Thermal Imagers: Understanding the new generation
Before buying a new TIC, know the differences in their technology
I remember very clearly when we received our first thermal imaging camera at my former department around the turn of this century. It was designed to be worn on the helmet, was big and bulky, and somewhat difficult to use.
We were on the cutting edge of technology that would revolutionize tactical firefighting. But that edge came with a price: $25,000 for that first unit and its three siblings that later outfitted our four truck companies.
As with all technology, TICs have gotten smaller, easier to use and thankfully less expensive. By the time I retired from the department at the end of 2007, we had smaller handheld TICs on all 19 of our first-out engines and five truck companies.
Much has been published about TICs since then about the positive impact this technology can have on firefighting strategy and tactics. I find it particularly gratifying that it's hard to read a discussion of firefighting tactics, or attend a class or conference on the subject, without the use of a TIC being part of the conversation. We've come a long way in our acceptance and use of TICs in the past decade and a half.
With TICs so widely accepted, it is important for department leaders to become smarter consumers of new TIC technology. The number of TIC manufacturers has continued to grow as have the number of different models on the market today.
The National Institute of Standards and Technology, in cooperation with the U.S. Fire Administration, conducted research on TIC image contrast, effective temperature range, resolution and image, and thermal sensitivity. NIST researchers objectively evaluated a variety of TIC models in both the laboratory and engineered live burns like those NIST uses to conduct other types of fire-related research.
Technical Note 1499 also provides science-based information to national standards developing organizations, including the National Fire Protection Association, in support of NFPA 1801, Standard on Thermal Imagers for the Fire Service 2013.
NFPA 1801 has been described as one of the most complex standards that NFPA has ever issued. Get a copy of this standard, which the NFPA's Standards Council recently approved with an effective date of June 18.
Although there are currently no TICs in the marketplace that meet the new NFPA standard, departments should not hesitate to purchase units that meet their operational needs. TICs in use across the United States and around the world are an important tool in reducing risk for firefighters and civilians alike, even if the current generation is not yet on a common platform.
How they work
The heart of any TIC is its engine, that is, the technology used to covert infrared radiation waves into a visual image. Earlier generations of TICs used Barium Strontium Titanate (BST) technology as primary component of the sensor. These TICs were classified as cooled detectors because they relied on a cryogenic cooling mechanism, the cryocooler.
Those earlier cooled detectors were popular with firefighters because of their extraordinary sensitivity to infrared radiation; the cryocooler substantially reduced thermal noise, that is, the infrared radiation from sources other than the objects being observed. The downside was that cooled detectors required periodic maintenance — typically between 8,000 and 10,000 hours of operating time — because a cryocooler unit is a mechanical device with moving parts.
But advances in technology have produced a more efficient and effective engine, the microbolometer. This uncooled detector is based on microelectromechanical (MEMS) technology, as its engine. Vanadium oxide (VOx) and amorphous silicon (ASi) are the two most common materials used in microbolometers for TICs.
TICs using VOx microbolometers are currently popular with firefighters because of their improved image quality over that delivered by BST technology. The new kid on the block, TICs that use ASi in their microbolometer, are earning high marks for their improved sensitivity, resolution, thermal time constant and uniformity as well as their compact size and relatively low cost.
A basic understanding of the different TIC technologies will enable leaders to better decide between models during hands on evaluations and to make more-informed decisions during the purchasing process. When I reviewed the available on-line information regarding TIC evaluation criteria, these were the most common:
- Temperature reading sensor
- Unit size and weight
- Ease of use, body ergonomics
- Battery life
- Field-proven ruggedness and durability
- Display screen: size, resolution, color, advanced options
- Upgradeability of software
- Apparatus mounting and charging options
- Cost per unit
- Warranty terms and conditions
Below is a snapshot of some of these criteria for selected TIC models. Each had an International Electrotechnical Commission ingress protection rating of 67. An IP 67 rating means the device is dust tight and there is no ingress of water in harmful quantity when the enclosure is immersed at 1 meter for 30 minutes.
- Bullard Eclipse: VOx microbolometer sensor, 320 x 240 pixel display, and 33-degree horizontal and 45-degree vertical field of view.
- Draeger UCF 1600, 3200: VOx microbolometer sensor, 320 x 240 pixel display, and 47-degree field of view.
- E2V Argus 4 HR320: ASI microbolometer sensor, 320 x 240 pixel display, and 50-degree horizontal and 37.5-degree vertical field of view.
- Infrared Cameras FX 160: Unspecified microbolometer sensor, 320 x 240 pixel display, and 41-degree horizontal and 30-degree vertical field of view.
- ISG/Infrasys E380: Unspecified microbolometer sensor, 384 x 288 pixel display, and 54-degree field of view.
- MSA 5800 Series: VOx microbolometer sensor, 320 x 240 pixel display, and 36-degree field of view.
- Scott Safety Eagle Attack: Unspecified microbolometer sensor, 320 x 240 pixel display, and unspecified field of view.