Thermal Imaging: Effective Hands-On Thermal Imaging Drills

Firefighters are an inquisitive group and I often receive requests to provide training tips for using thermal imagers. The fact remains, even in 2013, that training materials for thermal imaging are hard to come by. Part of the reason is that while thermal imagers are fairly simple to operate, understanding how they work is still a very technical discussion that requires specialized knowledge causing fewer people to seek the “expert” status usually required by one who is going to teach others. While I strongly recommend that every fire department seek some type of structured, qualified and detailed thermal imaging instruction, that does not mean that you can’t cover basic principles with minimal time and effort.

Most formal instruction starts in the classroom and includes some amount of lecture and book training prior to practical experience. What I suggest in this month’s column is to deliver the hands-on training first and then follow it with an explanation. This quick-drill approach lends itself to shorter, more frequent training and is no way meant to replace traditional classroom learning. Make thermal imager use routine and seek answers for the things you encounter that you do not understand. It is only through practice and experience that knowledge is gained.

The thing about public safety work is that it tends to administer the test before giving the lesson. With these quick drills, you can do the same thing without forcing attention during lecture time. Let’s look at a few quick drills that can be used daily and in less than 15 minutes to provide firefighters with a greater understanding of the technology.

• Identifying “heat signatures.” Heat signatures can take on many different forms from the in-your-face obvious to the more subtle indicators. Most firefighters think of “big heat” when they think about firefighting or thermal imaging and then fail to notice less-obvious heat signatures; however, there is much to be learned from smaller heat sources.

Somewhere in the fire station, place a space heater on the other side of a closed door. A solid-core door will work the best, but any door will do. Give the door some time to warm up. The door should develop a V-shaped “heat signature” on it. You may have to play with the temperature setting on the space heater or even boost the space heater up by placing it on some sort of non-combustible item to get the look right. Have the firefighters conduct a search and see if they recognize the heat pattern prior to opening the door. Whether they notice it or not, you can use the opportunity to talk about the benefit of recognizing smaller heat sources. If you have both solid-core and hollow-core doors in your station, you can set up several space heaters to show the difference between these different door construction types.

• The effects of reflections. Reflections can create confusion and disrupt otherwise well-laid plans. While you cannot plan for every possible scenario, creating awareness is at least a step in the right direction. Fill the shiniest pot you can find with water and place it on a burner of a stove with the burner on high. Grab a cast iron skillet and place it on a burner immediately next to the shiny pot and turn that burner on high as well. Wait for the water to boil and the skillet to get hot. You are now ready to go.

Everyone knows that water boils at 212 degrees Fahrenheit; however, when you use temperature sensing and point the crosshairs at the side of the pot, the temperature will read well below that. This is because of the reflectance of the outside of the pot. The thermal imager is reading the reflected temperature of the room rather than the temperature of the pot. Now look at the reflection of the skillet on the side of the pot. You should be able to see the colorization (if your imager is so equipped) or the extreme white of the skillet in the pot. If you place the crosshairs on the shiny pot where you see the reflection of the skillet, the imager will read the temperature of the skillet in the reflection from the pot.

Reflection can further be exhibited by other bright and shiny objects. The side of the fire apparatus, a dry erase whiteboard and most smooth tile flooring will all lend themselves to a mirror-like appearance if encountered with a thermal imager. In a fire, this can be a help or a hindrance, depending on the situation, but make no mistake – you will encounter them in a fire and if you will encounter them in the real thing, then you better make sure you encounter it in training first.

• Thermal latency. Ask several firefighters to sit or lie down on the furniture and assume different positions. Let them stay there for several minutes and then tell them to get up. What you will see is the amount of body heat that the furniture absorbed and is now re-emitting. This latent thermal effect can be used to show that firefighters, during search and rescue, may see “signs” of victims before they actually locate any. There may be latent thermal images on furniture or beds that can be indications that victims are present. This can also be used on motor vehicle accidents to assist in determining the number of occupants, especially in rollover accidents where ejections are more common. You can get both false positives and false negatives, so information from thermal latency is only one piece of information. If you happen to have a driver of a vehicle who is intoxicated and head injured mumbling about a passenger and you see a thermal latent imprint in the passenger seat, I would make sure that you search the surrounding area.

• Insulation. If you have access to one, grab a chemical hot pack, activate it and throw it on a table. Show the group what the hot pack looks like to the thermal imager, and then cover it with a thick blanket. This shows that victims on beds are hard to detect as the warmer the blanket is for people, the better insulator it is. The better insulator the blanket is, the harder it is for a thermal imager to “see.” You can even use a bed sheet, blanket and comforter. For this reason, all beds should be searched by a gloved hand regardless of what the imager says.

• Fire inspections and pre-plans. One of the easiest trainings to conduct is to simply take the thermal imager with you during company-level fire inspections or pre-plans. Use the thermal imager to look around the building and if you see something that you do not recognize, investigate it until you understand what is causing it and why it appeared the way that it did on the thermal imager. Building this kind of mental database is one of the most effective methods of understanding what the imager is trying to display.