Centralized fire pump set for clusters of buildings 5

[Aikah-Eng]

Hi Experts,

Thanks to everyone who's helping and answering in this forum, huge knowledge and experience in these posts.

I've a question regarding a clusters of 71 buildings, belong to government and under same client.
there is no public water mains, they've a provision to provide water tank with fire pump set in the center of these buildings to service them, please check the attached screenshot.

this fire pump through a private fire main network will be connected to each building (Ground+4 stories residential apartments),

the systems will be Automatic wet standpipe & residential sprinklers design as per NFPA 13.
The flow is 750 GPM and the head will be confirmed through the hydraulic calculation anyway.

I feel like it's too risky to proceed with this provision, is there anything preventing them from this design? one fire pump set to service 71 building.. ?! how they suppose to design for the sprinkler demand area? 4 heads for residential sprinklers for the most remote building only? Standpipe flow is 750 GPM as each building having 2 staircase so it's 2 risers..500+250 ..

Please advice this scenario is ok and can be proceed further or like each building shall have a separate water supply and pump? ..

I feel like 2 or 3 fire scenario can happen in the same time!!

Thanks in advance for your answers,

 

[LCREP]

I have encountered this in some industrial parks in the US with no public water supply from an insurance loss prevention point of view. Mostly warehouses with a significant higher fire load. Typically we see 2 fire pumps, one electric and one diesel connected to an above ground tank or a pond/lake. In the US we require a FDC for the FD to connect to the water supply. I have come across 1 FDC at the fire pump building and also an FDC on each building. How far, if any, is a public water supply from the site? Will they have fire hydrants on the private water mains if so spaced how far apart? Any involvement with the local FD or property insurance carrier?

Tom

 

[SprinklerDesigner2]

Depending on where you are other factors can rear their ugly heads that have nothing to do with NFPA standards.

"Fire Flows" are one. You won't find it in any standard but is some state building codes there's "Fire Flows" that stipulate how much water must be available from fire hydrants. I am a sprinkler designer and the calculations of fire flows are not my calling but the calling of the licensed professional engineer on the project.

Spacing of fire hydrants. In Florida I do believe that maximum distance you can have between hydrants is 1,100' as long as the buildings have sprinklers and without sprinklers the distance shrinks.

The issue of two fire pumps is pretty much left up to the insurance authority but on a project this size I would like to see an electric and diesel backup pump and the size I would pick would be 1,500 gpm.

Yeah, it is more money but let's put it in perspective.

Two pumps instead of one... what are we looking at? Maybe $200,000 at most"

Blah.

You got 71 buildings and if we value them at $2 million each (I am cheap there) we are looking at $142 MILLION and does anyone really think the extra $120,000 spent on the additional fire pump is really going to be an issue? An extra $845 per building to offer additional protection to a $2 million dollar building? Oh, and the $2 million I am probably light.

 

[LittleInch]

Aikah,

you're coming up as UAE, so I suppose this is some sort of government complex in the desert?

That drawing is very "busy" so difficult to see what is what. Are the buildings blue or pink or both? Where is the FW pond?

No one here can tell you whether it is "ok or not" - this is between you and the relevant authorities and regulation in the country of construction.

I don't think any code is going to tell you whether you need to consider more than one building on fire at the same time - that's a risk based thing which the client and the Fire Protection Designer will need to agree on. generally spread of fires from one building to the next takes some time and depending on the spacing may be only confined to two or three.

A lot will depend on what other fire water supplies the local fire truck will be able to bring with them or is this finite FW pond all you have?

Is this a burn down philosophy? otherwise your fire pond is gong to be rather large and evaporate a lot....

So yes it looks prudent to consider two buildings on fire at the same time and / or additional water supplies needed by the fire dept to fight or contain the fire from outside, but this is something which needs to be considered with the client and the AHJ.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TravisMack]

I have seen this scenario pop up quite often. You have a large site with multiple buildings and a central utility plan for the fire pumps and other distribution equipment.

How is this any different than a municipal pumping station? Take any moderate sized municipality, you will have a pumping station that provides for the public distribution system that will serve many buildings, both fire and domestic water needs. Most would not question this situation if it were supplied by municipal water. So, as long as the water storage is sized appropriately and the pumps are sized appropriately, how is this concept any different than what we connect into almost every day?

Generally, the government entities stay up to date on their IT&M, so this should be a reliable system. As others have said, I would want a backup pump. Honestly, I would probably try for a secondary tank as well. That way, if any one pump or tank is out of service for maintenance, you have the other completely functional.

