Thermal imagers are a critical tool for any fire department, and there are many choices on the market today. Technology is advancing quickly, offering more capabilities than ever before – better resolution, smoother images, options like video and still image recording as well as smaller-sized options. This is a good thing, but it can also become overwhelming when selecting the right thermal imager for your agency. Focusing on the important details can help you find the perfect unit for your application – and the three Rs is the place to start: resolution, refresh rate and ruggedness.
Thermal imager resolution
As is the case with your smartphone or any other camera, an imager’s sensor resolution is measured in pixels, and the larger the numbers, the more information the camera’s sensor can collect. When comparing cameras, look for higher resolution to ensure clear, detailed images. Lower-resolution camera cores make for lower-priced units, but beware of the reduction in clarity and image quality. This problem will be most evident when you are working in high-temperature environments where the camera is trying to display very hot and cold portions of a scene. This is where you really need to see details in the image – like victims and flow path signatures. The QXT from Bullard features 640 x 480 resolution, compared to some other manufacturers that feature sensors with resolutions of 320 x 240.
Thermal imager refresh rate
Thermal imaging camera cores sample the temperature of each pixel a certain number of times per second, measured in Hz. This is called the refresh rate and will dictate how often the image is updated. A lower refresh rate means less data per second and an image that can seem to “lag” behind or look jumpy. This is because the camera image processor is filling in the gaps between data points to create an image. Faster refresh rates help ensure that as you move the camera, the image will keep up with you – and this translates to heightened situational awareness. Look for cameras with higher refresh rates – 60hz is ideal.
Modern fire behavior also demands that we are more aware of flow paths and dynamic fire events. An imager with a lower refresh rate can struggle to display this movement and make it harder to pick up on the dynamic nature of a flow path. With a heightened refresh rate, you will see the movement of high-pressure flow paths down hallways, and see the hot gases pushing out of a fire compartment. This can guide where to flow water as you approach, ensuring that you are controlling the fire environment and fighting it on your terms.
Additionally, some fire service thermal imagers will periodically shutter for quick recalibration. This typically happens more frequently when moving between temperature extremes, like as you approach the fire room during a search. This could mean a shutter event happening while you searched a portion of a room. It requires discipline to make sure firefighters recognize a shutter and remember to double-check the last area to avoid missing anything.
Colorization of the hottest part of the scene also will change as the camera compensates for operating in higher-temperature environments. The camera needs to display this color to illustrate fire behavior but do so in a way that allows you to still see the detail behind the color. After all, it does us no good to see the corner of the room as all red if we can’t see the doorframe from which the heat is emanating so we know where to direct a hose stream.
Bullard’s NXT Pro features a fast 60-Hz refresh rate, no mandatory shuttering, and smooth viewing. In addition, X-Factor Image Enhancement can make sure you still see detail through the colorization.
There is a place for lower refresh rate decision-making thermal imagers. They can provide an additional layer of situational awareness and help with basic decisions like evacuation routes and locations of exits. These imagers can also be lower cost, so a department can equip each member on an apparatus with an imager, rather than just one tactical thermal imager. The Bullard TKS features a lower weight and small size but still features X Factor image enhancement and long battery life.
Thermal imager ruggedness
NFPA 1801 requires, among other things, that thermal imagers can withstand certain durability tests before certification. High heat, drops onto concrete and being bumped into debris all can happen during a fire attack.
NFPA certification also dictates how the screen is laid out, and things like on/off button behavior and color. Across all of their imagers, Bullard has these items standardized, reducing the need for additional training when users switch between models or imager types, reducing the chance of errors.
When purchasing a thermal imager, it’s good to evaluate whether the camera is NFPA certified, but this doesn’t tell the whole story. Digging deeper can reveal that some cameras in a vendor’s line may not be certified but are still as durable as the models that do have 1801 certification. All Bullard XT series cameras have IP 67 ratings and have a five-year warranty, regardless of certification.
Imager components like display covers, front bumpers and others that are field replaceable also reduce the cost of ownership. With Bullard field replaceable parts, an imager does not have to be sent back to the manufacturer for minor part replacements. Requiring the unit to be shipped back for minor repairs can mean an apparatus either has an imager missing or requires the department to purchase a spare unit to replace imagers that are out for service.
Final thoughts
Next time you are comparing thermal imagers, use the three Rs to make sure you select the product that can not only perform when you need it most but can last the test of time and reduce your cost of ownership.
