Control measure – Thermal imaging or scanning

Control Measure Knowledge

Thermal imaging cameras (TIC) and other thermal scanning equipment are devices that form an image using emitted infrared radiation as opposed to normal visible radiation. They gather information when normal observation may be inhibited due to smoke or lack of lighting. They also provide the option to search for specific points of interest such as casualties or seats of fire, which may not be obviously visible through the normal spectrum. In some situations, firespread may not be visible to the naked eye, but may be detected using TICs.

The range of thermal image cameras available is wide and they have varying specifications. However, many cameras have a numerical and colour gradient temperature scale, which may assist crews attempting to locate a fire and any casualties or for thermal scanning of a building.

The heat energy radiated from the objects in the form of infrared waves is picked up by the TIC, which is then able to identify the energy differences from the objects being scanned and convert the readings into visual images. The image displayed is therefore based on temperature differential.

Images may be displayed in black and white or in a colour range. The TIC manufacturer’s information should be referred to for descriptions of how higher or hotter temperatures will be displayed on their equipment.

TICs are available in different sizes and as an integral part of a number of different resources:

  • Hand-held
  • Helmet-mounted
  • Emergency fire vehicle-mounted
  • Self-contained
  • Remote-controlled
  • Aircraft-mounted (helicopter, drone and aeroplane)

Thermal imaging equipment can offer considerable benefits to incident commanders during the information gathering stage of an incident, including:

  • Establishing possible seats of fire
  • Establishing the extent of firespread
  • Establishing internal fire conditions and assessing the need for defensive or offensive action
  • Searching for casualties inside a structure
  • Wider search for casualties (during road traffic collisions, aircraft crashes, railway incidents, incidents in the open)
  • Improved search capability during low light or low visibility
  • Locating the seat of fire in large fuel supplies (for example in landfill or waste management centres)
  • Locating hot spots, bullseyes, small areas of combustion or heating
  • Establishing heat spread to adjacent hazards and fuel supplies
  • Establishing sources of overheating in electrical or mechanical scenarios (for example lighting chokes, vehicle brakes)
  • Establishing compromises or weaknesses in fire resistance
  • Locating hot spots in cylinders, vessels or pipework
  • Recording images and videos, which can assist subsequent investigations or debriefs
  • Assisting the incident commander via video link to command and control units

Operators of thermal imaging cameras should be aware that:

  • The equipment may not be intrinsically safe, limiting its use in some hazardous environments
  • Some surfaces can reflect or absorb infrared radiation, causing images to be misleading to an operator. For example, the devices often depict areas of the same temperature in the same shade or colour. This can obscure some hazards such as pits, surface liquid or unsafe ground which may be dangerous for operators in that area
  • Equipment using a different spectrum should not be relied on as a total replacement for normal vision. Standard service procedures for moving in smoke and darkness must be maintained and great care should be taken to ensure that personnel remain safe because battery power may be lost rapidly with little warning
  • Images displayed on the devices are computerised images created from the sensor equipment. Allowances should therefore be made for alterations to the actual size and distances involved for the objects on display
  • Images may be misleading as sensors may not differentiate between the heat of a fire versus the reflected heat from the sun on surfaces such as glass or polished metal. Well-insulated structures (e.g. sandwich panelled premises) do not readily allow for the passage of infrared radiation. Using a TIC may therefore indicate weaknesses in a structure but may not give any indication as to the conditions within it.

video developed by Greater Manchester Fire and Rescue Service shows the use of thermal scanning as part of its future firefighting techniques programme. 

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