The first three installments in this series, beginning in January 2011, talked about preliminary items that must be understood to have a successful rapid intervention team (RIT) on the fireground and asked what the true rapid intervention capability is for your fire department? Using...
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With the increasing technological advances in communication systems and networking in today’s world also comes an increased hazard to firefighters. Numerous cables and wires are run through drop ceilings to facilitate these various systems. Also now prevalent is appliance and ventilation ductwork made from wire that is covered with a plastic or aluminum “skin.” Once subjected to heat, the plastic melts and the wound wire becomes very difficult to see. These hazards are present in office and commercial occupancies as well as in residential structures. The entanglement often occurs in the area of the firefighter’s SCBA. Numerous techniques exist for handling this hazard – every firefighter should be trained in these techniques and carry cutters that can be handled by a gloved hand and be strong enough to cut the materials faced (Figure 6).
Basic physiology tells us that firefighters consume the air in their SCBA at different rates. A working air supply will also depend on the firefighter’s training, physical condition, activity and mental state experienced under the stressful conditions encountered during firefighting. Does your department complete air-consumption drills for each firefighter on an annual basis? NFPA 1984, Standard on Respirators for Wildland Firefighting Operations, specifically mandates them to be completed each year.
Air-consumption drills are not costly or difficult to conduct. Items normally found in the fire station can be used to create a consumption course. The only caveat is that they are set up the same way each time one is performed. Items measured in an air-consumption drill include how much air the firefighter begins with, how long it takes before a low-pressure alarm sounds, the amount of time it takes to have the low-pressure alarm stop sounding and the time after that it takes to completely exhaust the residual air in the cylinder where the mask sucks to the face of the firefighter. Measuring these parameters gives firefighters confidence in themselves and their equipment (Figures 7 and 8).
Point 8 – All members of our fire department understand the uses and limitations of thermal imaging technology on the fireground.
Do our members truly understand how the thermal imager (TI) works and what its limitations are? If not, we can be asking for trouble. The use of TIs can result in firefighters developing overconfidence and dependability on the use of the camera. The use of thermal imaging cannot replace a secure and basic foundation in firefighter search techniques.
Thermal imaging technology is based on infrared energy. All objects located in an area above absolute zero (zero degrees Kelvin) temperature will emit infrared energy to some degree. Heat is classified as a form of infrared energy. Our unaided eye cannot see this energy. Visible light is also considered infrared energy, but it is on a different wavelength than heat on the electromagnetic spectrum. The amount of heat energy given off by objects is different. The picture on the viewing screen of a TI is a visual representation of temperature differences within an area. Even though visual impairment has taken place for the firefighter, the heat of combustion continues to exist. It is the heat that the technological function of thermal imaging capitalizes on. This is why a firefighter can get a visual representation of an area on the viewing screen when products of combustion have brought visibility levels near zero. Even though visible light (which is blocked by smoke) is not required for use, a TI cannot see through objects. Mass and density of an object will have a direct effect on the image visualized on the screen of a TI.
There are three types of emitters when speaking of infrared energy, which helps to explain how mass and density affect the image on the screen. Passive emitters are inanimate objects whose temperatures vary depending on the environment and time limit that it is exposed. Basic physics tells us that heat moves to a cold object until the object is the same temperature as the surrounding environment. A passive emitter absorbs heat in the same manner. Active emitters such as human beings and animals generate their own thermal energy. These objects can be hidden, or “masked,” easily when searching with a TI. The density of turnout gear or debris (passive emitters) covering firefighters may prevent their bodies (active emitters) from being picked up by a TI. Gear that is wet can also mask an image on the camera. It is important that the user understands this and is able the recognize shapes or objects that may be a part of a victim protruding from underneath debris. A direct-source emitter gives off the most thermal energy and is easily detectable with a TI. Fire itself is a direct-source emitter.