maximum number of system risers on a multiple riser header

[pipesnpumps]

I can't seem to remember where I read this in the code, but how many systems risers can you have on a single building lead-in?

Maybe I just dreamed it one night, but I've got it stuck in my craw that the answer if five..

Can anyone help point me to the right section, or straighten me out?

Thanks In Advance

 

[spkreng]

The number of system risers (that I know of) is unlimited; BUT - you must conform to "System Protection Area Limitatations" (NFPA 13, 2002 8.2) 52,00 sq ft (light hazard)
etc, so for a 500,000 sq ft bldg you could have 10 or more risers off a incoming water supply. The commentary in the above referenced handbook states in part; "The total number of manifold risers on a single header SHOULD be limited so that in the event of an impairment to the supply piping, the total area impaired is limited." Now don't confuse this with a riser "protection area" because that gets into whether it is dry or preaction, racks, etc.
As long as the fire line service is sufficient to supply the worse system there isn't any limit, as long as it is with in the same structure.

spkreng, CET

 

[TravisMack]

If I recall correctly, IRI used to have a requirement of no more than 5 risers on a lead-in and FM used to be around 3-5 fire protection devices per underground isolation valve. So, you had to put a sectional valve in a loop if you had a hydrant and a lead-in with 4 risers, or something like that. Again, I may just be dreaming all of that as well.

However, NFPA 13 does not give a limit on that.

There are some really new things in FM that are coming out. 1 of them involves system area.

1. There is no maximum size of system. Instead, the “maximum area of coverage for a sprinkler system is limited only by the hydraulic requirements of the sprinkler system’s design for the occupancy being protected” (2-0:2.4.1.6).

I received that from an NFSA email today, along with other significant changes to FM guidelines.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[NJ1]

I agree with Travis Mack however if your insurance provider is not FM then it does not matter. NFPA 13 doe snot limit that but you must consider what the hazard area is to be.

 

[SprinklerDesigner2]

There is no maximum size of system. Instead, the "maximum area of coverage for a sprinkler system is limited only by the hydraulic requirements of the sprinkler system's design for the occupancy being protected" (2-0:2.4.1.6).

This makes sense and I wonder how long before NFPA #13 follows suit?

The only reason 52,000 sq ft is the magic number is 70 years ago a system was limited to 400 heads. 400*130=52,000.

Is it safe to assume FM did studies that show limiting a system in size offered any real life benefit?

 

[stookeyfpe]

Be sure to read the new version of FM 8-9. The density/design area method is no longer recognized for the protection of high-piled combustible storage. FM now prescribes "x" sprinklers/branch line at "y PSIG" and then prescribes the minimum number of hydraulically remote sprinklers to calculate.

FM also no longer recognizes control mode specific application. Sprinklers are either listed for controlling or suppressing the fire. This is an excellent move on their part. Hopefully it will reign in the folks who think that their is some magic pixie dust in sprinkler selection and performance.

 

[pipesnpumps]

A follow up on this. I finally found the source of my mental hang-up. It wasn't in NFPA 13 (or 24) like I thought, but thanks for the replies confirming that.

My 2 gigabyte brain is fried from having so many codes to follow and remember. It was in UFC 3-600-01 Fire Protection Engineering for Facilities (which applies for the DoD project being reviewed)

"3-7.2 Valves.
.. A sufficient number of sectional valves must be provided so that not more than a combined total of five hydrants and sprinkler systems, or not more than three sprinkler systems must be out of service due to a single break."

The design has 7 system risers off a single building lead-in.. Oops! This design was from one of the largest E&C firms in the world.

 

[TravisMack]

Ah..it seems like some one is going to be doing a lot of redesign to be in compliance with the UFC document

That document, while it can be a pain, is very thorough and "black-n-white" as to what is needed. I 'try' to re-read the document for each job I do that is req'd to be in compliance with UFC-3-600-1. There are too many 'gotchas' in that document that can really cause problems.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[MechEng2007]

I heard that FM was eliminating the maximum zone size because they wanted to reduce the number of control valves on a system. Less valves means there is less of a chance one is closed in the event of a fire.

 

[pipesnpumps]

Travis, you are exactly right.. "Gotchas" is the exact term I use to describe the UFC requirements.

Reviewing other people's designs is mentally exhausting. I know they had little time to design it if they were low bidder. That already spells disaster. Then I also have very little time to review.. I have to quickly figure out where the mistakes are, because 99% of the time there are mistakes. Some of them huge and obvious, some of them smaller and not as critical like the 7 risers.. Don't get me started on proper hydrant flow tests, use of a true FPE, or how nobody in the history of man has ever heard of installing in a permanent means to forward flow test BFPs. It might give me a migraine..

