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|A Briefing on NFPA 92 - Standard for Smoke Control Systems|
Issue 51: A Briefing on NFPA 92 - Standard for Smoke Control Systems
By Randolph W. Tucker, P.E., FSFPE
In the NFPA Annual 2011 cycle, the Technical Committee on Smoke Management Systems merged NFPA 92A1 and 92B2 into a new document, Standard for Smoke Control Systems.3 This article is a brief history of NFPA 92A and NFPA 92B and an overview of the new standard.
In the Beginning
During the mid-1970s, atrium design became prevalent, and with this architectural design approach became the need to address the management of smoke in these spaces. In 1985, the NFPA standards council established two subcommittees of the Technical Committee on Air Conditioning to prepare documents to address smoke movement in buildings.
The first edition of NFPA 92A was published in 1988 as the Recommended Practice for Smoke-Control Systems. Its scope was "smoke management using smoke barriers, airflows, and pressure differences to confine smoke movement to the area of origin." In 2006, it became the Standard for Smoke-Control Systems Utilizing Barriers and Pressure Differences.
The purpose of 92A was to provide methods to:
The design objectives were presented as:
The standard offered five basic design approaches to achieve the purpose and objectives:
The standard provided requirements related to building equipment and controls, smoke control system design documentation, and system testing. Annex materials offered examples of stairwell pressurization system design, types of HVAC systems, fire fighters' smoke control station (FSCS) considerations, advisory information on system acceptance testing, and information reference material.
The first edition of NFPA 92B was published in 1991 as the Guide for Smoke Management Systems in Malls, Atria, and Large Areas. Its scope was to "provide methodologies for estimating the location of smoke within large-volume space or in an adjacent space." In 2005, it became the Standard for Smoke Management Systems in Malls, Atria, and Large Areas.
The purpose of 92B was to either:
The design fundamentals presented addressed:
The standard also addressed calculation procedures to be followed, algebraic equations, requirements for equipment and controls, system acceptance testing, and design documentation to be provided. The Annex of 92B provided explanatory material, methods for predicting the rate of heat release of fires, explanation and use of t-squared fires, example problems demonstrating the use of the equations in NFPA 92B, zone and CFD fire models, additional design objectives, considerations regarding smoke stratification, comparison of the equations presented, and informational references.
Introducing the New NFPA 92
In the creation of the NFPA 92, the directive to the technical committee was to blend the NFPA 92A and 92B without making technical changes to their intent. In many cases, this allowed existing wording to be carried over into the new document intact and in its previous location. In others, existing wording was retained, but located in a more appropriate location. While there were several sections that were moved as well as modified, the committee was careful not to change the intent of the requirements from the previous documents.
So, what is new with the merged NFPA 92? First will be the name. The new document's title is Standard for Smoke Control Systems. Why the name change? Smoke control captures both the concepts of "smoke management" and "smoke containment" systems.
The scope of NFPA 92 is: the design, installation, acceptance testing, operation, and ongoing periodic testing of smoke control systems.
The new standard has five stated purposes to accomplish one or more of the following:
The standard offers two design objectives, either to contain the smoke to the zone of origin by establishment and maintenance of pressure differences across smoke zone boundaries or to manage the smoke within a large-volume space and any unseparated spaces that communicate with the large volume space.
The basis of design of systems is covered in five approaches, one for smoke containment systems and four for smoke management systems. The smoke containment approach may be followed for:
The other four approaches are for smoke management systems and include:
Chapter 4, "design fundamentals," from the two predecessor documents have been merged into a new Chapter 4 of NFPA 92. Chapter 5 of NFPA 92A, "smoke control systems and applicability," has also been relocated to Chapter 4 of NFPA 92.
The calculation procedures of Chapter 5 of NFPA 92B are still in Chapter 5 of NFPA 92 and are supplemented with the information previously in Chapter 6 of NFPA 92B.
Chapters 6, 7, and 8 have been recast as follows:
All of the previous annex material from both 92A and 92B has been retained and reorganized. As such, the document now has ten annexes.
Randolph W. Tucker, P.E., FSFPE, is with CCRD Partners.
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