I’ve often noticed that many new thermographers seem to have “glue” on the bottoms of their shoes! Once they lift the imager up to look at something, they become so absorbed they forget to move into an optimal viewing position. As a result, they often either miss what they really need to see or they don’t get the best image possible. While it is almost never safe to be viewing an image and moving at the same time, it is important to move around until we can find the best view of our subjects.
The single most important move to make is often the move closer to the target object, or at least as close as is safe and practical! Our aim should always be to fill the image with the area of interest. It is absolutely the least expensive way to increase resolution and see the detail we typically need to measure.
It is also critical that we move in order to understand how reflective a surface is. The image of a specular surface will change as we move, and will often reflect a different thermal background. As we move around, we also need to be aware of where the background is and what is being reflected! More than one thermographer has been caught failing to recognize this pitfall. I remember very well the first “hot spot” I found on a pole mount transformer connector—only to discover it was actually a reflection of the sun!
Building thermographers in particular, learn quickly how to position themselves and move parallel to a wall whenever possible. If they don’t, they’ll often end up with part of the wall out of focus, which is never good.
Out on the industrial floor, it is essential to move in order to see where the heat is coming from. The classic example, when looking at a motor control center “bucket,” is trying to see a problem on the “stab” to the bus work. It is nearly impossible unless you carefully look over and around the fuse block. In other words, you must move! The bearings on vertically mounted motors are also a challenge, one that may even warrant mounting a thermal mirror and moving into a carefully determined position so that you can see the reflection of the bearing in the mirror.
So get the glue off your feet thermographers! Moving—as long as it is done safely—is essential to using these remarkable tools and to understanding the answers we are interested in finding.
John Snell—The Snell Group, a Fluke Thermal Imaging Blog content partner