Infrared cameras: Simply measure surface temperatures with infrared radiation
Infrared cameras are imaging instruments similar to a conventional digital camera for contactless temperature measurement. zur berührungslosen Temperaturmessung. A thermal imaging camera makes heat radiation visible and thus shows the surface temperature of objects visually. The technical term for this method is thermography.
Thermal radiation is infrared radiation that is not visible to the naked eye. Infrared rays will emanate from any object that is warmer than the absolute zero point at -273.15 °C or 0 Kelvin. The amount of heat emitted depends on the temperature of the object and the nature of its surface. Sunlight, for example, emits large amounts of infrared radiation that we can feel as heat on the skin. Even cold objects such as frozen water emit infrared waves.
A thermal imager displays the surface temperatures of the environment in a two-dimensional image.
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Thermal imagers for troubleshooting and inspection
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Where are thermal imagers used?
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How does a thermal imager work?
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These characteristics are important for thermal imagers
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IR cameras with cooled infrared detector
Thermal imagers for troubleshooting and inspection
The resulting image on the display of a thermal imaging camera allows you to read the different surface temperatures, immediately recognize hot and cold zones and gain a precise impression of the temperature distribution. In addition to the visual control of the infrared image on the display, the image of the camera can be analyzed via suitable evaluation programs and stored for documentation purposes.
Modern thermal imagers are characterized by simple handling, short response times and a good price-performance ratio. They deliver clear images with high resolution. By the way, the abbreviation FLIR stands for Forward Looking Infrared and marks the IR imaging that is looking forward. FLIR is often used in conjunction with or synonymous with thermal imagers.
Among the best known suppliers of thermal cameras are Beha Amprobe, Dostmann Electronic, FLIR Systems, Fluke, LA CO Industries, Laserliner, PCE Instruments, RS PRO, Seek Thermal, Testboy and Testo.
Where are thermal imagers used?
Thermal imaging has become an important diagnostic process in the construction industry, mechanical and electrical maintenance. Thermal imagers are widely used in building diagnostics, electronics, electrical and safety applications.
Building diagnostics
Figure: This is where heat escapes through the walls.
Thermography can be used in building and building diagnostics to test energy efficiency and climate friendliness. The thermal images visualize energy losses on walls, walls, doors, windows and balconies. They assist in the identification of building defects such as peeling plaster or the formation of condensation water.
The thermal measurement by means of infrared camera helps in the detection of missing or defective thermal insulation, the localization of thermal bridges and leaks. The detection of moisture in the insulation or walls can provide information on the causes of mold formation. Further applications in the construction sector are the functional control of floor heating , heating elements and photovoltaic systems , the planning of building insulation as well as construction status and value assessments.
System monitoring
Thermography is helpful in assessing the condition of machines and technical equipment. Surface temperatures allow early detection of wear, anomalies and defects. The thermal image shows parts heating caused by friction, cracks and leaks where fluids leak. Overheating motors, worn bearings or overloaded shafts are also detected. This allows an estimation of the maintenance status and the operational safety of plants. Thermal analysis of industrial plants makes maintenance work on systems predictable before failures occur. Because FLIR infrared cameras work contact-free, an application is also possible during operation.
Electrothermography
Electrical faults are detected in electrical thermography. The process takes advantage of the fact that electrical components heat up differently depending on their load. As a tool for testing electrical systems, FLIR cameras display the heat generated by resistive losses. Even a slight warming is sufficient.
Thermal abnormalities can be used to detect defective components, uneven load distribution and bad connections in temperature measurement in distribution boards, control cabinets, fuse boxes, lighting systems and wiring harnesses, which pose a risk of overheating. Such electrical weak points on components are otherwise difficult to identify. With a thermal imager, you can test for possible damage in just a few steps. IR measurement is possible even over long distances , for example in high-voltage lines or electrical systems in secure areas.
Thermograms help to detect creeping power consumption and energy guzzlers . Unlike appliances that are disconnected from the mains, consumers in standby usually heat up.
One of the fuses appears to be overheated. You would never have discovered this danger with the naked eye.
Material testing
With the support of thermal imagers, non-destructive material testing of materials and components can be carried out within the framework of industrial applications. To do this, the workpiece is specifically heated or deformed, so that hidden defects can be measured by their different thermal behavior.
Sanitary, heating and air conditioning
A leak in the water pipe of your underfloor heating system is noticeable on the infrared image.
The photographs of FLIR infrared cameras help with the heat and climate planning and the design of ventilation systems. the time and cost-saving thermal imaging technology plays an increasingly important role in the detection and fault elimination of leaks at pipes, lines and valves. Other SHK applications include testing cable insulation and diagnosing possible damage to supply and district heating lines.
Security applications
Thermography detects unauthorized persons in safety areas, access control and accident prevention. In the agricultural sector, cultivated fields can be checked for hidden animals before harvesting with machinery.
