Minimum Pressure for ESFR at Low-Pile Storage?

8/23/2023

When using ESFR sprinklers to protect a low-piled storage/miscellaneous storage that is equivalent to an OH2 curve: what minimum operating pressure for the sprinkler do you use?

Do you just go by the nearest chart in the later storage chapters and go with the closest to your situation (so like 35 for a K16.8 and 15 psi for a K22)?

Or do you just go with 7 psi like you do a standard sprinkler?

The listings do not specify a minimum operating pressure except to say "per NFPA 13". Code references are always appreciated. Thank you for your time.

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3 Comments

Dan Wilder

8/23/2023 08:27:02 am

Is the configuration going to be used for higher storage in the future? This seems drastically more difficult and limiting for design and installation using ESFR vs a CMDA type sprinkler for this protection scheme.

Most of these sections only reference back to Density/Area Methods for protection schemes so there is no direct correlation between the Density/Area & ESFR/K-Factor/Minimum Pressure.. I'm not super versed in this type of arrangement so hoping I learn a little

4.3.1.5 - Low-Piled Storage
4.3.1.7.2 - Protection of Low-Piled Storage
4.3.1.7.1.1 - Discharge Criteria Table
If it references 19.2.3.1.1, this is the Density/Area Curves so no ESFR option.

If it goes to 20.19 - Racks with Solid Shelves, this will require protection under each level per Chapter 25

If it references out to Chapter 25, there are some options, but I doubt any would provide an OH2 relation. Section 25.5 is all design options with in-rack protection with 25.5.4.1 providing minimum pressure/K-Factor options for ESFR and seem very much overkill for a low-piled storage configuration if it even applies at all.

All references to NFPA 13 - 22' Ed

Anthony

8/23/2023 10:12:26 am

Based on the referenced code below you could use any design criteria to meet the requirements of OH2. It begs the question why would you? As Dan also stated ESFR/CMSA is a vastly more restrictive method for protecting miss storage or other area. If you don't have to don't use ESFRs.

If you're asking what design density should be carried so say a loading dock area near storage? The answer is the same density as is designed for the racking next to the storage as a similar commodity will be in the process of loading and unloading. This way any reconfiguration of the space for more racks and less truck bays wont also come with a sprinkler redesign.

From NFPA 13-2016:
12.6.7.1 ESFR sprinklers designed to meet any criteria in Chapter 12 or Chapter 14 through Chapter 20 shall be permitted to protect any of the following:
(1) Light hazard occupancies
(2) Ordinary hazard occupancies
(3) Any storage arrangement in Chapter 13 referencingOH1, OH2, EH1, and EH2 design criteria

12.6.7.2 Quick-response CMSA sprinklers designed to meet any criteria in Chapter 12 or Chapter 14 through Chapter 20 shall be permitted to protect any of the following:
(1) Light hazard occupancies
(2) Ordinary hazard occupancies
(3) Any storage arrangement in Chapter 13 referencingOH1, OH2, EH1, and EH2 design criteria

Pete H

8/23/2023 11:09:06 am

So I was spec'd into ESFR's when I asked this question.

To answer myself (since I found an answer I found satisfactory enough) my ultimate take is:

Even when using an ESFR head to protect an OH2 equivalent occupancy, it has to be as to listed ESFR design parameters from the later storage chapters.

ESFR sprinklers designed to meet any criteria from chapter 12 through chapter 20 are acceptable for OH occupancies.

But if they're meeting the design criteria from Chapters 12-20, they're no longer going to be at 7 psi.

So you can do it, but you are going to be stuck with 15 psi.

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Minimum Pressure for ESFR at Low-Pile Storage?

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