1. WHAT IS A THERMAL IMAGING CAMERA?

The thermal imaging camera (TIC) is a tool which: detects infrared radiation from thermal energy emitted by a body, an object, a surface, or an area (heat waves invisible to the naked eye), records infrared radiation, and transcribes this infrared radiation by displaying it on a screen so that the user can view this infrared radiation, analyze it and interpret it.

Thermal imaging cameras (TIC’s) for firefighters produce an image of the intensity of the thermal radiation detected. 
The colors displayed on the camera screen are therefore false colors.
As said before, the colors displayed on the screen represent only an intensity. Some infrared cameras have several colorization modes. Each colorization mode has its own color palette.

Below are examples of the color palettes used for LEADER TIC firefighter thermal cameras:

• Colors used in Fire mode = black, white, yellow, orange and red.
• Colors used in Cold mode = black, white and blue.

Thus, the same observed scene can produce a different image depending on the colorization mode used.

2. WHAT IS THE PURPOSE OF A THERMAL IMAGING CAMERA FOR FIREFIGHTING / SEARCH AND RESCUE? Why use a thermal imaging camera in Firefighting, Search and Rescue?

2.1 For Firefighting: Secure the firefighters in action and avoid trap

• The firefighting thermal imaging camera is useful for firefighters in the following situations: 
• Easier recognition and movement in a room invaded by smoke where it is impossible to see with the naked eye
• The rapid search / detection of the fire source or a smoldering fire

Identification of dangerous elements that could threaten the safety of firefighters / rescuers:

• Presence of gas cylinders
• Monitoring an overheating electrical circuit
• Identification at distance of the liquid level in a tank (fuel tanks, unloading of wagons or tanks, transport of hazardous materials, etc.) to collect the information necessary for the intervention
• Locate a hydrocarbon stain on the roadway following a road accident in the middle of the night
• Location of ventilation points
• Identification of residual hot spots after a fire has been extinguished (chimney fire, etc.) that could cause a new start of fire!
• Search for emergency fallback routes in a smoky environment, etc.

2.2 For Search and Rescue: Identify / locate victims ...

2.2.1 In a smoky atmosphere, in the dark

It is very often difficult to detect a victim with the naked eye during fire interventions due to lack of visibility. A thermal imaging camera for firefighters allows the rapid identification of unconscious victims in a smoky atmosphere or in low light (fires in apartments, underground car parks, factories, forests, etc.)

2.2.2 During road accidents

Portable thermal imaging cameras are also very useful for road accidents intervention in the countryside and at night. Indeed, they provide the ability to: assess the number of passengers in a vehicle involved in an accident by visualizing the heated seats by the person (s) (of course when the emergency services arrive at the scene within a very short time), more quickly identify road accident victims who have been thrown from a vehicle in the middle of the night, for example. Thus, when seconds count, it is faster to find a victim with a thermal camera than to search for the victim with a flashlight in fields.

Example below: Sitting in a chair for 10 seconds leaves a thermal signature on the back and seat of the chair.

2.2.3 During earthquakes, landslides, collapses

Thermal infrared cameras are also very useful for rescuers when searching for victims trapped under rubble or confined spaces. The USAR thermal imaging camera LEADER also allow the ability to easily spot unconscious victims in the dark, where a standard search camera will show nothing on the screen.

2.2.4 In the sea, in the mountains and in the desert

Widely used by coast guards and rescuers, in particular for looking for people overboard, LEADER TIC Long Range thermal imaging cameras (which can detect a victim up to 1000 m) are also used for looking for victims (skiers / hikers) in high mountains.

Example below with 3 thermal cameras located  at 100m from the vehicle:

• First image = view with a standard camera
• Second image = view with a LEADER TIC LR700 Long Range thermal camera
• Third image = view with a LEADER TIC LR1000 Long Range thermal camera

3. WHAT ARE THE MOST IMPORTANT CRITERIA FOR SELECTING THERMAL CAMERAS FOR FIREFIGHTERS / RESCUERS AND WHY? How to choose a Thermal Camera?

Thermal imaging cameras are now used in many fields such as :

• industry (e.g. monitoring of engine overheating of machines)
• military
• surveillance and security (detection of intruders),
• buildings (e.g. energy diagnostics), etc...

However, the choice of a thermal imaging camera depends on the application for which it is intended.

