Fire flow reqmnt for sprinklered building include sprinkler demand?
Fire flow reqmnt for sprinklered building include sprinkler demand?
(OP)
The required fire flow can be reduced up to 75% if the building is sprinklered according to the IFC.
Does the reduced fire flow requirement include water demand for sprinkler system? or just for fire department hose streams only?
If not, what method should I use to get the value to add the the reduced fire flow requirement to perform hydraulic model? Thanks.
Does the reduced fire flow requirement include water demand for sprinkler system? or just for fire department hose streams only?
If not, what method should I use to get the value to add the the reduced fire flow requirement to perform hydraulic model? Thanks.





RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
Fire flow versus sprinkler demand are two completely different design criteria. Fire flow is based on the type of construction and the building area. It was calculated using very empirical formulas that were formulated by the Insurance Service Office in the 1950s. Basically fire flow is an estimation of how much water does one need to control a fire in a building that is not equipped with sprinklers.
Since your question indicated that the IFC is being applied, open your book and turn to page 394 (06 edition). Assume a 50,000 square foot building of Type V-A (combustible with no fire resistance) construction. The prescribed fire flow is 2,750 GPM @ 20 PSIG residual pressure for 2 hours.
Let us assume that the owner equips this same 50,000 square foot building with a NFPA 13 compliant automatic sprinkler system. I will further assume the ceiling height is less than 14 feet and that the owner will not store hazardous materials, flammable or combustible liquids, or other high challenge commodities. The assumed building will house a hair care products retail outlet. Based on this I would most likely classify the building as an Ordinary Hazard Group II occupancy using the requirements in Chapter 5 of NFPA 13.
NFPA 13 states that for an Ordinary Hazard Group II design, a minimum discharge density of 0.19 GPM/square foot over a 1,500 square foot design area is required. This equals a sprinkler demand of 285 GPM.
IFC section B105.2 in the 2006 edition states in the exception that the fire flow can be reduced by 75% but must not be less than 1,500 GPM @ 20 PSI.
So your minimum fire flow will be based on the building area, construction type and if the building is or is not equipped with a NFPA 13 compliant automatic sprinkler system. Regardless, the IFC correctly gives you a great deal of credit if the building is sprinklered. Therefore, if the building is sprinklered, your minimum fire flow is 1,500 GPM @ 20 PSI. If it is not sprinklered the fire flow is 2,750 GPM @ 20 PSI.
Your sprinkler demand question cannot be answered without more information because its design is based on storage height, commodity, roof height and the like. See Chapter 5 of NFPA 13.
I apologize for my first answer. I should have gone to bed rather than provide a more comprehensive response to the question as I have now done.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
FYI. I work for a water district and we get fire flow requirements from fire departments (usually just one number i.e. 2750 gpm at 20 psi for 2 hours). Then, we (use a consultant to) perform a hydraulic model to determine available fire flow to compare with the requirements, and determine what improvements are needed to meet the flow requirements. Now, I am looking for appropriate methods to answer inquiries for flow/pressure information from fire sprinkler designers and wonder if I could use the hydraulic model to answer these questions. After a little research, I found out that the fire flow required by fire department may (not) include a demand for fire sprinkler. Then, I wonder if the hydraulic model we usually run is adequate. However, the difference could be a couple hundred gpm (+/-). And yes I try to add the apples to the zebras to cover all fire flow requirements.
Then, I conclude that the fire flow requirement of 1,500 gpm @ 20 psi in your case (sprinklered) does not include fire sprinkler demand.
Also, I should find an appropriate discharge density (0.19 in your example) and multiply it with the design area (1,500 sq.ft.) to get REASONABLE additional required flow to perform hydraulic analysis (1500 + 285 = 1,785). Note that at the very beginning of the project, we usually do not know a lot of details about the building i.e. proposed tenants, storage height, etc.
Are sprinkler heads still discharging water when the fire deparment arrive and start the hose streams? Frankly, I do not know how they operate.
Again, thank you for the information. It is very helpful and I would appreciate if you could confirm that my understanding is right or have more suggestions.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
1st - Stookey: OH Grp II is 0.20 / 1500 - no big deal. That is per NFPA 13: FIGURE 11.2.3.1.5 Density/Area Curves.
And, as Scott said, you figure the 2 completely independently. Fire Flow is typically a requirement of 1500 @ 20 psi based on IFC tables. This does not, and is not required to include fire sprinkler demand.
The sprinkler demand - in the case of an OH Grp II requirement, would be approximately 300 gpm for sprinklers (0.2 *1500) + 250 gpm hose allowance if hydrants are taken from the supply - as is the case in most installations.
In order to do the fire sprinkler system calculations, the designer is going to want a static pressure in the lines, then a residual pressure at some flow rate. For example, you may have 80 psi static pressure, while dropping to 50 psi when flowing 1500 gpm. That is what the sprinkler guy would want to do his/her calculations.
