I got a real problem with a self storage facility

[SprinklerDesigner2]

This is a small portion of the building that comes out to 30,000 sq ft.

4" bent metal purlin construction. Yes, 4" deep purlins.

The roof is 10' on low side and 14' on high side. Pitch is 1/4" in 12".

As noted all partitions extend to roof deck except for the front partition where the roll up overhead door is which has a gap. I was told the space runs between 1'-0" and 3'-0" depending where it is in the building.

I have to believe this is an Extra Hazard II Occupancy because I just have to believe it is full of mattresses and upholstered furniture. Try as I might I can not talk myself into an OH2 which would make life super simple. I just can't and won't unless some engineer wants to put that in writing which I doubt they will. Any engineer here wanna volunteer? I will make it worth your money.

My problem is spacing.

It it was all 100 sq ft cubicles life would be easy but they vary from 150 sq ft down to 25 sq ft.

I looked at standard spray sprinklers .40/2,000 and I got a mess. Luckily the water is there (good very flat curve) but I am coming up with 2,000 gpm. It's nuts.

I briefly looked at ESFR and while I would love design 12 heads the obstruction requirements care me to death and so does the minimum distance requirements.

Next I looked at CMSA Table 22.3 (NFPA 13 2019 Edition that I am still getting used to, but I can't find solid pile Exposed expanded plastic. With a max height of maybe 10' how do I classify it whether palletized or solid pile?

I wish it had racks then the CMSA would make it easy.

And on a quick draft my 30,000 sq ft bldg has 752 heads.

And for the record I feel very uneasy with self storage buildings. To many unknowns.

 

[UFT12]

I don't understand how you come up with 2000 gpm really. You only need 0.4 x 2000 = 800 gpm plus some small allowance for uneven head pressures. It is irrelevant from the number of sprinklers you intent to install. Each sprinkler covers the intended area based on the separations you have or the distance with the nearby sprinklers. So if your sprinklers are spaced, say, around 40 ft2 each, you would need 50 in the design area, each flowing 0.4 x 40 = 16 gpm. Similarly, if the coverage was 100 ft2 you would need 20 flowing 0.4 x 20 = 40 gpm each. So 50 x 40 x 0.4 = 20 x 100 x 0.4 = 800 gpm.

 

[skdesigner]

This is why the NFPA 13 Owner's Information Certificate exists, so you don't have to talk yourself into a hazard classification. I have taken to referring to that document as my 'get out of jail free' card. It is very nice to have a signed OIC stating 'no storage over 12 feet' when I walk into, say, a car dealership at the end of the job and the Parts Storage room has 18' high racks being built.

For what it's worth, I agree with you on the EH classification. The first time somebody asked me what I thought the hazard classification of a self-storage facility would be, my exact response was 'whatever classification is appropriate for memory foam mattresses stacked one on top of the other to within 18" of the sprinkler deflector'.

 

[SprinklerDesigner2]

UFT, Each cubicle covers anywhere from 25 sq ft to 150 sq ft.

If you select a 2000 sq ft area on the drawings with the 1.2 times the sq ft I think you will find the area has at least 40 sprinklers and not the 20 we would expect in a wide open building.

With 40 gpm per head (40x40)+500=2100 gpm.

So if your sprinklers are spaced, say, around 40 ft2 each, you would need 50 in the design area, each flowing 0.4 x 40 = 16 gpm.

If we have 50 sprinklers in the design area each sprinkler will have to discharge 29.6 gpm = 1,480 gpm plus 500 for hose.

25.2.3.1.5 For design densities greater than 0.34 gpm/ft² (13.9 mm/min), standard-response CMDA sprinklers with a K-factor of K-11.2 (160) or larger that are listed for storage applications shall be used.

But then you get to a 100 sq ft room and your minimum discharge is 40 gpm even in the rooms of 25 sq ft.

 

[UFT12]

Other than the hose allowance which you need to add anyway, why are you stuck with the 40 gpm/head since we are going by the density/area method? 40 gpm seems calculating with 100 ft2 per sprinkler. But it's obviously not the case. See 27.2.4.7.1 of edition 19. The area of sprinkler operation is basically the area per 9.5.2. What is the area of each of your sprinklers then? Regardless of sprinkler amount, the standard never imposed any number of heads, only density and area, that is for the density/area method of course.

 

[UFT12]

SD2, I saw your edited post after my reply. You are correct about the limit of 0.34 gpm/ft2 which would need K11.2 so it seems you are bound to ~30 gpm/head but... see if 21.3.3.1 (ed. 19) is applicable (if you are under low-piled storage) which allows reduction of area. By the way, I noticed we were both wrong on one thing, EH2 is 0.4 over 2500, not 2000 ft2 unless you applied the reduction.

 

[Cidona]

I have the 2013 Handbook at hand so that’s what I’m referencing for section numbers, etc.

