Tupelo Fire Equipment is more than a company that just "wants to make money" from Emergency Services, we want to make sure you are as informed as possible. We want to help you make the best decisions for the needs of your staff. This page is solely for information purposes and it not intended to "sell" one product or brand over the other. Please see below for some of our more commonly asked questions on equipment.

THERMAL IMAGERS

I know what the camera is supposed to do, but I really don't understand all the wording. Can you help?

We understand that terms can sometimes get confusing. Hopefully, these definitions will clear things up a bit.

PIXELS: These are the independent squares on the infrared detector that sense and react to the infrared energy. Pixel size, as well as the number of pixels on the detector, helps determine the resolution and quality of the thermal image. However, the processing hardware and software play a far greater role in determining picture quality. The detectors in the fire service are available as 160x120 pixels or 320x240 pixels. Most of the small-format TIs use a 160x120 detector. The 320x240 detectors have four times, or 300%, more pixels than the smaller detectors.

WHITE OUT: This term is a holdover from the early days of fire service TIs. The first handheld TIs introduced to the fire service could be easily overloaded by an intense heat source, such as a fire. These systems would either fail as a result of the thermal overload, or they would shut down as a means of “self-preservation.” The end result in both situations was that the TI would have an all-white display. This “white out” could only be eliminated by removing the TI from the environment and giving it time to recover, or by replacing the damaged sensor. All of the technologies available today are immune to “white out.” The sensors can be overloaded by a fire, but they do not suffer irreparable damage in the process. In short, white out is no longer a concern for departments buying a modern thermal imager.

SATURATION: This term reflects the fact that every TI sensor has a maximum amount of energy that it can receive and process. If the sensor is exposed to more heat (thermal energy) than it can measure, then it is said to be “saturated.” Therefore, if a sensor can receive up to 1000°F in energy, then it will not be able to display a difference between a 1000°F item and a 1500°F item ... the most it can sense is 1000°F. If a large number of pixels become saturated, then an image may be mostly white or clouded by white. This is not “white out.” The detector, and thus the TI, is performing properly. It has been exposed to a significant heat source and is generating a mostly white image as a result. If the TI has a colorization system, then the saturation will be indicated by the “hottest” color (normally red).

DYNAMIC RANGE: This has two meanings. The technological definition of dynamic range relates to how many temperatures can be displayed in any given scene. Each TI has a maximum range of temperatures between black (cold) and white (hot). The larger this range, the more gray scales are available to the system and the greater is the range of temperatures that can be shown in a given image. In a very dynamic scene, this larger range generally results in a higher quality image. The second meaning of “dynamic range” is probably more common in the fire service. It refers to the maximum temperature that the detector can receive before it is saturated. This usage of the term is synonymous with “saturation point.”

MICROBOLOMETER: This is a type of infrared detector. The term refers to the way that the individual pixels on the detector receive thermal energy and then translate it into an electrical current for the software to analyze. Most new thermal imagers are microbolometers, based on detectors made of vanadium oxide or of amorphous silicon. The primary advantage of a microbolometer is that it can be designed to calculate surface temperatures based on the readings its pixels receive. All microbolometers have a shutter, which will “fire” at different intervals to refresh the image. When this happens, the image on the display appears to freeze. The picture freeze is normal on all fire service microbolometers.

BST DETECTORS: The other type of sensor is a ferroelectric detector. These are commonly referred to as BST detectors, since the material on the sensor is barium strontium titanate. Ferroelectric detectors are not inherently better or worse than microbolometers; they merely operate on a different electrical principle. Ferroelectric detectors do not have a shutter, so there is no image freeze. However, these detectors cannot calculate surface temperatures from their pixels. Remember that any surface temperature measurement is subject to inaccuracy based on a number of factors outside the user’s control.

GAIN LEVEL: Just as with a radio, an infrared detector must adjust its gain level to filter out background noise. Current fire service TIs have automatic gain adjustment systems, thus the firefighter does not have to concern himself with adjustments. The gain adjusts based on the amount of thermal energy in any scene. Microbolometers commonly have two gain levels, “normal” or high gain and “EI mode” or low gain. When these TIs switch modes, the shutter will fire, and there will be a momentary freeze of the image. Some TIs display a symbol to indicate that the TI has switched from high gain to low gain mode. Two examples of symbols that indicate low-gain mode are “EI” and “L”.

OPERATIONAL RANGE: Many TI specification sheets will indicate an operational temperature range. This refers to the temperature of the detector, not the scene being scanned or the environmental temperature. If the detector itself has a temperature outside of the range, it loses electrical conductivity and will not produce a proper image. The newest TIs have operational ranges of 0°F to 185°F. Insulation and heat management devices inside the TI help keep the detector in this range during normal operations. Depending on the TI, it could take an hour or more of exposure at an extreme temperature to actually make the detector temperature move outside its operational range.

What camera is really better - handheld or helmet mounted?

Again, it comes down to preference of the fire department. In ideal circumstances, fire equipment companies will let your fire department "borrow" different cameras for your fire department to use and get a feel of before making such a large purchase. This decision comes down to the fire department itself and what is important to them. Is it color? The ability to drop and camera and it be unhurt? The abilty to submerge the camera in water? Is it important for the camera to be "hands free" and mount on your helmet so that you can have both hands to fight the fire? Do you want the camera shaped in such a way as to be able to look under objects without getting on the ground? As you can see, there are many different circumstances that may need to be addressed before a camera is purchased. Only your fire department can decide what camera fits their circumstances best.

Exactly how much does price factor in?

As with any other saleable item in the world, price is a factor. Does your fire department need the most expensive camera on the market today? Only your fire department can determine that. What does factor in to price is, as with anything else, the quality of the imager and the features the imager has. If your fire department is small and the firefighters seldom enter the house, but may stand at a window looking in through the smoke, a temperature reading and heat indicator may not be that important to you. However, if your fire department is constantly performing interior attacks, those very same features are the most important ones on the imager. Again, evaluate your fire department to decide what is really needed before spending too much or too little money.