In recent years, a growing number of fire departments and rescue agencies have purchased thermal imaging units to assist them in their operations. Valued for their ability to locate victims under adverse conditions, these devices have become more suitable for fire and rescue work due to their increasing portability and affordability. With a number of different designs now available, they can be used in a wide variety of applications.
"Infrared technology was borne out of a military need in the Vietnam era," says Doug VanDover, regional sales manager for Raytheon Systems Company, a Dallas, TX-based manufacturer of thermal imagers. "Texas Instruments developed infrared technology for the U.S. Air Force. It was originally for airborne applications so an aircraft could fly over and look for an enemy or find targets."
Raytheon eventually purchased Texas Instruments' defense company and continued to develop the systems for military use, says VanDover.
These military units detected the radiated heat from a target and displayed an image of that heat source for the operator. The principle behind these and later systems is that all objects emit heat, some more than others. The more heat detected, the easier it is to find the target. At night or when visibility is threatened, being able to detect the heat from an object or lost person can help in identifying that object or person.
Though they share similar principles of operation, first-generation units work differently than later designs.
First-generation thermal imagers are temperature-sensitive. They feature detectors that have to be cryogenically cooled in order to view infrared energy generated from a heat source.
According to Mike Richardson, thermal imaging training specialist for Bullard, a Cynthiana, KY-based manufacturer of a handheld thermal imaging system incorporating Raytheon solid-state technology, due to their size and complexity, these systems were initially limited to fixed-vehicle applications on tanks, helicopters and planes. They are still used in some military and commercial applications, and they offer some features that some newer designs don't have; however, as technology developed, the market moved away from these systems toward uncooled units.
According to VanDover, Texas Instruments started developing uncooled technology about 10-15 years ago. Today's generation of solid-state uncooled systems offer some advantages over earlier cooled designs. Since they require less energy to run than cooled units, they are lighter, smaller and easier-to-use. They are also significantly less expensive. VanDover says a cooled infrared camera installed on a helicopter for SAR/law enforcement applications can fetch about $150,000, compared to the $10,000-$12,000 cost of an uncooled handheld unit.
According to information supplied by Raytheon, they are effective at night, in light fog, smoke, dust, clouds, light rain and through most camouflage. Since they measure radiated body heat and not available light (as light-dependent systems do), they can also be used during the day.
However, they are not foolproof. They cannot see through glass, and some forms of camouflage and fog may degrade an image, making it more difficult to find a target.
Additionally, according to Richardson, to most effectively detect an individual in a wilderness application, that individual must have a heat signature greater than his background. This won't happen on a very hot day, but at night, in cooler temperatures or during winter, a thermal imager will work better in this application.
Finally, while the cost of these units has dropped dramatically, $10,000 per unit is still expensive for many agencies.
"For marine rescue, they're an excellent complement to radar," says VanDover. "With radar, a marine craft may know something's out there but can't tell what it is. Beyond that, low-profile objects, like a log in the water or a fiberglass boat, often cannot be seen by radar, so thermal imaging is going to see those and avoid hazards."
John S. Ehrhart, RN, a maritime planner with the U.S. Coast Guard, says thermal imagers have helped his district locate victims in the rugged Alaskan environment. Ehrhart works for the District Response Advisory Team, for U.S. Coast Guard District 17, in Juneau, AK. He says thermal imagers have been used to help locate people who become stranded on ice floes or other formations in the extreme cold, and to determine the size, location and flow of oil spills in the area.
District 17 recently purchased three handheld thermal imagers from a Raytheon dealer to replace an older system it was using.
Brian Bazemore, president of BCon Consulting, the Anchorage, AK-based dealer who handled District 17's purchase, says the district scrapped its old unit because of high maintenance costs and a lack of in-state support.
The new Raytheon systems, at 2 1/2 lbs., resemble camcorders, produce black and white images (which saves the district money), and allow information to be recorded for subsequent playback at training and review sessions. Ehrhart says the new devices are "far superior" to the older units, though they don't reveal as much detail or measure body temperature, as the district's cooled unit could.
VanDover says the applications for snow and ice rescue are just being explored.
"There are some promising indications that you might be able to find avalanche victims under the right conditions with thermal imaging. Big utility companies have to operate 24 hours a day and have lines going through the mountains. They send crews out in snow caps, but if you have a blizzard condition, they've lost navigation ability. A thermal imager can see through downpouring snow and locate navigational aids."
"Imagine going into a house you've never been in before and having to close your eyes to find anybody who might be alive," says VanDover. "The task would be pretty daunting, let alone the fact that the place may be burning and coming down on top of you. With one of these devices, you can go into a structure filled with smoke, scan a room in seconds rather than minutes on your hands and knees, walk through the whole house and find somebody rapidly. You can see through smoke, find the fire and look for a way to put it out."
Aircraft rescue and firefighting (ARFF) missions are another combined fire/SAR application. These specialized operations involve large ARFF vehicles that respond within minutes to a downed plane or other aviation emergency per Federal Aviation Administration (FAA) requirements. During an emergency, these vehicles may be part of a full-scale operation that includes fire suppression, SAR and hazmat response.
