After years of working with new thermographers in our training classes, I’ve learned a lot about how people learn. First, we never get it right the first time! Don’t worry about making mistakes, in fact, it is important to make them. But it is also equally important to learn from them. In class we let people “stumble” once or twice but we help them find where the learning “trip hazards” are and protect them from major failures.
A very common mistake new thermographers make is to stand in one position. Not surprising! They get so fascinated with their new “toy” that they forget to even move. Moving, but doing so safely, is crucial to getting good results.
Whether we are searching for an anomaly or trying to get a detailed image of one we’ve already found, it is important to be in the right place. When searching, plan to move a lot. Get in a spot with a good vantage point and scan over large areas using appropriate level and span settings, usually set manually (Learn more about setting level and span manually here). Avoid walking and looking at your screen at the same time. To do otherwise is just asking for an accident. Move, stop and image.
If you are detailing something you’ve already found, whether a hot electrical connection or an area of missing insulation, get as close as you can safely to show exactly the area you want to document. Typically for an electrical connection, this means showing at least two of the three phases, and preferably all three at once. For insulation or air leakage, show the problem and an easily recognized object, like a door or window, to help locate where you are looking. In all cases, move closer. Every pixel in our image is important and the closer we are the more value they have.
I’ve also watched new thermographers struggle with focus. Often this is because they are simply in the wrong place. In a building, for instance, they often try imaging a long wall from one spot with the result being part of the wall is out of focus. Remember modern imaging systems have a very shallow depth of field. It is far better to move and stay parallel to the wall and take several images, all of which you can easily keep in focus. The same thing happens when looking at an overhead buss duct. Focus, image, move and repeat.
Remember that like visible light, infrared radiation travels in a straight line. We need to get in a position that we can see the “target” with our eyes before we have any chance of seeing its thermal image. Once you get the basics of camera operation down pat, you can more easily think about where you need to be to get those great images. But when you move, do it safely. Watch for trip hazards and moving vehicles and don’t move and view the image at the same time.
Next week I’d like to return to the topic of industry standards. We don’t need to re-invent our profession. We just need to be smart enough to follow the “recipes” others have developed for us.
John Snell—The Snell Group, a Fluke Thermal Imaging Blog content partner