Is the Container Half Full or Half Empty?

One of a fire department’s biggest fears is fear of the unknown when responding to a call. When information is relayed over the radio while en route, firefighters and officers are trained to mentally prepare themselves for what they are about to encounter. When firefighters hear they are responding to a warehouse fire that contains 45-gallon drums of fuel oil and a bulk propane tank is adjacent to the warehouse building, the crew is now preparing their attack plan.

Using a thermal imaging camera (TIC) can be an effective tool to give firefighters valuable information to help mitigate circumstances such as the example above. The air space in two propane tanks and 45-gallon drums (photos 1 and 2) gives the crew a better understanding of what they are facing, and they can pull a line faster for exposure protection to prevent a catastrophic event.

Another scenario involves a residential structure with an attached garage. Think about what’s in your garage. Now, think about your next-door neighbor. I’ll bet your neighbor is a handyman who stores lots of hazardous liquids such as gas, oil, propane, and paints in his garage. Photos 3 and 4 show the liquid levels in your typical five-gallon fuel container and a propane tank for use with outside grills.

Consider one more scenario: You respond to a residence and find a closet full of chemicals (photo 5). Even worse would be to find these chemicals sitting open in plain sight, which could turn out to be a clandestine lab. If this scenario happens, your day just got a whole lot worse.

Determining liquid levels in containers takes a bit of practice, and the image interpretation perceived is only as good as the operator of the TIC who fully understands what he is looking at. When you have some time, pull your TIC off the truck and walk around the station and look for liquid levels in containers such as gas cans, propane tanks, buckets of water, or fuel tanks. The exercise is to learn how to interpret what your TIC is showing you. The more experience you have using your TIC in these situations, the more valuable it will be to you and your crew. Having the ability to see the content level of an enclosed container at a safe distance is critical to the safety of the firefighting crew.

Remember, not all containers or vessels will give you a TIC reading level, since they must be single walled or noninsulated. You must know these limitations, or the information will be inconclusive. For example, photo 6 shows liquid levels in the left propane tank but not in the right tank. Photo 7 indicates no levels at all in the 45-gallon drums.

When examining for liquid levels, try to perform a 360-degree search, if possible, to get the best reading. If you can’t get a reading, consider that the container/vessel may be empty or filled to the top. Materials in contact with the surface of a container can conduct heat through the walls of the container at a slower rate than the dead air space above the product. Unless the product was heated prior to being placed in the container, its level will be identified by a darker image (indicating cooler temperature) on the lower part of the container wall. The dead air space or vapor area will usually show as lighter on the TIC screen. If the container is insulated, it will not show the temperature difference.

To determine if a container is full or empty, use the TIC to scan other containers in the area to look for variations in color. The difference in color of the container may be attributed to a difference in material construction. When viewing containers or piping, remember that shiny surfaces can reflect heat from the surrounding area and give erroneous readings of the actual surface temperatures. The firefighter reading the TIC may be seeing a reflection of the heat of something in the background.

Whatever the call is that you are responding to, pull the TIC off the truck and scan the area around you for hidden dangers like containers or vessels. The more you know, the better you will be at determining if the container is half full or half empty!

Manfred Kihn is a 19-year veteran of the fire service, having served as an ambulance officer, emergency services specialist, firefighter, captain, and fire chief. He has been a member of Bullard’s Emergency Responder team since 2005 and is the company’s fire training specialist for thermal imaging technology. He is certified through the Law Enforcement Thermographers’ Association (LETA) as a thermal imaging instructor and is a recipient of the Ontario Medal for Firefighters Bravery. If you have questions about thermal imaging, you can e-mail him at manfred_kihn@bullard.com.