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Rated Fire Flow
Just a little something for you die hard fire hounds out there like myself. How about some equations on how you figure rated fire flow for a structure in your districts or whatever your apart of???
For intance ours is Length X Width
_______________ (Divided)
3
Now for us this gets you a 100% involvement and in the case only a 1/4% is involved we multiple the number of 100% you come up with on the above equation by .25 or so on with how ever much is being eaten and that gives us a pretty close figure of how many lines we need on the ground to supply the wet stuff on the hot stuff, make since?
In layman's terms or whatever terms you use lets say the fire is calling for 800 gpm for fire suppression (You know put the wet stuff on the hot stuff and your useing 2-1/2" hose and 2-1/2" adjustable gallonage nozzles which most nozzles and not all are capable of 250 gpm and not exlude friction loss of lets say we have 200' (foot) down on the ground per connection of 2-1/2" hose, with that being said approximately 10 psi per a 100' of hose of friction loss then we would need how many lines on the ground to handle this fire????
The answeer is approximately Four (4) preconnects of 200' of 2-1/2" hose with a nozzle capable of 250gpm on each preconnect with one heck of a water load feeding that truck....
Now this is just a short version we use and is very quick with that handy-dandy cell phone everyone has in there pocket that has a calculator in the tools part...
Now its your turn to give everyone food for thought and lets learn something new today!!!!!!
Replies to This Discussion
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Permalink Reply by FETC on
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Your thread is about securing the right amount of lines to suppress fire, with your formula.
Unfortunately, most fire departments (on arrival) when command or the first due officer is figuring his required fire flow formula cannot obtain the GPM for 100% involvment, due to lack of manpower, water supply or equipment. Once fully involved, the building is already beyond max BTU's and inreality you are actually catching up to the required GPM in the decay stage with whatever GPM's you can provide.
At the point of "fully involved" in which the entire dwelling is all on fire, most fire departments can't supply the required GPM without "interuption" at any stage of the fire (meaning, on arrival, 10 mins or an hour later).
Therefore, it is a born loser, and in my opinion pre-planning on correct fire flows for 25% or 50% involvement is more realistic and far more progressive.
All fires go out eventually, some quicker than others...
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Permalink Reply by CHIEF NORMAN on
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Your correct FETC my thread is about securing the right amount of lines to suppress a fire, but with you last comment you changed gears on me and talked about pre planning, which in that case means prior to correct? In any pre fire plans most should plan for the worst and hope for the best, correct. With that being said 100% is a fires highest point with the calculation as I have provided just like I have said it will give you a 100% involvement but in conjunction it will be a starting point to figure your 25% which in that case would be the multiplication of .25 or the 50% would be the multiplication of .50 and so on...But don’t forget in the case you have a structure within thirty feet of your fire scene the rated fire flow go's up. I'm not attacking your creditability but maybe we should give more credit where credit is due in the fact that most fire depts. should figure 100% involvement if they do pre fire plans or have automatic aid which in most cases its within its own entity or outside support upon that first call, with that being said the amount of manpower, water supply and equipment is there or on its way within what you have giving me a 10min or hour window. Preparation is the key and if you’re prepared ahead of time nothing can catch you by surprise.
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Chief, no disrespect but you missed my point and are playing wth words. This thread is pretty much pre-planning because we are looking at formulas for potential future fires.
Now that being said, I give more credit to departments that identify there limitations instead of false sense of security. In my area (fairly rural) most departments cannot provide the required GPM for a fully involved dwelling within 10 minutes, seeing most FD's haven't arrived on scene yet. Now your district may be totally different and can provide 800 or 1000 gpm uninterrupted due to municipal water supply but I also know others that still can't provide the fire flow within an hour because of manpower, district size, apparatus and water supply limitations (tanker shuttle).
So if you do not have interruption of fire growth in the incipient stage, at that point (duration of time) with the new higher producing fuels, around here many departments are seeing larger losses and when full operations are in effect, they are in fact catching the fire with suppression on the decay side of the thermal curve.
Your last sentence is a tough blanket statement, Preparation is the key and if you’re prepared ahead of time nothing can catch you by surprise. Even auto or mutual aid is not a guarantee around here.
