite hot. You can get burned due to careless handling.
5. The device must not be immersed in water, as it is not sealed. Such negligence can damage the pyrometer or cause it to malfunction.
6. Do not touch the investigated object with the device, hands or any other parts of the body.

A pyrometer is a useful device that makes it possible to determine the temperature by a non-contact method. If everything is done correctly and the recommendations of professionals are followed, then you can quickly perform the required measurements and get the most accurate results. During work, one must not forget about personal safety.