Recently, the Omaha Airport Authority Fire Rescue Department (OAA), in Omaha, NE, entered into a contract with Raytheon to purchase a thermal imager for installation on one of its ARFF vehicles.
According to Gary Schott, OAA fire chief, the department, which responds to aviation emergencies at the city's airport, realized that thermal imagers could assist its 18-member crew in conducting thermal scans of a plane's brakes and help locate victims who may be trapped inside a burning plane.
The OAA's unit is mounted to the front of one of its ARFF vehicles. The driver inside the vehicle controls the camera with a joystick, while the image is presented on a monitor inside.
Schott says plans are underway to purchase three more thermal imagers so that the district's three ARFF vehicles and one equipment-carrying rescue truck all carry the devices.
According to VanDover, the FAA now requires all new ARFF vehicles to have infrared cameras for navigation and heat source location.
"When a plane is on fire or has crashed, the number one problem, especially in inclement weather or darkness, is finding the aircraft, as crazy as that might sound. Airports are big places. You can quickly find something in a big, black, open area with a thermal imager."
"One of my distributors specializes in this market," adds VanDover. "They've done testing showing that where they did a controlled burn of an aircraft, you can pinpoint the hot spot through the fuselage in moments with a thermal imager."
"There are a few things to learn, such as the fundamental technology that thermal imaging is different from traditional night vision," says VanDover. "It's fairly intuitive, and the cameras are simple enough to operate that little training is required."
According to Richardson, training should focus on identifying and interpreting what you're looking at, which is especially important for urban search and rescue and structural firefighting applications.
Richardson also says it is important for agencies to not get lulled into a false sense of security just because they can detect an object they wouldn't otherwise see with the naked eye.
"Keep operating under your normal procedures," he says.
In order to save money, a SAR agency that does not handle fire suppression may want to purchase a device that doesn't have firefighting protection and that can produce black and white images, says Richardson.
SAR personnel should look at handheld, lightweight devices because they don't want to get tied down while conducting a search.
"You don't want something that requires a battery belt," says VanDover. "The older cameras used to have that. You'd probably use something like a law enforcement handheld. You'd have different lens options depending on your needs. If you need a close-up, wide field-of-view focus, you'd use a lens with a shorter focal length. If you need to look at a distance, down a ravine or across a canyon for somebody, you'd use a longer focal length lens."
Conversely, agencies involved in fire suppression require more rugged equipment. Firefighting cameras are somewhat larger, built to withstand a high-heat environment and are helmet- and suit-mounted in addition to being handheld, so that the firefighter can keep both hands free while entering a burning facility.
After determining the type of camera to purchase, the next step is to assess how much sensitivity and resolution you need. SAR applications require high sensitivity levels, says Richardson.
VanDover agrees: "You can miss key information if the camera is not discerning small pieces of information, so performance is a big issue."
Another issue is battery life. Units offering long battery lives are essential for SAR applications.
"If you're searching for a lost kid in the woods, you don't want to be swapping batteries out every 10 minutes," says VanDover. "A standard, long-life battery that will give you four or five hours on one charge is important when you're in the field."
By contrast, in a structural firefighting situation, where the goal is to enter and exit as fast as possible, a long battery life is less important.
An agency should also look for a unit that is simple to operate, user-friendly and has a variety of options and features (like the ability to record). Good service is key, as units will need to be replaced from time to time.
The new imagers allow temperature to be measured through the lens, says Richardson. Using uncooled technology like solid-state units, they are smaller and have fewer moving parts. However, one of their drawbacks is that they require a smaller, precise range of operating temperatures to work effectively. They are also currently more expensive than portable, solid-state units.
Another development is the use of thermal imagers in pedestrian vehicles to increase a driver's night vision.
Raytheon has integrated its NightDriver infrared thermal imager into the 2000 Cadillac DeVille to help drivers see better at night and avoid accidents.
According to Raytheon, the uncooled system helps motorists avoid parked or stalled cars, pedestrians, animals and other potential hazards in the road. A detector captures the target and delivers a video image to a heads-up display (HUD) projected on a standard vehicle windshield near the front edge of the car's hood. The displayed image is the same size as an image seen through the windshield. Raytheon says this will help drivers react easier to the image and allow them to keep their eyes on the road, since it facilitates "glancing looks" through the display.
Product Resource GuideBullard 1898 Safety Way, Cynthiana, KY 41031800/227-0423; fax 606/234-8987; www.thermalimager.com e-mail: kevin-halstead@bullard.com Thermal imaging cameras, fire and rescue helmets, supplied air respirators, breathing air equipment, personal cooling vests.
CairnsIRIS, div. of Cairns & Brother, Inc.,
EMX Inc.,
Fire Research Corp.
FLIR Systems, 16 Esquire Road, N. Billerica, MA 01862
Intec Video Systems, Inc.
Intermediate Safety Instruments, Inc.
ISG Thermal Systems USA, Inc.
Raytheon Infrared Products
Scott Health and Safety, 309 W. Crowell St., Monroe, NC 28112 704/282-8400; fax 704/282-8423 |