OK here we go. This debate is as passionate as the smooth bore Vs fog nozzle debate. I am going to take a stab at it. I believe that there are situations that allow for a low friction loss 1-3/4" or 2" handline to be used in a highrise fire. And you say?
Raising the temperature of one gallon water from 62o F to 212o F requires 1,250 btus. In
other words, that amount of heat is absorbed (1,250 btus) by raising the temperature of
that gallon to 212o F. When one gallon of liquid water is vaporized at 212o F, this change
of state requires 8,080 btus. This number is more than six times greater than the number
of btus absorbed by simply heating the liquid water to 212o F.
The most creative contribution of Royer and Nelson is the discovery of the Iowa Rate-of-Flow
Formula. This formula is based upon two scientific facts: (1) One gallon of water expands to 200 cubic feet of steam.
(2) One gallon of water absorbs all the heat produced by the oxygen in 200 cubic feet of air.
It isquite remarkable that both facts validate the same number, 200.
The Iowa rate-of-flow formula, generalized
with time as a variable is:
NFF x t = Vol
where NFF = Needed Fire Flow in gpm, t = time in minutes or fraction of a minute, Vol = volume in cubic
feet, and 200 is the Iowa constant.
Let’s do one simple calculation of the right amount of water. Let’s Take an average size room, say 2,000 cubic feet. To distribute the little drops of water, let’s take the minimum time of 10 seconds, or 1/6 of a minute. Substituting these numbers into the formula gives
NFF x 1/6 = 2,000/200
The fraction 2,000/200 = 10 gallons—the right amount of water. So multiplying both sides of the equation by 6 produces the answer.
NeededFireFlow = 60 gpm
Only 10 gallons of water is needed for fire control, and a flow of 60 gpm brings fire control in 10 seconds.
The constant “200” is based solidly on two scientific facts.
1. One gallon of water at 212oF expands instantly to 227 cubic feet of
steam. This number is rounded down to “200” to allow for a 90% rate
of conversion to steam.
2. One gallon of water with a margin of safety absorbs all the heat
produced by the oxygen in 200 cubic feet of normal air.
ARE FOG NOZZLES NOT THE ANSWER?
By John D. Wiseman, Jr.
Strategy and Tactics for Fog Nozzles
By John D. Wiseman
Here we go with "the book" again. You know, "the book" states that according to the laws of aerodynamics, it is impossible for the bumble bee to fly. The bumble bee either, never studied law, can't read, or simply doesn't give a damn and flies anyway. Raising the temperature of that one gallon is more efficiently accomplished by breaking that gallon of water in to as small a particles as possible. Nailing the wall or ceiling with your choice of smooth-bore solid stream will not accomplish this task. Your most likely result is going to be opening up said wall or ceiling and allowing what steam you have managed to generate to escape. This brings us back to the reputed "fog" nozzle.
Knowing already that "fog" is actually an act of nature cooling the inherent humidity in the air to the point at which it becomes visible droplets seemingly suspended in front of you, and blocking your ability to see farther ahead, the term "fog nozzle" is a misnomer. What we commonly call a "fog" nozzle, does however break that solid stream into much smaller particles, creating more surface area with which to absorb heat, and accomplishing the task of creating large volumes of steam more rapidly and efficiently. I've fought a hell of a lot fire back in the day, and actually put it out, using the old "fog" nozzles of varying sizes.
Now I do have to admit to not having any experience at all with solid stream nozzles when attacking a fire, nor have I ever stretched many feet of large diameter hose up several flights of stairs to do battle with the beast at high altitudes. I do however concur with the above post by Jack/dt, in that the physics and formulae presented appear correct. Me thinks that the fire service of today has become much too reliant on technology and less utilitarian of tried and proven methods of killing the beast we all know and love.
