Firehouse Magazine, October 2004
Company Hazmat Drills
By Jonathan Bastian

Each month, this column provides quick tips that help you and your firefighters learn how to use their thermal imagers more effectively. As we did in June, this month we will review a few potential drills that you can run in and around the firehouse to improve your image interpretation skills. These drills focus on the use of thermal imaging in hazmat.


Drill 1: Hazmat Identification

Obviously, our taxpaying public would not appreciate it if we regularly practiced hazardous materials evolutions with toxic substances. However, you can practice hazmat evaluations in your firehouse with common foodstuffs.


Fill the kitchen sink with warm water, then pour a small amount of cooking oil into the water. This exercise will give firefighters practice with seeing relative surface temperatures, and determining the presence and flow of a material. For firefighters newer to thermal imaging, make the temperature difference significant to decrease the difficulty of identifying the product. For experienced members, especially those assigned to hazmat companies, try to make the water and oil temperatures closer to increase the difficulty of identifying the product.


After everyone has seen how lighter-than-water materials show on the water’s surface, refill the sink and pour milk or juice into it. This gives firefighters the opportunity to see how miscible or heavy materials rapidly disappear from the view of the TI. The effects of water can be reinforced as well by having one member immerse his hand in the sink, while the rest view it on the TI.


Drill 2: Hazmat and Emissivity

To most firefighters, emissivity is a foreign concept. Briefly, emissivity is the notion that all materials absorb heat and release heat at different rates. Think about the last time you baked a dish in the oven and had to cover it for part of the cooking time. Whether it was a glass or metal baking dish, you needed to wear oven mitts to remove it safely. However, you could pull the aluminum foil from the top of the dish with your naked fingertips. The dish and the aluminum foil were both exposed to the same oven temperatures, so they should be the same temperature. However, because aluminum foil does not absorb heat at the same rate as the baking dish, you can touch it without burning yourself.


Emissivity affects how materials appear on your TI. Your thermal imager is programmed to expect a certain emissivity level, with most units set to accurately read temperatures of objects with an emissivity reading similar to concrete or brick. When your TI views an item with an emissivity similar to aluminum foil, it does not know how to calculate its true relative temperature. As a result, certain materials (generally, shiny metals) appear artificially cold on the TI display.


To see the effect of emissivity on a thermal image, partially fill several containers with water. The containers should be made of different materials, such as plastic, glass and aluminum. Ask firefighters to view product levels in the containers by scanning them with the TI. This exercise shows how certain materials may hide heat differences better than other materials.


Next, place cold, warm and hot water in different containers to demonstrate which materials show product levels the best. To keep crewmembers on their toes, occasionally challenge them with an empty container to emphasize that firefighters cannot fool themselves into seeing product levels when none are present.


Drill 3: Hazmat Tracking

Under certain conditions, a TI can help you identify a leaking container or the source of a leak. To help firefighters practice, fill several containers with water and place them in a row. Tip one over to pour some water onto the floor or table, and ask a firefighter to use the TI to identify which container is the source.


You can use different temperatures of water to make the drill easier. Make pinhole leaks in a container to add realism. Perform the drill in low light conditions to force firefighters to rely on the TI more than their eyes, aiding their image interpretation skills.


While your TI will not see leaking gases, it will identify a container that is cooler because it is leaking. If it is easy for you to refill SCBA cylinders, place two or three next to each other. Carefully release about a quarter of the air from one and then ask a firefighter to determine which cylinder was leaking.


Conclusion

You cannot expect to take your thermal imager out once a month and be comfortable with image interpretation. Image interpretation requires regular practice. By regularly practicing with the TI in and around the firehouse, you can improve your image interpretation skills and keep them honed for emergency incidents. Practice also reinforces to your firefighters that the TI is a valuable tool with many uses.


These simple drills, and creative adaptations of them, can give your firefighters additional practice understanding thermal images. For training tips on two common TI options (temperature measurement and video overlay), visit the Technology section of Firehouse.com.



Photo 1: A thermal imager shows the presence of a material floating on the water in the sink. Vegetable oil is excellent for this drill.


Photo 2: Filling different containers with different temperatures of water helps firefighters learn proper image interpretation and how to identify product levels. Note that one container is empty.

Firehouse.com

The October Thermal Imaging Training column in Firehouse Magazine explained several drills that you can perform in your firehouse to help your members better understand their thermal imager, as well as become more proficient at interpreting thermal images. If your thermal imager is equipped with one of two common options, you can use your drill time to reinforce the limitations of these options. The following exercises emphasize safety considerations for your firefighters and help them avoid poor decisions based on image misinterpretation.


Temperature measurement devices (called radiometers or pyrometers) are available on almost every thermal imager currently sold to the fire service. You must understand, and communicate to your company, that radiometers and pyrometers do not estimate air temperatures. They only estimate surface temperatures. For details on how temperature measurement works, read the author’s article on Myths vs. Realty in the Firehouse.com archives ( http://cms.firehouse.com/content/article/article.jsp?id=4741§ionId=10).


While temperature measurement can be accurate when viewing common construction materials, it can be extremely inaccurate when viewing reflective materials, such as metals. To demonstrate why firefighters cannot make critical decisions based on an indicated temperature, fill a shiny aluminum or steel pot with water, place it on the stove and bring it to a boil. Then walk firefighters carefully through the following questions:


This is the easiest way to demonstrate clearly how temperature measurement devices can lead firefighters to make poor decisions. Everyone who uses a thermal imager with temperature measurement must understand that the reading cannot be used to make life-or-death decisions.


Video overlay systems are also an available option and can cause confusion if they are not properly understood. These systems utilize a video camera and mix that image onto a thermal image to create an image that is partially from light and partially from heat. Note that this system does not give special qualities to the thermal imager; it will still not see objects behind glass or under water. If the objects in the scene are all of the same temperature, they will still be difficult to see with the TI.


If you activate the video overlay, the thermal image is reduced (by about 30%) to allow for input of the video image. In dark, stable environments, this can make the TI nearly useless. Take your TI into a windowless area of your firehouse and turn off the lights. Scan first with just the TI and no video overlay. Objects will be difficult to distinguish, but you should still see furniture and structural features. Now activate the video overlay. The TI image should be nearly black. Why? The video overlay sees what your eyes see, light. Therefore, it is laying a black image onto the subtle gray image created by the thermal imager.


Teach your firefighters to recognize the appropriate screen symbol that indicates video overlay is active. Then, if they encounter problems in a particular environment, they can determine if the video overlay is interfering with the thermal imager. Ensure your firefighters understand what the system is actually doing and how it may inhibit or improve their ability to perform.


Temperature measurement and video overlay may make your job easier in certain situations. It is important that you train on the benefits of these options, as well as the limitations. By properly understanding these devices, you will ensure that you do not misapply the technology and that you do not make improper decisions on misinterpreted information.


Use your TI often, wisely and safely.