Myths vs. Reality in Thermal Imaging - Part II

The first article (January 2003) of this series dismissed five common myths about thermal imagers (TIs). These myths were:

Because TIs arise from a new and somewhat complicated technology, there are a number of misconceptions regarding what TIs can and cannot do. The first five addressed in the previous article in this series are the most common, and potentially place firefighters at the greatest risk. This article continues with more common myths and explains the reality.

Myth #6-Microbolometers are New Technology

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Photo courtesy of Bullard
Figure 1: BST sensor engine with chopper wheel.

Two basic thermal imaging technologies are available today in the fire service, based on three different sensor materials. Generically, the technologies are known as ferroelectric and microbolometer. The two terms describe how the infrared detector receives thermal energy and then converts it into electrical signals to be processed. The detector, often called a sensor or focal plane array (FPA), is the key portion of the technology that allows TIs to detect heat.

The ferroelectric technology in the fire service today is often referred to as BST. BST stands for barium strontium titanate, the material that coats the sensor. Because all ferroelectric TIs sold in the fire service today have a BST sensor, the two terms are often used interchangeably.

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Photo courtesy of Bullard
Figure 2: Vanadium oxide microbolometer sensor and engine.

Microbolometers have not followed the same pattern. There are currently two microbolometer sensor materials available to the fire service: vanadium oxide and amorphous silicon. The fire market considers vanadium oxide as the standard "microbolometer," while usually identifying amorphous silicon by name. The core technology behind both materials is similar; the primary difference is the sensor material itself.

All of the confusion about terminology has created an interesting myth. A number of people believe that microbolometers are new technologies.

Under the guidance of the US Department of Defense, Honeywell patented ferroelectric (BST) and microbolometer infrared detectors in the early 1980s, with about 18 months separating the two discoveries. Both technologies were highly advanced at the time and were classified by the US Military. Raytheon, Boeing and Lockheed-Martin (which sold its infrared business to British Aerospace or BAE) all licensed the technology from Honeywell and manufactured infrared detectors for military applications. After the 1991 Gulf War, these technologies were declassified, and preparations for introducing these sensors to the fire service ensued.

For a number of technical reasons, BST was the easier technology to adapt for the fire service. The BST sensor easily gained acceptance in the fire service because it dramatically outperformed earlier TI technologies, and it started to make major inroads around 1997.

Microbolometers (specifically those based on vanadium oxide or VOx) were delayed entering the fire service because they had larger technological hurdles to overcome. These devices made initial entry into the fire service in 1999. Amorphous silicon (or aSi) is the "newest" microbolometer technology, introduced in 2001 to the fire service.

This short history lesson shows that all of the confusion about the "newness" of each technology relates to when it entered the fire service market. Regardless of the entry time, however, the fact is that firefighters are using technology developed during Ronald Reagan's presidency.

Rather than worry about the newest technology, fire departments should concern themselves with selecting the TIs that will best meet their operational needs. They should also ensure that the chosen TI is easy to use, durable and offers excellent training and service.

Myth #7-Newer is Better

NOTE:As the next article in this series is developed, I would like to hear from firefighters. What are the myths you have heard? What is your TI not doing that you thought it should? The next articles will incorporate your questions with more common myths of thermal imaging.

TIs are technical pieces of equipment, loaded with transistors, capacitors and digital processors. They even sound technical: like computer chips, update speeds are measured in hertz. Update speed refers to how often the received thermal information is updated on the display screen. This is measured in hertz, or number of times per second. The fact that, like computers, few people understand how TIs truly operate makes it easy for firefighters to compare them to computers. Some fire departments have even delayed buying TIs because they want to be sure that they do not buy something that is "outdated."

The computer comparison is unfair for firefighters and oversimplifies thermal imaging technology. Computers advance and evolve because new software (programs) makes more demands of the existing hardware (computer chips). A competitive cycle is created as the chip manufacturers try to stay ahead of the software manufacturers. The chemistry of fire, however, is not changing over time. The materials involved in common structure fires have changed, but the fire tetrahedron (oxygen, fuel, heat and chemical reaction) is unchanged because it is governed by the laws of physics.

Rather than compare TI technology to computer chips (say, Pentium 3 vs. Pentium 4), firefighters should compare TI technology to vehicle engine technology. For the most part, automotive engines are limited to gasoline, diesel and hybrids. With automotive engines, as with TI sensors, "newest" does not automatically mean "best." Every engine (like every TI sensor) has advantages and disadvantages that shoppers must consider prior to deciding which type to buy. For example, a hybrid engine is the newest technology. However, a fire department would never specify one for a new fire engine. The technology is very fuel-efficient but lacks torque for moving heavy vehicles at reasonable speeds.

Software written in 2006 will probably not run on computers from 2000. However, fires and victims in 2006 will still be visible on TIs purchased in 2000. Firefighters choosing TIs should think of the sensor choices as they do automotive engines: every one has a job it does well, and firefighters need to match the "engine" with the job at hand.

