The last three articles written for this column addressed the common misperceptions associated with thermal imagers (TIs). One of the best ways to dispel these myths and to help firefighters clearly understand and apply the technology is to provide them proper training. To review, some of the common misperceptions are:
- Anything white on a TI means fire or hot spot
- Fire victims will be displayed as white
- TIs will see through windows and walls to find victims faster
- Temperature readout is accurate
- TIs indicate air temperature
- Microbolometers are new technology
- Newer is better
- TIs are useful only at structure fires for overhaul and search
- TIs make firefighters safe
- The TI will identify everything in the structure
Left uncorrected, these misperceptions can lead to improper or unsafe use of thermal imaging, placing firefighters at increased risk. For example, believing that "TIs make firefighters safe" may lead a firefighter to advance into a structure without a hoseline or rope line. This misperception may also convince him that he can stand and walk inside a structure fire. To maximize the potential of the technology, and to do it safely, firefighters must receive thermal imaging training before TIs are put into service, and they should be involved in regular ongoing training activities to reinforce safe and effective use of thermal imaging.
While most Fire Service training follows standards or official references established by the National Fire Protection Association, this is not yet the case for thermal imaging. To fill this gap, some state fire academies have developed training plans. There is also an organization, the Law Enforcement Thermographers' Association, that has established training for police departments. In general, though, there are few firm or established guidelines for fire departments. As a result, department officials may find it challenging to determine the best approach. Departments can seek training assistance from private agencies, state agencies and TI manufacturers. However the training program is designed, it should include classroom training and hands-on training (preferably in realistic firefighting conditions).
Key Points of Classroom Training
Review Unit Operating Procedures
In this important foundation-building step, students should master all operating procedures of the unit, including turning it on, changing or charging batteries, activating transmitters or other special features, and conducting standard inspection and maintenance procedures. As part of the maintenance review, ensure that the department's battery charging and rotation system are explicitly stated. This simple task must be standardized, especially for departments not using a charging truck mount system, to ensure functionality of the tool. Fire departments will encounter problems if each shift or officer is left to determine its own battery charging procedures. As a result, this should also be addressed as part of the standard operating guideline (SOG).
This is also the time for the instructor to make sure firefighters can operate the unit in zero visibility just like any other piece of equipment they use when fighting a fire. Include training that verifies the ability of firefighters to perform emergency procedures, such as changing a battery, in blackout conditions with firefighting gloves.
Explain the Basics of Thermal Imaging
Before firefighters use TIs on the job, they should learn the basics of thermal imaging technology. Just as firefighters must understand fire behavior to perform effective suppression and ventilation, they should have a basic knowledge of how a TI functions. They should understand the properties of infrared energy, infrared emitters, heat transfer and what to expect from temperature measurement devices. (For more details on temperature measurement, see Myth #4 in the January 2003 issue of this column.) The instructor should explain key principals such as reflection, thermal contrast, and thermal inversion. These topics can be a significant challenge for new TI users who are learning to interpret thermal images. It is critical that firefighters realize how infrared radiation behaves in comparison to visible light, as well as the difference between the way a thermal imager develops images using thermal energy and the way the human eye develops images using light. As with all good training, the instructor should clearly explain the practical use of the information in everyday operations.
As with most training programs, it is helpful to have still images or video clips to help demonstrate visually what the instructor is teaching orally. If the fire department cannot record its own images, it may be able to download images from a manufacturer's website, such as www.thermalimager.com.
Teach Thermal Imaging Applications
During the classroom portion of training, the instructor should offer an introduction and overview of basic applications for thermal imaging, including fire attack, search and rescue, ventilation, overhaul, hazmat and wildland firefighting. Creative departments have also used TIs successfully in tracking lost individuals, looking for victims ejected at motor vehicle accidents and searching for amputated body parts.
It is critical that this portion of training review the proper techniques and uses of thermal imaging in each application, as well as the limitations and common pitfalls that may be encountered. For example, one of the most common safety issues with a TI is that the user tends to get "tunnel vision," focusing only on the TI image, ignoring other senses and forgetting to maintain a "mental map" of the structure. Fire departments must understand the risks, address the solutions, include the solutions in the SOG, and then teach and train to them. As with any other tool, fire departments must have adequate SOGs in place to ensure safe, proper and effective use.
This section of training is most valuable and effective if images can be presented to the group for vision interpretation practice. It takes a tremendous amount of time and practice to understand the information that thermal images convey. Correct image interpretation, for example, is the only way a TI can be used to help identify pre-flashover conditions. It is also important for training officers to show trainees how the TI will show certain environments much differently than the human eye.
Maintaining Basic Principles of Firefighting
While a TI might assist at almost any emergency incident, reliance on a thermal imager alone is dangerous. As mentioned earlier, firefighters may gain a false sense of confidence when using TIs, causing them to take actions that could place them at risk. Instructors must reinforce basic firefighting principles and procedures at all times.
