Thermal image of the heat, radiated by hand when touching the painted wall surface, it can be detected with a thermal imager.

Thermal imager senses infrared radiated, emitted by the object

Thermal wakes can be seen on the thermal image of the engine, this may indicate a problem of coupling coincidence, while at the ordinary image everything looks normal

Examples of production supervision based on the infrared imaging

Examples of thermal imaging applications

Infrared Thermography

Infrared thermography – is the field of science studying the usage of electronic optical devices for registration and measurement of radiation and comparing it with the surface temperature. Radiation is a heat transfer in the form of radiant energy (electromagnetic waves) without an intermediate medium used for transfer. Modern infrared thermography uses the electro-optical device for measuring of radiation flow and the calculation of temperature at the surface of studied surfaces or equipment.

People can always sense the infrared radiation. Nerve endings in human skin can detect changes in temperature of ± 0,009°C (0,005°F). Despite its high sensitivity, the human nerve endings are completely inappropriate for non-destructive thermal control. Even if people had the same ability to feel heat, like animals that can find warm-blooded prey in the darkness, still they would need better tools to detect heat. And since people have physiological limits in sensing heat, supersensitive mechanical and electronic devices were developed to detect thermal radiation. These devices have become widely used for thermal control in lots of tasks.

Principle of thermal imagers operation

Infrared light is focused by the optical system of the thermal imager on the radiation receiver. Usually the output signal is in the form of changes in voltage or electrical resistance. The resulting signal is recorded by electronic thermal imaging system. The output signal of thermal imager is converted into an electronic image (thermogram), which is displayed on the display screen. Thermogram is the image of the object, digitally processed for displaying so that different gradations of colors correspond to the distribution of infrared radiation on the object surface. Thus, the operator can just see the thermogram, which corresponds to the heat radiation coming from the surface of the object.

Troubleshooting

Thermal imaging plays an important role when searching for malfunctions in commercial and industrial systems. In case of an abnormal condition or behavior of the equipment, its condition must be examined. Some of obvious symptoms may be considerable vibration, noise or temperature values. If no visible manifestations detected, the underlying cause of the problem may be difficult or impossible to see.

The thermal signature is an artificial color image of the infrared radiation, or heat, emitted by an object. Comparison of normal thermal signatures of operating equipment with the equipment tested provides a great way of troubleshooting. The main advantage of the infrared thermography is that tests can be carried out quickly and without interfering with the equipment. Since the thermal imagers do not require a direct contact, they can also be used at a time when the equipment or its components in operation.

Even the heat image cannot be fully assessed be the thermographer, it can be used to determine the necessity of additional checks. For example, you can make a quick inspection of electric motor and find out whether there are any anomalies in the behavior of bearings or couplings. Engine bearings, which look much warmer than the motor housing, may have problems with lubrication or alignment. If one part of the clutch is warmer than the other, it may be sign of problems in coincidence of axes.

Preventive maintenance

Preventive maintenance – is a scope of routine works necessary for maintaining the equipment in good operating condition. Preventive maintenance reduces the number of malfunctions and failures ensuring the optimum efficiency and safe production conditions at the same time. It allows you to extend the life of equipment, reduce downtime and improve overall production efficiency. Types of preventive maintenance and the frequency of its usage at each element are determined by the requirements of the equipment manufacturer, equipment operation manuals, industrial publications and experience of a service personnel.

Strategy, aimed at ensuring a deep understanding of the operating state based on the assessment of equipment and the control its state, is an important part of preventive maintenance programs. Applications for preventive maintenance, including the evaluation and control of the equipment condition are much easier to perform with the use of thermal imaging equipment. In there are thermal images of equipment, it’s much easier to make a decisions on the repair/replacement, it’s becoming more efficient, reducing total costs, and increases the reliability of the equipment. If the manufacturing department requires an element of equipment to be fully operational, the company’s management can be fully confident that it would be completely ready for operation.

Service is a complex set of different measures. It was recently discovered that many of old methods, such as preventive maintenance, often result in more problems than solving. Moreover, they often do not pay off.

Temperature measurement error

The accuracy of modern infrared measuring instrument is high enough. When examining surfaces with a high radiation coefficient, having the average level of temperature within the system resolution, the measurement error is typically of ± 2°C (3,6°F), or 2% of the measured value (but can vary depending on the thermal model). Also, since the infrared measuring devices do not require contact with the object to be measured, infrared technology has significant value by improving the accuracy of measurements.

Since the measurement of the temperature is based on the basis registration of infrared radiation, the temperature measurement error may increase due to the following factors:

  • The value of the radiation coefficient below 0.6;
  • Changes in temperature of ± 30°C (54°F);
  • Conducting of measurements beyond the system resolution (the object is too small or too far away);
  • Line of sight.

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