Have you noticed that there are numerous color palettes and color temperature associations with fire service thermal imaging cameras?
Why is this so? Doesn’t NFPA 1801 standardize this issue and prevent confusing color temperature associations? Sadly, this isn’t the case. This is the NFPA 1801 approved color/temperature progression for thermal imaging cameras under the TI Basic Color Palette (black, grey, white, yellow, orange & red). According to NFPA 1801 (Standard for Thermal Imagers for the Fire Service section 6.6.4.2.2 & 6.6.4.2.3) colors should meet the following criteria:
“Colorization shall overlay the grayscale thermal images produced by the thermal imager. Details within the thermal image and within the colorized area shall remain resolvable by the user other than at saturation.”
“The colors yellow, orange, and red shall have a corresponding, temperature-dependent change in hue as temperatures increase”
Notice that there is no uniform standard “corresponding, temperature-dependent” for each color. Why is this? Doesn’t this confuse firefighters when they pick up one TIC that fails to show color until 1000 degrees Fahrenheit when another brand shows colorization at 500 degrees? What happens when we associate colors with specific dangers and fail to recognize the severity of the thermal threat in gray scale?
In many cases, fire service thermal imaging camera manufacturers pick and choose which temperature they want colorization to appear and it can be detrimental to a firefighter to rely on seeing color as an indicator of severe heat if the manufacturer chooses to follow the color/temperature progression as shown below in the MSA color palette. Therefore, it is imperative that the firefighter know and understand their specific brand/model of TIC and it’s benefits and limitations.
And in many cases, thermal imaging manufacturers offer various other color palettes that are NOT intended for the fire environment such as: rainbow (high color), iron bow, all grayscale, reverse polarity (sometimes known as Inverse or Black Hot), Green Hot, and more.
These color palettes were designed for specific industrial applications in lower contrast and lower temperature environments NOT for the Fire environment. When these color palettes are used in high temperature environments they can confuse firefighters and produce a very obscure image.
In teaching this curriculum internationally, we have discovered that firefighters don’t respond to gray scale (much to the displeasure of many thermographers and TIC manufacturers). The human eye can identify 4 shades of Grayscale imagery under stress, but many manufacturers use between 30-246 shades of grayscale. This in combination with too many colors often confuse and overwhelm firefighters who only have seconds to interpret the image and make a decision.
To further exemplify this point, see the following infographic with the Max Fire Box. Firefighters would be prone to think that blue & green would be cool but, in this case, it is cooler than the fire, but it is still very hot. In researching many of the thermal imaging camera manufacturers, most of these fail to provide the associated temperatures with these colors. If this color palette is to be used, it would be useful for locating overheated components in a structure but not during fire attack. Notice in the second photo of the Max Fire Box, that green is VERY HOT! These color/temperature associations are camera specific and must be learned by the firefighters to use the TIC to its maximum benefit.
In closing, thermal imaging manufacturers and NFPA need to standardize the color/temperature associations. If a requirement of NFPA 1801 is interoperability, a TIC that offers different color/temperature associations compared to another NFPA 1801 TIC will only further confuse firefighters. And in many cases, it may lead to improper interpretation, injury, or worse. Firefighters have to make quick decisions based on incomplete information. Let’s not make a firefighter’s decision making process more complicated. Simplify thermal severity and the interpretation by making a uniform color/temperature association that ALL fire service manufacturers SHALL abide by.
