The United States military initially declassified thermal imager (TI) technology; the mindset was that a TI was used just for firefighting.
As time has gone by, through training, education, and widespread adoption, the fire service has come to realize that there is a TI application on every response—simply take the blinders off and think outside the box.
Not all calls a fire department responds to are actual fires or have working fire conditions, but there are many calls where a TI should be used. These applications include size-up, overhaul, search and rescue, hazmat, industrial, and smells and bells—all calls that require investigating the unknown. The unknown is anything that can’t be seen by the naked eye, such as heat signatures from passive emitters (inanimate objects), active emitters (living organisms), and direct emitters (energy sources).
Investigation of the unknown comes with great responsibility to keep the public and homeowners safe. They look to the fire department as experts, and to make a mistake or miscalculation is not an option. A TI, in this case, is that valuable tool that you can’t afford to leave in your apparatus. It is often a difference maker in uncovering that lingering or hidden heat source.
Uncovering the Unknowns in Smells and Bells Calls
The most common smells and bells calls are electrical issues, such as an overheated light ballast; electrical panel breakers; an improperly wired receptacle; or, in an industrial facility, overheated motors, bearings, or conveyors. Other applications besides smells and bells calls at which a TI can unveil unknown information include liquid levels in containers at a warehouse or propane tank levels at a bulk station during hazmat responses. In all cases, a TI is your most valuable tool for investigating and uncovering these unknowns.
Unknown heat signatures discovered behind a wall— 1 thermal and 2 naked eye view. (Photos courtesy of Bullard.)
3 A ceiling fan not working and 4 a ceiling fan working properly.
5 A wall heater.
At a recent TI training session, we compared the heat signature of two ceiling fans, one nonoperational (photo 3) and one operational (photo 4). It was discovered that the nonoperational ceiling fan had an overheated motor. This particular call didn’t require us to cut a hole in the wall to investigate further because the ceiling fans are exposed. Our TI clearly showed that the fan’s motor was too hot to be nonoperational. However, identifying hidden heat sources, like those behind a wall in photos 1 and 2, can be more challenging.
Understanding the Noise Sensitivity Temperature Difference (NETD) of a TI can help firefighters interpret hidden heat sources. The NETD allows the TI to distinguish between very small differences in thermal radiation within the image. This is sometimes referred to as “thermal contrast.” NETD is typically expressed in milli-Kelvin (mK), and today’s fire service TIs range anywhere from 30mK to 100mK, making some of these devices highly sensitive for investigating unknown heat signatures or sources. TIs with lower NETD generally have better image quality and allow a firefighter to better interpret the details of an image. This additional detail can sometime prevent a firefighter from having to open a wall because it’s easier to distinguish between, for example, a hot water pipe or another unknown heat source hidden behind a wall.
Those unknown heat signatures behind the wall in photo 1 were investigated during another TI training session. It was concluded that there was a heater on the opposite side of the wall (photo 5) and piping from the boiler water heating system inside the wall—mystery solved!
This was a good training exercise for the fire department members, who were apply their newly taught TI skills in a real application. Practice starts with you as a firefighter or officer who is assigned the use of a TI. As with anything, practice makes perfect. The more often you use and experiment with a TI, the more proficient you will become in its operation and interpreting images.
Whatever or wherever the response takes you, be sure to take your TI with you, as it is a valuable tool to aid in investigating the unknown.
Manfred Kihn is a 19-year veteran of the fire service, having served as an ambulance officer, emergency services specialist, firefighter, captain, and fire chief. He has been a member of Bullard’s Emergency Responder team since 2005 and is the company’s fire training specialist for thermal imaging technology. He is certified through the Law Enforcement Thermographers’ Association (LETA) as a thermal imaging instructor and is a recipient of the Ontario Medal for Firefighters Bravery. If you have questions about thermal imaging, you can e-mail him at manfred_kihn@bullard.com.
