Residential heads in lobbies

[jkampana]

I am designing a NFPA 13 system in a senior housing facility. The two wings consist of dwelling units and the center area contains the Lobby/Office/Class room area. My question is can I use Residential sprinklers in the center area under NFPA 13 code. NFPA 13R states that I can under 6.8.2.3 but I don't see any allowance in 13. The only thing I can find on the issue is 11.3.1.4 and if I am understanding correctly I would be prohibited from using a residential sprinkler in these areas. Can anyone help clarify?

 

[skdesigner]

NFPA 13 2010 8.4.5.1 Residential sprinklers shall be permitted in dwelling units and their adjoining corridors, provided they are installed in accordance with their listing.

NFPA 13 2010 3.3.8 Dwelling Unit. One or more rooms arranged for the use of one or more individuals living together, as in a single housekeeping unit normally having cooking, living, sanitary, and sleeping facilities. For the purposes of this standard, dwelling unit includes hotel rooms, dormitory rooms, apartments, condominiums, sleeping rooms in nursing homes, and similar living units.

Definition of CORRIDOR (from Merriam-Webster.com)

1 a: a passageway (as in a hotel or office building) into which compartments or rooms open

 

[jkampana]

Ok so would your answer then be yes you are allowed to?

The only issue I see is that the corridor to the dwellings units from each wing is separated by a doorway to the center section of the building thus that area would not be the adjoining corridor, at least by my understanding.

 

[pipesnpumps]

I'd say no, you cannot use them if the building has an NFPA 13 system. Seems crystal clear to me.

The center area is not a corridor adjoining (with direct openings to) a dwelling unit. The standard reads such that it does not intend for residential heads to be used outside of the dwelling units and their adjoining corridors.


Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[skdesigner]

"Ok so would your answer then be yes you are allowed to?"

No.

 

[jkampana]

Thank you for the help guys.

 

[SprinklerDesigner2]

skdesigner is correct. You can not use residential sprinklers outside the dwelling units with the exception of corridors.

From NFPA #13 (2002):

8.4.5 Residential Sprinklers.
8.4.5.1* Residential sprinklers shall be permitted in dwelling units and their adjoining corridors provided they are installed in conformance with their listing.

A.8.4.5.1 The response and water distribution pattern of listed residential sprinklers have been shown by extensive fire testing to provide better control than spray sprinklers in residential occupancies. These sprinklers are intended to prevent flashover in the room of fire origin, thus improving the chance for occupants to escape or be evacuated.

The protection area for residential sprinklers is defined in the listing of the sprinkler as a maximum square or rectangular area. Listing information is presented in even 2-ft (0.65-m) increments from 12 ft to 20 ft (3.9 m to 6.5 m). When a sprinkler is selected for an application, its area of coverage must be equal to or greater than both the length and width of the hazard area. For example, if the hazard to be protected is a room 13 ft 6 in. (4.4 m) wide and 17 ft 6 in. (5.6 m) long, a sprinkler that is listed to protect a rectangular area of 14 ft × 18 ft (4.5 m × 5.8 m) or a square area of 18 ft × 18 ft (5.8 m × 5.8 m) must be selected. The flow used in the calculations is then selected as the flow required by the listing for the selected coverage.

One thing I enjoy about this forum is if I am wrong, often enough I am, my error is quickly pointed out so here goes.

In an NFPA 13 system you can use residential sprinklers inside the dwelling unit but be careful that the density meets the .10 gpm requirement per NFPA #13.

Consider the VK466 - Residential Pendent Sprinkler (K5.2) residential sprinkler.

http://www.vikinggroupinc.com/databook/sprinklers/residential/091406.pdf

In an 18'x18' room the discharge requirement is 17 gpm @ 10.7 psi for NFPA #13R systems but 17 gpm hardly satisfies the requirement of NFPA #13 which require a discharge of 32.4 gpm @ 33.5 psi in order to achieve the .10 gpm density.

If the room is long and narrow, say 18'x8', the discharge would have to be 14.4 gpm to achieve the .10 density but the data sheet requires 17 gpm @ 10.7 psi in accordance with the listing for residential use.

Basically you use the higher of the two which, in the case of the 18'x8' room, would be 17 gpm @ 10.7 psi.

For Georgia I can say the state fire marshal will require the higher of the two discharges and the higher of the two is what I have always used inside or outside the dwelling units.

As for the corridor I believe the standard requires only four sprinklers need be calculated but here in Georgia the state fire marshal requires five heads calculated and it doesn't matter if the system is designed per NFPA #13 or #13R.

Is Georgia correct in requiring a density of .10 gpm in or out of the dwelling units themselves?

 

[skdesigner]

Absolutely correct.