Thermal imagers are used by the fire department and plant fire departments to detect a fire, perform fire fighting operations and find people. In production and in the warehouse, detection prevents otherwise undiscovered heat production from possible industrial fires.
How does a thermal imager work?
Thermal imaging camera systems consist mainly of four components: Lens, detector, electronics and screen.
This is how it works: The heat radiation passes through the lens of the system to the infrared detector as a sensor. This converts the infrared rays into electrical signals depending on their intensity. The electronics calculates temperature data from the electrical information and makes it visible on the display as a thermal image.
Infrared radiation is longer than normal visible light. The longer waves spread differently from light and can penetrate smoke. For example, the fire department uses this feature to look through smoke with thermal imagers.
FLIR thermal imagers can monitor the temperature distribution of an entire surface . In contrast to a selective infrared thermometer, the image of a thermal imager displays considerably more heat information. Measuring a larger area reduces the risk of missing individual critical points and hotspots.
Our practical tip:
An important point when using thermal imagers is the surface properties. Very smooth surfaces such as glass or polished metals reflect the heat radiation. You should consider this aspect when evaluating your thermal imagers.
These characteristics are important for thermal imagers
Purchasing a thermal imager is an investment in the longer term. This is why the device should fit perfectly to your individual requirements. The following features will help you select the product you are using.
- Thermal sensitivity
The thermal sensitivity or temperature resolution is expressed in °C or MK (Millikelvin) and indicates how well the camera can separate two temperature values close together . The better the thermal sensitivity, the lower the temperature difference that the camera can still detect.
- Temperature measurement range and accuracy
The temperature measurement range is the working range of a thermal imager and can vary between -40°C and +2,000°C. The accuracy indicates the maximum deviation of the measured temperature from the actual temperature value and thus the fault tolerance.
- Bolometer matrix
The bolometer matrix represents the number of measuring points and thus the thermal camera resolution . Together with thermal sensitivity, it forms the two key features of a thermal imager. The bolometer matrix usually ranges from 60 x 60 pixels in low-cost devices for beginners up to 648 x 480 pixels in the top models for demanding tasks. Rule of thumb: You can measure more accurately with a larger bolometer matrix.
- Display resolutions:
Depending on the size of the display and the resolution, how comfortable you can view the recordings depends. The display resolution indicates how high resolution the device's screen is and how detailed your infrared recordings can be played back. The resolution of the LCD display is technically independant of the bolometer matrix and generally higher.
A high resolution is also relevant with regard to the conventional digital camera integrated in many thermal imaging cameras. Image-in-image or Thermal Fusion (overlay) view combines visual images on the display with infrared images, which can simplify mapping, image interpretation, and analysis.
- Frame rate
If you want to record moving objects or take continuous shots, the frame rate is an important factor. The higher the frame rate, the faster the camera works and the more frames per second it can take.
- calibration
Cameras with thermal imaging procedures are factory calibrated for accurate temperature measurements.
- Interfaces and connections
Cameras equipped with USB can be easily connected to a PC or notebook. The camera then appears either as an external removable media for convenient copying of image files or it transmits the live image to the computer. There it can be displayed and evaluated via thermography software and you can record thermal imaging videos. Common connection variants for FLIR cameras are USB-C, micro-USB and mini-USB.
Models with Wi-Fi or Bluetooth are wireless and transfer recordings or live images without connecting cables to a PC, notebook, smartphone or tablet .
IR cameras equipped with Apple Lightning are optimized for connection to Apple's mobile devices. They are paired with the iPhone or iPad via the Lightning plug.
HDMI and DisplayPort enable the display of the thermal image on monitors , televisions and video projectors.
If the infrared camera has an SD slot or microSD port , you can save the recordings to an SD card.
- Color palettes
The size of the color palette determines how multifaceted the colors of your infrared images are. Many thermal imagers offer you the option of changing the color mode via a color menu . The color modes determine how the camera represents the different temperatures. The color settings are manufacturer-specific and therefore model-dependant. Among the color palettes available in most manufacturers is the grayscale mode , in which increasing heat is represented by brightness gradations of white.
With the full color palette or Rainbow color setting, you can see a colorful thermal image in which different temperatures are reproduced in high contrast and thus clearly visible in different colors.
The Heat Finder color palette provides a monochrome representation in which warmer areas are white and the hottest zones are colored for better identification. The color palette for heat marking is a variant of the heat finder color palette, in which specific temperature zones are colored by the IR camera, which are of particular relevance to the user.
IR cameras with cooled infrared detector
If you want to carry out particularly precise infrared measurements and have the highest demands, you should consider purchasing a thermal image camera with cooled infrared detector. These models deliver outstanding image quality compared to their uncooled peers. However, they are usually much more expensive and not quite so handy.