American Architectural Manufacturers Association

NFPA Appeal Denial Offers Opportunity to Strengthen the Case for Smoke Vents

Sponsored by


Bob Sampson, RCS Consulting 

The principal standard governing the use of smoke and heat vent products is National Fire Protection Association (NFPA) 204 2012, Standard for Smoke and Heat Venting. There are also allied standards, such as NFPA 92B, Standard for Smoke Management Systems in Malls, Atria and Large Spaces. Various code requirements are based on these standards, such as the International Building Code (IBC) and the International Fire Code (IFC).

Other standards address the proper design and operation of smoke vents without touching on their role in building fire safety:

• UL 793-08, Standards for Automatically Operated Roof Vents for Smoke and Heat
• FM Global FM-4430 (2010), Approval Standard for Smoke and Heat Vents
• ICC-ES AC331-2008, Acceptance Criteria for Smoke and Heat Vents
  

There are alsothe international standards ISO 21927-2:2006, Smoke and heat control systems -- Part 2: Specification for natural smoke and heat exhaust ventilators, but the UL, FM and ICC standards most often govern in the U.S., and cross-references exist among these standards. For example, UL-793 is referenced within ICC-ES AC331.

Governing Document
In terms of thoroughly addressing the use of smoke vents, the recently approved NFPA 204 – arguably the most influential of the standards – remains essentially a draw. The optimum goal of getting a definitive guideline for the use of smoke vents written into the standard was not achieved; however, neither was the goal of opponents to have them eliminated entirely. 

In the latter case, a proposal to the NFPA Technical Committee to rescind approval for the use of smoke vents in sprinklered buildings and remand the issue to the NFPA Smoke Management Committee for further study, submitted by perennial and persistent opponents of smoke vents in sprinklered buildings, was denied. A last-resort appeal of the proposal was once again defeated on August 11 by the NFPA Standards Council.

When the smoke cleared, as it were, NFPA 204 kept the door open for smoke vents but fell short of encouraging them. In effect, it avoids the heat and smoke venting issue by not requiring them; specifically stating in its scope that the standards shall not specify under which conditions venting is to be provided. It does require, on a case-by-case basis, a professional engineering analysis of smoke vent effectiveness in sprinklered buildings, using manual and computer-modeled methods to aid in design calculations. NFPA 204 requires sprinkler systems to comply with NFPA 13 2010, Standard for the Installation of Sprinkler Systems, which contains provisions for the use of roof vents in sprinklered buildings. At the periphery of the issue, specific guidance on the location of draft curtains with respect to aisle spacing was added to NFPA 204, a move positioned as addressing a void in the draft curtain requirements of IBC and IFC, which include requirements for roof vents and sprinklers in buildings, but do not address where draft curtains should be located.

Pros and Cons
In the way of background on the pros and cons for the use of fire vents in sprinklered buildings, a debate has been raging for 35 years.

Opposition to requirements for smoke/heat vents in sprinklered buildings often centers on the rationale that venting interferes with the proper performance of sprinklers by:

• Enhancing the burn rate by making more oxygen available
• Delaying sprinkler activation by reducing smoke and temperature at the ceiling
• Increasing the number of activated sprinklers, thus increasing water damage

Plus, opponents feel smoke/heat vents add unnecessarily to the first cost of a building.

Standing firm against these arguments are the following points made by those in favor of smoke vent use:

• Minimizes structural damage. By preventing heat from mushrooming over the fire area and heating other materials to the point of ignition, fire venting has a marked effect on reducing the lateral spread of fire. 
• Improves fire-fighting efficiency and safety. Fire vents allow arriving firefighters to quickly determine the approximate interior location of the fire by observing the exterior location of the smoke plume from the open vents. Prompt venting has also been proven to reduce dangerous heat, vision-obscuring smoke and toxic or potentially explosive products of combustion.
• Enhances occupant life safety. Raising the smoke layer inside a burning building not only improves visibility of exit paths, it helps save lives, given that the vast majority of fire fatalities are due to smoke inhalation.

In addition, tests conducted using real-world configurations confirm that smoke/heat vents do not enhance the burn rate, delay sprinkler activation or decrease the number of sprinklers activated.

Advocacy
Given the current (although likely temporary) respite in the code change process, it’s time for smoke vent advocates to regroup and build a more effective and fully vetted case for the value of smoke vents in both sprinklered and non-sprinklered buildings. Previous efforts have fallen short of expectations due to a shortage of personnel and financial resources engendered by the slow economy, but now is the time to assemble our best argument based on existing research results in order to ready a more effective offense for the next round of NFPA code changes. The industry has potent allies in the form of the fire services themselves, who strongly favor smoke venting as a firefighting aid. 

Attendees of the Smoke Vent Committee at the AAMA Fall Conference were invited to view an interesting video produced by the University of Ghent (Belgium) recording full scale tests on a building equipped with both sprinklers and smoke vents. 

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