Thermal Imaging and Heat Detection
STEVEN P. WOODWORTH
Thermal imaging units are increasing in popularity in the fire service at a tremendous rate. The units offer fire departments a wealth of information that has never before been available to the firefighter, company officer, or chief officer. These units can be of great assistance during those “nuisance” calls, such as a difficult-to-find light ballast or an overheated electrical wire. More importantly, thermal imaging units also provide an added safety factor during calls such as the one discussed in the accompanying article. Should there be more than one fire or a fire in a void space or both, such as in this case, the thermal imager has the ability to identify the fire`s location early in the incident. The ability of the thermal imaging unit to detect these hazards depends on four factors: the unit itself, the amount of heat being generated, the building`s construction components, and the single most important factor–the firefighter using the unit.
THE UNIT ITSELF
The sensitivity of the unit will be a factor in whether the unit will pick up hot wires. This will be determined by the unit`s electronics. The electronic operating principle is far beyond the scope of this article. The units available today are really quite sensitive, with most being sensitive to 0.5 degrees F and even less. As the technology of the units becomes more and more sophisticated, the need to train with the unit increases dramatically.
THE AMOUNT OF HEAT GENERATED
The amount of heat generated will have a great impact on whether the thermal imaging unit will present an image. The more heat present, the clearer the image will be. The stage of the fire will have an impact on the amount of heat being generated. The stage of fire will also present different clues to the user, which will be an indication of the amount of fire present. The amount of heat present in the image will also be changing, a key factor in determining whether you are dealing with hot wires or actual fire behind the wall.
CONSTRUCTION COMPONENTS
The materials through which the unit is trying to locate heat will have a large impact on how clear the image will be and how much information can be gained. Wires that run behind suspended ceiling tile are easily distinguished, whereas wires running behind layered construction materials may not be.
THE FIREFIGHTER
The single most important factor is the firefighter using the unit. The firefighter must be trained in how to interpret the image presented. An example would be using an instrument to take a reading at a hazardous-materials incident. A value of 10 would be absolutely no good to the firefighter. The firefighter must know if the reading is in percent of an LEL (lower explosive limit), percent oxygen, or part per million. This information will provide you with the ability to make tactical decisions. The same holds true with thermal imaging. The key element often overlooked in thermal imaging is training. It must include more than how to turn on the unit and where to place the battery. Training should include how to interpret what is seen in the image. Identifying a hot light ballast is quite simple. Leave the lights on for a short time to allow the ballast to become hot. Then turn off the lights, and scan with a thermal imager. You should be able to identify the bad ballast immediately.
Identifying electrical wires in walls is a fairly simple task. All thermal imaging units are set to show that white indicates the presence of heat; black indicates the absence of heat. This seems like an easy task to perform, yet quite the contrary is true. Just because white is present does not mean that fire is present, nor does it mean that a wire is overheating. The ability to correctly identify hazardous situations comes with effective training and then experience.
The incident in the article was handled without thermal imaging. This brings up another good point to ponder. Although thermal imaging is a tremendous benefit to fire departments, it must not be relied on solely. This incident was safely handled by firefighters using sound judgment and experience. Fire departments that can and do move forward with technology, such as thermal imaging, must not overlook the basics that have brought them through so many incidents in the past. I do believe that thermal imaging is the way of the future for fire departments; however, we must not forget to dance with the one that brought us.
STEVEN P. WOODWORTH, a 15-year veteran of the fire service, is a lieutenant with the Atlanta (GA) Fire Department, assigned to the Atlanta Fire Academy. He is vice president and regional training director for SAFE–IR, a training company specializing in thermal imaging and firefighter survival training.