I hope that makes some sense and adds to your clarification.
Also, yes, sprinkler heads are still discharging when the FD arrives. The sprinklers that have activated due to heat (NOT EVERY SPRINKLER IN THE BUILDING) will be flowing water until the supply is exhausted or the control valve on the system is shut down - essentially exhausting the supply.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
Just remember that fire flow is independant of the sprinkler demand. Generally speaking, fire flow is > sprinkler demand. The exception is something like a flammable liquid warehouse or acetylene charging plant. These can have sprinkler demands on the order of 2,500 to 3,000 GPM. I am also aware of some aircraft repair hangers with hydraulic demands on the order of 5,000 GPM. These are fairly rare.
The example I used (and thanks Travis for correcting me) is probably typical for about 75% of the buildings you may see in your community. The other 25% I would estimate require larger sprinkler demands because of their storage heights. Using a conservative NFPA 13 sprinkler design based on the use of ESFR sprinklers (125 GPM / sprinkler x 12 sprinklers) + 500 gallons for hose streams, I calculated a sprinkler demand of 2,285 GPM.
So Travis, have you found where you are going to shop for your little piece of Texas tranquility?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
Thank you very much!
I think I am confused about the word "hose streams" and how you came up with 2,285 gpm. Is it 1500 gpm fire flow + 0.19x1500 sprinkler demand + 500 hose streams?
Water used to extinguish fire in a sprinklered building consists of:
1. Fire flow, for fire hose streams connected from hydrants around the building?, obtained from IFC table, 2750 gpm reduced to 1500 gpm in the above example.
2. Sprinklers and hose allowance boosting the sprinkler system?, = (discharge density x design area) + hose allowance (250 or 500 gpm).
These two are calculated independently. However, the water district wants to confirm that there will be adequate flow for all demands (items 1 and 2) and I believe that the Fire Marshal would want to ensure that everything is covered for fire fighting.
Do you think what available fire flow Fire Marshal want to see in a Water Avaialbility Certificate? 2285 gpm or 1500 gpm? (The Certificate is required for permits i.e. building, fire, etc.) What do you see typically?
I do not know about your background but if you know of something, please let me know. Thank you.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
The stated value is wrong. I recalculated it and I came up with 2,000 gpm:
[(125 GPM/Sprinkler)(12 sprinklers)]+500 GPM for hose stream demand = 2,000 GPM.
The Fire Department will always want at least 1500 GPM @ 20 PSI. However, in the case presented the sprinkler designer would need at least 2,000 GPM @ 20 PSI.
My experience with fire flow is that it will also be driven by the type of development. For example:
Single or multiple family dwellings: 1,500 GPM max
Light commercial: 1,500 to 2,000 GPM
Industrial park: 2,000 to 3,500 GPM
Again, I apologize for the math error.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
My wife is still surfing around for the DFW area. She is set on that area. I have been trying to get her to look around San Antonio and Austin areas.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
I think you are still trying to add 2 things that are not additive.
If you have the non sprinklered building..say an industrial park, you must have a minimum flow at any hydrant of 2000-3500 gpm at stookey stated above.
If you have the sprinklered building, for example with ESFR heads, you would need around 1750 gpm (12 heads flowing at 1500 gpm + 250 gpm hose allowance [Stookey - it is just my day to cover your back; ESFR only requires 250 gpm hose])
Now, based on my understanding, here is how the scenario works and may help you understand....
Fire occurs in an unsprinklered building. By the time the FD gets there, the fire is raging pretty heavy and the FD will be drawing a lot of water from the municipal supply - say at 3000 gpm to attack the fire. That is where the fire flows come in to play.
Fire occurs in SPRINKLERED building. Let's assume there are ESFR sprinklers to stay with the example above. By the time the FD gets there, the fire is suppresed or contained to a relatively small area (1200 sq ft or less) and the FD only needs to draw a small amount of water (to complete the final knockdown on the fire). The hose allowance that is mentioned above accounts for the relatively small amount of water that the FD will be taking from the supply in addition to the demand from the sprinklers. So, in this case there would be about 1500 gpm flowing from the sprinklers and about 250 gpm for the FD to finish the attack.
The scenarios are 2 completely different situations to try so show how the numbers are really independent of each other.
Hopefully that helps to clear up some of the differences for you.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
Good job. I had those words in my head but you did a better job. I think I was spooked by math errors and you correcting me on NFPA 13 (note to self - read the standard before posting).
You will like the Metroplex. Just gravitate towards Fort Worth. I always liked that side of town.
When you decide to begin the hunt, e-mail me and I will make a trip up from Austin so I can meet you. We can have our own fire protection Pat's Pub in Fort Worth. And buddy I do have a great steak house in Fort Worth. Best in the state...my treat. Heck, I will give you a star just so you can remind me about it next year.
