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In a few months, a new edition of NFPA 13, the 2016 edition, will be available. There were a few NITMAMS at the NFPA Technical Session in Chicago this past June. But, those have been dealt with and the way is clear for approval by the NFPA Standards Council. The document will be available sometime this fall.
In this column, I will touch on what I feel are pertinent changes to NFPA 13. There are several significant and useful changes. I will touch on what I feel are the more important and interesting items. Many of the changes are related to storage protection.
The bulk of the material for this column is “borrowed” from a presentation at the NFPA Conference in Chicago given by James Golinveaux, of Tyco; Matt Klaus, of NFPA; and William Koffel, of Koffel Associates.
3.6.4 New definition for Control Mode Density/Area (CMDA) Sprinkler
The term was introduced in the 2013 edition without a definition. In the 2016 edition, it is defined as, "A type of spray sprinkler intended to provide fire control in storage applications using the design density/area criteria described in this standard."
126.96.36.199 definition for Available Height for
The committee felt the definition was not needed since this term is not used elsewhere in NFPA 13 and the guidance in Annex A.4.3 addresses the issue. I believe the original intent of this definition was to get a requirement into NFPA 13 that called for storage sprinkler design to be based on the maximum height of storage that the building can accommodate.
This has been a problem with spec warehouses that had high ceilings but were getting building permits with minimum sprinkler designs for Ordinary Hazard Group II. I understand that definitions in NFPA documents are not supposed to include requirements. So, you enforcers that want to avoid having buildings like this being built in your jurisdictions may want to submit a change to NFPA 13 for the 2019 edition.
Definitions for 188.8.131.52.9 Solid Shelf Rack, 184.108.40.206 Solid Shelving modified
In 220.127.116.11.9 a rack is also now considered a solid shelf rack if it cannot meet the definition of an open rack. 18.104.22.168 now indicates that the placement of loads on the rack must be considered in determining whether or not one has solid shelving.
The changes along with the new paragraphs 22.214.171.124 & A126.96.36.199 and 188.8.131.52 & A.184.108.40.206 (see below) will result in fewer racks being classified as open rack and thus, more in-rack sprinklers.
Changes to Section 220.127.116.11 Commodity Classification
These changes are intended to assist the designer to more accurately classify the type of commodity. New paragraph 18.104.22.168.1 clarifies that the classification of a commodity includes the packaging and the pallet.
The definition for Class III commodities has been revised to address the differences between expanded plastics (5 percent or less of unexpanded plastics by weight or 5 percent or less of expanded plastics by volume).
The definition for Class IV commodities has been modified to address the difference between expanded and unexpanded plastics, as well as several other storage configurations.
A requirement to classify Group A plastics as either expanded or unexpanded has been introduced. A definition of expanded plastics has been added, and an extensive definition for exposed, expanded plastics has been added.
These revised definitions also introduce two new figures which are intended to graphically illustrate the percentages of plastics, both unexpanded and expanded. There is one figure for commodities in cartons or wooden containers and one figure for exposed commodities.
12.3 Adjacent Hazards
Where hazards are separated by a draft curtain or barrier, language has been added requiring the draft curtain or barrier be located above an aisle and at least 2 feet horizontally from either hazard on each side.
22.214.171.124, 126.96.36.199, and 188.8.131.52
When ESFR, quick response CMSA, or standard response CMSA sprinklers are used in the context of storage in Chapters 12 and 14 through 20, in addition to being permitted to be used to protect
Light hazard occupancies (quick response only) and ordinary hazard occupancies present in the area, it has been clarified that they may also be used to protect any storage arrangement in Chapter 13 Miscellaneous Storage, based on ordinary or extra hazard design criteria.
Chapter 13 renamed, 'Protection of Miscellaneous and Low-Piled Storage'
The list from paragraph 13.2.1 of the 2013 edition has been moved to new paragraph 13.1.1 to become the Chapter 13 applicability criteria. These changes recognize that there are cases where the criteria of Chapter 13 can be used even if the storage is not defined as miscellaneous storage.
184.108.40.206, A220.127.116.11, 18.104.22.168 and A.22.214.171.124 These new sections appear to have been added to warn us that the design criteria in Chapters 16 and 17 is based on an open rack and that the designer better get it right when determining whether the rack is truly open-rack or not.
126.96.36.199 and 188.8.131.52 Alternative Protection
This section contains design criteria in the case where pockets of a higher hazard commodity are introduced into a rack system protected with ceiling only sprinklers designed for the more common less hazardous commodity. This permits these pockets to be protected using a combination of horizontal or vertical barriers and enhanced in-rack sprinkler protection, without forcing modification of the ceiling sprinkler system.
184.108.40.206.3 and 220.127.116.11.1
Clarifies that for storage in racks less than 12 feet (Chapter 16) or 5 feet (Chapter 17) with solid shelves that do not qualify as miscellaneous storage, in-rack sprinklers are required below the solid shelving.
In previous editions of NFPA 13, there was no protection criteria for the protection of Exposed Expanded Group A plastics stored in-rack. As a result of research conducted by the Fire Protection Research Foundation, Section 18.104.22.168 (for storage up to 25 feet) and Section 22.214.171.124 (for storage over 25 feet) now include design criteria for protection of this commodity storage arrangement.
23.5 was modified to remove the term “Computer Generated” to clarify that hydraulic calculations are not required to be done by computer.
126.96.36.199 summary sheet
The information required on the hydraulic calculation summary sheet has been increased to be consistent with industry practice and the requirements of several AHJ plan reviewers.
This addition notes that velocity of pipe flow shall not be limited provided such a limitation is not required by other NFPA standards (NFPA 15 and 20 for example) and as long as the hydraulic calculations are based on either the Hazen-Williams or Darcy Weisbach formulas.
A helpful annex note was provided for this new paragraph which states:
"A.188.8.131.52 NFPA 13 does not provide a specific velocity limitation for the use of the Hazen-Williams formula."
This is, in part, due to an expectation that excessive friction loss values will result in increasing pipe sizes, thereby serving as an inherent limit on velocity. However, the fact that NFPA 13 does not provide a specific limit should not be taken as an endorsement that the formula can be used for any velocity of water flow.
The formula was empirically determined using "normal" conditions. When the velocity in the pipe exceeds that which was used to determine the formula, the formula might no longer be valid. There has been some research performed (Huggins 1996) in which results using the Hazen-Williams formula and the Darcy-Weisbach formula were compared, and the conclusion was that a specific velocity limit applied to all pipe sizes is not appropriate.
23.4.5 and 23.4.6
This new section clarifies that in-rack sprinklers must be hydraulically designed when part of a calculated system and that the demand must be added to ceiling sprinkler design at the point of connection and balanced to higher pressure. The same text was included in 23.5 dealing with pipe schedule systems but was not included in the section for calculated systems.
Similarly 23.4.6 has been added to indicate where the location to include the hose allowance is to be applied. The same text was included in 23.6 dealing with pipe schedule systems but was not included in the section for calculated systems.
Next month, we will look at the changes contained in the upcoming 2016 editions of 13R and 13D.
Please note that none of this information is official until it is published so proceed with caution.
Samuel S. Dannaway, P.E., is a registered fire protection engineer and mechanical engineer with bachelor’s and master’s degrees from the University of Maryland Department of Fire Protection Engineering. He is past president and a Fellow of the Society of Fire Protection Engineers. He is president of S. S. Dannaway Associates Inc., a 15-person fire protection engineering firm with offices in Honolulu and Guam. He can be reached via email at SDannaway@ssdafire.com.