THERMAL IMAGING FOR THE FIRE SERVICE, PART 6: THE SEARCH
BY STEVEN P. WOODWORTH
Fire departments that purchase thermal imaging devices must understand that these units are only a tool. This tool, like any other tool, is only as good as the firefighter operating the unit. Knowing how to operate a thermal imaging device properly can cut in half the time required to search a given area and increase the safety of the search operation while increasing the search`s effectiveness.
Despite this technology, a firefighter can still miss a victim if the unit is not operated in a systematic searching pattern and the image is not interpreted properly. As is the case in all search operations, if the search is not conducted systematically, areas will be missed. Thermal imaging devices can greatly reduce the chance of missing areas as long as they are operated properly.
When entering a structure to perform a thermal imaging search, stop on entering a doorway or window and scan the area using a six-sided approach. Start with the unit to the extreme top right corner (Point 1) and scan slowly to the top left corner (Point 2). Then bring the unit back to the extreme right approximately midway down the wall (Point 3) and scan across this level to the extreme left (Point 4). Repeat the same process at floor level [from the extreme right (Point 5) across the area to the extreme left (Point 6)].
By using a six-sided approach, the scan will cover all the visible area between the four walls, the ceiling, and the floor. This is not to say that the search is complete yet. You still will have to look under beds and on the other side of furniture or whatever else is stored within the area. You may detect an energy source through partitions, depending on the infrared source (see “Thermal Imaging for the Fire Service, Part 3: Thermal Characteristics, Fire Engineering, November 1996). Make sure that the lens of the unit scans the entire area. Thermal imaging devices do not provide peripheral vision; in fact, they give the user tunnel vision. The user must compensate for this by ensuring that the field of view (see “Thermal Imaging for the Fire Service, Part 4: Thermal Imaging Devices, Fire Engineering, February 1997) for the unit covers the entire area being scanned. If you do not cover the entire area, small portions of the area may be overlooked, and a victim or hazardous condition could be missed.
The process of scanning the area should have the following three objectives: identifying life hazards, evaluating fire conditions, and evaluating structural integrity.
IDENTIFYING LIFE HAZARDS
You should try to identify civilian victims or evidence of civilian victims. If a victim is located, inform the search team of the quickest route to the victim. Also pass along to the search team all information about any obstacles or identifiable landmarks they might encounter. The life safety objective should also include identifying the number and approximate locations of other firefighters working in the area. Should conditions deteriorate and interior operations be abandoned, the operator of the device would be able to assist others in locating the nearest exit.
As I have stated previously in this series, it is all about interpreting the image. It is possible for the operator to become confused while viewing the image–for example, by losing track of which door is the exit. One method that can be used to avoid this confusion is to place a flashlight on the floor beside the exit door. This light will generate heat which in turn will create a white dot beside the door, hence identifying which door is the exit. The light can be further enhanced by identifying it better: using silicon caulk to affix a letter “E” (for exit) cut from sheetmetal on the lens of the light. As the light generates heat, the sheetmetal will heat up. You will have created your own exit sign. Everyone must be made aware of this procedure and be instructed not to move the light. This method will also make it possible for firefighters who do not have a thermal imaging device to identify the exit if smoke conditions are light enough down low, allowing the light to penetrate. Another way to identify an exit is to chock the door open on entering the structure (to maintain the exit). The cool air on the outside of the structure will appear in the lens as a dark area.
EVALUATING FIRE CONDITIONS
The operator should determine whether there is fire in the area to be searched, the level of the thermal layer in the room, the amount of convected heat movement within the room, and whether there are signs of fire in void spaces. If you are to be the operator, I strongly urge that you learn how to identify these conditions in a controlled situation. Don`t wait until you are in the middle of a two-story frame structure fire to try to learn how to interpret the image.
