HEN Demonstration Burn - Large area fire

[@Rescue-mt7fl]

It’s still a broken stream. Water droplets entrain air. Moving the nozzle increases the entrainment. It’s still an attempt to create a better fog nozzle. The NIST UL studies pretty much spell out the science.

[@dennislegear8690]

Your missing the geometry, think ice pick, vs clever, vs sledge hammer with a watermelon. Solid Jet, Blade, Fog Cone. The air entrainment is no where close to a fog cone. The surface capture and fuel pick up plus gas interaction and the proper amount of air entrainment make the Bladed fire stream truly out perform at may critical levels in suppression. I was involved directly in the Air Entrainment Studies that UL did. It is a "attempt" to make a better fire nozzle, both smooth bore tip and fog tip. I believe they have succeeded based on the testing I have seen and also been involved with.

[@Rescue-mt7fl]

@@dennislegear8690 I appreciate your thoughts and perspective. I’ve worked with the hen and several other nozzles. Of course we all have differences of opinion. My experience with the hen is that it’s still utilizing a modified fog. We weren’t able to get the penetration to the base of a well seated fire on its fog or blade mode and while it didn’t entrain as much air as a conventional fog it still entrained air. We considered where we would utilize a fog in a fire. For structural firefighting, our department has a large volume of vacants, we wanted reach and penetration and really a fog isn’t used by us until wet down at the end of overhaul or for hydraulic vent in the immediate work area. As you noted, while it doesn’t entrain as much air as a conventional fog it can still move air, it didn’t however move as much as we wanted for vent. We got an appreciable difference by spinning the nozzle clockwise in the window, while on fog, much as you can do with a solid bore gated to half bale. Next we considered use on things like gas leaks or fuel tank ruptures on car fires. The fog works well to push those burning fuels or displace gases like propane. The hen was virtually useless for us in those applications. We still wanted to solid bore performance and some ability to fog. For our department the hen wasn’t it, we went with the TFT vortex with 15/16 solid bore tips and a 1/2 overhaul tip the officer can pull out of their pocket and put into use. The hen was interesting, just didn’t perform for us in the ways we work.

[@Rescue-mt7fl]

@@dennislegear8690 I will beg to disagree. While it entrains less air than a conventional fog, in the times I’ve had to see a hen in play, it still will entrain air on a broken stream. You stated right balance. I would counter with saying that there is no right balance of air entrainment in a super heated fuel load. During fire attack, the goal is to utilize adequate reach and velocity to extinguish the fire from as safe a location as possible. A solid bore or straight stream will penetrate a long hall way, while allowing solid lintel and frame hits to redirect streams into compartments. On the bladed broken stream you see far less reach and ability on the bladed hen stream than your solid stream fire attack. This places yourself at far greater risk while reducing your ability to use your reach and volume.