Did Removed ESFR Design Criteria Fail Testing?

7/26/2023

The 2016 and 2019 standards are allowing ESFR designs that the 2022 standard does not.

For example: A warehouse with a ceiling at 35-ft. Group A Unexpanded Exposed on floor probably to 20-ft.

Sprinkler design is ESFR, (12) K16.8 pendents @ 52 psi. This was okay in 2016 and 2019, but now, 2022 does not allow for this.

Does this mean they completed tests that show this 12@52 K-16.8 WILL NOT work?

Is there fire testing to prove this?

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8 Comments

Josh

7/26/2023 08:18:56 am

I'm not sure I follow. Table 20.17.1.2(c) shows the options for ESFR for storage and has the 30' ceiling height would put you solidly in the 25.2 k-factor range. There are heights where there are only a few options though.

Jesse

7/26/2023 08:26:10 am

Great question. I'm on 3 NFPA committees but not 13. I've reached out to a buddy of mine that is to see if I can get an idea.

Years ago, I was at a symposium discussing this, or rather the design curves for Commodity Storage. I was surprised to learn how much testing was done, or rather how much wasn't done. I had figured that every point on every design curve had fire testing to support it. There was obviously testing that went on, but a lot of of design curve data was extrapolated.

If I find out why I'll follow up here

Casey Milhorn

7/26/2023 08:56:29 am

I'm curious as well. There has definitely been a push for larger K factor ESFRs over the last decade, protecting a broader range of storage heights. Might be some pressure from manufacturers as well to gravitate towards K22.4 and larger due to lack of sales in the smaller sizes.

Pete H

7/26/2023 09:01:23 am

My best guess:

Table 23.3.1 (2022 edition) for ESFR design no longer separates storage protection by storage height. Just by maximum ceiling/roof height. And for ceiling/roof heights that go up to 40 ft and 45 ft ceilings.

Whereas table 15.4.1 (2016 edition) storage heights is the main controller to maximum ceiling heights, but the maximum ceiling heights for exposed unexpanded plastics caps at 40 ft instead of 45 ft.

---

I imagine maximum storage height part was taken out of the code for this section because it's becoming too often that warehouses "keep it to x storage height at installation and at expected fire marshal review, it's the wild west every other day of the years." But I'm basing that on nothing

Glenn Berger (for Renee)

7/26/2023 09:07:39 am

The SFPE has had some presentations from FM on sprinklers for storage systems. I recommend checking out information at their website.

Chuck

7/26/2023 09:41:53 am

My understanding is, part of the k-16.8 approval was based on tests conducted on the k-14 head which later proved to be inaccurate. So, when they constricted the k-14 designs, the k-16.8 was caught in the revision.

Dan Wilder

7/26/2023 09:55:51 am

The FM Global report on the ESFR testing
https://www.fmglobal.com/research-and-resources/standards-and-certification/-/media/32D2C5A91AD840B196E96E53701FBA69.ashx

or if that doesn't work (it's a direct link for download), it's at teh bottom of this page

https://www.fmglobal.com/research-and-resources/standards-and-certification/code-support-reports

Some commentary:

From
https://risklogic.com/notable-changes-in-nfpa-13-2022-edition/

Chapter 23 “ESFR Requirements for Storage Applications” has been updated with new design requirements for ESFR protection for some storage arrangements. An example of this is rack storage of uncartoned (exposed) unexpanded (non-foam) plastics. The example below compares the requirements for ESFR protection of 20 ft. high rack storage of uncartoned unexpanded plastic under a 35 ft. roof. Under the 2019 Edition, this storage can be protected with either K14 or K16.8 sprinklers operating at 75 psi and 52 psi respectively. Under the 2022 Edition, this same storage cannot be protected by either K14 or K16.8 sprinklers. One will also notice the 2022 table does not include the storage height only the roof height. Thus, for our 20 ft. high storage under a 35 ft. roof, one would have to use the criteria for a 40 ft. high roof and utilize K22.4 or K25.2 sprinklers operating at 75 psi and 60 psi respectively. These new criteria more closely track with FM Global Data Sheet 8-9 requirements (also shown below).

Franck

7/26/2023 01:46:06 pm

I had (alsmost) a similar issue a few weeks ago.
Warehouse designed for K14 ESFR to a ceiling height that was previously allowed and that is now in the NA (not applicable) category per NFPA 13.

I was anyway not too concerned for the following reasons:
- the design was still acceptable per FM 8.9 (this was for cartoned unexpanded plastic)
- the delivered density was roughly the same as with larger K-factor (a K14 at 75 psi delivers 121 gpm, K16.8 at 52 psi delivers 121 gpm and a K22.4 at 29 psi delivers 118 gpm - note that NFPA requires 40 psi when FM ask for 29 psi).

This means that we (my company, as an insurance company) accepted the situation, considering it as "acceptable" and not "adequate".
The design is not in adequacy with NFPA 13, but still in line with FM Global data sheet 8.9.

But in this case, if the commodity classification is exposed unexpanded plastic, there is no back up solution from FM (they require K22.4 at 75 psi. for rack storage, and even k25.2 at 75 psi for pile storage...).
And the required delivered flow is much higher (respectively 194 gpm and 218 gpm compared to 121 gpm with K16.8 @52 psi...).
Because of that, I would be very cautious and probably recommend to retrofi the ceiling sprinkler protection to be in line with the latest NFPA requirements.

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Did Removed ESFR Design Criteria Fail Testing?

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