Example:

1. A thermal imaging camera that is intended to detect fever in humans will not be suitable for firefighting because it will certainly have a lower temperature range compared to a firefighting thermal imaging camera with a much higher temperature range from 450°C to at 1150°C (842 to + 2102°F).
2. Conversely, a firefighting thermal imaging camera will not be suitable for detecting fever. For fever detection, we will need a camera with a very high sensitivity and which will therefore be able to display the temperature very accurately (to the nearest tenth of a degree). The temperature range of a firefighting camera of up to 1150°C (2102° F) will therefore be too much power in this case. 

In addition, the two thermal imaging cameras do not measure with the same emissivity rate, which obviously will not give the same results.

So, how to choose a thermal imaging camera dedicated to firefighters /rescuers ?

In addition to ergonomics, compactness, size, resolution and sensitivity of the sensor, the resistance of the camera and its battery to high temperatures... the most important criteria for the selection of a firefighting thermal imaging camera are as follows:

3.1 The field of vision must be as wide as possible

A firefighter thermal imaging camera does not behave like a human eye. Indeed, it reacts to infrared and not to light. In addition, the field of vision of a thermal imaging camera is much smaller than that of humans.

Typically, human binocular vision is in the range of 120° horizontally and 105° vertically (45° up and 80° down). This vision will be reduced with a thermal imaging camera.

Example: During a tourist visit, you have certainly already had to back up several meters or feet in order to be able to take a picture of a monument. Your camera's field of view is smaller than your field of view (unless you have a wide angle camera of course)! It's a bit the same with a thermal imager.

This field of view will be even more reduced by wearing a breathing apparatus mask.

As the use of the camera is most often done while wearing a breathing apparatus, the attack team will therefore have to use "scanning" techniques in order to collect as much information as possible during this recognition phase. The “scanning” technique is used to visually sweep with the TIC the entire volume in which rescuers are walking. This is to avoid the "tunnel effect" that is to say: looking only in front of you which could lead to a dangerous misinterpretation of the situation and create a "tunnel" effect! 

For this, 2 areas are particularly important:

The ground: vision being limited in the lower part (due to the wearing of the breathing apparatus mask + the vertically limited viewing angle of the camera), it will be impossible to secure the user's progress and to identify victims located at the right or left simultaneously.

The ceiling: smoke progression threshold with all its associated risks must also be carefully monitored.

The scan technique, whether done in strip, Z, X or 6-sided, must be done with rigor and repeated during the recognition phase, to allow the construction of a mental image of the progress. The combination of repeated scans and progressions without a camera will allow to identify dangers.

The LEADER TIC thermal imaging cameras have a viewing angle that is among the highest on the market, 51° horizontally and 40° vertically, thus making it possible to scan an intervention area more quickly.

In addition, since the camera has a greater field of view in width than in height, it is interesting to modify its grip in order to position it vertically to increase the field of view on this axis.

The handle option of LEADER TIC cameras allows this action to be carried out easily by tilting it in "portrait" mode very simply in order to carry out the recognition phase even more quickly.

3.2 The temperature range should be as wide as possible

As said before, the selection criteria depends on the use of the thermal imaging camera.
In the case of a “Firefighting” thermal imaging camera, it is important to choose a camera with a wide temperature range in order to guarantee the reliability of the device and especially the safety of firefighters.

3.2.1 To avoid image saturation:

A camera equipped with a wide temperature range going beyond 1000°C (1832°F) allow to analyze all the situations encountered without risk of saturation (inability to discern the observed scene).
Indeed, when the maximum detection temperature of the camera is exceeded, the image is saturated and it is no longer possible to clearly see the contrasts on the camera screen, thus making it impossible to read / understand the situation.

Satured image = situation impossible to analyze
Max T°C threshold: 650°C (1202°F)

Unsatured image = understandable situation
Max T°C threshold: 1150°C (2102°F)

3.2.2 To avoid bad reading / misunderstood / misinterpretation of the intervention scene and thus endanger the rescue teams:

Depending of the temperature range, it will not be possible for the firefighter to analyze all the elements of the observed scene. A thermal camera with a temperature range of up to 450 or 500°C (842 to 932°F) will not be able to:

• Understand perfectly the triggering of a flash-over occurring between 600 and 650°C (1112 to 1202°F)
• Analyze the risk of collapse of a metal structure building knowing that steel loses all stability from 850°C (1562°F)

Even for first responders, it is necessary to be equipped with a firefighting equipment that can warn them of a danger!

LEADER has chosen to endow its portable thermal imaging cameras for firefighters with the widest temperature range on the market (from -40°C to + 1150°C) (-40 to + 2102°F ) in order to give firefighters the opportunity to analyze all the situations encountered.

