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Changes to the 2013 edition of NFPA 13
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Issue 63: Changes to the 2013 edition of NFPA 13

By Roland J. Huggins, P.E.

NFPA 13 – Installation of Sprinkler Systems, continues to evolve with the 2013. During development of the 2013 edition, the responsible committees addressed 606 proposals and 380 comments. As usual, the majority of the changes clarify issues, but there have been some very significant changes. This article will focus primary on changes that can affect the design of sprinkler systems.

3.3.18 The terms "continuous" and "non-continuous" have been used for many cycles to describe obstructions and the criteria to be applied. These terms now have definitions, with "continuous" being obstructions that affect two or more adjacent sprinklers. Although typically thought of as a single item, such as a duct, prior editions did identify in the annex (A. that even if the obstructions are not connected, but affect adjacent sprinklers, such as adjacent light fixtures, they are considered "continuous."

7.6 Only listed antifreeze solutions can now be used, except in listed ESFR sprinklers, where propylene glycol is permitted. Currently, there are no listed antifreeze products on the market. Although not an update for NFPA 13, a significant change occurred in NFPA 25 Inspection, Testing, and Maintenance of Water-based Systems; many existing antifreeze systems will require a risk analysis to remain in service (see ESFR sprinklers can be used with solid shelves if in-rack sprinklers are provided.

A. Residential sprinklers have always been allowed to be used in hallways, but restricted to hallways leading only to dwelling units. Residential sprinklers are now allowed in hallways leading to residential units and other uses, such as elevator lobbies and seating areas. There has been past confusion on whether residential and fast response spray sprinklers could be used within a single compartment. This was cleaned-up by deleting the legacy reference to fast response sprinklers. The allowance to omit sprinklers when a space is completely filled with insulation has been revised to permit a 2 inch (50 mm) air gap. This issue was initially added to the 2010 edition but only in The omission of protection for small bathrooms, which has been in the standard for all dwelling units for just over 20 years, is now allowed only for hotels and motels. and A.3.3.23 In buildings greater than two stories, every floor is considered an individual sprinkler system and must have a floor control valve assembly (with some exceptions). This assembly is still portrayed only in the Annex and only under the wet-pipe test connection section. Freeze protection can be omitted in areas that are below 40 ⁰F (4 ⁰C) but should not freeze if a heat loss calculation by a professional engineer confirms it will not freeze. It is explicitly stated that each floor of a high-rise shall have a waterflow device. Although this has always been understood, it was not explicitly required by NFPA 13. This will permit shared piping support to also support systems other than the sprinkler system if the supports are designed by an engineer.

11.1.7 & 12.1.4 Guidance is provide for High Volume Low Speed (HVLS) fans. It states that HVLS fans can be used in buildings protected by either control mode or ESFR systems when the following is applied:

  1. Fans shall have a maximum diameter of 24 ft (7.3 m).
  2. Fans shall be approximately centered between four adjacent sprinklers.
  3. The minimum vertical clearance to the sprinkler deflector is 3 ft (0.9 m).
  4. Fans shall be interlocked and shut down immediately upon receiving a signal from the alarm system. When using residential sprinklers and there’s a concealed, combustible space that is unprotected, the 2010 edition required remote area of 3,000 sf (280 m2). This was changed to 8 residential sprinklers so as to mimic the philosophy of doubling the initial size of the remote area. Early Suppression Fast Response (ESFR) and Control Mode Specific Application (CMSA) sprinklers designed to meet storage criteria can be used for light or ordinary hazard occupancies. This was previously permitted only for ordinary hazard occupancies, but was extended to light hazard in recognition that it makes little sense to remove these systems when a change of occupancy occurs.

12.8.6 Hose stream and duration has been expanded and is summarized by sprinkler type and size of remote area for CMDA sprinklers and by storage height for CMSA and ESFR sprinklers. The information was consolidated from chapters 12, 14, 15, 16, and 17. It now better reflects the expected performance of each system. For instance, previously chapter 16 required a 2 hour duration for both systems with a remote area of 25 or 30 sprinklers. The new duration for a 30 sprinkler design is now 2.5 hrs. The revision also addresses smaller areas, such as 1,200 sf (110 m2) for CMDA and fewer than 15 CMSA sprinklers that would apply using the room design method. For example, a CMSA design with less than 15 sprinkler now has a demand of 250 gpm (960 l) with a 60 minute duration. The protection of exposed, unexpanded Group A plastics when using spray sprinklers for rack storage up to 25 ft (7.6 m) was previously permitted only for cartoned commodities. This restriction did not apply to multiple row racks over 25 ft (7.6 m), which created confusion. This has been clarified, and new sections were added providing the needed criteria. It is interesting that the source this data was derived from was not used to also provide criteria for exposed expanded Group A plastics. That topic is the subject of a project within the Fire Protection Research Foundation.

New Chap. 21 Although this section’s title indicates it applies to alternative sprinkler designs for storage, it’s really just explicit guidance to the manufacturers and testing laboratories for developing guidance for specially listed sprinklers. It does, though, provide useful information for those pursuing an equivalency approach.

Deleted old When performing hydraulic calculations for ESFR systems and sprinklers that are located beneath obstructions, it is no longer required to include up to two additional sprinklers. & .5 How to hydraulically calculate small systems when they are less than the minimum required area (such as preaction systems for computer rooms and dry pipe or antifreeze system for loading docks) is now addressed. One effectively adds the additional water flow required for the full area based on the area/density curves without accounting for any discharge overage nor hose stream demand and adds it to the point of connection of the most remote branch line.

Table Historically, galvanized steel pipe for dry pipe systems has been assigned a C-value of 120. The C-value has been reduced to 100. A combined supply main can now be 4” (100 mm) instead of 6” (150 mm) without adding domestic demand to the hydraulic calculation. New annex text also confirms that the reason that the calculation for the larger pipe could ignore the domestic demand is that it is such a small fraction of the total flow that it doesn’t make a significant difference in the results. Unfortunately, the annex adds the ambiguous statement that if the domestic demand is considerable, it should be added to the calculation for 4" (100 mm) pipe. As a result of a problem with a previously marketed additive, biocides or corrosion inhibitors must be be compatible with system components and each other (since they are typically combined). The whole issue of compatibility is in a state of flux so there may be additional changes next cycle.

Roland Huggins is with the American Fire Sprinkler Association

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