The most common safety issues that arise while using TIs are:
- Standing or walking in hostile environments
- Forgetting, or not adhering to, basic firefighting skills and safety measures
- Advancing too quickly or too slowly
- Misinterpreting the image
- Misapplying the technology
Fire departments must ensure that training and SOGs address these key issues. By providing regular reminders in training, practice in live-fire environments and well-crafted SOGs, department leaders can help keep firefighters from falling into one of the common traps.
Thermal Imaging Drills
Ideally, live fire training is the best way to practice with the TI. While live fire experience is important, it is not the only way to practice. Dark rooms and smoke machines can be used to reduce visibility, and heat sources such as space heaters or gas burners can be used to simulate fire conditions. Firefighters can gain valuable knowledge about thermal imaging just by walking around inside and outside the firehouse, viewing surroundings under normal conditions. Training can also be enhanced by using thermal imaging videotapes collected in previous live fire training sessions, recorded with the aid of a thermal imager equipped with a wireless video transmitter.
During thermal imaging training, reinforce the safety issues and train against them. In any drill, consider taking the TI from the students and asking them to continue the search with traditional techniques, and then find their way out of the structure. Or give the students an evacuation order and tell them to turn the TI off, simulating a dead battery. Participants will quickly see how important it is that they do not rely on sight alone to guide their work. It is also helpful for the trainers to use a TI to monitor the students, ensuring that they do not get "tunnel vision," stand, move too quickly, etc.
Reinforce the notion that TIs actually have a number of uses outside of standard firefighting applications. One manufacturer, Bullard, identifies at least nine potential usage areas for TIs. Some of these uses are obvious, but others challenge firefighters to be creative. Consider using TIs in any environment where visible light and the firefighters' eyes are not giving all of the desired information.
A thermal imager will provide an image, but the user must determine what the image is indicating. Image interpretation is a critical component of training. Trainers must emphasize that thermal images produced by a TI are not the same as the images we see using visible light. Firefighters must spend a great deal of time viewing various scenes with the thermal imager so they can apply their understanding of basic thermal imaging principals in a fire. Following are some drills that will assist firefighters in properly interpreting what they see on the screen of a TI:
- In a training environment, use a highly reflective (for infrared) material, such as a window, mirror or silver-coated insulation. Have firefighters practice differentiating between reflections and true objects.
- Have firefighters walk around familiar surroundings, such as the firehouse, using the TI to try to determine what items are located where. Ask them to consider why the objects on the TI may or may not be showing as similar temperature items.
- Practice using the TI in stable environments, such as storerooms or apparatus bays, where most objects are the same temperature. This challenges firefighters to practice looking for specific shapes and reinforces the importance of thermal contrast.
- All temperature differences are relative. When looking for hotspots, teach firefighters to use additional techniques to verify questionable images, such as feeling the surface with the back of a hand or comparing the item in question to similar items in the vicinity. By using additional techniques, firefighters will see that not every white object on the screen of a TI is a hot spot.
- Place two similar covered containers next to each other, one filled halfway with cool water, and the other filled to the top with room temperature water. Ask firefighters to interpret the image.
Search and Rescue
Because many firefighters train in room temperature environments, they may believe that the victim will always show up as white on the screen of the TI. This is one of the most important myths to dispel during training. Following are some tips for search and rescue training:
- When training to use the TI for search and rescue efforts, make sure the "victim" is not the warmest object in the environment. In safe environments, heavily clothe the human victim to reduce the heat signature. Remember that turnout gear is a great insulator!
- When using rescue dummies (such as in live fire evolutions, per NFPA 1403), leave them at room temperature or in the burn building for a few hours before the drill, allowing them to become relatively cool.
- Since victims rarely present in full, recognizable form, ensure that search drills place victims in difficult, but realistic conditions. For example, hide a manikin under a bed, or have a victim dangle his arm out of a bathtub. When practicing rapid intervention, have the "injured" firefighter partially covered in debris so that members of the RIT practice looking for shapes that may be indicative of a downed firefighter.
There is no question that when employed properly, thermal imagers reduce losses in both dollars and lives on a daily basis. The bottom line is that a tool is only as good as its operator, and a firefighter using a thermal imager without proper training may actually face a greater risk than a firefighter with no thermal imager. As with any other training program, instructors must evaluate the progress of trainees through written tests and practical hands-on skill evaluations. Firefighters who have only a partial competency with thermal imaging may be more likely to place themselves in harm's way than are firefighters who are not using the technology at all.
Use your TI often, wisely and safely.
Jonathan is happy to answer any questions about thermal imaging; contact him at firstname.lastname@example.org.