Travis Mack, SET, RME-G,
MEPCad, Inc
AutoSPRINK | AutoSPRINK FAB | AutoSPRINK RVT

 

[LittleInch]

The difference is that this is a standalone FW system and its capacity is being limited to only supplying enough water for a fire in one building at a time if I understand that correctly, for an unknown period of time as Aikah hasn't told us very much detail. Most municipal system would have the capacity for a lot more than one building and an unlimited supply.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Aikah-Eng]

Thanks Mr. Tom for your respond, this project in Middle east and we don't have public water supply dedicated for fire, only some new residential cites having fire flow as per the IFC Table from the infrastructure authority. which has nothing to do with me as a fire water based-system designer dealing with NFPA Standards only. exactly as SprinklerDesigner2 said.

same as you said, per our local code in UAE, our typical water supply is a suction tank with fire pump set (E+D+J) or (E+D). even small building must have this setup. no public water for fire.

I'm going to design residential sprinklers systems + standpipe and private fire main network connected to the same suction tank. all these buildings as 2 types 2BHK (blue one) & 3BHK (red one) all residential apartments. the infrastructure discussing the fire flow with public hydrant if I call it properly. not sure it will be there. but as per NFPA standards we need to create a water supply always (suction tank & fire pump set with back up). typically every where.

there will be FDC to each building and for re-filling the water tank by either civil defense vehicles or by the fire flow public hydrant is it will be conducted by the infrastructure (not sure).

I really appreciate your replay. I wanted to get options from the experts here as always a useful forum if we provide clear picture of our case.

 

[Aikah-Eng]

Really appreciate it, I was waiting for your response and Mr. Travsmack. I knew it if you two replies, it will be useful. and sure with respect to all opinions that will help me.
I used to deal with single project or building and applying NFPA standards only as you mentioned. nothing to deal with for Fire flow and everything related to hydrant is clouded in our area. except the private fire main having hydrant connected to our typical water supply (suction tank with fire pump set (E+D and J if any). Please check below as per our local code for spacing and hazard class. everything here is costly as hell! I've supplied many Aurora fire pumps typically shipped to us as fire pump set.

Fire flow will be handled by infrastructure authority as per the IFC Table annex B (properly) but I did not see anything physically conducted, all on papers only and not sure it's there or not and normally will not be conducted. so I'm totally ignoring this part. I've suggested them with residential sprinkler systems (only corridor I will be using QR spry sprinklers and other small areas) remaining is all RS. + class 1 standpipe automatic wet. this is my territory ^^
up to here I'm ok. the thing is to reduce the cost my fried engineer who is working as AHJ suggested to provide central pump. Thanks . reading the opinions here will defiantly be useful.

 

[Aikah-Eng]

Thanks for the useful replay.

so I suppose this is some sort of government complex in the desert? exactly as you said and we have pretty straight forward setup. no public water main (no water source). typically we are creating the water supply suited with the hydraulic calculation. Suction tank with capacity and duration as per the local code. fire pump set (E+D+J).

the discussion is going on, just I was worried about this scenario of providing central fire pump specially that we don't have proper follow up to NFPA 25. getting opinions from here always useful.

 

[Aikah-Eng]

Thanks Travis for the useful thread,


actually this scenario is difficult in our area, due to lack of water in the city main,
calculation of Fire flow also is authorized by infrastructure authority not in the local code. this is the issue.

but we came to the same idea as you mentioned central water tank with fire pump set.
it's in the tender stage so more fire companies giving opinions and solution. finally it will be reviewed by AHJ and civil defense. I came up with these results after all opinions above:-
1- no issue for providing one pump set to service all the buildings.
2- apart from the fire flow calculation, we will submit our shop drawings and submittals based on the NFPA standards as it's our part. finally the civil defense will select either our proposal or the fire flow if submitted by the infrastructure.
3- As it's not common for us so now feeling confident to go ahead with the pan after all above threads

Thanks for all info's and opinions above,

 

[Aikah-Eng]

my apologies if I was late in reply when you guys helping, I was sick actually today only I saw the replies and I'm thankful to all of you. it's as you said the capacity is being limited. we're just providing water for 30mintes duration in order to satisfy the sprinklers system and standpipe. if the private fire main will be connected to fire hydrant as per our local code then the the pump capacity will be 1000 gpm for 1 hour duration, 228m3 tank. no fire flow or municipal water will be related to fire, it's for other domestics supply .

Thanks