Question: My name is Garrett and I am the captain at a volunteer fire department. Our membership is mostly older guys. We have smooth-bore nozzels on some of our pre-connects and fog nozzels on the others. Most of the guys believe that fog nozzels are better and are more effective than smooth bores. I have shown all types of written materials that have proven differently, but most still do not believe me. I understand that both nozzels have their place, but others don't. Any recomendations to help prove my point?
Answer: Brother, To extinguish fire you must understand fire. Nothing other than charcoal burns in and of itself. Gas is given off by anything that will burn when it reaches its ignition temperature. It is that gas that burns. So . . . extinguishment means that you must cool the product (not the flames) to below its ability to give off the gas (fuel). In the fire service, we do that with water because it is plentiful and cheap.
Enough of the tooooo basic stuff.
An effective hose stream (according to age-old hydraulics and fluid mechanics) is one that will deliver 85 percent of its volume in a 15-inch circle at the point of the flaming fuel source. Water evaporates at a rate dependent on the surface of the water shape exposed. Automatic nozzles are self-inpinging and makes small water droplets tremendous surface area when compared to the ¾- to 1-micron size of the eliptical ideal drop in the stream. In short, much more volume converts to steam before it has a chance to get to the fuel source. If protection of the advance of firefighters is more important than "making" the seat of the fire and starting water, then automatic nozzles have that advantage. Just an opinion. Remember straight stream IS NOT solid stream!
Write me at my email address, and let me know what you think further on this subject.
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Write if you agree or dont agree or on anything. Tbrennan@firenuggets.com