It would seem that you are getting to your EH2 hazard classification by going to Chapter 15: Protection for Palletized, Solid-Piled, Bin Box, Shelf or Back to Back Shelf storage of Plastic and Rubber Commodities and taking a worst case scenario of Group A Plastics Expanded Exposed.
In section 15.2.6 you would end up in the first row. Depending on the commodiy and storage arrangement the densities there are either .2, .3 or EH1 or EH2. It would seem that if you are using .2 or .3 then you can use the smaller K-factor sprinklers for the lower densities stated in section 12.6 of Chapter 12 (i.e. 5.6K for .2 gpm/ft2 or 8K for .34 gpm/ft2).

Or else you are using EH1 or EH2 for the more demanding storage configuration. If going with the EH1/EH2 then section 15.2.8 is referencing you to Figures in Chapter 13. Also section 15.2.10 states:
“For storage of Group A plastics between 5 ft (1.5 m) and 12 ft (3.7 m) in height, the installation requirements for extra hazard systems shall apply.”

The commentary in the handbook goes on to say:
“The requirement in 15.2.10 is necessary in NFPA 13 to fill a gap in installation requirements for sprinkler spacing, types of pipe that can be used, and other installation requirements outlined in Chapter 8. NFPA 13 contains installation criteria for light hazard, ordinary hazard, extra hazard, and high-piled storage. There are no installation criteria for low-piled storage. If the low-piled storage can be protected as miscellaneous storage, then Chapter 13 instructs the user to follow the rules for ordinary hazard or extra hazard. But for low-piled storage that has to be protected in accordance with Chapter 15, some rules need to be stated for sprinkler spacing (and other installation rules). For storage under 12 ft (3.7 m) in height, the rules of Table 8.6.2.2.1(d) do not apply, because the rules in this table are only for storage above 12 ft (3.7 m). Without 15.2.10, the user would not have any direction for the sprinkler spacing (and other installation) criteria that should apply to low-piled storage situations.”

On the first page of chapter 13 in the handbook it states:
Although the title of Chapter 13 is “Miscellaneous Storage,” the chapter also contains the protection criteria for many other types of storage. Several of the requirements for low-piled storage in Chapter 14 through Chapter 19 direct the user back to Chapter 13. Once the user has been directed back to Chapter 13, all of the rules of Chapter 13 apply, even if the storage configuration does not meet the definition of “miscellaneous” storage.”

It goes on to state:
“The rules of Chapter 13 are independent of the other storage rules in NFPA 13. The general rules of Chapter 12 do not apply to Chapter 13, as noted in Section 12.1. This difference is in recognition of the fact that miscellaneous storage tends to burn more similarly to the hazards defined in Chapter 11 rather than the hazards outlined in Chapter 12 through Chapter 21.”


So, what’s interesting in that commentary is the line “…the general rules of Chapter 12 do not apply to Chapter 13 as noted in Section 12.1”.

If the rules of Chapter 12 do not apply then it would seem you are not mandated to use the higher K-Factor sprinklers (11.2K as would be for a .4 density in section 12.6.3 if doing something that wasn’t referencing you back to Chapter 13).

Section 12.1 states:
“The requirements of Section 12.1 shall apply to all storage arrangements and commodities other than miscellaneous storage (see Chapter 13) and as modified by specific sections in Chapter 14 through Chapter 20”.

The commentary goes on to say:
“Sprinkler systems that protect miscellaneous storage or low-piled storage have more in common with ordinary hazard or light hazard occupancies than they do with storage occupancies. Fires in these occupancies do not generate the same kind of forceful vertical fire plumes that can be found in other storage occupancies. Therefore, the discharge criteria for systems designed in accordance with Chapter 13 ultimately revert to criteria in Chapter 11 for ordinary or extra hazard systems; the more stringent criteria found in Chapter 12 do not apply in this case.”

So, question – since the table is referencing you to EH1/2 in Chapter 13 would you therefore be able to ignore Chapter 12 and use smaller K-factor for your smaller storage compartments and get a more balanced calc?

 

[SprinklerDesigner2]

Cidona,

I would love to end up with miscl storage or, better yet, OH2 where I can use QR and reduce my area.

Georgia recently adopted the 2019 edition and I am still learning how to navigate.

 

[UFT12]

SD2, you mentioned above mattresses, racks and building height of 12 ft max so I would assume as a worst case scenario protecting Group A plastics in shelves of low-piled storage or in general storage below 12 ft. I really do not see any way to classify the application as miscellaneous storage.

My interpretation of the situation and as to how to follow the standard is, starting point, per edition 19, is 4.3.1.5 which directs to chapter 25. In there you need to satisfy 25.6 for in-racks as well as 25.2.2.2 for ceiling in which all 25.2.2.2.x sections turns you back to 25.2.2.1.2 which means OH2. You will then need to see what would be the lowest K factor you could use in order to make the system as cost effective as possible and with the given actual coverage areas per sprinkler.