The thermal layer will appear as a horizon. Note this, and compare the level with a distinguishable landmark when possible. Make a mental note of the level of the thermal layer. If it is at the top of the windows, you should periodically check during the search to see if it is continuing to bank down. Commercial buildings should have exit signs that can provide an indication of how far down the heat is banking. Private dwellings usually will have something on the walls, such as pictures or paintings. If the truck company has a vent hole in the roof and the thermal layer is still banking down, then you have a problem somewhere, and you should pass this information on to Command. This condition could indicate the following: the vent hole is too small, the hole is over a large closet, a fire is in a void space, or sufficient water is not being applied to the fire. Whatever the case may be, the device user must see that the information gained from the image is applied to the fireground. If the information gained from interpreting the image is not used for making tactical decisions, it does no good to send the unit into the building in the first place.
THE “ANCHOR MAN”
As previously stated, thermal imaging devices can greatly increase the speed of the search operation. This can be a tremendous benefit. But, it is a double-edged sword. The team can move too quickly. When this happens, the operator does not have time to properly interpret the image, and the team can quickly enter an area it does not have to be in. Therefore, it is the anchor man`s responsibility to “keep the team honest.” By not having vision, the anchor man will slow down the team, providing the operator with time to interpret the image for life safety and evaluate fire conditions.
The anchor man must also continue to evaluate the fire conditions and make mental notes of the search. The same habits that have kept us alive for numerous years still continue to work. We cannot let ourselves become so dependent on technology that we cannot perform without it. Should the thermal imaging device fail, we must still know how to continue the search or find our way out of the structure without its aid. The anchor man must still look for signs of flashover. It is quite possible that the operator may not be recognizing the signs in the image.
One method of searching with a thermal imaging device is the IR-led search. The firefighter operating the thermal imaging device leads the search team through the structure while passing along information to the remainder of the search team. The firefighter operating the thermal imaging device determines the direction of the search and identifies obstacles or hazards to the search team. Should a victim who cannot be reached from a position on the wall be located, the firefighter will maintain a position on the wall. Using a personal rope, the anchor man is guided to the victim. The victim is then brought back to the operator`s position and moved to the nearest exit by the team. If a personal rope is not available, the anchor man can be guided for a short distance to the victim. Should the unit fail, the anchor man can be guided back by following the voice of the firefighter on the wall. Using the personal rope is obviously the safer of the two approaches.
THE POINT-TO-POINT SEARCH
The point-to-point search is used for moving through the structure. The operator identifies a distinguishable landmark and moves the team to that point. The team searches along the way. Once this point is reached, the operator scans the area again, using the six-sided approach. The next distinguishable landmark is located, and the search team proceeds to that location. Search team members should continue to probe with a tool in case the operator should miss a victim or encounter a hole in the floor. The point-to-point search is more commonly used with handheld units.
Thermal imaging units are extremely helpful in team search operations, again when used in conjunction with accountability and while monitoring conditions. Team search is a discipline in itself and is beyond the scope of this article.
Thermal imaging devices are gaining in popularity at a tremendous rate. This technology is a tremendous benefit to the fire service. Unfortunately, training for these units is not growing at the same pace. The fire service would never give a breathing apparatus to a firefighter and expect him to use it safely without having been trained in its use, yet thermal imaging devices are placed in service oftentimes without their intended users having had a single training drill; sometimes only classroom training is provided. Firefighters can make effective use of thermal imaging equipment only if they have ongoing and realistic training. As my friend Lieutenant Mike Cogan (Ret.) of the City of New York (NY) Fire Department`s Rescue Company 3 noted during FDIC `97: “If Joe Montana threw the football only once a year, he wouldn`t make it to the Super Bowl.” n
When a six-sided approach is used in searching with a thermal imaging device, the scan will cover all the visible area between the four walls, the ceiling, and the floor. (Photos by Matt Daly.)
The point-to-point search, most commonly used with handheld units, is used for moving through the structure. The operator identifies a distinguishable landmark and moves the team to that point. The team searches along the way. Once this point is reached, the operator scans the area again, using the six-sided approach. The next distinguishable landmark is located, and the search team proceeds to that location.
STEVEN P. WOODWORTH is a firefighter with the City of Atlanta, Georgia, assigned to Squad 4. He is an adjunct instructor at the Georgia Fire Academy and a volunteer firefighter for Fayette County. He is co-author of Fighting Fires with Foam (Van Nostrand Reinhold: New York City, 1992).