Sprinkler Type for Tires with Limited Clearance?

8/20/2024

We have a project that is a retail tire store. In the back, there is a Tire Storage Room with a mezzanine of open grate flooring that takes up the majority of the floor plan for the room. The top of the open grate flooring is roughly 10-ft and the top of the roof decking is about 11-ft above the mezzanine.

Tires are stored on racks on both levels.

I think that CMDA sprinklers are the only real solution here because of the clearance to storage requirements. But, if we tried to use CMDA or ESFR, the owner would have little usable storage height.

Can anyone think of another good solution?

We have FP plans as part of the bid documents, and they specified something that won't work, so we kicked back an RFI for clarity, but we thought it would make good discussion here.

5 Comments

Peter Howard

8/20/2024 06:49:35 am

If you're worried about storage height, I would say CMDA is your best shot as long as it's single row racks and you have the water to go extra hazard group 1 as per table 13.2.1 (NFPA 13 2016 edition).

Todd E Wyatt

8/20/2024 08:35:14 am

From NFPA 13-2019's "Enhanced Content" for 23.8 ESFR Protection of Rack Storage of Rubber Tires :

The criteria for rubber tire storage being protected with ESFR sprinklers can be found in Table 23.8. Note that the table contains protection for a wide range of storage arrangements, including laced tire storage, which is the most difficult tire arrangement to protect. In a laced tire array, one tire is set at an angle into the hole of a tire below it. Another tire is then inserted at a right angle to that one with its tread in the hole of the tire below it (see exhibit below). Because the tire above blocks sprinkler discharge to the tire below, the laced array is extremely challenging to protect. ESFR sprinklers can protect laced arrays, but the discharge must be increased from the typical 12 sprinklers to 20 sprinklers (five sprinklers on four branch lines) with a minimum design area of 1600 ft2 (149 m2). Unlike other commodities protected with ESFR sprinklers, a rubber tire storage fire is only controlled rather than suppressed.

The design criteria in Table 23.8 must be selected based on the variables in the first five main columns of the table: piling method, pile height, maximum building height, nominal K-factor, and orientation. The user selects the maximum pile height, which would include the proposed storage height for the facility, and checks to see if the proposed ceiling/roof deck height is within the allowable maximum permitted for that selection. If it is not, a higher ceiling/roof height selection must be made that is within the maximum allowed. The available sprinkler options can then be identified.

Todd E Wyatt

8/20/2024 08:39:26 am

From NFPA 13-2019's "Enhanced Content" for 21.6 Control Mode Density/Area Sprinkler Protection Criteria for Rack Storage Rubber Tires.

Before deciding to use the protection criteria in Section 21.6, the user must determine whether the storage can be considered miscellaneous tire storage. The definition for miscellaneous tire storage in 3.3.124 differentiates it from any other type of miscellaneous storage:

The storage of rubber tires that is incidental to the main use of the building; storage areas do not exceed 2000 ft2 (185 m2), and on-tread storage piles, regardless of storage method, do not exceed 25 ft (7.6 m) in the direction of the wheel holes. Acceptable storage arrangements include (a) on-floor, on-side storage up to 12 ft (3.7 m) high; (b) on-floor, on-tread storage up to 5 ft (1.5 m) high; (c) double-row or multirow fixed or portable rack storage on-side or on-tread up to 5 ft (1.5 m) high; (d) single-row fixed or portable rack storage on-side or on-tread up to 12 ft (3.7 m) high; and (e) laced tires in racks up to 5 ft (1.5 m) in height.

If the rubber tire storage meets this definition of miscellaneous tire storage, the user should follow 4.3.1.6.

The selection of protection criteria from Table 21.6.1(a) and Table 21.6.1(b) requires identification of the specific tire storage configuration to be protected.

Where the rubber tire storage is being protected with standard spray sprinklers using density/area criteria, the user can use either Table 21.6.1(a) or Table 21.6.1(b) within the bounds of the applicable storage arrangement and storage height permitted by each. Table 21.6.1(b) is referenced in Table 21.6.1(a) for the storage of tires on palletized portable racks and fixed rack storage from 5 ft (1.5 m) to 20 ft (6.1 m) with the tires on-side or on-tread and would be limited to such applications. In most cases, Table 21.6.1(a) and Table 21.6.1(b) provide the user with one density and one area (depending on whether ordinary- or high-temperature sprinklers at the ceiling are used). In some cases, however, the design is required to include a dual design criterion. In a few cases, the user is given some choices of sprinklers only at the ceiling, sprinklers at the ceiling in conjunction with in-rack sprinklers (see Chapter 25), or sprinklers at the ceiling with high-expansion foam.

Dan Wilder

8/20/2024 09:02:42 am

As to the storage height and clearance, running sprinklers down each row, and offsetting sprinklers between rows to avoid cold solder is one approach. The other is a baffle.

With the open grate mezz, you're looking at a total tire rack storage height above 12'. Have the owner lay down a solid horizontal barrier (either wood above or something under the grating) at the mezz level to split the heights up and get the density requirements down.

If they agree, this gets things down to a EH1, then use High Temp or 11.2K sprinklers for the area reduction to 2,000 FT².

Some discussion on the mezz separation
https://www.meyerfire.com/daily/does-a-mezzanine-change-ceiling-level-density

Jack G

8/20/2024 06:09:49 pm

oh 2 systems are not permitted for tire storage any more. NFPA 13 2022.
Miscellaneous storage for tires follows NFPA 13. 3.3.131*

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Sprinkler Type for Tires with Limited Clearance?

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