 

[Cidona]

UFT12, I don’t believe we are talking about protecting racks as SD2 stated “… I wish it had racks..” in his original post. Therefore I would think we are discussing it being considered piled storage.

In my previous post where I was referencing the possibility of utilizing Misc Storage criteria it wasn’t with the intent of classifying it as Misc Storage but rather being directed to the Misc Storage chapter/criteria from Chapter 15.

TBH, I haven’t dealt much with NFPA of late as am no longer US based and usually end up having to use other standards (FM/EN/LPC). FWIW, I miss NFPA something fierce as for whatever ‘gaps’ there seems to be with NFPA in my opinion they are minuscule in comparison to some of the other standards.

I do like to keep somewhat current on NFPA so will be interested to get some knowledge from where this whole discussion ends up… I have reviewed the new NFPA 13 (2019) so will reference that from here on.

There’s a couple of aspects that I’m confused about that would need to be clear to have be able to confidently determine possible options as it relates to SD2’s dilimea.

I guess first thing to mention SD2 is where you said “I would love to end up with miscl storage or, better yet, OH2 where I can use QR and reduce my area.”; sure that would be great but unless you are looking to limit the type of storage that would not seem to be on the cards. Like you said it could well end up with mattresses and upholstered furniture, etc. so would seem beyond OH2.

If that is the case then it would seem that the best case scenario would be able to treat it as EH2 so that you can use different K-Factor sprinklers so that you’re not over discharging in some of the small compartments. The worse scenario is if you have to treat the calculation in full compliance with the High Piled storage criteria including the minimum K-Factors for density, as this will lead to large amount of water flowing in the small compartments if you are mandated to use large K-Factors.

So, some of the aspects that I’m confused on…

Definition of High-Piled Storages is in 3.3.95 which says “Solid-piled, palletized, rack storage, bin box, and shelf storage in excess of 12ft in height.”.

Given the height of SD2’s building and the required clearance from sprinkler to storage it would seem that keeping the storage below 12ft would be expected/acceptable. So by the definition of High-Piled Storage, we’re not that.

Definition of Low-Piled Storage is in 3.3.118 which says “Solid-piled, palletized, rack storage, bin box and shelf storage up to 12ft in height.”. That seems to be what we’d be falling into for SD2’s case.

4.3.1.7 is “Protection Criteria for Miscellaneous and Low-Piled Storage.
4.3.1.7.1 The protection criteria for miscellaneous and low-piled storage protected by ceiling sprinklers only shall be selected from Table 4.3.1.7.1 and Figure 19.3.3.1.1. in accordance with the density/area method of 19.3.3.2.

Table 4.3.1.7.1 has Exposed, Expanded up to 12ft storage height in 15ft ceiling as being EH2.
Chapter 20 (General Requirements for Storage) section 20.1.1 says “Miscellaneous and low-piled storage, meeting the criteria of Chapter 4, shall be protected in accordance with the relative occupancy hazard criteria reference in that section”.

So I would have thought that should have been the end to it. You’d protect as a EH2 occupancy and not be subject to the K Factors being determined by what the density is as you would be for High Piled storage. However what I find interesting and is confusing me is:
Chapter 21 is called “Protection of High Piled Storage Using Control Mode Density Area (CMDA) Sprinklers. The fact that it’s got ‘High Piled Storage’ in the title of the chapter and by the definition in 3.3.95 that would be storage in excess of 12 ft it would seem that it would not apply. However in Chapter 21 Table 21.3.3 (a) Design Densities for Palletized, Solid-Piled, Bin Box or Shelf Storage of Group A Plastic Commodities, there is criteria for storage less than 12ft in height. If you had to comply with this section it would seem you’d have to use the minimum K-Factors dictated in Chapter 21. However if you were to protect as Low Piled Storage in 4.3.1.7.1 it would seem that you wouldn’t.

Why is there criteria for Low Piled Storage even in the High Piled storage chapter since there is already criteria provided in the Low Piled Storage section (Table 4.3.1.7.1 via section 4.3.1.7.1)? Can the user opt for either of these options? Must one take the worse case scenerio?

Will be interested to hear the thoughts of others in this regards.

 

[UFT12]

I like the restructure of edition 19 for the majority of the standard but I can't say the same for the storage chapters.

 

[SprinklerDesigner2]

What we have might not fit the definition of High-Piled Storages contained in 3.3.95 but it still is.

That is in Chapter 21 which makes it storage.

We all seen at least a little snippet of "Storage Wars" and the few I watched seemed to always have a mattress tucked in there along with some foam furniture.

I turned the job down today because if I can't be 100% sure about what I am doing I would rather not do it and I can assure someone in the competition will bid it OH2 and I just can't do that.