Come home to Texas brother. You will do well here...
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
As stated above, they are all separate entities and the water supply needs to be sized to supply each independently.
1 - Site fire flow requirements: This is often found in the IFC or whatever fire code you fall under. It is typically something like 1500 gpm @ 20 psi at any hydrant on property for a residential complex.
2 - Standpipes: You need to figure out if you have manual or automatic standpipes. If automatic, you need to be able to supply 100 psi @ 250 at the topmost outlet, 250 at the next outlet and 250 for each additional standpipe to a total of 1000 gpm for a sprinklered building. If it is a manual system, then you still need the same flows, but the FD pumper truck will provide the pressure. This will coincide with the site fire flow requirements, but they are not addititve.
3 - Sprinkler system: For a residential system, assuming NFPA 13R, you flow 4 heads at a max of 20 gpm each for a total of 80 gallons. With a 13R system, you then figure a domestic demand to add to the common point of domestic / fire lines. This may be a couple hundred gallons, depending on the domestic fixtures and the loads as illustrated in NFPA 13R. Remember, you only have to figure 1 area in 1 building going off at a given point in time. You do not calculate 4 heads on each floor in each building at one time.
Again, each of these are independent and not additive.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
If you can tell me the construction type and the height and area of the largest building in the complex, I can tell you the required fire flow.
Travis, you sure are racking up some stars...
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
I only care about getting to the Lone Star
Looks like I will be there in Jan for a scouting trip. I will let you know when I get the dates firmed up.
T
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
5-9.1.2* Hydraulic Calculation Procedure.
Hydraulic calculations and pipe sizes for each standpipe shall be based on providing 250 gpm (946 L/min) at the two hydraulically most remote hose connections on the standpipe and at the topmost outlet of each of the other standpipes at the minimum residual pressure required by Section 5-7. Common supply piping shall be calculated and sized to provide the required flow rate for all standpipes connected to such supply piping, with the total not to exceed 1250 gpm (4731 L/min).
I was assuming 250 at the top floor and 250 at the next floor down for a total of 500 gpm flowing through the most remote standpipe.
I don't know if that makes more sense or just makes it more confusing.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
You didn't provide me a construction type. However, your building area and height tells me that the building is sprinklered in accordance with the 2003 IBC, which is the adopted building code in the state of New York. I am going to assume that it is steel construction and the steel has no fire resistance.
Based on my description of the construction, it is assigned as Type 2B construction. Based on the construction type and building area the fire flow is 2,000 GPM using the requirements in Table B105.1 and applying a 75% reduction in fire flow because the building is sprinklered. See 2003 IFC, section B105.2, exception.
Please confirm the type of construction and that the building will be protected throughout by an automatic sprinkler system. If not, you got a much larger problem.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
Required Fire Flow for Type IIa construction with area >166,5001 sq ft is 6000 gpm for a 4 hour duration. Since you have apts, I am assuming an R occupancy. Therefore, you can reduce the flow by 25% to 4500 gpm as indicated by footnote A in the same table.
Per B105.2 exception, you can reduce by 75% where it is a light hazard occupancy and protected throughout by an automatic sprinkler system. Therefore, you have 4500 - 4500*.75 = 1125. The exception also states that the minimum fire flow shall not be less than 1500 gpm.
Per IBC 2003 Table 503, you are allowed 24000 sq ft per floor for type IIa construction. You can increase that an additional 200% for a sprinklered building in accordance with NFPA 13, so you get up to 72k sq ft per floor. I trust the architect has already taken the floor area limitations per building into account.
Good luck. Now that Stookey and I have pointed you in the right direction for all of this, you should really research the IBC and IFC sections quoted and verify the information for yourself. After all, you will be the engineer of record on the project and need to have an understanding of what all of this means. I don't want to sound mean, but I still am not sure you understand the fire flow vs. standpipe vs sprinkler calculations based on one of the responses to Stookey above.
Good luck and have a good weekend.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
The values I quoted on November 14th are estimations. Those values are based on what I have seen over the past 20 some odd years as a fire protection engineer. The values that are binding are those that are published in the adopted fire code. Sorry if I mislead you -- it wasn't my intent.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
This thing called the internet is absolutely unique.
So Travis, when do we meet?
Babe, are you happy with our answers?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
How about Friday, Jan 19. You up for dinner at the place you mentioned in Fort Worth?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
Joe
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
Thats a great thread and it provides a lot of information that amy seem counter intuitive to people like my boss.
If the fire flow and the sprinkler demand are independent, what code from IFC or NFPA can I quote to show my boss the hydrant and sprinkler demands are not additive?
fyi - my project is a newspaper press.
Would really appreciate any help.
