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Sprinkler system design 1

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Weldinspect

Weldinspect

Mechanical
Feb 13, 2010
204
I am supervising the specialties designs of a new building and for the srinkler system I would like to know if NFPA 13 incise 11.2.2.5 applies to a single floor of a builing or to all of them? Also how do I select form table 11.2.2.1 the total flow from 500-750 gpm that includes hoses. Is it 750 for 30 minutes and 500 gpm for 60? this is a 14 floors building with a total 1667 ft2 covered area per floor.-
 
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You are likely not going to be doing a pipe schedule system for your 14 story building. Therefore, those sections don't apply. Likely, it will all be calculated based on density / area requirements if using standard spray sprinklers.

Travis Mack
MFP Design, LLC
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Thanks Travis, I didn`t find in NFPA 13 where it says what number of stories this method is for and your comment will help me a lot
 
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Our system will have:

(3) New systems of 5000 ft2 (465 m2) or less

Per story

But anyway I willl use the hydraulic method, thank you
 
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Ok, I have calculated 317.5 total flow for one builging and I have 4 buildings in total (2x14 stories, 1x5 st. and 1x17 st.). For Class II hoses and sprinklers in every level do I have to consider adding the flow of all buildings for the pump calculation?
 
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Do you have any scenario where all four buildings would be on fire at the same time? Likely not. We typically base the pump size on a single area in a single building.

Not to sound ignorant, but you do realize that not all sprinklers activate at once. It is only the sprinklers where the fusible link has been removed due to heat from a heat source such as a fire. For your 14 story building, you do not need to figure all 14 floors flowing at the same time.

Travis Mack
MFP Design, LLC
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It`s just that the "FIRE PROTECTION HANDBOOK" 20TH Ed. at 16-194 (Minimun Flow rate and Minimun Pressure (System demand)) says: "Acording to NFPA 14, Class I and Class III systems are tipically required to deliver 500 GPM for the first standpipe, plus 250 gpm for each aditional standpipe , up to a maximun 1250 gpm."

And no, of course the all at once scenario is not a possibility. Just checking the code .:
 
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You should read the information in 14 and not just the handbook. That is 250 gpm @ the top 2 outlets of the remote standpipe. Then, add 250 for each additional standpipe, up to 1000 for sprinklered buildings and 1250 gpm for unsprinklered buildings.

I doubt your 5000 sq ft floors have more than one standpipe, so you have a 500 gpm standpipe demand. Due to the height, you will need to deliver 100 psi to the top valve on your standpipe. So, you pump must be designed to handle that pressure and flow. Many falsely put that 100 psi at the hole in the pipe for a standpipe. But, you may lose about 5-7 psi through a hose valve, nipple and welded outlet.

Travis Mack
MFP Design, LLC
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We have 4 buildings in the same project and that`s why I had this doubt about the manual, guess I have to study more over the weekend :)-) thanks again:

Sin_t%C3%ADtulo_gfrgzo.png
 
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Reach out to the insurance carrier some have an engineering department and can help you. Also they can review the plans and provide feedback. At the very least you will have a 2nd set of eyes review the plans.

 
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Have you considered professional engineering assistance? You are sliding down a slope that will litigate you out of existence in the US. Overseas, liability laws are yours to determine.
 
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Thanks LCREP and stookeyfpe actually we are not in the US and the designer is an expert. I have to rechek his designs so I am learning
 
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How much sense does it make that you learn the very basics and than check the expert?
 
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We have to remember that his project is outside of the US. I have found that projects outside of the US seem to run very different than we are used to seeing.

Also, in the US, you may have an AHJ that does not have significant experience in an area and is reviewing plans for projects. So, it does happen when the less experienced guy is reviewing the more experienced guy. It can get frustrating, but it does happen.

Travis Mack
MFP Design, LLC
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This is because in my case I check FFS, Electricity, VAC and Hidraulics but also I have consultants helping me. And of course I always like to learn from the Eng-Tips advises... Thank you
 
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