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The moment of truth has arrived. You are kneeling outside the attack entrance. Boiling, black and gray smoke pushes from the top of the door. Your hoseline stretch is complete; you and your partner are donning the rest of your personal protective equipment (PPE). It’s time to push in and extinguish the fire.
For those called to be firefighters, there is no greater job than having the nozzle at a fire. There is no greater praise than the words “nice job” after extinguishing a fire. But don’t forget what got you to this moment – preparation and training, conducting a good size-up and stretch estimate, knowing your job and making an efficient stretch.
The basics of suppression
Before we get into the particulars of how to make our advance, we must make sure we have a thorough understanding of the tools, techniques and theory of how to safely and efficiently extinguish a fire. We are taught in basic training that water extinguishes fire by absorbing heat, but in order to be effective, water must be applied at a rate faster than the rate of heat being generated. The goal is to cool the involved combustibles, dropping them below the temperature at which they produce ignitable vapors and heat to support the fire’s growth. According to the National Fire Protection Association (NFPA), the application rate and type of stream are the key factors that ultimately determine the speed of extinguishment.
• Application rate – When we talk about application rate, we are talking about how many gallons of water a particular size hoseline and nozzle combination can flow per minute (gpm). NFPA 1710, Standard for the Organization and Deployment of Fire Suppression Operations, Emergency Medical Operations, and Special Operations to the Public by Career Fire Departments, 2010 edition, establishes a flow rate of 300 gpm from the first two handlines, each of which should flow a minimum of 100 gpm. Other research and testing has established a minimum of 150 to 180 gpm from any single hoseline as the flow rate for fire attack in today’s modern fire environment. Simply put, as the heat-release rate of modern combustibles increases, so must the application rate of water to extinguish the fire.
• Type of stream – When selecting the appropriate nozzle and stream, firefighters must understand the differences between them. The purpose of this article is not to recommend a particular type of stream or nozzle, but rather to make sure you are well-versed about the nozzles carried on your engines. Are you aware of their flow range, stream type and pattern capabilities? Do you realize that all nozzles are not created equal and that each possesses characteristics that will affect your extinguishment effort?
Nozzles & streams
A combination fog nozzle produces a broken water stream. The stream is broken apart as it makes contact with the baffle, or disc, inside the nozzle creating small fine water droplets as it leaves the nozzle. The water droplets have more exposed surface area to allow for maximum heat absorption. It is capable of providing a wide to narrow fog stream and a compact straight stream as well.
The stream produced by a smooth-bore nozzle is a continuous bore of water that flows unimpeded through the control handle, or “bale,” and out the tip. It creates large, coarse water droplets when deflected off of a solid surface such as a wall, ceiling or floor. The water passing through the nozzle moves at a higher velocity, allowing for maximum reach and thermal penetration.
Combination fog nozzles come in different types and configurations – do you know what type is carried on your engine? Do you understand its basic design and are you aware of all of its moving parts and what they do? How do you shut the flow on and off? Which way do you turn the bezel to go from fog to straight stream? How do you adjust the gpm setting? Does one part perform multiple operations? You must know this information well before the advance!