Thermal Imaging Mode Confusion:
Firefighters need to be aware of when the camera switches modes and the color ranges associated with it. TIC’s have modes based upon sensitivity which are typically high, medium, and low. For example, one camera switches from high sense mode at 350 degrees Fahrenheit while another switches to low sense mode at anything over 200 degrees Fahrenheit. How fast it changes especially if we are staying locked in on the same focal point should alert us to a rapid progression of the fire this impending flash-over. For example, a given reaction will increase its rate 100 percent for every 18 degrees Fahrenheit increase in temperature” (John L. Bryan p.7).
A firefighter should be trained to read the color palette not just the direct temperature measurement (focal point). Firefighters must understand that the focal point will affect the mode, the color ranges, and the level of clarity at which we view an image. And that the focal point is typically a measurement of temperature of a 12 inch area only. The temperature reading that is displayed in the bottom right hand corner of the screen is for the focal point. The color palette gives the firefighter a broader interpretation of the temperatures in their immediate environment.
Notice the DTM (direct temperature measurement in the bottom right hand corner of the screen) in photo #1. The environment is obviously over 87 degrees Fahrenheit. Notice the color palette is gray, yellow, orange, and red as all cameras are but the temperature range for this mode is 0-500 degrees. This particular Thermal Imager (ISG X380) has three modes which are High, Medium, and Low. It is currently in the Medium sense mode which is defined by the M in the upper left hand corner and the temperature range associated with it.
It’s important to understand its limitations and when the camera changes modes/sensitivity. For example, while using an ISG camera a multi-colored scene may seem worse to an MSA user (like myself) when in fact the ISG camera has more colors at the lower temperature range at high sense mode. High sense mode in most Thermal Imaging Cameras implies the camera is viewing more colors at a lower temperature range.
Notice the gray scale in the second photograph is nearing the 600 degree temperature mark. Most of us would associate gray with a cooler environment but due to this TIC is in the low sense mode (higher temperature range) the colors associated with it are increased. Without proper training the firefighter might be inclined to believe that they are in a position of relative safety when they are actually exceeding the limits of their PPE.
Be aware of the modes and learn the colors associated with your particular camera. Learn them, know when the TIC changes, and know the signs of flashover not just optically but thermally. This short video is a brief explanation of temperature modes and TI Basic Color Palette.
Stay safe & keep learning,
Instructor Andy J. Starnes Scott Safety – Fire