What Exactly is Infrared Thermography?
Infrared thermography is the method of detecting radiation (heat) from an item, converting it to temperature, and showing an image of the temperature distribution using a thermal imager. Thermograms are images of the measured temperature distribution that allow you to see heat-producing things that are otherwise invisible to the human eye. It is extensively utilized in predictive maintenance and condition monitoring.
Thermal imagers can detect and show infrared wavelengths regardless of ambient light since all things above absolute zero (-459.67 degrees Fahrenheit) emit thermal infrared radiation. Using night-vision goggles to detect objects in the dark is a common example of this.
Infrared thermography’s primary objective is to validate that machinery is operating normally and to detect abnormal heat patterns within a machine, suggesting inefficiency and faults. Infrared thermography inspection of mechanical equipment is a significant benefit for asset managers engaged with condition monitoring. Although infrared imagers are simple to use, comprehending the data they generate can be more difficult. Not only should you understand how infrared imagers work, but you should also understand radiometry and heat transfer mechanisms.
Infrared Thermometer Types
In its most basic form, an infrared thermometer consists of a lens that focuses infrared thermal radiation onto a detector, which converts the radiant energy into a color-coded signal.
Infrared thermometers are intended to measure temperature from a distance, eliminating the requirement for physical touch with the object being measured. Infrared thermometer versions for specific applications are now available. Here are three of the most prevalent varieties of infrared thermometers.
• Spot infrared thermometers: A spot infrared thermometer, also known as a pyrometer, looks like a handheld radar gun and is used to detect and measure the temperature at a precise place on a surface. Spot infrared thermometers are useful for detecting thermal radiation on difficult-to-access equipment or assets operating in harsh environments.
You may have seen heating, ventilation, and air conditioning (HVAC) specialists use a spot infrared thermometer to monitor the temperature of a ventilation system in your office building or house by aiming the gun at the ceiling vents.
• Infrared scanner systems: These infrared thermometers are commonly employed in manufacturing plants with conveyors or web processes. Infrared scanner devices are commonly used to scan goods on a conveyor belt or sheets of Glass or metal leaving an oven.
• Infrared thermal-imaging cameras: A thermal-imaging camera is a form of advanced radiation thermometer that measures temperature at several places over a vast region and generates two-dimensional thermographic images.
Thermal imaging cameras rely on far more software and hardware than a spot thermometer. Most cameras provide real-time images and can be linked to specialized software for more in-depth examination, accuracy, and report generation. Thermal imaging cameras are now portable.
Users of infrared thermal imaging cameras can switch between numerous color palettes to assist them in comprehending temperature variations.
- Iron palette: The iron palette is the most commonly used. It depicts the coldest places in black, the slightly hotter parts in blue/purple, the mid-range temperatures in red/orange/yellow, and the hottest areas in white.
- Black and white color scheme: This color palette, often known as grayscale, exposes details exceedingly well by solely exhibiting black-to-white hues that flow through several shades of grey. Grayscale is most commonly used in night vision or security cameras. Because it is more difficult to discern temperature variation when only two colors are utilized, it is rarely employed in machinery imaging.
- Rainbow palette: The rainbow palette best demonstrates thermal sensitivity by depicting temperature differences in different hues. The rainbow palette, like the iron palette, uses more color to signify more temperature fluctuation.
A color alert, picture-in-picture, and fusion blending are other features of an infrared camera. The color alarm allows you to choose a temperature below or beyond which the camera will only display a color thermal image of an item. Fusion blending allows you to blend a thermal image’s minimum or maximum average temperature with a standard digital image.
Industrial Applications of Infrared Thermography
Test and measurement
Infrared technology provides fast and exact temperature measurement, critical for research and testing applications in industrial and academic laboratories. Researchers reportedly used infrared cameras, infrared thermometers, and multi-color pyrometers to measure the temperature of individual particles in coal combustion reactors in order to better understand the transient phenomena that occur when coal particles burn in order to practically design a new low-emission burner technology. This infrared technology can detect transitory changes that occur in milliseconds and cannot be monitored by a traditional thermocouple. It is a recognized and approved sensor technology for measuring, monitoring, and controlling process temperature in industrial situations.
Injection molding
In injection molding or 3D-printing applications, temperature determines the quality of the end goods. Getting the temperature right is critical to ensuring that the created products are defect-free. This is especially true in the manufacturing of automotive products, where minor dents or flaws are not tolerated. The thermal imager was utilized in an online system to measure the product’s surface temperature distribution. It can be coupled with the PLC system to automatically reject assemblies if the detected temperature is outside the prescribed range.
Manufacturing
Temperature is one of the criteria that significantly impacts the quality of manufactured goods in the manufacturing business. For this reason, a specific thermal imager for monitoring glass temperature has been designed. Monitoring the temperature of the molten metals is critical in the metals business for accurately maintaining the process temperature during casting. This necessitates the use of a specialized infrared sensor with a wide spectral range and quick response time.
Condition monitoring
One of the most sought-after technologies as a preventive maintenance tool in industrial process applications is the thermal imaging camera. It can be used for condition monitoring applications, such as detecting hot spots on critical industrial equipment like pumps. Hot spots in equipment often signal a problem, which could be caused by loose screws, bearing wear, or overheating. Early detection of faults enables the repair and maintenance of equipment before a catastrophic breakdown occurs, potentially saving lives and money for the company. Handheld pyrometers are ideal since maintenance personnel may transport them around to perform the measurement.
The Benefits and Drawbacks of Infrared Thermography
The benefits of employing infrared thermography in preventive maintenance:
- No contact with components or machines required
- Real-time output
- Capable of obtaining data on large surface areas at once
- Easy-to-read visual images
- Data can be uploaded to software for further analysis
- Infrared cameras provide excellent mobility
- No downtime or production interruptions for testing
While there are numerous benefits to employing infrared thermography, it is always a good idea to be aware of the following drawbacks:
- Infrared equipment is relatively costly. Consider the time and labor involved and the savings you will obtain from infrared technology’s early detection warnings.
- Suppose a non-transparent material, such as a glass cover, separates a component. In that case, infrared technology cannot detect temperature. Glass appears non-transparent when examined using an infrared imager.
- To analyze imaging results using infrared data, a great experience and a broad knowledge base are required.
You must read this article: How structural inspections can prevent accidents and grow building life
Conclusion
Infrared (IR) thermography is the science of collecting and analyzing thermal data using non-contact thermal imaging instruments. IR thermography detects electromagnetic radiation released in the infrared range. This relates to wavelengths that are longer than those of visible light.
Infrared thermography is based on the idea that subsurface abnormalities in a material create localized changes in surface temperature due to variable heat transfer rates at the defect zones. Thermography detects thermal radiation emitted from a material’s surface and generates a visual image based on this thermal signal, which can be related to the extent of an interior flaw.