Summary
The Article delves into NFPA standards, breaking down the technical components of fire protection systems. It discusses subtleties such as the “Single-Point Density Table” in NFPA 13 (2022), stressing defined default densities and hazard classification zones. It defines the “Order of Design Area Reductions,” emphasizing the need to satisfy minimal changes to area restrictions. It also discusses the “Multiple Adjustments Remote Area in Extra Hazard,” outlining NFPA 13 (2019) constraints on combining area adjustments for specific sprinkler types. The need for a waterflow switch in hybrid systems, storage regulations in fire pump rooms, and the complex criteria for restraining strap installation per NFPA 13 (2016) are all discussed. It provides in-depth knowledge of NFPA regulations, ensuring clarity and compliance with fire safety measures.
The 3,000-square-foot design area applies only where a sprinklered space is adjacent to a non-sprinklered concealed space (as defined in Section 19.2.3.1.5). That is why each of the hazard classifications has an asterisk after the 3,000-design area.
To address the case, the default in Table 19.2.3.1.1 for an ordinary hazard group 1 design is 0.15 gpm/sq ft across a 1,500 sq ft area. If Section 19.2.3.1.5 applies (unsprinklered combustible concealed spaces), the designer shall employ a density of 0.12 gpm/sq ft over 3,000 sq ft. Only when a sprinklered space is adjacent to a combustible concealed space does the 3,000 sq. ft. design area apply.
The final design area differs depending on the order in which these alterations are made. Over 2,500 square feet, the starting density/area is 0.3 gpm/sq ft, with two options:
Starting with.3/2500, add 30% for dry system and 25% for HT sprinklers for a total area of 2,437 sq ft.
Alternatively, starting at.3/2500, reverse it. Reduce HT sprinklers by 25% but not below 2,000 sq ft, then add 30% for dry system, which is 2,600 sq ft.
Question 2. Which method from the above is the proper one?
Ans. The order in which concurrent adjustments to the area of system operation are implemented is unimportant as long as the ultimate minimum area limitation of 2,000 sq ft for extra-hazard occupancies with high-temperature sprinklers is fulfilled. When numerous alterations are made, the 2,000-square-foot limitation is imposed after the other changes are made.
The final area in the mentioned example would be 2,437.5 sq ft, with a density of 0.3 gpm/sq ft.
2,500 x 1.3 x 0.75 = 2,437.5 square feet, or 2,500 x 0.75 x 1.3 = 2,437.5 square feet
Although NFPA 13 (2022) does not address this expressly for extra-hazard occupancies with high-temperature sprinklers (Section 19.2.3.2.6), it is analogous to applying the 3,000-square-foot minimum area of sprinkler operation where certain unsprinkled combustible concealed spaces exist.
According to Section 19.2.3.2.8.2, the 3,000 square foot minimum area limitation for unsprinkled concealed spaces applies “after all other modifications have been made.”
It should also be noted that for Extra Hazard occupancies using K-11.2 sprinklers, the design area can be reduced by 25% but not less than 2,000 sq ft; however, this reduction cannot be combined with the other area of operation changes.
Ans. No, according to the 2019 edition of NFPA 13, Section 19.3.3.2.7 area of operation adjustment for K=11.2 or bigger sprinklers is not relevant to Section 19.3.3.2.8.1 for multiple adjustments and thus cannot be combined with other adjustments.
If changes need to be made to the area of operation more than once because of 19.3.3.2.3, 19.3.3.2.4, 19.3.3.2.5, or 19.3.3.2.6, these changes must be added together based on the area of operation that was chosen in the first place from Figure 19.3.3.1.1. This excludes Section 19.3.3.2.7.
For sprinklers with a K factor of 11.2 or more, Section 19.3.3.2.8 does not include or refer to Section 19.3.3.2.7. This means that the area of operation adjustment from Section 19.3.3.2.7 for larger K factor sprinklers can not be added to the original area of operation. It can still be utilized and applied when sprinklers have a K factor of 11.2 or above; however, it cannot be combined with the other area of operation changes described in Sections 19.3.3.2.3, 19.3.3.2.4, 19.3.3.2.5, or 19.3.3.2.6.
The standard’s aim is to allow for a 25% area decrease for either high-temperature-rated sprinklers or sprinklers with a K factor of 11.2 or more, but not both.
Question 4. Is a waterflow switch necessary at the main riser into the building on a hybrid manual wet standpipe/wet sprinkler system riser?
Ans. No, with a combined manual wet standpipe/automatic fire sprinkler system, a “standpipe-specific” waterflow mechanism is not necessary.
