Last month, we looked at the origin and development of the thermal imaging standard by the National Fire Protection Association (NFPA) as well as the state of the industry. This month, we will review the result by looking at the document itself. While it would be impossible to cover all of the details within the space of this column, we will take a high-level look at the various parts of the document. If you want to read the document for yourself, a copy is available at www.nfpa.org.
The first three chapters of the 1801 standard are consistent with many NFPA documents in structure and content, covering Administration, Referenced Publications and Definitions. In the interest of space and attention, we will skip these chapters and go straight to chapters four through eight, which are where more of the rubber meets the road.
• Chapter Four — Certification; and Chapter Five — Product Labeling and Information. Chapter Four digs into the nitty-gritty of getting the product certified as compliant to the 1801 standard. While there is nothing extraordinary contained in this chapter, there are several things worthy of note. Section 4.1.3 contains the prohibition against claiming compliance to only a portion of the standard. While this is common to other NFPA standards, as I alluded to last month, several manufacturers have claimed partial compliance with the 1801 standard. Some manufacturers have, for years, advertised that their thermal imagers were compliant with specific sections of the self-contained breathing apparatus (SCBA) standard, which is in conflict with section 4.1.5 of the 1981 standard 4.1.5, which is apparently left up to the customer to catch and admonish.
Chapter Four requires the certification to be issued by a third-party organization that cannot be owned or controlled by the product manufacturer and sets standards for the certification organization itself. Chapter Four also requires annual recertification via random and unannounced testing and sets forth a safety alert and product recall system. Chapter Five is pretty straight forward in the fact that it requires a compliance label be present on the outside of a compliant product and on the wording of such label.
• Chapter Six — Design Requirements. Chapter Six is where things begin to get interesting. The first thing to note in Chapter Six is the establishment of two distinct operational modes for the thermal imager: TI BASIC and TI BASIC PLUS. One of the needs identified by the National Institute of Standards and Technology (NIST) workshop (Amon, Bryner and Hamins, National Institute of Standards and Technology, June 2005, NIST Special Publication 1040, Thermal Imaging Research Needs for First Responders: Workshop Proceedings) was a standardization of user interfaces and TI BASIC is the NFPA attempt to accomplish this.
TI BASIC represents an operational mode where the only requirements are grayscale, white-hot imagery, power source status and overheat indicator. Optional features are restricted to high-heat colorization and temperature sensing only. No other feature can be active in TI BASIC mode. The imager must be equipped with a green power button that, when activated, will always power up the imager in TI BASIC mode. This standardization is intended to create a consistency of operation that would simplify training and allow mutual aid companies to use one another's imagers.
TI BASIC PLUS is a somewhat unrestricted mode of operation with a couple of caveats. TI BASIC PLUS features are not allowed to interfere with the operation of any TI BASIC feature and TI BASIC PLUS mode must be designed to limit access. There is no clear verbiage within the standard as to what this actually means other than you must purposely access the TI BASIC PLUS mode of operation and the language "limit access" is somewhat ambiguous. Other than those restrictions, everything else is relatively fair game with the apparent exception of polarity inversion (black-hot imagery), which is something that I have written about in previous Firehouse® columns. Although currently offered by several manufacturers, polarity inversion is a dangerous feature for a thermal imager and apparently restricted by the 1801 standard. I use the term apparently because I am not a certification organization and cannot make the final determination.
Chapter Six also defines how the viewable area of the imager shall be structured and what should be displayed. The 1801 viewable area is split into thirds. The right third, much like today, is reserved for temperature sensing, and a newly added requirement for a high-heat colorization reference bar that is intended to allow the user to reference what temperature range is being represented by what color. The center third is reserved for alarm and operational indicators, including the power status indicator, while the left third is reserved for additional information such as TI BASIC PLUS indicator, low-sensitivity mode indicator and activation of any TI BASIC PLUS features.
• Chapter Seven — Performance Requirements; and Chapter Eight — Test Methods. Chapter Seven sets forth a multitude of performance requirements, including ingress protection, electromagnetic emissions, electromagnetic immunity, vibration resistance, impact resistance, corrosion resistance, abrasion testing for the display viewing area, heat and flame resistance, field of view requirements and what is likely the most controversial part of the 1801 standard when it establishes image recognition requirements.
Image recognition is a new requirement specifically to thermal imagers. It is designed to make sure that a certified thermal imager offers a newly defined minimum image quality. This value is represented by the notation PIQ and the minimum pass criterion is 0.80. The controversy stems from the fact that NIST gathered a representative sampling of thermal imagers on the market today and tested them to determine their inherent PIQ values. This sampling spanned multiple manufacturers and multiple models with resolutions from 120x90 up to 320x240, which is the highest resolution currently available to firefighters. After collecting the performance data of these imagers, the decision was made to establish the minimum acceptable score at 0.80, which is significantly higher than any tested thermal imager. This effectively established that every thermal imager on the market today has insufficient image quality to be certified per 1801 standards.
While some may applaud the NFPA for pushing to higher levels of image quality, please consider several key issues. First, with better image quality comes higher prices. No firefighting thermal imaging manufacturer in the world manufactures its own detectors. We all acquire them from someone else. We are at their mercy when it comes to the pricing of these detectors and better performance will lead to higher prices.
Second, the NIST test does not necessarily lead to better image performance from a user perspective. Anytime you attempt to replace a human's observational skills with a computer's, there will be a deficit. In this case, the testing process captures artifact, not normally discernible to the human observer, which is then manipulated out digitally. This digital removal actually allows for the introduction of artifact by the manufacturer (an issue normally controlled during the development process) because it will be digitally removed during testing. In this regard, image quality could degrade in some aspects and still pass the image-recognition test.
Chapter Eight examines the specific testing procedures for each of the tests mentioned above. It is both lengthy and extremely technical so I will not bore you with the details but I encourage you to read them. Information is the key to an educated decision and it is there for your reading enjoyment.
As with all newly created standards, the NFPA 1801, Standard on Thermal Imagers for the Fire Service, 2010 edition, will evolve over time. Although still not testable due to clerical errors that currently prevent a lab from successfully testing an imager, the standard is published and technically effective. Manufacturers are working hard toward certification while awaiting the correction of the standard. In the meantime, if NFPA certification will be important to your future purchasing decisions, I encourage you to get educated. Read the document, ask questions and investigate the changes. Before you spend any money, you should know exactly what you are getting.
BRAD HARVEY is the Thermal Imaging Product Manager at Bullard. He is a veteran of public safety as a firefighter, police officer and paramedic and is certified through the Law Enforcement Thermographers' Association (LETA) as a thermal imaging instructor. Harvey has worked as a high-angle rescue instructor and is a certified rescue technician and fire instructor. If you have questions about thermal imaging, you may e-mail him at [email protected].