3.3 The color modes must be complementary

The use of several color modes allows the user to analyze the observed scenes with greater precision in order to facilitate understanding (temperature level, smoke propagation, traffic axis, danger, etc.). This is why it is important to have the ability to change the colorization mode, in order to highlight other unseen elements.

LEADER offers up to 5 colorizations modes on its LEADER TIC cameras: Fire, Search, Inverse, Cold and Multicolor. Each colorization mode has its advantages, disadvantages and limitations.

It is therefore essential to know the specificities of each mode in order to choose the most suitable according to the situation encountered. This is why the training of the users is essential for a good understanding of the observed image.

FIRE MODE: the main and essential 

Display at screen: The attack team must progress in unfamiliar spaces with often zero visibility while being exposed to high temperatures. They therefore need simple and intuitive indications allowing them to quickly collect the information necessary to understand the situation.

With this in mind, the colors used for FIRE mode indicate levels of danger like those encountered on the road circulation code: 

• Yellow color: increased vigilance, a danger is near you must be able to react
• Orange color: danger confirmed, be ready to stop to avoid further exposure
• Red color: stop, observe and if necessary, reverse

Interests for the user: The most basic and easy to understand: one color = one meaning

SEARCH MODE:

Display at screen: Black and white display with orange / red colorization of the hottest 7%; Interests for the user: Used primarily for victim search and hot spot identification.

INVERSE MODE:

Display at screen: This function inverts the black and white colors of the FIRE mode. The other colors are identical to the FIRE mode above 200°C (392°F).

Interests for the user: Used in low temperature situation to:

• Facilitate observation,
• Observe an outside scene in sunny weather,
• Vary the colorization of the background of an image to better identify details

COLD MODE:

Display at screen: Colorization in blue of the coldest points of the observed scene.

Interests for the user: Used in a low temperature situation to highlight the coldest elements. Can be useful for:

• Look for gas leaks, liquefied gas leaks, liquid or refrigerant gas leaks,
• Observe ice plates on a lake/sea, etc ...

MULTICOLOR MODE:

• Display at screen: The observed scene appears with 5 colorization.
• Interests for the user: Used for technical controls and risky operations

4. THE IMPORTANCE OF TRAINING

As with any firefighting equipment, it is important that the firefighter is trained to properly use their thermal imaging camera. Indeed, this knowledge will allow them to fully understand the situations encountered during interventions by integrating into their analysis the information obtained thanks to the thermal imaging camera.

Since training is too often forgotten, it turns out that many firefighters do not always appreciate the value of their thermal imaging cameras and are unable to use them properly. It is for this reason that thermal cameras are too often left in trucks and are therefore underused.

Contrary to what many may think:

• A thermal imaging camera is not a thermometer. It is too often used as such when it does not have the characteristics or the function.
• A TIC cannot see through a wall or an obstacle. The thermal camera reproduces on the screen the heat stored by a body or the heat flow of a wall when a fireplace is behind, for example.
• Glass and water do not pass infrared rays, so it is not possible to measure the temperature of an object behind glass or through water with a thermal imaging camera.

Polished surfaces such as polished metal, glass, plastic or painted surfaces can look like a mirror with the thermal imaging camera. In this case, the information transmitted by the thermal camera is incorrect and may mislead the firefighter and endanger him.

An object, depending on its emissivity rate, may appear on the screen at a much lower temperature than it actually is.

As you have clearly seen from the few examples given throughout this article, it is very important to be trained in the use of the firefighting thermal imaging camera but it is also very important to be trained in the interpretation of thermal images.

LEADER, manufacturer of thermal imaging cameras specifically designed for firefighting, assists all its customers in choosing the thermal imaging camera that best suits their needs and also trains them in the use of its firefighting equipment.

Wishing to join the firefighters and rescuers in a process of acquiring knowledge for the use of thermal cameras, LEADER also trains all its customers in the interpretation of thermal images so that they can know:

• the value of a thermal camera in firefighting and search & rescue,
• the differences between human naked eye vision and infrared rays,
• the main principles of thermal energy,
• the essential characteristics and functions of a thermal camera,
• the limits of a thermal imaging camera and know how to overcome the traps linked to an erroneous thermal signature which could threaten the safety of workers,
• how to read and interpret the measured temperatures (emissivity),
• the different coloring modes, know in which situations to use them and know how to interpret them correctly.

Original text: Leader - How to choose a thermal imaging camera