Is there anything in the standards that addresses riser manifolds? 2

[SprinklerDesigner2]

I have a 196,000 sq ft warehouse that has a street frontage of approximately 700'.

Not that it really matters but the warehouse will store exposed Group A plastics and I am looking at an ESFR system using pendent K16.8 heads. Pretty standard.

I am going to need six systems with a fire pump but there is a problem. I can not run a bunch of underground because of the street in front and railroad lines at the back and one side. What I would like to do is single 8" run-in to the pump then install a single 8", or 6" if I can make it work, overhead manifold that will end up being around 550' long. Where I can I would drop down to install a separate "riser" with it's own flow switch and control valve.

We've all seen riser manifolds with two, three, four or even five systems being fed off it but what about "stretching" this manifold out over a 550'?

I don't remember where I saw it but I remember seeing something about a maximum of four systems once but that was a long time ago and I could be mistaken.

As far as the local fire official goes he will go with whatever the standard allows.

As far as the standards go I don't think there's a problem but what have you run into?

 

[cdafd]

Sounds like a man with a plan.

Go for it.

I would have a flow switch, at the beginning of that feed pipe, to indicate water flowing in that supply pipe.

Whether a fire or break

 

[SprinklerDesigner2]

cdafd,

And something else that we have all done is run underground overhead through a building when there is no other alternative.

And I agree with you on the flow switch also we have a fire pump on the project so when the pump starts up we'll get an alarm as well.

You know when you think about it what's the difference between this and a 10-story building with a standpipe?

 

[cdafd]

Yep

Almost brought up the standpipe set up.

Same thing, I have seen long supply runs in mainly warehouses, to feed other risers.

 

[TravisMack]

Exactly, when someone questions this, I just turn the detail sideways so the pipe is running vertical. I then ask if they have a problem with a 6 story building and a vertical supply. The answer is of course no. So then I ask is it an issue if the floors are 200' apart? Again, "No." So what is the difference is the pipe is run horizontal or vertical? Again, as CDA stated, we always put a flow switch on that bulk pipe. Pump run is often set as trouble or supervisory, but not alarm. If that pipe starts leaking enough to trip a flow switch, I want that in full alarm and someone investigating right away.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, a Ferguson Enterprise

http://www.mfpdesign.com

 

[SprinklerDesigner2]

I can't remember where I saw it but it was years ago there was something about limiting the manifold riser to four systems which, in light of standpipes, doesn't make any sense but I did see it.

Perhaps a proposal to change NFPA #13 or maybe it was simply something from an insurance company from way back when?

 

[TravisMack]

Art:

I think you are referencing something from FM and IRI days. If I recall correctly, FM only allows 6 devices on a single lead in and/or between isolation valves on a loop.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, a Ferguson Enterprise

http://www.mfpdesign.com

 

[SprinklerDesigner2]

Travis,

I think you are correct... must have been left over from the olden days but I do believe FM still holds to the maximum six (or is it five) systems. Seeing as how it is not an FM job I'm going to treat it as if it were a six floor storage building.

 

[TravisMack]

They go with 6 devices between UG isolation valves on a loop. So that could be 2 hydrants and 1 lead-in serving 4 systems, or a single lead in serving 6 systems. You would be following the standards with just a single lead-in and 6 risers on the header.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, a Ferguson Enterprise

http://www.mfpdesign.com

 

[RainbowFS]

I service several (fairly recently built) Lowe's locations and they all have seven systems on a single manifold behind a huge pump. As for a "master" flow switch, if the pump is upstream of the systems, wouldn't the pump alarm serve as your alarm for the entire building? I may be assuming too much, because for all the uniformity of the Lowe's store model, the alarm systems are different at each location I service. Infuriating to try to perform complete testing in a timely manner.

Alex Traw
Rainbow Fire Sprinklers
Albany, Oregon

 

[cdafd]

Alex

On the fire side,,, it is nice to know which riser is flowing.

Especially when the fork lift busts the spk pipe.

Plus if there is say a three hundred foot supply pipe, off the header, to say a dry pipe system,,, it would be nice to know, via a flow switch on the pipe, it busted or was leaking.

 

[TravisMack]

To answer the question about the pump as the indicator, many times pump run is a supervisory or trouble signal and not an alarm signal. If I have water flowing, I want an alarm. I don't want someone to just go silence the trouble/supervisory indicator and not investigate. You will get alarm investigated.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, a Ferguson Enterprise

http://www.mfpdesign.com