Apt. Sprinkler Design Area

[FireSprinkler]

I am working on the design of Fire Sprinkler system in a high rise building that will have both hotel floors and apartment floors.
Due to the fact it is a high rise building, I would believe that the design is in accordance with NFPA 13 rather than 13D or 13R.
My question is, for the Apartment floors would the design area be Hydraulically Calculated using the area/density method or the Room Design Method?
I would think I could use the Room Design method, but do I include closets and small washrooms in the Calculations? The design area would be less than 1500sq ft. The job is also an FM job with FM requirements.

Any thoughts?

 

[gouveia]

A couple quick thoughts:

1. Not a FM expert but a while back when I last checked no one made a FM approved residential sprinkler. So better verify what the project requires.

2. Check with your regional FM rep and verify what their requirements are. They are usually very helpful in my area.

3. Definitely a 13 system (NOT 13R or 13D) as you noted. Assuming no special FM requirements (which there always are) you could pick a room design method as long as you comply with all the requirements. As for the omission of small rooms from the design area, it is my understanding this is only applicable when using the area design method AND when your design area is greater than those shown on the density curves. An option I used one time was to make the design area larger, pickup a few heads with more square footage and then omit the small room heads. You still come out ahead on pipe sizes in the end.

My real recommendation (not factoring in FM requirements) is just to do 1,500 sq ft and include the small rooms. If it is a high rise with proper pipe sizing I would think the pipe size difference would be small.

You can also check the sprinkler Handbook. Let us know what FM's requirements are.

 

[FireSprinkler]

gouveia:
I can verify that FM does not approve Residential heads - or at least none of the ones I've looked at. Actually, the heads I am using are all NFPA 13 heads. I'm using an Ext-Cov sidewall for the most part with SSP concealers on the soffits and ceilings. All of which are FM approved.

You've pretty much verified what I thought about the design area. The Pipe sizes I'm having to use are just surprisingly large. It seems I am flowing more heads than what I need. It's all the small closets that are killing me.

Then, I've also the problem that, because I'm using Ext-Cov sidewalls, the pressures and flows required for the heads are "overflowing" or over-discharging the other SSP heads. So, more, unneeded, water = higher friction losses.

I would like to meet with the FM rep but I'd also like to see who exactly the owner will send the drawings to so I can talk to that person directly (sometimes the local person is not the rep for the owner if they are a large enough company).

But, thanks for the clarification on the design area.

If there are any other thoughts on this issue I'd appreciate them.

 

[gouveia]

I see why you are asking now. You probably have already tried the following options but I'll throw them out there:

1. Try using K=4.2 or smaller pendents in the closets?
2. Play with the balancing to limit the flows to pendents, smaller pipe sizing, more elbows, etc..

 

[FireSprinkler]

Well, I just finished up with one calc. I did end up making the remote area greater than 1500 sq ft. So, I actually end up with less flowing heads because I don't need to flow all those heads in the small rooms etc. The numbers are now coming out the way I would expect them to.
2 1/2" cross main with 1" branchlines.

I love doing calcs... when they work

 

[concetta]

I recently specified a system where FMG was the underwriter. I found the local FMG field office and spoke to the plan reviewer. Hopefully, when the sprinkler layout technician gets the job, all his questions will be answered.
Another time when I was the layout tech for a sprinkler company, I needed guidance with Kemper requirements and followed the same course. If you are not sure how to proceed when you are in unfamiliar territory, the best advice is to ALWAYS use unimpeachable sources for questions regarding codes and standards.
FYI, I am certified in Plumbing Design as well as automatic sprinkler layout.

 

[FireSprinkler]

Well, as it turns out, FM is not the insurer for the owner any longer. So, all the FM stuff is out the window. Thanks for everyones input on this issue.

 

[TSDavis]

You can use residential sprinklers within the dwelling units and the adjoining corridors and calculate just 4 sprinklers in accordance with the sprinkler manufacturers data sheet and NFPA13

Start with the definition of "dwelling unit"

Then go to
5-4.5.1
7-9.2.1

This appears in the 1996 and 1999 editions.

Area's that are not dwelling units or adjoining corridors will still give you fits but they are usually located near your sprinkler riser and don't dictate pipe sizes.

Terry S. Davis
TriStar Fire Protection

 

[TravisMack]

However, when using residential sprinklers in a NFPA 13 application, you must provide 0.10 GPM / Sq Ft over the design area. If you are using the sprinklers as extended coverage, it can require some pretty high pressures to get 16'x16' spacing with a sprinkler that has a 4.9 K-Factor.

 

[TSDavis]

Strange. I posted to this and it's gone.

You only need to provide the .10 gpm/sq.ft. in areas that are not dwelling units or their adjoining corridors. Discharge rates in the dwelling units and the adjoining corridors (if res. sprinklers used in corridors) "shall be provided in accordance with minimum flow rates indicated in individual residential sprinkler listings". Usually in the .05 to .06 range. Storage rooms, mechanical rooms, etc. will need a density that corresponds to their particular occupancy.

I've used and have had approved the special design approach incorporating residential sprinklers in the dwelling units and adjoining corridors on more than one occasion. The designs were approved by multiple reviewing agencies. (TVA, FireSafety, BOCA plan review, Firedyne)

Terry S. Davis
TriStar Fire Protection
tdavis0114@comcast.net

 

[TravisMack]

Refer to the TIA that was issued in 1999. You must provide 0.10 over the room area (using SxL) requirements, or the listing of the head, whichever is greater.

This has been further clarified in the 2002 edition of NFPA 13.

11.2.3.5 Residential Sprinklers.
11.2.3.5.1* The design area shall be the area that includes the four hydraulically most demanding sprinklers.
11.2.3.5.2* Unless the requirements of 11.2.3.5.3 are met, the minimum required discharge from each of the four hydraulically most demanding sprinklers shall be the greater of the following:
(1) In accordance with minimum flow rates indicated in individual listings
(2) Calculated based on delivering a minimum of 0.1 gpm/ft2 (4.1 mm/min) over the design area in accordance with the provisions of 8.5.2.1

I guess that you have been fortunate to have those designs approved, as they do not meet the minimum intent of NFPA 13, 1999 (due to the TIA) or NFPA 13, 2002.

 

[TSDavis]

Perhaps I have been fortunate.

Would a TIA to the 1999 edition apply to previous additions of NFPA?

Terry S. Davis
TriStar Fire Protection
tdavis0114@comcast.net

 

[TravisMack]

not sure. The TIA was issued as an ammendment to the 1999 edition sometime in early 2000, if I recall correctly. You can find the exact info on the NFSA or NFPA websites.

I didn't mean to shoot you down...just wanted to make sure you had the most up to date info. There are very few avenues for fire sprinkler education, that we need to use every avenue possible.

 

[TSDavis]

Your certainly right on that one. Very difficult to get info on fire sprinklers. It's like a black art. I was thrilled to find this forum to bounce ideas off of. Every once in while I find something in a standard that makes no sense. Then what? We rarely have time to wait for an interpretation from NFPA.

The International Building Code and in turn our local building code specify the 1996 edition of NFPA 13. That may be the reason the systems were allowed.

Terry S. Davis
TriStar Fire Protection
tdavis0114@comcast.net