Myth #8-TIs are Useful Only at Structure Fires for Overhaul and Search

The origin of this myth may be multifaceted. In part, this myth may have originated because of the emphasis that the fire service places on structure fires. Firefighters train extensively for structure fires, and many become firefighters because of their desire to fight structure fires. Another reason for the focus on structure fire applications is that fire departments often justify the TI expenditure by making emotional appeals: TIs save civilian lives by shortening search times. Many fire departments also do not have enough TIs (or the TIs are difficult to access), so the tool arrives only in time for overhaul. As a result, some firefighters have unintentionally boxed themselves into considering TIs as a limited firefighting tool.

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 the firefighters' eyes are not yielding enough information. Below are the nine potential uses, and brief comments on each one:

  • Size Up: Prior to making entry, a company officer can survey the structure with his/her eyes and the TI. Just as the human eye will show concentrations of flame and smoke, the TI may show which walls (and possibly interior rooms) are truly the hottest, thus helping to identify fire spread. A TI may show that a fire in a balloon frame house has already run up a chase into the attic. Imagine the advantage fire companies have in knowing such information before they begin suppression and ventilation efforts.

  • Fire Attack: A hose team equipped with a TI will find the fire faster. They will negotiate the building with greater speed, safety and ease. Because they will be able to see the exact location of the fire, the team can apply water more effectively and efficiently.

  • Firefighter Safety: TIs enhance firefighter safety in two primary ways. First, the tool helps the firefighter monitor structural integrity in low-visibility conditions. Exposed or damaged trusses are seen more easily. A company with a TI will more easily distinguish holes, missing floor sections and high heat below the firefighters. Second, firefighters with proper training will be able to identify thermal layers and possibly recognize pre-flashover conditions.

  • Ventilation: The TI can be used during size up to determine potential ventilation points. Because superheated gasses are visible on most TIs, the technology also can help the firefighter verify that a vertical ventilation point is properly performing its task.

  • Search and Rescue: Firefighters frequently think of this application but rarely have an opportunity to attempt it. Too many fire departments do not have enough TIs or have placed the TIs in areas that are hard to access. If the TI is not on the first-in company, it cannot help in the primary search. If the TI is stored in a compartment with the smoke ejectors, it will probably stay there until the smoke ejectors come out. For TIs to be effective in search and rescue, they must arrive early in the incident and they must be taken off the rig at the same time as SCBAs.

  • Overhaul: Many departments use their TIs successfully in this application. The TI can help identify hot spots or areas of concern and limit the amount of damage caused during overhaul. TIs enable them to identify hot spots quicker, reducing wasted effort and greatly reducing overall on-scene time. Remember that after a fire, everything in the room will be hot and will show as white on the display. This is called "thermal saturation." In this situation, firefighters must be proficient in using other features of their TIs (like thermal throttles, EI modes or pyrometers) to identify the hottest spots.

  • Wildland: In this environment, TIs can track the locations of personnel and vehicles. The exact fire line can be located with a TI, and the presence of hot spots determined. A handheld TI used from a vehicle or aircraft still will not see through glass, so the user must operate it safely through an opening.

  • Hazmat: TIs will not abate a hazardous material incident, but they can be used to monitor, confirm or evaluate a potential or known hazard. TIs may help determine liquid levels in sealed containers, including pressurized containers. Spilled material may be traceable and visible with the TI, both on the ground and in the water. Concentrated gasses may even be visible in the air.

  • EMS: The TI may help any time the human eye fails. Amputated digits, so difficult to find on a factory floor or in a yard, may be found quickly by firefighters or medics using a TI. At motor vehicle accidents, the TI may help find any victims ejected from the vehicle, in conditions of darkness, concealment or fog. A creative department might even use the TI to help rule out that a child safety seat was occupied prior to an accident.

  • Training: Firefighters using TIs can monitor the safety of a building and its occupants during live-fire evolutions. Structural integrity can be monitored and dangerous building conditions can be identified before firefighters are injured. Firefighters exposed to too much heat can be easily identified before their turnout gear is damaged or before they are injured by heat or steam. If the TI is equipped with a transmitter, the image can be monitored remotely and recorded for later review and learning.

By no means is this list exhaustive. Firefighters, by nature, are very creative individuals. They can and should find more applications for TIs.

Conclusion

While TIs are technical tools, they should not overwhelm firefighters. Some firefighters equate new to better when none of the technologies is very new and every TI sensor technology has advantages and disadvantages. Firefighters should make every effort to rethink their approach to TIs, from understanding the technology to using these tools in the field. TIs are not limited to overhaul and rescue efforts; they can be used any time the human eye does not provide enough information.

As the next article in this series is developed, I would like to hear from firefighters. What are the myths you have heard? What is your TI not doing that you thought it should? The next articles will incorporate your questions with more common myths of thermal imaging.

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Jonathan Bastian is a Thermal Imaging Specialist for Bullard. He is certified as a thermal imaging instructor by the Law Enforcement Thermographers' Association (LETA). He is also the author of the FD Training Network "FireNotes" book, Thermal Imaging for the Fire Service. Bastian served 12 years on the North Park, IL, Fire Department, including the last three as a captain. He has taught classes on thermal imaging, rapid intervention teams and search and rescue operations. He is currently a police officer in Lexington, Kentucky. If you have questions about thermal imaging, please send them to jonathan_bastian@bullard.com.

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