## TABLE 21.3.2 Sprinkler Protection Criteria for Open-Frame Rack Storage of Class I Through Class IV

## TABLE 21.3.2 Sprinkler Protection Criteria for Open-Frame Rack Storage of Class I Through Class IV

(OP)

I have a job where the K35.2 (360) extended coverage heads just might be the answer but there is one thing I can not find... I know it's here and if it were a snake it'd bite me but I can't find it.

TABLE 21.3.2 Sprinkler Protection Criteria for Open-Frame Rack Storage of Class I Through Class IV and Cartoned Unexpanded Plastic Commodities

Ceiling height does not exceed 30' and I am looking at 6 heads discharging at 30 psi. For the calculations I discharge 3 sprinklers through 2 lines for a total of 6 heads?

How does that work with 8 sprinklers? Is it 4 heads on a line?

In the meantime I will continue looking because I know it is here somewhere.

Thank you all.

TABLE 21.3.2 Sprinkler Protection Criteria for Open-Frame Rack Storage of Class I Through Class IV and Cartoned Unexpanded Plastic Commodities

Ceiling height does not exceed 30' and I am looking at 6 heads discharging at 30 psi. For the calculations I discharge 3 sprinklers through 2 lines for a total of 6 heads?

How does that work with 8 sprinklers? Is it 4 heads on a line?

In the meantime I will continue looking because I know it is here somewhere.

Thank you all.

## RE: TABLE 21.3.2 Sprinkler Protection Criteria for Open-Frame Rack Storage of Class I Through Class IV

You take the max coverage per sprinkler allowed in the standard and multiply by the number of sprinklers required. You then do 1.2*sqrt(design area). This gives you the length along the branch line. You basically adjust from there.

16.2.2.3 Protection shall be provided as specified in Table 16.2.2.1 or appropriate NFPA standards in terms of minimum operating pressure and the number of sprinklers to be included in the design area.

The number of sprinklers in the design area is provided in Table 16.2.2.1; however, the table does not provide the arrangement (number of sprinklers to calculate on a branch line) for the design area. For this information, the user should go to 23.4.4.3 and calculate a design area by multiplying the number of sprinklers from Table 16.2.2.1 times the maximum allowable area of coverage per sprinkler from 8.11.2.2.1. The number of sprinklers on the branch line is calculated by multiplying 1.2 times the square root of this calculated design area.

For example, consider rack storage of Class IV commodities stored 25 ft (7.6 m) high in a 30 ft (9.1 m) high building (with noncombustible unobstructed ceiling construction) that is protected with a wet pipe sprinkler system using upright K-16.8 CMSA sprinklers. Table 16.2.2.1 would require 15 sprinklers in the design area, and Table 8.11.2.2.1 would allow 100 ft2 (9.3 m2) per sprinkler. Multiplying these two numbers gives the user an effective design area of 1500 ft2 (139 m2).

Per the requirement in 23.4.4.3, the user multiplies the square root of the effective design area by 1.2 to get the distance of the design area parallel to the branch line. In this case, that would be 46.5 ft (14.2 m). If the sprinklers are installed with 10 ft (3.0 m) between each sprinkler on the branch line, it would take five sprinklers to cover 46.5 ft (14.2 m). Therefore, five sprinklers would be needed on the most remote branch line, five sprinklers would be needed on the second most remote branch line, and five sprinklers would be needed on the third most remote branch line to make up the 15-sprinkler design area required by Table 16.2.2.1.

If the space is used for palletized storage of the same type and height of commodity storage, the allowable area per sprinkler from Table 8.11.2.2.1 will be 130 ft2 (12.1 m2) with an effective design area of 1950 ft2 (139 m2) and a resultant design area length of 53 ft (16.1 m). With the sprinklers again spaced at 10 ft (3.0 m) along the branch line, it would require only six sprinklers to cover the required 53 ft (16.1 m). For the 15-sprinkler design area, six sprinklers would be needed on the most remote branch line, six sprinklers would be needed on the second most remote branch line, and three sprinklers would be needed

on the third most remote branch line. For maximum flexibility in design and use of the space, it might be advisable to use the more conservative design application with the larger number of sprinklers along the branch line.

Travis Mack

MFP Design, LLC

www.mfpdesign.com

"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...

## RE: TABLE 21.3.2 Sprinkler Protection Criteria for Open-Frame Rack Storage of Class I Through Class IV

## RE: TABLE 21.3.2 Sprinkler Protection Criteria for Open-Frame Rack Storage of Class I Through Class IV

Travis Mack

MFP Design, LLC

www.mfpdesign.com

"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...