Page 141n of your datasheet states:

"For systems designed to NFPA 13: The number of design sprinklers is to be the four contiguous most hydraulically demanding sprinklers. The minimum required discharge from each of the four sprinklers is to be the greater of the following:

The flow rates given in the Approval Chart on data page 141l for NFPA 13D and NFPA13R applications for each listed area of coverage, or Calculated based on a minimum discharge of 0.1 gpm/sq. ft. over the “design area” in accordance with sections 8.5.2.1 or 8.6.2.1.2 of NFPA 13."

As for corridor calcs, the fire marshall would be correct again (maybe it has changed between 2002 and 2010?).

NFPA 13 2010 11.3.1.5 Where areas such as attics, basements, or other types of occupancies are OUTSIDE THE DWELLING UNITS but within the same structure, these areas shall be protected as a separate design basis in accordance with section 11.1

NFPA 13 2010 11.2.3.3.6 Where the room design method is used and the area under consideration is a corridor protected by a single row of sprinklers with protected openings in accordance with 11.2.3.3.5, the maximum number of sprinklers that needs to be calculated is five or when extended coverage sprinklers are installed, all sprinklers contained within 75 linear feet of corridor.

NFPA 13R 2010 7.2.1 For areas OUTSIDE THE DWELLING UNIT, the design discharge and design area criteria shall comply with NFPA 13, unless permitted by 6.4.7 and 7.2.2

7.2.2 (1) limits you to compartmented areas of 500 sq.ft or less by 30 min fire-rated construction.

Given that most corridors will not meet the exceptions of 7.2.2, we are returned to NFPA 13 2010 11.2.3.3.6

 

[skdesigner]

Also, for the 18' x 18' option, I believe you would require

((18x18)*(0.1) / (5.2))^2 = 38.8 psi from the most remote head while flowing 32.4 gpm.

 

[rmae]

SKDESIGNER,

You are only saying that the Georgia state fire marshal is correct in that when residential sprinklers are utilized as permitted in residential portions (and adjoining corridors) in NFPA 13, 2010 protected occupancies the minimum density must be 0.10 gpm/sq.ft?

The marshal is going in excess of NFPA 13 in requiring five sprinklers be calculated in the corridors if residential sprinklers are installed in the corridors. A four sprinkler calculation is permitted by 11.3.1.3. Figure A.11.3.1.3 clarifies this by showing a diagram of a corridor adjacent to a dwelling unit with 4 sprinklers in the calculation area.

You are correct in that a 13R protected occupancy a corridor does require that five sprinklers be calculated in most cases.



R M Arsenault Engineering Inc.

http://www.rmae.ca

 

[SprinklerDesigner2]

SKDESIGNER,

I agree the fire marshal is going in excess by requiring 5 heads in the calculated corridor but I've been round and round with them on this and they won't budge.

 

[skdesigner]

I have always noted the conspicuous absence of the wording "...and their adjoining corridors..." in 11.3.1.5.

I also note that the title of Figure A11.3.1.3 is "examples of design areas for dwelling units". "Adjoining corridors" is again absent, even though A11.3.1.3 (b) appears to be a corridor.

Crystal clear to some, ambiguous to me. It rarely makes a difference in pipe sizes since the corridor heads are usually fed directly from the main, as opposed to feeding two or three suite heads off a 1" branch.

 

[rmae]

Hmmmmmm. You're right about the pipe sizes likely having no effect in most cases but if an AHJ told me that I have to submit a five sprinkler calculation to prove the use of residential sprinklers that I might have spaced at 18' or even 20' (where the listing flow would trump the 0.10 density flow)in said corridor then I think would say...8.4.5.1 says I can use residential sprinklers in corridors adjoining dwelling units and I can space them according to their listing, 11.3.1.3 says I only need to calculate 4 sprinklers, Figure A11.3.1.3 clearly shows a picture of a corridor with 4 sprinklers adjacent to a dwelling unit (or it's one heck of a skinny room. Case closed, here's my 4 head calc, thanks to NFPA 13 for saving me that extra 20+ gpm and gaining 7-10% extra factor of safety or maybe even a smaller main.

p.s. 11.3.1.5 doesn't have to mention corridors because they were already dealt with by 8.4.5.1. This sentence I believe is intended to stear the really clueless designer to the main sections of Chapter 11 so they use the appropriate design method outside dwelling units and their adjoining corridors in case they started at this section for whatever reason.
My head hurts.

R M Arsenault Engineering Inc.

http://www.rmae.ca

 

[rmae]

....My curiosity got the best of me. Further to my previous post, I ran a little example through Autosprink doing a 4 sprinkler calc. vs. a 5 sprinkler calc. The difference is more significant than I expected.

R M Arsenault Engineering Inc.
www.rmae.ca