This video is not a scientific test with identical scenarios. It is just a visual demonstration of two methods in similar scenarios. And in this particular case, both methods work well at protecting the firefighters from flames rolling above their heads.

The fog stream is very good at absorbing energy close to the firefighter, in this case in the zone just in front of the doorway. And it does not require a surface for doing this. The small droplets that evaporate in the flames have a high efficiency and may prevent water on the floor. This efficiency is very important if water resources are low or if you need to minimize water damages. Some droplets will also travel through the smoke and cool and wet the surfaces in the ceiling. If very short bursts of water are used (like in this video), there is little air being moved by the stream and the turbulence created is small. But if water applications are longer than those in this video, much air will be pushed into the next compartment. That air will come back with heat, if there is no outlet in that room. The method is therefore limited in its ability to cool flames/smoke far ahead of the firefighter. You cannot throw droplets very far, and pushing large amounts of air in front of you is often problematic.

The straight stream passes straight through the flames, providing little or no cooling when doing so. The stream instead hits the ceiling and other surfaces on the other side and the water flows over those surfaces. The cold and wet surfaces created, and the droplets created when splashing into different surfaces, cools the flames down. This cooling is less efficient compared to the fog and will cause more water on the floor. But in doing so the straight stream pushes less air in front of the firefighter (if the movement of the stream is fairly slow) thus allowing cooling into compartments ahead of the firefighter, without pressurizing it. The straight stream is therefore able to cool flames/smoke further ahead of the firefighter. Both by its abillity to create cooling further ahead, but also by allowing to flow water through doorways into other compartments. But the straight stream depends on surfaces to be able to cool the flames/smoke. Surfaces to wet down and surfaces that may help to break the stream up into droplets. If the ceiling is burned through, or if the ceiling has a sloped angle, or if the ceiling has a false ceiling (the droplets created cools the false space above, not the room the firefighter is in), or if the ceiling is very high. It is then hard or impossible to get effective cooling close to the firefighter, where the heat/flames may be.

These are by no means my full thoughts on this topic. And this is also a simplification of the two methods as they blend into each other, for instance a straight stream mimics a fog if moved very fast. This text might just turn out to be a slightly insane mans ramblings. But right now I believe both methods have important advantages and disadvantages. And a true professional masters both. Although most firefighters are not true professionals, and there lies the biggest problem of them all.

PS: Join my online fire behavior and fire suppression course after summer! :-)
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