The Truth Behind Temperature Sensing — Part 2

Last month, we opened the discussion on temperature sensing with your thermal imager. As a quick review, the actual name for temperature sensing is radiometry. Temperature sensing is a generic term used by the fire service referring to the ability of a...


type='node' cid='351817' />Last month, we opened the discussion on temperature sensing with your thermal imager. As a quick review, the actual name for temperature sensing is radiometry. Temperature sensing is a generic term used by the fire service referring to the ability of a thermal imager to...


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type='node' cid='351817' />Last month, we opened the discussion on temperature sensing with your thermal imager. As a quick review, the actual name for temperature sensing is radiometry. Temperature sensing is a generic term used by the fire service referring to the ability of a thermal imager to determine the temperature of an object and display that information to the user; however, this feature is often misunderstood and misapplied on the fire scene. We talked about how temperature sensing works and how some of those factors can play a role in the accuracy or inaccuracy of the reported temperature. This month, we focus on how this technology can or should factor into your fireground decisions. We will also look at ways in which you can compensate for the inherent inaccuracies and how you can practice and train personnel on the proper use of this feature.

What kind of temperature sensing do I have? One of the first things you need to do is identify and become familiar with the type of temperature sensing your imager employs. There are bar-graph displays that indicate the intensity of the temperature by moving a graphical indicator vertically along a temperature bar and there are digital readouts that display a number in the upper-right or lower-left of the display area. Some imagers use both types of display simultaneously.

There are pros and cons to both types of displays. A bar-graph indicator tends to provide a better "impression" in the mind of a firefighter as to approximate temperature levels. Given the inaccuracies we discussed last month, many fire departments prefer the generality of the bar-graph display, since most do not see temperature sensing as an important or overly valuable feature. On the flip side, however, some departments dislike bar-graph-only displays for this very reason. Some fire departments feel the bar-graph display lacks specificity and prefer something more concrete like a displayed number.

How should I use it? This becomes the big question. Temperature sensing is inherently inaccurate, even under laboratory conditions. Add in the variables of a typical fire scene and these inaccuracies can become exacerbated to the point of making the information totally useless. Given all of this, is there any way that temperature sensing can be employed effectively on a fire scene? The answer is yes. Just like any other piece of equipment, you need to understand the limitations of the technology and then implement it within its intended use.

Temperature sensing is best used when evaluating the temperature differences in the same or similar materials. This means that when performing overhaul, you may use temperature sensing to tell you what portion of drywall is hotter than another portion of drywall, as long as both readings are evaluating drywall. When comparing like materials, the temperature displayed does not matter as much as the difference between the temperatures — the temperature delta. If I look at two different areas of drywall on the same wall and one area measures 50 degrees Fahrenheit hotter than another, then I can assume this delta to be correct; however, I cannot compare the temperature difference between drywall and wood paneling on the same wall as most wood paneling is far more reflective than drywall and will have an effect on the displayed temperature.

Other applications may include the evaluation of different areas of heating duct (again similar materials) or temperature differences in a roof that you are getting ready to ventilate (works best at night so as to eliminate the effects of the sun on the roof temperature). Again, the evaluation of the temperature delta in like materials is the best implementation strategy.

How can I practice and train? Like anything else, practicing and training are the best methods of incorporating and understanding a skill. There are several ways you can create drills to reinforce the main two points, which are that temperature sensing can be wildly inaccurate and comparing the delta in like materials can be effective.

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