This standard shall cover the design and installation of automatic sprinkler systems for protection against fire hazards in residential occupancies up to and including four stories in height in buildings not exceeding 60 ft 18 m in height above grade plane. The height of a building above grade plane is determined by model building codes, which base the height on the average height of the highest roof surface above grade plane. For further information on the building height story limits, see model building codes. It is the intent of this standard that if NFPA13R is appropriate for use, it be used throughout the entire building.
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Email Over the past few decades, building, fire, and life safety codes have been forced to continuously adapt to changing architectural trends. While smoke control systems are required to be provided in certain situations, they are sometimes provided as an alternative to having to comply with other requirements, usually for aesthetic or financial reasons. As the prevalence of design features such as large open spaces and open corridors without vestibules continues to increase, so do the number of new smoke control system installations and, consequently, the need for experienced individuals who understand and know how to correctly apply the applicable codes and standards.
NFPA Standard for Smoke Control Systems is a standard published by the NFPA that provides requirements, recommendations, and guidance regarding the design, installation, acceptance testing, operation, and ongoing periodic testing of smoke control systems. These two were maintained as separate documents from until The NFPA Technical Committee on Smoke Management Systems then decided to combine the two into a single document, in part to remediate the use of confusing terminology and duplicate provisions.
Chapters one through three cover the typical NFPA standardized introductory topics: Administration scope, purpose, retroactivity, and units , Referenced Publications, and Definitions, respectively. Chapter 4, Design Fundamentals, contains exactly what the title implies, the fundamentals of smoke control design.
The chapter walks users through a logical design process, which first involves selecting the desired smoke control method or methods to be used based on the selection of the specific design objectives.
The ideal smoke control method for a particular application depends on the desired design objectives, four of which are listed in Section 4. Three additional objectives are listed in Annex A and include providing increased visibility for fire department personnel, limiting the spread of toxic gases, and limiting the spread of combustion products to protect building contents.
These are sometimes referred to as secondary objectives because, like anything contained in the Annex of an NFPA code or standard, they are not part of the mandatory requirements unless adopted so by the authority having jurisdiction AHJ.
For example, a system designed to maintain the smoke layer interface at a predetermined elevation will usually meet all three of these objectives to some extent or for some specified period of time.
As you may have already guessed, the hierarchy of terminology used in this chapter is often misunderstood and misrepresented. These approaches, along with the smoke management system approaches, are contained in Figure 1, which should help to clarify the major design terminology used in NFPA Criteria for smoke control systems Chapter 4 also contains several design requirements and criteria for smoke control systems.
You may wonder why the chapter is not simply divided into two sections, one containing criteria and requirements regarding smoke containment systems and the other regarding smoke management systems. This is due to the fact that a large number of the requirements and criteria apply to all systems, regardless of which smoke control method is used.
For example, Section 4. This criterion applies to both smoke containment systems such as those that use the stair pressurization approach, and smoke management systems such as those that utilize mechanical exhaust within large-volume spaces.
Section 4. Power may be transferred to exhaust or pressurization fans, while at the same time, HVAC units may be shut down and dampers or vents may be opened or closed. Regardless of the components that are used as part of a particular system design, Section 4.
The calculation of the system start-up time requires consideration of a number of factors in accordance with Section 4. One of the primary reasons this requirement is contained in the standard is to ensure that the designer does not simply overlook these time delays as doing so could have a negative impact on the ability of the system to operate effectively in meeting the design objectives.
While these and other requirements apply to all smoke control systems, NFPA 92 also contains some requirements and criteria that apply exclusively to either one type of system or the other.
Selected criteria are discussed below. For nonsprinklered buildings, the minimum pressure difference depends on the ceiling height. Note that NPFA 92 also requires that factors such as wind forces, stack effect, and buoyancy be considered, and where the designer determines a higher minimum pressure difference is necessary, the higher minimum supersedes that contained in Table 4. A numerical maximum pressure difference is not specified in NFPA 92; rather, it is calculated based on the maximum door opening force permitted by NFPA , as mentioned earlier.
The edition of NFPA requires that this force not exceed 30 lbf to set the door in motion and 15 lbf to fully open the door. Because the door is much easier to open once it is slightly opened and the pressure difference drops, the criteria used is the 30 lbf. Annex A. Alternatively, the maximum pressure difference can be determined using Table A.
Note that these requirements are not intended to apply to sliding elevator doors. While there is no maximum opening force specified in the standard for elevator doors, it is the intent that the pressure differential should not be sufficient to cause jamming of the door. Research has shown that this is not typically of concern because only a modest force is required to open elevator doors, even when significant pressure differentials are present.
Keep in mind other codes may specify design criteria different from or in addition to that contained in NFPA 92, and whenever these codes are applicable, the more restrictive requirements must be used.
Table 1 illustrates some of these differences. Smoke management systems Several criteria specified in Chapter 4 are written to apply exclusively to smoke management systems. Most smoke management system designs are required by Section 4. In the current revision cycle, consideration has been given to creating a new Annex to address tenability. This requirement applies to the majority of smoke management system designs, as three of the four possible design objectives contained in Section 4.
This requirement coincides with that of section 4. Chapters 5 through 8 Chapter 5 contains calculation procedures for smoke management system designs. Section 5. NFPA 92 does not contain calculation procedures for smoke containment systems. These handbooks also contain additional information regarding smoke management system design. Chapter 7 contains requirements regarding the two documents required to be generated during the design process, the Detailed Design Report and the Operations and Maintenance Manual.
Chapter 8 contains smoke control system testing requirements. Annexes As noted earlier, the annexes are included for informational purposes only, and are not part of the requirements of NFPA Information in the 13 annexes includes additional calculation procedures and examples, assistance with choosing a design fire and associated heat release rate, and additional information regarding CFD and zone modeling, HVAC air-handling and stairwell pressurization system types compensation types , and testing.
NFPA is still accepting public comments on the first draft report visit www. Nevertheless, it is certain that the edition will feature several editorial revisions and minor revisions to comply with the NFPA Manual of Style and clarify the intent of the standard. For example, Section 6. One of the only major changes that has been proposed and is currently under consideration is a substantial revision of the balcony spill equations contained in Chapter 5 Section 5.
New correlations have been proposed as a result of significant research in the area by Roger Harrison at the University of Canterbury, New Zealand. These new correlations have the potential to yield more accurate calculations and cover a wider range of scenarios than the existing correlations.
William E. Nicholas Sealover is a fire protection engineer with Koffel Associates. Related Articles.
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