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NFPA Journal®, May/June 2012

By Matt Klaus

In June, a new edition of NFPA 13, Installation of Sprinkler Systems, will be presented at the Association Technical Meeting at NFPA’s Annual Conference & Expo in Las Vegas. The NFPA 13 technical committees have spent many hours reviewing hundreds of concepts and discussing their merits for inclusion, or elimination, from the next edition of the standard. The 2013 edition of NFPA 13, along with NFPA 13R, Installation of Sprinkler Systems in Residential Occupancies Up To and Including Four Stories in Height, and NFPA 13D, Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, contain a number of changes, some of which will be met with certified amending motions (CAMs) at the technical meeting. The following topics highlight just some of the issues in store for the new edition.

1. CPVC CompatibilityThe interaction between chlorinated polyvinyl chloride (CPVC) piping and hydrocarbon- or petroleum-based materials used in the installation of building systems has created a problem that has become more prevalent over the past five years. The issue comes down to a chemical incompatibility that is known to cause chemical stress fractures in the piping. These stress fractures can cause leaking pipes and, in some instances, failures at fittings and pipe connections. Examples of this incompatibility include the installation of CPVC pipe downstream of steel pipe that has been protected with antimicrobial coatings, and CPVC pipe that has come in contact with oils used for cutting steel pipe. The increased frequency of failures is linked to the increasing number of systems that combine CPVC with hydrocarbon- or petroleum-based materials or processes.

As this issue has developed, some CPVC pipe manufacturers have instituted compatibility programs to highlight materials that are known to be chemically incompatible with their products. While the presence of these programs and the lists of incompatible products have become an invaluable resource to the industry, NFPA 13 remained relatively silent on this issue in the 2007 and 2010 editions.

During the development of the 2013 edition, however, the Technical Committee for Sprinkler System Installation Criteria discussed the concept of compatibility and accepted new language aimed at addressing the issue. The new language requires that, where corrosion inhibitors are used in combination systems that include coated steel pipe and CPVC pipe, the coating must be tested for compatibility with CPVC. Furthermore, the new requirements state that when CPVC pipe is used in combination systems using steel pipe, cutting oils and lubricants used in the fabrication of the steel piping shall be compatible with CPVC materials. These changes are designed to provide guidance on two of the major culprits associated with chemical incompatibility failures in CPVC piping.

In addition to addressing the coatings and cutting oils, the technical committee added language requiring that other construction materials such as paint, electrical and communication wiring, thread sealant, and gasket lubricant shall not come in contact with CPVC unless they have been evaluated as being compatible with CPVC materials by a testing laboratory. This section is aimed at limiting potential failures from materials not yet known to be compatible with CPVC piping. The Technical Correlating Committee (TCC) for Automatic Sprinkler Systems acted to include this language in the 2013 edition of NFPA 13R, as well. Although this language was not accepted by the Technical Committee for Residential Sprinkler Systems, the TCC felt that the issue of compatibility needed to be the same in both NFPA 13 and NFPA 13R, as it is a “material issue” and would not vary whether the system was in a residential occupancy or not.

2. Antifreeze and Freeze Protection RequirementsThe tentative interim amendments (TIAs) that were approved by the Standards Council in March 2011 were reviewed by the technical committees responsible for NFPA 13, NFPA 13R, and NFPA 13D for inclusion in the 2013 editions of the standards. With the exception of a revised definition for premixed antifreeze solution, the requirements in the TIAs, including the antifreeze concentration limits and testing criteria, were accepted. Following the committee’s work in late 2011, the Fire Protection Research Foundation published a report discussing antifreeze use with standard spray sprinklers that cast new light on the antifreeze issue and may result in more changes by the technical committees before the release of the 2013 edition. (For more, see the “Antifreeze Update,” sidebar)

The concept of freeze protection did not end with the antifreeze discussion. The Technical Committee for Sprinkler System Installation Criteria also updated the language addressing electrical supervision of the heat tracing system, which must provide positive confirmation that the circuit is energized. This will ensure that where heat tracing is used, there is a means to visually confirm that the system is active. Another option that has historically been permitted as an equivalency by authorities having jurisdiction (AHJs) is the concept of using heat loss calculations to allow pipes in areas with ambient temperatures less than 40°F (4.4°C). NFPA 13 will now specifically permit water-filled piping to be installed in areas where the temperature is less than 40°F when heat loss calculations performed by a professional engineer verify that the system will not freeze.

