NFPA #13-2013 Fig 17.2.1.2.1(b) "Storage 15 ft (4.6 m) in Height with Up to 10 ft (3.1 m) Clear

[SprinklerDesigner2]

I have a 40,000 sq ft warehouse for a rack storage of non-expanded Group A plastic most of which is cartoned but there is some that is exposed. I didn't take count but would estimate 20% to 30% is exposed.

Building measures 200'x200' having 25' bays and your typical bent metal purlin construction.

Eave is 19'-8 1/2", roof has 1 in 12 pitch which puts peak at exactly 28'-0 1'2" AFF.

Existing system designed 30 years ago for .17/2,000 using public water. Line from the city is 103' of 6" cement lined ductile iron. Riser is in the corner of the building.

Just ran a flow test this morning and obtained:

Static 62 psi
Residual 45 psi
Flow 1,163 gpm

For full flavor see photo below:

The recommendation letter from the insurance company reads "Plastics warehouses; at least of of the areas has a ceiling height of 22' and for rack storage 15' high in an area with a 22' ceiling NFPA 13 Chapter 17 Figure 17.2.1.2.1(b) requires either 1 level of in-racks with a ceiling density of .3/2000 or a ceiling density alone without in-racks of .6/2000."

The .6/2000 is clearly out but I can barely make it with .3/2000 with one row of 1/2" in rack sprinklers discharging at 15 psi minimum. By barely make it I have a pretty large grid and I am stuck with a 3 psi safety factor.

But given the clearance (13') I don't see where this is appropriate.

I am fairly new to using both the 2010 and 2013 editions of the standard so am I missing something here?

 

[stookeyfpe]

SD2

I am completely empathetic to what your scenario. I suggest a different approach and that is to apply Section 2304.2 of the Georgia Fire Code. This provision allows one to address the storage of high hazard commodities like expanded, exposed Group A Plastic by relocating the high-challenge commodity closer to the sprinkler riser and take advantage of the increased pipe diameters and reduction in friction loss to hopefully demonstrate adequate fire protection. Your challenge is a older sprinkler system that was never properly designed (the AHJ is not the sharpest tool in the wood shed for allowing a OH1 density for high piled combustible sotrage) and a lousy water supply.

You'll never get a 0.60 GPM/Sq.ft. discharge density and I appreciate that conclusion. My concern is the 10 foot clearance. High clearances impact the ability of the sprinkler droplets to penetrate the gases generated when these materials are burning. I beleive employing the cited IFC Section along with in-rack sprinklers will solve your commodity clearance issue and allow you to calcualte the system in such a manner that you'll achieve a higer factor of safety.

I deal with this weekly. Fortunately for me, my water utility is sensitive to fire flow issues in warehouses because we have destroyed a lot of wet noodles beating their engineers with our fire flow requirements. They understand we won't back off from higher fire flow values for areas of my town where warehouses are built. I've also been lucky that we've been fairly consistent in enforcing the IFC (and legacy Uniform Fire Code) by enforcing an ordinance provision that prescribes speculation warehouses be designed with sprinkler systems based on Class IV commodities.

 

[LCREP]

Insurance companies only follow NFPA you need a fire pump and ESFR system to satisfy the recommendation. Reach out to the carrier and let them know the clearance is 13' not 10' thus the referenced section of NFPA does not apply, what should you do. Since they are the AHJ and will want to review fire protection plans, anything you do you will need to make them happy. Remember your client can always change insurance carriers.

I work for an insurance company and deal with this stuff on a daily bases. The insurance rep that came out to the site did not pick up on the 13' clearance.

 

[SprinklerDesigner2]

Stookey, thanks that is pretty much what I figured but I needed to make sure.

LCREP, I feel I have a very good reputation around here and I mean to keep it. I the end the most valuable thing any of us has in our reputation.

I can not afford to be wrong which is why I sometimes wander in here to ask a question I already know the answer to, just to make sure. On complex issues I do what every technician should do and that is hire an FPE for the correct answer which is about the cheapest insurance a technician can purchase.

I don't know who the insurance people are, all I got was a fraction of an email but I will spell it out in my proposal.

 

[LCREP]

Sprinkler2

I was not saying you do not know what you are doing. Just the opposite the insurance company has no clue. The person they sent out did not know what they were doing and made a recommendation that does not meet NFPA. To save a lot of time I would get everyone in one room and explain the problem you have. Ask the insurance company what is the solution and or tell what you plan to do to meet NFPA. Once you get them to agree now you look like the expert ( which you are) to your client. Your client may not like the $$ he will have to pay, but at least he knows the $$ he spent will control or extinguish the fire.

Do not be surprised if in the meeting your client asks the insurance company what happens if he does not spend the $$ to upgrade the sprinkler system. Some insurance companies will not renew, some will just rate the building nonsprinklered and just get more $. Or he will ask his agent to have other insurance companies to provide a quote on his business. Some insurance companies do not have a loss prevention department and will just quote on past losses. Some insurance companies have folks that visit the site and as long as they see sprinklers they are happy. And some like the one I work for will pick up on the inadequate sprinkler protection and make a recommendation to upgrade the sprinkler system.

About 50% of the warehouses we look at the sprinkler protect is not adequate!

 

[SprinklerDesigner2]

I proposed a system designed per NFPA #13 (2010) TABLE 17.2.2.1 CMSA Sprinkler Design Criteria for Single-, Double-, and Multiple-Row Racks Without Solid Shelves of Plastics Commodities Stored Up and Including 25 ft (7.6 m) in Height. I am using the Tyco Ultra K17 Upright Control Mode Specific Application Sprinkler which is the first time I've used CMSA (used to be large drop) sprinklers in a long time.

15 sprinklers discharging at 22 psi with 500 gpm hose stream added on at the street. I will have to add a 1,000 gpm @ 75 psi pump.

But I am curious about something.

I understand why upright ESFR sprinklers can't be used to protect exposed group A plastic but upright ESFR can be used to protect cartoned group A plastic. It's the droplets penetrating the fire plume, I get that.

But why, when using K16.8 CMSA sprinklers, aisles are limited to a minimum of 8' over for cartoned but appear to not have this lower limit for uncartoned? Seems to me it would be the other way around but obviously someone did some testing and I am curious as to what was discovered.

Note: I am brand new to using the 2010 version so I may have missed something but I got all weekend to re-visit which I plan to do a number of times.

 

[cdafd]

Stookey has the answer

Guess carton as lower ignition temperature ?