Section 5.6.1 of the NFPA 14 Standard for the Installation of Standpipes and Hose Systems was changed in the 2019 edition to help explain the requirements for waterflow and supervisory alarms.
The substantiation for Public Input No. 26 clarified that a manual wet standpipe in a combined system would already be required to contain a waterflow alarm device as part of the combined system’s fire sprinkler section. This eliminates the requirement for a separate waterflow mechanism to be put on the manual wet standpipe or main riser.
Question 5. Is it permissible to place storage or equipment that is not required for the operation of the fire pump within a fire pump room?
Answer- The fire pump chamber may only contain equipment related to the fire suppression system and the fire pump. The only exception is residential water service equipment for that building. It should be noted that this allowance does not include anything that could cause additional dangers, such as a hot water heater. (See Section 4.14.1.1.6 and its appendix.)
For whatever reason, storage is not permitted in the fire pump chamber.
According to the Automatic Sprinkler Handbook (2016), Exhibit 9.23, the straps must be tightly fitted to the beam.
Question 6. Is it necessary to fit the restraining strap to the beam?
Answer- No, NFPA 13 (2016 edition) does not require the restraining strap to be form fitted to the beam; instead, it must simply wrap around the beam flange at a 1-inch minimum. Later editions of the NFPA 13 handbook show examples of both straight restraining straps angled to the beam flange, where they then wrap around, and fitted restraining straps. The strap would only be required to be form fitted if the maker of the restraining strap specified such a requirement for installation. Excessive bending of the strap beyond the manufacturer’s specifications may weaken the strap, depending on the production and material factors.
Question 7. Is it legal to utilise high-polyethylene pipe with a standard dimension ratio of 11 as an underground service for a fire sprinkler system?
Answer- Yes. According to the cut sheet provided, HDPE water service pipe is constructed in accordance with ANSI/AWWA C906. NFPA 24 and NFPA 13 Table 10.1.1.1 (Manufacturing Standards for Underground Pipe) expressly permit AWWA C906 piping in this application.
This product is suitable for use as an underground supply for a fire sprinkler system. It is also FM-certified and NSF-61-designated as a lead-free, drinkable water supply.
Another factor to consider is that the underground pipe must be rated for maximum working pressure but must not be less than 150 psi.
Unless a municipal ordinance bans the use of C906, the minimum fire sprinkler standards, NFPA 24 and NFPA 13, stipulate that it can be utilized.
Question 8. It appears that the flammable requirements only apply to the 12-inch to 18-inch requirement. Is this correct?
Answer- Yes, the 12 to 18-inch range applies only to noncombustible and limited-combustible ceilings. The 6 to 12 inch range applies to all ceiling types. If this section applied to all types of ceilings, it would simply specify a range of 6 to 18 inches. It should be noted that the obligation to list the sprinkler for that distance still applies to all ceiling types.
A fire sprinkler system is required for a Type V structure, according to the 2016 edition of NFPA 13R. Over the entryway is a flammable canopy that leads to a common space.
Question 10. Is it necessary to install sprinklers under this entry canopy in accordance with NFPA 13R, or the International Building Code?
Answer- No, the International Building Code (IBC) and NFPA 13R only require protection when the covered balcony, deck, or patio is directly attached to and serves the dwelling unit. “Sprinklers shall be provided to exterior balconies, decks, and ground floor patios of dwelling or sleeping units,” states IBC Section 903.3.1.2.1. Section 6.6.5 of NFPA 13R (2016) contains comparable criteria.
Because it is not immediately connected to the housing or sleeping unit, the roof over the main entrance door does not require a sprinkler.
It should be emphasized that the notion of a flat ceiling differs from that of a horizontal ceiling; a flat ceiling is merely one on a single plane that can be sloped. (For more information, see Section 3.3.5.1). Furthermore, according to the 2013 edition of NFPA 13, a smooth ceiling means “a continuous ceiling free from significant irregularities, lumps, or indentations.” The word significant was defined as “greater than 4 inches in depth” in the 2022 edition of NFPA 13. (See Section 3.3.28.4 of the NFPA 13 2022 version.)
Because the specified slope of the ceiling exceeds 2 in 12, extended coverage (pendent or upright) sprinklers must be particularly listed (per 8.4.3 (4)); nevertheless, the slope cannot exceed 4 in 12, and the unobstructed ceiling must be regarded as flat and smooth. (See preceding paragraph.)
It should also be noted that the mentioned extended coverage sidewall sprinklers are permissible if they are installed at the “high point of the slope and positioned to discharge downward along the slope.”
Courtesy: Roland ASP, CET NFSA Technotes (Best of Sept 2023)
