Sprinkler Criteria for Compact Mobile Shelves?

2/18/2021

Having trouble getting a good feel for fire sprinkler design criteria for compact, mobile storage shelves. These contain Class I-IV commodities. As I understand it, NFPA 13 only covers light hazard for compact shelving.

The metal shelves have a height of 8-feet, the ceiling height is 26-feet. The room is 3,000 sqft, and the shelves have a footprint within that space of 21 x 30 feet. Any help is appreciated.

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7 Comments

Dan Wilder

2/18/2021 08:32:55 am

Depending on what your current adopted standard is...

13-16' Table 13.2.1 if the storage is less than 10' (unlimited ceiling height) design criteria is only OH2 (.2/1500) is one approach (but not specific to "compact mobile" storage)

I do see Section 20.6 and that allows light hazard protection schemes specific to the conditions in that section. You could go with the OH2 approach as an alternate option with approval from your AHJ.

If your situation does not fall into those two categories, the design falls outside of 13 and will require a FPE provide options/review. Possibly utilize FM standards for moveable racks (they don't have anything specific to this last I checked)

You can request the download the archived NFPA report from 2008 or google "Compact Mobile Shelving System Fire Testing Project Final Report" to read. Summary was that fires were contained, but only to the extent of the metal encasements but the fire continued to burn within the array so not considered suppressed which is understandable with how these are built.

https://www.nfpa.org/News-and-Research/Data-research-and-tools/Suppression/Archived-reports---Suppression

Brian Gerdwagen FPE

2/18/2021 09:10:17 am

I'm getting hung-up on the "mobile" part. Do you mean this type of shelving?

https://info.kardex-remstar.com/us/vertical-carousel-module

FMDS 8-34. Protection criteria for automated storage and retrieval systems.

Dan Wilder

2/18/2021 09:29:02 am

More this setup is what I'm thinking...

https://bradfordsystems.com/high-density-mobile-storage/

Franck

2/18/2021 11:04:40 am

As indicated by Dan, by considering this as an OH Gr 2 based on NFPA 13 13.2.1 (!4.3.1.7.1 in 2019 Edition ), you are fine with cl IV and all classes of storage, from pile to shelves, from single to multiple row racks.
Your configuration is less than the worst in the list because the metallic shelves will prevent the fire from spreading from one row to another, eventhough, if no manual firefighting is implemented, you may burn everythin within one row.
Note that §20.5.2 (NFPA 19) define movable racks as multiple row racks for sprinkler protection.

Franck

2/18/2021 11:20:41 am

Otherwise, you are right, if you consider the same storage arrangement with a class III commodity, this is covered under §20.6 in NFPA 13 2016 (21.12 in NFPA 2019) and is considered as a Light hazard occupancy.
It is indicated in the annex that other storage (class IV or plastic, for example) are out of the scope of NFPA 13 and not covered by the standard. A case by case approach is then to be made and the one proposed by Dan seems the most resonable one in that case.
In NFPA handbook, it is indicated that if the same storage of class III products were stored in fixed racks (library stacks) then the required density would be OH Gr 2.
In other words, the movable rack storage arrangement is less problematic than fixed record storage racks or library stacks.

Jesse

2/18/2021 11:37:09 am

A Class-IV Commodity stored to 8-ft is protected as OH-2 in any arrangement

Arnold Wilkins

2/18/2021 12:50:15 pm

The compact storage shelving I have been seeing lately is similar to this link.

https://www.youtube.com/watch?v=cbs_7jhcEa4

Here is my thought process. Please let me know if I am missing something. The following is from 2016 ed. of NFPA 13.
Section 13.1.1(5) - Storage Class I-IV.... as directed by 14.2.3.1 and 16.2.1.2.

Section 14.2.3.1 does not cover multiple-row racks.
Section 16.2.1.2 kicks you back to 13.2.1.

Section 16.2.1.2.3 is for 12 ft or less that does NOT meet definition of Miscellaneous storage. States it shall be protected with in-rack sprinklers.

If in-racks are the only option then maybe look at something like a Metraflex seismic joint.

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