Thread: rate of flow formulas
01-27-2001, 06:17 PM #1Larry WelleFirehouse.com Guest
rate of flow formulas
young firefighter welle would like to know the name of the flow rate calculation length times width divided by 3.
example: 10 foot x 10 = 100 divided by 3 =
Iowa State Calculation is length x width x height divided by 100. Flow rate equals 10 gpm for same problem as above
01-27-2001, 08:44 PM #2Company40Firehouse.com Guest
I believe it is called the NFA method (National Fire Academy). It is length x width x # of floors all divided by 3 for a structure that is fully involved. Factor in 25% of the flow for each exposure. I hope this helps.
02-19-2001, 06:23 PM #3Larry WelleFirehouse.com Guest
02-19-2001, 09:06 PM #4John_FordFirehouse.com Guest
Plus multiply by the number of floors. Had a serious argument if you count the basement. I say you do as it has stuff that burns too.
02-20-2001, 11:45 AM #5BIG PAULIEFirehouse.com Guest
I have a question. Can this formula be applied on the fireground or is it just good for preplanning and training?
02-20-2001, 12:39 PM #6LHS*Firehouse.com Guest
2500 square foot home
200 gpm 833 gpm
One is based upon over one hundred actual tests and the other on the opinions of students.
02-20-2001, 06:06 PM #7CorvinFirehouse.com Guest
The NFA theory is more oriented to knowing quickly how much water you need to have available to you to handle a structure fire. ie, you arrive at the mentioned 2500 square foot house, (well involved) and you are able to quickly determine that 800+ gpm of water supply will be needed.
Iowa State University's Royer formula would have you take the cubic feet of the largest room (for preplanning)or the involved space, divide by 100 and apply that flow for 30 seconds to achieve a knockdown. This formula is more apt to be accurate with a tightly confined fire and achieving a steam conversion.
Having used both formula's before and having taught them both, I refer to NFA formula as fireground guideline for water supply and the Royer formula as more of a laboraty answer.
Both are great learning tools and discussion items.
02-20-2001, 06:46 PM #8Larry WelleFirehouse.com Guest
Big Paulie you are my hero. I know who you are and you know the answer to this question!
Yes, you have to have a clue before you go--
training is the ultimate. Preplan and preplan again.
Your greatest fan,
02-20-2001, 08:02 PM #9LHS*Firehouse.com Guest
100 x 200 foot building
iowa nfa iso-What all the model codes use
and sprinkler industry uses
2000 6666 2545
No doubt NFA formula is bogus
02-20-2001, 09:48 PM #10BIG PAULIEFirehouse.com Guest
Thanx for the nice words Larry. I think the formulas are great. Ilike the NFA the best however I think both can be hard to use under a stressfull situation such as a fire. What if the structure involved can't be seen completely by the first due company because of heavy smoke and fire conditions? I like to use a more simple formula. It's called hitting the fire with everything you've got. Know your capabilities and know how to read fire. What are the maximum flows from you nozzles both small and big handlines? What are your master streams capable of? What are your water supply evolutions capable of delivering? Training for these type of operations with first in companies will really pay off when you get one. And guess what . If you hit the fire with more water then the formulas require the only thing that will happen is that the fire will go out faster.
02-21-2001, 06:57 PM #11Larry WelleFirehouse.com Guest
OK..one more question......
Is there any rate of flow formulas for CAF
systems? Like 30 GPM of solution and 30 CFM is equal to ...... lets say 350 GPM of water?
Some advocates say it is 10 to 1 better than just plain water. Thinking of going with CAF system when we replace our attack piece.
02-24-2001, 12:42 PM #12Larry WelleFirehouse.com Guest
02-25-2001, 08:56 AM #13S. CookFirehouse.com Guest
Larry, LHS may be able to answer your question, email him at firstname.lastname@example.org He travels a lot so it might be a few days.
Also, check out the Apparatus Innovation
Forum, there's a thread going about CAFS titled Questions About CAFS.
[This message has been edited by S. Cook (edited 02-25-2001).]
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