NFPA 13 Figure 17.2.1.2.1(b) ? (Plastics Protection) 2

[arion]

Hi,

Figure 17.2.1.2.1(b) of the NFPA 13 shows in-rack sprinkler requirements for 0.60 gpm/ft^2 per 2000 ft^2 and 0.30 gpm/ft^2 per ft^2.

If I am analyzing an existing building that was designed for a 3,000 ft^2 design area, how can I find the equivalent gpm/ft^2 for this? Is it as easy as I think it is (as follows)?:

0.30 / 2000 = X / 3000
X = (0.30 (3000)) / 2000
X = 0.45 gpm/ft^2

FOLLOW-UP QUESTION:
If this is the case, and the flow is 0.45 gpm/ft^2, how am I supposed to analyze the existing building for it's actual design density/area, which is 0.33/3000 in the NFPA 13?

Does it mean that if your warehouse is designed at 0.33/3000, it is simply not able to adequately protect group A plastics?

Thanks!

 

[stookeyfpe]

Yes, as I understand your question. I'm assuming you're apply NFPA 13, 2010 edition.

 

[arion]

Hi Stookey, thanks for the reply. What are you saying yes to? That my calculation of 0.45/3000 is correct, or that my client is not able to house plastics with his existing system? Furthermore, what should I tell him he must do in this case? Have the sprinkler system redesigned and reinstalled to support plastics?? Most of his products are flammable/combustible liquids or plastics. The warehouse is small (~6600 sq. ft.) What are some possible options?

Thanks!

 

[stookeyfpe]

Yes, your calculation is correct.
Yes, the system currently does not meet the requirements in NFPA 13 for the storage of Group A plastics based on the Figure you cited. It appears you could make the system work if in-rack sprinklers are installed.

Sorry about my message not being more accurate.

Your latest e-mail introduced a new variable, and that's the storage of flammable and combustible liquids. These could drive a much greater density in comparison to Group A plastics. Depending on how the liquids are packaged, this becomes an even more complicated issue because the container's material of construction, liquid miscibility and its viscosity will need to be analyzed before one can apply the applicable NFPA 30 decision trees.

 

[arion]

Hi Stookey, thanks again for the clarification.

After looking in that section though, there does not seem to be any actual ceiling sprinkler system criteria... only in-rack sprinkler locations. Am I to assume it does not matter what the ceiling sprinkler system is designed to, since the in-rack sprinklers will be now solely responsible for managing a fire? There does not seem to be additional reference to the ceiling system itself, or even that it is ok to be below the minimum ceiling system design/density IF in-racks are installed.

 

[stookeyfpe]

Look closely at the right illustration in Figure 17.2.1.2.1 (b). The in-rack sprinkler protection requirements are based on a minimum discharge density of 0.30 GPM/sq.ft. with a 2,000 sq.ft. design area.

See Section 17.2.1.2.1 for additional guidance concerning the ceiling discharge density and area of operation requirements.

 

[pipesnpumps]

Arion,
I have been where you are,when I was advising my industrial client on potential use of existing industrial plants (for lease or purchase). It is a huge amount to consider. Go slow take your time. If the ceiling plus inracks are greater than available water supply consider a separate building, separated but unsprinklered, depending on insurance rates and local codes/ standards.. When I was doing this as a PE with 12 yrs experience I knew I was in over my head as far as knowledge of NFPA 13 and 30 (flamm combust liquids) so I called in the corporate expert. If you don't have anyone else to help be very cautious and thorough... I am concerned about the overlook of the ceiling sprinklers, of course this matters! Good luck and keep asking questions and learning.

 

[stookeyfpe]

Pipes and Pumps

As someone who has done dozens of flammable and combustible liquid sprinkler designs your words are very important. This is a very serious arena with some data: more in the private domain than in the public. Clients don't want to share this data.

I was responding to his plastics questions. However, when it comes to F&C liquids, jobs need to be specified with a supervising FPE, especially one who has a clear understanding of the many variables in protecting these high challenge commodities.

I understand what's required for this analysis. It's not inexpensive and worst, in many cases I find the packaging and liquids has never been tested. I've forced a lot of changes in packaging methods.

 

[arion]

Well, the more insightful you guys get, the more disheartened I get when imagining my immediate future! (haha) You're right. I will deliver this project to my FPE.

For the record, Table 3404.3.6.3(5) of the IFC says that I can only allow the client to store Class II liquids and below at .30/3000. In addition, in-rack sprinklers are required.

He's got quite a few Class 1A commodities as well. I have no idea what I'm going to say to him! Yikes.

Thanks for the knowledge, guys!