Some 25 years ago when infrared technology was allowed for use by the fire service, who would have thought that a fire service thermal imager (TI) would be such a valuable tool used by firefighters to detect and locate sources of heat, such as fires; hidden victims; and structural weaknesses.
While it provides significant benefits, it also has some limitations that firefighters should be aware of to use it effectively and make informed decisions during firefighting operations. Here are some of the main limitations of a fire service TI.
- Visibility in smoke: TIs rely on detecting heat signatures, and in severe, thick smoke conditions, their effectiveness can be reduced. Smoke particles can obscure the infrared radiation emitted by the heat source, making it challenging to see through some dense smoke.
- Reflective surfaces: Highly reflective surfaces, such as mirrors, glass, ceramic tile, linoleum floors, stainless steel, and other polished metals, can interfere with the thermal imaging process. These surfaces may reflect ambient heat, leading to inaccurate readings or difficulty detecting objects behind them.
- Limited penetration: TIs have limited or no ability to penetrate thick materials. For instance, they may not be able to see through warehouse polydividing curtains that could hide potential hazards or shower curtains or dense vegetation that could hide victims.
- Distance limitations: The effective range of some TIs is typically limited. Most TIs can detect from 3 feet to infinity. Beyond a certain distance, the resolution and clarity of the heat signatures may decrease, making it challenging to identify smaller heat sources or victims at a distance. The surrounding background plays a big factor as well—the cooler the background, the greater the heat signature, the greater for distance.
- Temperature measurement accuracy: While TIs can display temperature variations, they are not always accurate in providing precise temperature measurements and should NOT be used as a thermometer. For accurate temperature readings, specialized thermal measurement devices such as a laser temperature gun are required.
1 Is it a reflection or a hole in the floor or a stairwell—image interpretation! (Photo courtesy of Bullard.)
- False positives and negatives: TIs can sometimes generate false positives or false negatives. Factors like reflections, thermal patterns unrelated to fires, or the inability to detect small or low-temperature heat sources might lead to incorrect interpretations.
- Battery life: TIs rely on battery power, and their operational time is limited by battery capacity. Lithium-ion batteries generally offer a longer operational life compared with NiMH type replaceable batteries. Extended firefighting operations may require additional batteries or backup imaging devices.
- Sensitivity to environmental conditions: Extreme weather conditions, such as heavy rain, fog and snow, or high humidity, can affect TIs’ performance. They may struggle to distinguish heat signatures clearly under such circumstances. It can also be challenging on a bright sunny day with solar loading while conducting a 360° initial structural assessment when arriving on scene.
- Water: Water can give false indicators such as a hole in the floor because of its cooler temperature. It can also cause surface reflections. While infrared cannot penetrate water, anything floating on the surface may be detected based on its temperature differences.
- : Interpreting thermal images requires proper training and experience. National Fire Protection Association 1408,
- , Section 4.2.7 clearly states that firefighters shall be trained to understand the limitations and potential misinterpretations of thermal data to make informed decisions effectively.
Despite these limitations, TIs remain an invaluable tool for firefighters, significantly enhancing their advanced decision making and improving their ability to navigate hazardous environments during firefighting operations. Continuous advancements in technology are making TIs even more efficient and reliable for fire service personnel.
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, e-mail him at Manfred_kihn@bullard.com.
