Firefighters must be trained to properly evaluate fire incidents based on training and by incorporating thermal data to enhance their strategies and tactics on the fireground. A thorough understanding of fundamental building construction, fire behaviour and thermal imaging combined will allow an individual to grasp and apply these concepts effectively.
Unfortunately, we must first overcome two common obstacles in thermal imaging. First, firefighters must carry the thermal imaging camera (TIC) as a part of their PPE. A recent study conducted in partnership with Firehouse magazine showed that the TIC was left on the fire apparatus approximately 50% of the time. Secondly, firefighters must be trained on how to properly scan the environment.
However, both of these issues can be overcome through understanding the importance of thermal imaging use on the fireground and how to properly interpret the data they are viewing. If they’re not trained in understanding the key attributes of thermal imaging, firefighters may fail to understand the importance of what they are actually seeing.
Tom Zind summarises it well in the following quote:
‘Deploying the technology improperly, inaccurately interpreting the raw information it produces, and even failing to create an action plan that supports it can render results confusing at best or useless at worst.’ (Zind p.1)
In order to properly apply, a firefighter must first understand why; this is achieved through education and training on the following key attributes before they use the TIC:
ν Field of view
ν Temperature modes vs application modes
ν Resolution & colour palettes
ν Distance to spot ratio
In addition to understanding and properly interpreting the thermal image, the firefighter must understand how the object they are viewing can change thermally based on their field of view, overall heat, type of surfaces, environment, insulation and the type of the camera they are using. Firefighters must understand the limitations of the TIC. It detects long-wave infrared radiation emitted by surfaces based on a preset non-adjustable emissivity. A fire-service TIC does not detect gas or smoke temperatures, nor should it be used for quantitative measurements (such as elevated body temperature checks).
Therefore, when firefighters begin to view the building, we have developed the following acronym which will be helpful in understanding the thermal data presented to them:
S: SURFACES What is the thermal conductive properties and/or emissivity? A low-emissivity surface (such as glass or shiny surfaces) will reflect more energy, producing inaccurate temperature measurements.
T: TEMPERATURE What levels of heat and/or temperature do they see that are abnormal? What is the temperature of the weather? Weather affects temperature measurement dramatically. A windy day can reduce temperature measurement accuracy by as much as 50% in certain cases.
I: INSULATION What level of insulative properties does this building possess? In older, poorly insulated buildings, firefighters may readily see heat loss or thermal cues of fire spread more readily than in a more insulated newer building.
C: CUES What areas of thermal bridging/conduction can indicate areas of concern that should be investigated. A thermal bridge is an area of significantly higher heat transfer. An example is the metal components inside of a building that heat up producing a heat signature visible on the exterior through the TIC.
K: KIND OF THERMAL-IMAGING CAMERA What type of fire-service TIC is being used? Situational-awareness TICs should not be used for these types of assessments. Is it high resolution or low resolution? What application mode is being used?
Robert Madding, who has over 40 years of field and teaching experience in thermography, summarises this concern in the following quote:
‘You have to know as much about what you’re looking at as what you’re looking with. These advanced imaging devices can simply make it easier to get the wrong answer sometimes. With IR images, some users can easily fall into the trap of thinking they know what they’re viewing. They just don’t know what they don’t know.’ (Zind p.1)
Why should firefighters use this methodology?
- They can assess priorities for corrective action.
- They are not looking for exact measurements but thermal anomalies.
- These anomalies may indicate the fire’s location, the direction of fire spread and cues/clues that may indicate rapid fire progression along with victim location/identification.
However, if a firefighter doesn’t have an understanding of a normal heat signature, how will they recognise an abnormal one? When a physician studies an x-ray or a scan of a patient, they compare their findings to a healthy or normal patient. Just as a hazardous-material-incident technician uses a metering device with a ‘calibration gas’, we as firefighters must understand how the buildings, objects and people will appear in normal conditions so we can identify abnormal conditions that could be hazardous.
Firefighters are required to routinely tour or visit buildings in their response area or district. Through continual visits, firefighters gain valuable insight of the building’s infrastructure, occupancy and any potential hazards or special risks they may encounter when called for an emergency. A simple addition to their routine of carrying the TIC will gain valuable information and reconnaissance for when they are called to respond. Thermography experts recommend having regular and routine assessments that start with a baseline assessment. Firefighters should be very well educated about what they are looking at, its normal thermal footprint, and in this way be able to quickly identify any problem areas through proper interpretation of thermal data. This eliminates problems with misinterpretations due to solar loading, areas that may already have a higher heat signature (such as exhaust ports or chimneys) and problems due to reflective surfaces.