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FETC your wrong sir this formula can be used prior to or during or even on your way to that scene just by what is giving to you by your dispatch...FETC I can say this brother even in your area your still not giving yourself credit...The potential is there it all falls back to who is running the show and how it is being run...In the event you have these higher BTU's on structures and you have done your homework and no matter what you have done to affix the problem it is still a problem...Now we are getting off track here from the discussion but what your telling me is you have a large % of homes. business and so on that if the fire is between 25 to 50% margin you can fight it but if it gets above that 50% there is nothing you can do, and so they just burn due to the fact you don’t have the resources available to you???? Well to me the solution would be fix it!!! Like the old saying go's if there is a will there is a way....If it calls for more sub stations, apparatus, manpower then that is your goal and that is what you should work toward. There is nothing out there that stands in your way to make this happen other then work...If the fires your attending is already on the decaying side every time then you should find that to be unacceptable and its up to you to make a change or get it changed. Remember what we stand for and that is life first, then property...And just like I said preparation is the key and if your prepared ahead of time nothing can catch you by surprise.
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Chief, your clearly living in a perfect world. The area has many 3000-4000 sq ft new McMansions that are kiln dried upright lumber yards. I have seen many volunteer fire departments with 6, 8, 10 members total, try to protect these with 2 man cab pumpers, with maybe 4-6 SCBA certified personnel, and they all use auto or mutual aid but by the time those volunteer departments turn out and arrive on scene it can be 30+ minutes. You can have a modern 1500 or 2500 gallon pumper-tanker on scene fairly quickly but if you can't supplement it, (without interruption) then your formula is out the window, after 120 seconds of unleashing the proper GPM you stand there and watch it (decay). It is called you get what you pay for, and your homeowners insurance policy better be paid.
Yes more manpower, more substations, more equipment is all needed, very much desired, and requested every year at town meetings by rural departments but the all mighty dollar is the critical factor.
Our state fire marshall is leading the push for residential sprinklers... not more substations or manpower.
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Well I clearly understand your situation and if these are vol. depts. then maybe someone should put a vote to the people to become a fire protection district that works off of property tax. With the size of dwellings I could only imagine if they can afford to build that type of structure they might be able to support the departments providing fire protection that has a chain reaction of lowering there insurance...To me that’s a win win situation for everyone and you’re able to meet those demands. I'm not saying sprinkled buildings is a bad thing by no means but in reality it doesn’t help you as a department with the buildings that are already there that will be grandfathered in if a law is passed.
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Sorry but once again speaking without all the facts. Our entire state funds "everything" off local property taxes. Some of the communities that I mentioned have homeowners who pay $10,000-20,000 a year in property taxes. The tax bill is more than the mortgage premium. 30 dollars per every $1,000 of your property assessment. But everything like the roads, water, sewer, cops, fire, ems, municipal workers, libraries, school buildings and teachers are funded off the property tax.
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Well FETC I only wish you the best brother and good luck on your journey to being the best you can be!!!
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Permalink Reply by Ben Waller on
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Installing commercial and residential sprinklers will help the community in the long run, as it will reduce the number of fires where max fire flow is required.
Manpower and the ability to purchase fire apparatus come and go with flluctuations in the economy. Sprinkler systems don't cost the community anything once they are installed, and they last for a very long time, indeed.
Grandfathered buildings are a problem, but it is possible to legislate a retrofit clause in the local sprinkler law.
Using "it won't completely solve the problem" as an excuse to avoid tackling the issue at all isn't a good answer. If you never start working on the problem, you will never make any impact on solving the problem.
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Permalink Reply by Paul Shapiro on
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With all due respect, I don't think this is a practical tool for the fireground. Hit the fire hard and fast with everything you have based on some good common fireground sense.
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Permalink Reply by Norm Tindell on
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I am very interested in what all these chief officers have to say. These guys have plenty of experience. And the formulas and theories they speak of are based on the experience of many who have gone before us. We must seriously consider their experience or as somebody once said, "If we do not learn from the mistakes of history, we are doomed to repeat them."
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Permalink Reply by dan on
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Absolutely great conversation here, let me say I understand both sides as I have been a vollie and a career FF and Chief Officer. The formulas are simply a way to assess the possibilities or the needs of your community. As the fire professional you can use these formulas in two different ways, 1. To plan and prepare for future dept purchases, larger hose, larger pumps, larger tankers, etc based on having or not having hydrants, ponds, rivers lakes swimming pools etc to draft and set up shuttles, yes the houses burn faster and hotter but you are usually notified much sooner than in the old days before cell phones and pagers. Even wit that you are behind the ball without a plan. Use the formulas for planning what you need and sell that idea to your city council with a long tern plan. Go together with your neighboring dept and dont duplicate equipt use each other, train together.
2. Use the formula to know you are out gunned and stay out in a defensive mode and dont risk a FF life if you know you are out gunned. Cover the exposures, flying brands, and critique the fire sitiuation with the city council after each big fire at your monthly meetings, and let them hlep you make that long term plan a reality. I know its easier said than done, but if not you.......who?
With respect to all.
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