Thermal imaging is especially useful for making temperature comparisons because it helps us and our customers visualize the temperature differences between multiple points. A thermal imaging camera looks at surface temperatures by picking up infrared waves and turning them into visual light images, so it can’t “see” temperatures through glass or other surfaces.
When you’re using thermal or IR cameras, you need to make sure you can use them safely; you don’t want to stick your hand inside of operating equipment and can use tripods, wireless technology, etc., to keep yourself safe. You also want to be aware that certain surfaces respond differently and must make a few corrections for some surfaces.
Setting the span and the level is also important for the proper use of a thermal imaging camera; the level sets the range for the color palette on your screen, and the span is the differential; these will determine how the camera interprets temperature, especially when measuring reflective surfaces with low emissivity. Unlike span and level, focus cannot be changed in software, so you must make sure your image is focused before you take it.
You’ll also want to follow a pattern or path to keep track of your work. Most importantly, you’ll want to know what your equipment should look like under normal operating conditions vs. abnormal conditions so that you can verify problem areas. You will want to make sure that your pictures are in focus.
Thermal imaging cameras can be useful for helping you identify heat in electrical components and could help you identify a loose connection. However, the camera could also be picking up a heat source near the electrical parts, including your own body heat.
A thermal imaging camera can show you purely thermal images, fusion images (thermal and visible), and visible. It is important to use the visible image as a reference to the thermal image, as the thermal images could show reflected heat signatures of people or things that aren’t actually in the frame. A picture-in-picture image mixes a larger visible image with a smaller thermal image; in these images and fusion images, the alignment is critical.
Thermal imaging is a valuable tool for qualitative data and allows you to compare surface temperatures quite effectively, but it can get tricky when you get into quantitative measurements because of the emissivity. Emissivity allows us to evaluate a surface’s ability to emit heat (vs reflect it) compared to a perfect black body, which has an emissivity of 1; all other emissivity values are less than 1.
Tape can have a different emissivity than the metal you’re measuring, so you need to keep that in mind when you’re trying to take pictures of things with two different thermal masses. When you’re dealing with reflective surfaces, you can put a target spot on the surface with a known emissivity in the editing phase.
Thermal and fusion images are exceptionally good at helping you find loose electrical connections, misaligned belts, air leakage, and overheating (poorly lubricated) bearings. Temperature differentials between the indoors and outdoors, as well as level and span adjustments, can make these issues easier to see. You can also use thermal imaging cameras on entire buildings to see which spots are hotter than others.
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