Perhaps a more efficient and productive method is in the offing though and we're just not using it? Owing to the fact that American business has found it vastly superior to employ the techniques of the Japanese via Six Sigma, 5S, and Kaizen workouts, all we need to do is bring those folks over here and let them teach us how to make the fire so impotent at destroying anything, burning buildings will simply cease to exist, much like the ability of American business to produce anything. Said fire will be so tied up in meetings and politically correct BS, it will have neither the time nor desire to go about the business of burning and kicking our sorry asses all over town. We then outsource all our fires to cheaper and more cost effective areas of the planet, thereby eliminating the need for a fire dept. and its expensive staffing and equipment. Problem solved. See how easy that was?
Seriously, there is much debate as to whether solid stream or diffused stream is best in any given situation. I've personally shoved an inch and a half into an open window with flame shooting out of it, whipped that sucker around in a rapid circular motion for approx. 15 seconds, and viola! Fire out. Amazing what can be done "IF" you know how to use the tool that's in your hand. I've also been in those situations where it was a lost cause by the time we got the first alarm on it and we were doing the old "surround and drown" technique of waiting for the fire to run out of shit to burn while we appeared to be putting it out over a long period of time and with much expenditure of water and manpower. It's really amazing that any of us "old school" firefighters survived at all.
Bottom line is fires will continue to burn and do their very best to outfox and outlast anything and everything we throw at them. Rather than argue over which nozzle or hose size should be used on what fire, get the training and tactics down to get the job done. Not all departments are the same. No two fires are the same. Not everyone has multiple high rises with infinite occupancy types. It's for damn sure not every responding engine company has all the seats on the rig filled with a warm body rolling out on every call. Like was said by another poster, "by the time you get all that large line stretched, you WILL need it." Hit it quick, hit it hard, with what you have to work with. If that isn't enough, then call for help and hope like hell it arrives before you find yourself in the "surround and drown" mode, which as we all know, makes for really great lead stories on the evening news.
we have the "high-Rise Nozzle" (Coward Stick; or Floor Below Nozzle) which works very well. Ive only trained on it and haven't actually seen it in action at a job but if you have blowtorch conditions it would work great.
Jeff, I stand by the theory of smaller lines, well used. In my experience, an 1 1/2" or 1 3/4" provides all the water you need for an apartment or two or a fire that has not yet vented itself. Once a fire vents and has figured out a way to breathe, it does get more exciting, but you need a massive blaze to get beyond what a smaller handline can manage.
The downside of the larger lines is they are very difficult to manoeuvre. Let's assume you are getting all the water you want - the 2 1/2" weighs a ton and if it's at all overpressured can be so stiff you can barely move it in a confined space. On a 4 man engine, you have 3 guys attacking - an officer, nozzelman and back up, who needs to be very close to support the nozzle on a 2 1/2". This means either the officer moves back a length to hump hose, or assists with the nozzle and can't do officer things. Neither are appealing. If you think it's a big-un, but can still be attacked from inside, drag the 2" and go nuts, but chances are you can use the 1 3/4 to very good effect if you use it correctly (attacking from upwind, venting correctly, etc). 2" is a good compromise, it gives more flow, but one guy can manage the nozzle, and the other can hump hose. If you don't have the assets to manoeuvre and advance the line once it's charged, you are going to have problems. There have been LODDs from crews that could not move the 2 1/2" once it was charged.
For arguments sake.. the Officer SHOULD be right behind the nozzle man. "Assuming" a four-person Engine crew, which may or may not be acurate, the Officer should have his/her shoulder on the nozzleman's back. Though we could argue engine tactics for ever. There have been some excellent examples at FDIC and other such training programs on the how's, do's and don't's of advancing hose-lines, especially 2.5" hose.
There are several factors that come into play. But if the fire is down the hallway of an open corridor with apartments off both sides, and perhaps either the fire got through the door, the door was left open...whatever, once it gets into the hallway, and self-vents out the apartment window...now you may have fire blowing through the apartment, right into the hallway, your smaller line isn't going to do much at all, I don't care how well of a marksman you are with the nozzle. THAT has been proven over and over. Three on a line can advance down the hall, working the line, absorbing the heat and containing the fire. Make it to the apartment, a slight turn, work the nozzle around, you got a shot at knock-down.