3. Sprinkler Requirements for Elevator Hoistways and Elevator-Related SpacesSprinkler protection requirements for elevator hoistways and elevator machine rooms have never been correlated between the model building codes, life safety codes, elevator codes, and sprinkler design standards. The 2013 edition of NFPA 13, however, takes a large step towards getting these documents in harmony.

The new language allows fire sprinklers to be omitted from elevator machine rooms, elevator machinery spaces, control spaces, or hoistways of traction elevators where a number of conditions are met, including where the system is installed per NFPA 101®, Life Safety Code®, or the applicable building code; the space is dedicated to elevator-related equipment only; the space is protected by smoke detectors or automatic fire detection in accordance with NFPA 72®, National Fire Alarm and Signaling Code; the elevator machinery is not of the hydraulic type; the spaces are separated from the remainder of the building as specified in the applicable building code; and no materials unrelated to elevator equipment are stored in these spaces.

4. The Title of NFPA 13RWhile the early editions of NFPA 13R left the decision to the applicable building code to determine how the four-story limit was to be measured, a question remained as to what the committee had intended. Some would argue the intent of NFPA 13R has been to allow a four-story residential occupancy constructed above a non-combustible podium to use an NFPA 13R sprinkler system in lieu of the NFPA 13 sprinkler system. The idea of allowing a podium approach has often been rejected simply based on the title of the document, which as originally developed and interpreted has been assumed to set a limit of four stories to the entire building. This approach prohibited the use of a 13R sprinkler system in a four-story portion of a building that is constructed above a non-combustible podium.

To clarify this application, the Technical Committee for Residential Sprinkler Systems approved a recommendation to revise the title of NFPA 13R to “Standard for the Installation of Sprinkler Systems in Low-Rise Residential Occupancies.” This change provides a general description of the requirements outlined in the standard, while leaving the actual scope of the document to Section 1.1.

5. Sprinklers in Small BathroomsThe 2010 edition of NFPA 13 allows sprinklers to be omitted from dwelling unit bathrooms that are less than 55 square feet (5 square meters), are not located in limited-care facilities, or do not open on to a public corridor. The 2013 edition of NFPA 13 will see a significant change to that concept, as this allowance will now only apply to dwelling units in hotels and motels. Apartment buildings designed with NFPA 13 systems with bathrooms less than 55 square feet (5 square meters) must now have sprinkler protection where they were not required to do so in previous editions.

This is not a new concept for the sprinkler technical committees, since it was the subject of a CAM before the release of the 2010 edition of the standard. Similar language was accepted at the technical committee meeting, then rejected through CAM 13–6 at the Annual Technical Meeting in Chicago.

6. Shadow AreasIn addition to the many changes that were made in the sprinkler standards, a couple of concepts were discussed in great detail during the committee meetings that did not result in changes to the standards, one being the concept of shadow areas in NFPA 13.

Both the installation and residential committees reviewed several proposals and comments dealing with proposed definitions and requirements for allowable shadow areas, which are areas not covered by the spray pattern of a sprinkler due to the presence of obstructions. The proposals and comments were aimed at establishing an area limit for portions of the floor that are not covered by the sprinkler spray pattern due to obstructions.

This concept was handled differently by the technical committees responsible for NFPA 13 and NFPA 13R. In NFPA 13, there are multiple sprinkler obstruction rules in place, specifically the three- and four-times rules that provide spacing criteria from certain obstructions, which essentially allow dry areas where obstructions prevent sprinkler discharge from reaching certain areas of the floor. These obstruction rules prompted the technical committee to reject all the proposals that considered adding definitions for shadow areas, along with the proposed requirements citing specific permissible shadow areas for certain configurations.

NFPA 13R does not have the three- and four-times rules, and the technical committee found value in quantifying maximum allowable dry areas for sprinklers. In addition to a definition for a shadow area, the committee specified that shadow areas are permitted in the protection area of a sprinkler as long as they do not exceed 15 square feet (1.4 square meters) per sprinkler.

7. The Definition of “Sprinkler System”Most changes to definitions go largely unnoticed, but one amended definition in NFPA 13 may have a significant impact. The definition of a “sprinkler system” has been modified to describe a system as an integrated network of piping that includes a water supply source, a water control valve, a water flow alarm, and a drain. This means that, where individual floor control valves are used in multi-story buildings, each floor will be considered a separate system. This change will affect the inspecting, testing, and maintenance (ITM) requirements of NFPA 25, Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, as many ITM tasks require a specific action for each “system.”  

