Fire flow reqmnt for sprinklered building include sprinkler demand? 6

[NTTT]

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.

 

[thebabe]

stookeyfpen nov. 14, you indicated that the max fireflow demand for a multi family res. development is almost always 1500 GPM,but you indicate a max flow of 2000 for a building of Type 2B const. that is sprinklered. so, what is added? in the end, i just want to know what the max. TOTAL fireflow required from the water distribution system would be for this project. THANKS AGAIN.

 

[TravisMack]

IFC 2003 Table B105.1
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.

 

[stookeyfpe]

How these values were developed is interesting. First, their are a number of methods for calculating fire flow. This includes the National Fire Academy method, the Iowa State Method and the ISO method. ISO (Insurance Services Office) method is the basis for the table in International Fire Code.

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.

 

[thebabe]

travismack&stookeyfpe: we use the new york state code which is,of course,based on the IBC. don't yet have the IFC, but will certainly get it. have been doing research as you suggest and have a better handle on it at this time. my thanks to boyh of you for your input. it was helpful and appreciated. wish you a great holiday season.

 

[stookeyfpe]

So, Travis has impressed us as the great poobah of sprinkler design and a damn good explainer of fire flow. I, a old, whiteheaded AHJ will sit back and hope my pal Travis finds himself a place called Texas.

This thing called the internet is absolutely unique.

So Travis, when do we meet?

Babe, are you happy with our answers?

 

[TravisMack]

Stookey:

How about Friday, Jan 19. You up for dinner at the place you mentioned in Fort Worth?

 

[JoeWill123]

Is there a room size limitation to NOT have a fire suppression sprinkler? like under 200 sq ft?

Joe

 

[atxeng]

All,

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.

 

[TravisMack]

Richard,

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.

 

[stookeyfpe]

Atexeng:

You are in Austin? So am I. Get ready for some rain.

See 2006 IFC section B105.2, exception.

 

[atxeng]

Thanks stookey,

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.

 

[stookeyfpe]

Atxeng

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.

 

[atxeng]

Thanks Stookey,

fyi - The sprinkler demand is over 2,200 gpm at 77 psi for the old paper press.

 

[atxeng]

Not that it matters to anyone else but me, but anyway....

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.

 

[cdafd]

any rolled paper storage??? if so how many sq feet

 

[stookeyfpe]

Atexeng

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.

 

[cvg]

"... they do not care what the fire sprinkler demand is, they just want to know their line has enough capacity for their fire engines...".

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.

 

[LCREP]

I would HOPE the Fire Department would follow NFPA 13E and pump the fire department connection on the sprinkler system at 150 psi. Since after all the sprinkler system knows where the fire is and the fire department has to find it in the smoke. If not we have a BIG problem!

 

[stookeyfpe]

Atex:

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.

 

[LCREP]

"The sprinkler demand is over 2,200 gpm at 77 psi for the old paper press."

For a printing press this is a huge water demand, what is the sprinkler design? Any flammable liquid used on the press?