In order for a firefighter to properly interpret the image they are viewing they must understand how the following key attributes will affect their scan and the overall image:
Field of view: Firefighters must first understand that a TIC has a much narrower field of view when compared to the human eye. The human eye has a field of view of 60 degrees vertically and as much as 170 degrees horizontally. Firefighters understand how their field of view can be limited by the loss of peripheral vision when their facepiece is in place; therefore, they can understand how the TIC can further diminish their overall field of view. The photo below shows how the field of view is greatly diminished from optical, through the facepiece view, and then through the lens of the TIC.
A firefighter who understands the importance of field of view can greatly increase the success of their efforts by scanning in one of the following methods:
Standard grip: If a firefighter is assessing a wide area such as a wide building, great room, or auditorium, the standard orientation of the TIC will most likely benefit them, as the majority of TICs have a larger horizontal field of view than a vertical field of view. This is shown in the following image where the first numbers listed are for the vertical field of view multiplied by the second numbers listed which are the horizontal field of view.
Sideways grip (gangster grip): If a firefighter is viewing a hallway or an entrance point to a structure and their TIC has a larger field of view horizontally, it is advantageous for them to turn the camera sideways to gain a taller field of view. This technique was first mentioned by Carrollton Texas Fire Department many years ago. As the following two photos demonstrate, the first photo is in the standard ‘pistol’ grip with the TIC looking down the hallway. The second photo is the TIC in the sideways grip (gangster grip) held at the same height as the previous photo.
This allows firefighters to view the two areas they are most concerned with in one view which are as follows:
- The floor area
- The ceiling area or highest point of the room
In a standard home with a ceiling height of up to 9ft (3m), this technique allows the firefighter to capture both critical areas in one view. It also makes their initial look or scan more efficient. Rather than the six-sided scan that is taught by most TIC training programmes, the scan is reduced to three movements: scan left, scan centre, scan right.
The standing problem: The majority of firefighters are standing up or not kneeling low enough when they scan. This is a common mistake. Standing up will place the TIC in the path of the exhaust and will often cover the germanium window (which is the lens of the TIC) with moisture, soot and debris. It will greatly diminish, limit the detail, or even block the lens completely, producing a white screen. It has occurred so often that we have answered hundreds of firefighters’ complaints internationally who have stated that they made entry and the TIC whited out on them. However, newer TICs do not white out due to heat. The white screen or white image they are viewing is actually moisture blocking the lens. A TIC cannot see through water. This often occurs when a crew leader is ahead of the hose-line during fire-suppression efforts. Firefighters are often unaware that as often as they have to wipe their facepiece they should also be wiping the lens of the TIC so it may ‘see’ the environment appropriately.
Never looking down: Firefighters who use the standard grip in these situations often miss important details such as victim location, layout of the room and, in many cases, they miss the fire due to scanning too fast. If the firefighter is looking up, the TIC’s field of view is limited to the top area and often misses the area which is located 4ft and below. Therefore, they will often see the fire or signs of the fire in the form of convection currents, but they have missed the victim in many cases. When this occurs, many firefighters stay focused on the target (such as the heat source) and fail to scan the entire room such as the lower areas where victims may be located. We often assist fire departments in after-action reports involving TIC problems where we have learned firefighters have crawled over or past the victim. In other cases, due to improper scanning techniques, many firefighters have missed the fire room. My friend and mentor Battalion Chief Mike Mitchum summarises this well in the following statement: ‘The firefighter holding the TIC should take seconds to save minutes.’ By scanning intentionally and not too quickly they can then direct their firefighters more effectively and efficiently. By slowing down their scan they can speed up their overall efforts. As shown in the photo below, if a firefighter fails to stay low and scan low the TIC stays in Low Sensitivity due to the focus on the higher heat. This leads to a loss of detail and the potential for missing the victim is increased.
In summary, part one of this article focuses on gaining understanding of the thermal data the firefighter is seeing and how they carry the thermal-imaging camera. The firefighter must understand the key attributes of thermal imaging and how the environment they are in can cause the image to change or be misinterpreted. Through education and training, firefighters can assess environments or situations, thereby enhancing their decision-making in areas of fire suppression, search, ventilation, rapid intervention and more.
For more information, go to www.insighttrainingllc.com
- Zind, Tom (2013). The Language of Heat. EC&M Magazine. Retrieved from: https://www.ecmweb.com/electrical-testing/article/20900278/the-language-of-heat