Richard in Austin.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
The sprinkler demands will typically include a hose allowance, and will also be at higher pressure requirements than the site fire lines. For example, a sprinkler system may need 300 gpm at 50 psi at the base of the riser, and 550 gpm @ 55 psi at the city tap. The extra 250 gpm is the hose allowance you are required to account for in calculations.
The site fire line demands are required flows at 20 psi. Since most water purveyors don't like the water main pressures to fall below 20 psi, this will insure that the FD has adequate water to go through the FD pumper truck while maintaining the pressure in the city water mains.
I can't think off the top of my head where you will find the quote to show they are not additive, but you will not find a quote that says they aren't. If you check the appendix B in the IFC, it indicates the site fire flow requirements. It does not say that you are also to incorporate the sprinkler demand to these.
I hope Stookey checks in on this. Since he is the resident ICC expert, he can likely give you a better point to look in the I-codes.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
You are in Austin? So am I. Get ready for some rain.
See 2006 IFC section B105.2, exception.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
but that is the reduction in fire flow for sprinklered buildings. I am looking for something in print to tell me the fire flow and sprinkler flow are independent and not concurrent uses. The exception to B105.2 would lead me to believe that in order to reduce the fire flow demands, the sprinklers would have to be sprinkling.
It seems most of the civil site engineers believe the two should be modeled concurrently, but the mechanical engineers I talk to believe the two demands are independent and do not have to be modeled together.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
Your not going to find such a provision in the Fire Code. I believe the closest provision I can send you to is the definition of fire flow in section B102.1. Fire flow is defined as:
The flow rate of a water supply, measured at 20 pounds per square inch (psi) (138 kPa) residual pressure, that is
available for fire fighting.
The important phrase is "fire fighting." This is manual fire suppression operations involving laying of supply hose lines and deploying attack hose lines for interior firefighting operations. Manual fire fighting is generally more demanding to a water supply when compared to sprinkler demand. A standard 1 1/2-inch nozzle and attack line carried on a fire truck discharges a minimum of 150 GPM. Conversely, a sprinkler designed for an Ordinary Hazard Group II density discharges about 20 GPM using a 100 square foot spacing.
Sprinkler demand is completely different in that the discharge density (GPM) is based on the stored hazard within the compartment or design area.
Sorry but the Fire and Building codes don't always provide a clean, intuitive explanation.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
fyi - The sprinkler demand is over 2,200 gpm at 77 psi for the old paper press.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
I just talked to the reviewer for the Fire Department and she said that they do not care what the fire sprinkler demand is, they just want to know their line has enough capacity for their fire engines. I told her they will both be drawing off the same line, but it did not make any difference to her.
Thanks everyone who helped me out on this one.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
That response is uncommon. I find a lot of fire code officials who lack a understanding of the difference between sprinkler demand and fire flow.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
That makes sense when you think about it. Since the fire hydrant is the first fixture on the line coming from the distribution main in the street, the department will be able to draw essentially all the water they need for the pumper truck. Unfortunately, the result is that the sprinkler system will get whatever is left and may fizzle out due to the reduced pressure of 20 psi (possibly less since it is farther down the line and sprinklers are at higher elevation than the hydrant). If afraid that if you want both to work at the same time, you will need to model them both simultaneously.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
You are not considering the efficacy of the automatic sprinkler system. If you review the NFPA data for sprinkler performance, over 90 percent of the fires are controlled by 3 or less sprinklers. Even if you are dealing with a large demand like your printing press issue and you are using large flow sprinklers (let's assume 100 GPM/sprinkler) the Engine company can still supply the system and their attack lines.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
For a printing press this is a huge water demand, what is the sprinkler design? Any flammable liquid used on the press?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
"Fire Sprinkler System: Worst-case design flow demand estimate: 2214.9 gpm @ 77.17 psi (for existing system Zone 1 per hydraulic information placard)"
I do not know of any flammable liquids or rolled paper inventory.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
This sounds like rolled paper storage. The question I have is the rolled paper storage separated from the press? If so, your printing press will have a far smaller demand than the rolled paper storage.
By separated I mean is a 1-hour or 2-hour fire barrier with a fire door separating the printing press from the rolled paper storage?
Atex, something is driving a very large discharge density. A printing press at most is an Extra Hazard Group I density (0.30 GPM over a 2500 square foot design area). You got something else in the building that needs to be examined.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
Did you work for the AFD in 1990? You don't really notice things until you have a reason, but I seem to be noticing Stookey signatures on sets of plans around the office.
RE: Fire flow reqmnt for sprinklered building include sprinkler demand?
Since it is outside your scope you have no obligation. Your responsibility is only to get the H2O to the site.
I think the question is solved. It sounds like the MEP has reviewed and evaluated the hazards and just wants you to deliver the GPM at a given pressure.