 

[TravisMack]

That UFC has the full gotcha about the forward flow of the BFP as well. If I recall correctly, they pretty plainly state what they want with those. You almost end up with a nice test header for some larger systems.

Actually, I am probably the odd duck because I like being involved with systems governed by the UFC document. There is very little left to chance on any of those projects. You just have to simply follow the very detailed rules. The drawings require a fair bit of detail that you don't often do on many projects. Some of the requirements may seem very odd, but they don't really change much of their information.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[pipesnpumps]

Travis, since this is my thread I don't mind diverging a bit.. What are some other examples of the detail required by the UFC that is not often done on drawings? I am not aware that the UFC requires any more or less than NFPA 13.

One thing that people are obviously not used to is documenting the hydrant flow test correctly by showing UG piping and the location of both the flowing and non-flowing hydrant. That no one does this baffles me.. I had to do it in private industry when submitting simple PE sealed performance documents; if not they were rejected.

 

[TravisMack]

There are more things that I see like design areas. UFC starts at 3000 sq ft for most non-storage occupancies. They just recently started allowing the QR reduction.

Other things such as the hose allowances, if I recall correctly, are different than NFPA.

The thing I see the most is the forward flow testing of the BFP. In most cases, on a regular, run of the mill project per NFPA (non storage, typical LH/OH), you can typically justify the main drain as the forward flow test for the BFP. However, with the UFC document, you have to provide a test header for the BFP forward flow test.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[spkreng]

If I have a typical header, say 3 - 4" risers, wet or dry, usually I would use a six inch header with welded outlets capped at the end, so (A) I could remove the cap and run a play pipe or hoses outside the valve room and I have my forward flow test or (B) remove the clapper in the FDC check or remove it and put a filler in and flow thru the FDC right?

spkreng, CET

 

[TravisMack]

Actually, on all of the UFC projects I have done, you are req'd to have a test header, just like a pump header. You need a 2½" hose valve for about every 250 gpm in sprinkler demand. You can't just flow through the FDC. That may just be the Southwest and Pacific regions.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

 

[pipesnpumps]

http://www.wbdg.org/ccb/DOD/UFC/ufc_3_600_01.pdf

3-7.5.3 Test Connection.
When backflow preventers are installed in fixed fire protection systems, test connection must be provided downstream of all backflow prevention valves for flow tests at system demand."

NFPA 13-2007, 8.17.4.6.1 "means shall be provided downstream of all backflow prevention valves for flow tests at system demand"
The appendix A.8.17.4.6.1 states "can be performed with a test header or other connection downstream of the valve." The appendix also suggests that a supervised bypass valve around the FDC check is acceptable. It doesn't say anything about using a flange or removing the clapper.

I personally think a tee with a supervised valve and a cap, a supervised bypass around the FDC check valve, a supervised valve with a simple test connection, or a test header with individual hose valves is good enough.

I understand most people interpret the above NFPA 13 passage to allow use of the FDC with clapper removed or a grooved flange for doing forward flow tests, since that is what is done for the NFPA 25 flushing of the lead in, but I don't consider that to be an NFPA 13 required "means provided" since you have to take the entire system out of service rather than just hooking up valves and hoses and then quickly opening a valve.. On a single riser setup you'd have to drain the whole system if the BFP is used as the system control valve.

The good thing is the UFC has that covered in greater more prescriptive detail (rather than a shady wording 'means provided'), and this helps increase the chances this will actually be tested per NFPA 24..

 

[pipesnpumps]

Can't edit or delete posts, so my mistake will live on forever. Got NFPA 24 and 25 reversed in the above, obviously.

 

[ChrisConley]

You can 'Red Flag' the post, then repost it correctly. I hate making typos as well.. feels so permanent.

 

[SprinklerDesigner2]

The easiest way to comply with forward testing of BFP's would be to add a grooved weld outlet, 4" butterfly and pipe down as if it were a main drain.

On systems having higher demands, such as .60/2000, you could replace the 4" with 6".

Valve is normally closed, and does not control sprinkler water, so tamper is not required.

$250 for butterfly valve
$20 for weld
$10 for 4" 45 deg elbow
$20 for two 4" 90 deg elbows
$20 for pipe
$60 for couplings

Less than $300 would do it.