The weight, flow, and nozzle reactions have been explained regarding 2" and 2.5". With less-than-optimal staff, I'm going to go with the 2', which I KNOW can be stretched, and advanced just as easily as a 1.75", yet will flow the same as a 2.5". Of course the difference is in pressure. I don't have anything beyond 12 stories here, so it's not an issue. However as I said, I have reports from Chicago in which the combination of 2.5" at the discharge (100') and 100' "working line" of 2" solved that problem.
We all know that famous line "how goes the first line, so goes the fire". Given the time it takes to access a fire floor 5, 6,...10 floors above the ground floor and get a line in service off a stand-pipe, there is absolutely no reason to gamble on a small line maybe controling a fire, considering the time for the second line is going to be at least that long. 1.75" hose was never meant to replace "the big line'. It was just a reaction to the beginning of the increased fire loads using synthetic materials as furnishings, combination nozzle popularity, and the first wave of staffing cuts that occurred right after the decline of the 'war years" in the late 70's to early 80's.
Yet everyone invested in the 1/4" difference, yet failed to adjust for the actual hydraulic differences. Most ended up spending lots of cash to achieve the same flows they were getting with inch and a half. You can witness the misuse of 1.75' hose almost daily on fire videos in which it's the first line pulled for everything including exposure attack and heavy fire involvement of commercial property...becouse it's 'easy" to stretch and use! Yet the lack of a rapid knock-down shows how ineffective it CAN be.
One person can stretch a 2.5" line and handle it for knock-down of heavy fire. It's been proven time and again. (FDIC, etc.) But for high-rise use, you MAY be able to get a knock-down with a smaller line, absolutely. But WHY take that chance? When fire load dictates 200-plus gpm for control, you can be the best nozzle-wrangler there is, but your 175 gpm is just gonna be devoured. It's simple science.
It is a proven fact that it takes GPM's to combat BTU's. It is also a proven fact that the primary reason why most departments choose smaller diameter lines for their high rise operations is simply because stretching a larger diameter line is labor intensive and manpower dependent. Another proven fact is that smaller diameter lines( 1 3/4" or 1 1/2") do not provide the necessary GPM to effectively and efficiently combat friction loss due to elevation, appliances, plumbing, etc...in regards to high rise operations. The NFPA recommends at least 2" diameter line with smoothbore tips. This is for any one of many reasons. In my area, we have alot of low income high rise apartment buildings. We have found everything from bags of weed to baby diapers in the standpipes. Smoothbore nozzles can clear obstructions far more effectively than a fog nozzle. Also,if for whatever reason the Eng Co stretches short from the standpipe, the smoothbore nozzle can be used as a gate valve to connect more hose instead of shutting down the standpipe, removing the fog nozzle, connecting more hose, reconnecting the fog nozzle, etc...Also, with pressure reducing valves, we need less pressure from the Eng Co assigned to the FDC to operate smoothbore nozzles vs. fog nozzles. Look, I know stretching a larger line is tough, but so are we. What it all comes down to is simple: 1 Meridia Plaza, Philadelphia, PA. Anyone who prefers smaller lines with fancy fog nozzles for high rise operations, look it up and then let's talk.
Well said Brother. There are some other excellent examples out there. But it just falls on deaf ears...so let 'em use what they want, I wish them all the best. Burns suck. You have ONE chance. The idea of a firefight is to bring a weapon that is capable of killing the fire DEAD...not engage in an all fight.
You can fight alot of fire with a booster line! That's what I was told back in the 60's. Yet they routenely pulled and used 2.5" for dwelling fires. Now you are hard-pressed to find companies that lead-off with big line.