8. Backflow Preventer RequirementsAlthough backflow preventers are not specifically required by NFPA 13, NFPA 13R, or NFPA 13D, they are common components of sprinkler systems. The 2011 edition of NFPA 25 added a requirement to conduct a forward flow test on all backflow preventers installed in NFPA 13 and NFPA 13R systems, even though previous editions of NFPA 13 did not require the inclusion of a device to make this test possible. This loop will be closed in the 2013 edition of NFPA 13, which will require a test connection for all backflow prevention devices. In addition to this change, language has also been added to NFPA 13 and NFPA 13D that will allow the backflow preventer to serve as a system control valve without the need for an additional control valve to be installed.

9. New Storage Chapter
The 2013 edition of NFPA 13 will include a new storage chapter dedicated to performance-based protection approaches for storage applications. Although the authority having jurisdiction has always had the opportunity to approve a performance-based design approach through the equivalency clause in Section 1.5, it has never been clearly defined as to what must be submitted to support the approach. The new Chapter 21, “Alternative Sprinkler System Designs for Chapters 12 Through 20,” provides manufacturers and designers with the information necessary to implement an alternative design approach.

10. Sloped CeilingsNFPA’s residential sprinkler design standards have never clearly defined how to determine the appropriate number of sprinklers that need to be calculated under a sloped ceiling or a ceiling with beams. This has led to a range of opinions on how to handle these situations and has added to the challenges of implementing sprinkler system designs in occupancies with such ceilings.

In 2010, the Fire Protection Research Foundation sponsored a project conducted by Hughes Associates to determine if there was a way to better quantify the impact of these ceiling arrangements on system design. The information gathered in the study, Analysis of the Performance of Residential Sprinkler Systems with Sloped or Sloped and Beamed Ceilings, available at nfpa.org/foundation, was used to develop code language that provides five common ceiling arrangements that can use the “two-sprinkler hydraulic calculation” found in NFPA 13D and the “four-sprinkler hydraulic calculation” found in NFPA 13R without the need for each arrangement to be included in the listing for the sprinkler.

11. Water Mist SystemsOne of the common themes during the code-development process for the 2013 editions of NFPA 13, NFPA 13R, and NFPA 13D was whether water mist systems fit into the definition of an automatic sprinkler system. The sprinkler technical committees acknowledged the benefits of water mist systems, but determined that, due to differences in design intent and functionality, they cannot be considered automatic sprinklers.

Each of the standards added language to send users to NFPA 750, Water Mist Fire Protection Systems, which provides direction on these systems, as they do not fall under the scope of the NFPA 13 technical committees.

12. Cloud CeilingsAnother topic that has seen much debate over the years is sprinkler system design for cloud ceilings, which are “floating” ceiling panels installed below the main ceiling that do not make a complete wall-to-wall horizontal surface. Cloud ceilings are becoming more and more prevalent in architectural design, and many NFPA 13 users are looking for a specific section that addresses this concept.

While the Technical Committee for Sprinkler System Installation Criteria reviewed potential language addressing sprinkler protection for cloud ceilings, the concepts were not supported by full-scale testing and were not adopted into the standard. The use of the obstruction rules in Chapter 8 will continue to provide direction as to where sprinklers need to be provided where cloud ceilings exist. The Fire Protection Research Foundation is currently reviewing a proposal to conduct testing on cloud ceiling arrangements that would provide the committee with more data to consider when developing the next edition of the standard.

13. ESFR and CMSA SprinklersAnother loop closed in the 2013 edition of NFPA 13 surrounds the use of control mode specific application (CMSA) and early suppression fast response (ESFR) sprinklers in light- and ordinary-hazard occupancies.

The standard has never formally stated that these types of sprinklers are permitted in light- and ordinary-hazard occupancies, as they are typically associated with storage protection. This lack of clarity has led to debates in the field as to whether the omission of a declarative allowance of these devices in light- and ordinary-hazard occupancies was by design. This has been an increasingly common problem as buildings are being turned over, and fire and building officials require the new owners to replace existing ESFR and CMSA sprinklers with sprinklers more commonly associated with light-hazard occupancies (i.e., K-5.6) where the occupancy hazard is being reclassified to light- and ordinary-hazards. The ESFR and CMSA sprinklers will easily meet the density requirements required for light- and ordinary-hazard occupancies and will now be explicitly permitted to protect these areas.