FI RE RATED DUeTING Fire Rated

Fire rated enclosure of duct located in exit passageway, protected with flexible wrap

Shaft Alternative for Air Distribution Systems (ADS)

Fire rated duct enclosures are increasingly being accepted as a shaft alternative By Sarah Brewer for air distribution systems (ADS) by design professionals and code officials. Group Product haft alternatives, such as ducts protected with normal operating conditions and emergency fire Manager, Unifrax I LLC flexible fire rated duct wrap, provide solutions situations. This is accomplished through a combina­ Sfor better space utilization and tion of code prescribed passive fire resistant build­ physical access to air control equipment. Listed ing and active smoke control systems . and Labeled systems verify performance when tested under duct application conditions and Fire rated duct requirements. provide documentation necessary for code com­ challenges and benefits pliance. The benefits of these systems can help Innovative design, retrofit changes and resolve current project issues and offer potential the push to achieve greater efficiencies in all future building design options. aspects of building construction present challenges for designers, installers and code officials. These ADS ducts function under operational challenges certainly include balancing air distribu­ and emergency conditions tion system functionality with Multi-story commercial and residential requirements within the shared space of structural must utilize a variety of air distribution systems building elements and other building service items. (ADS) to provide the necessary heating, cooling, Requirements for fire protecting duct systems are and ventilating functions required to provide occu­ clearly defined in the International pants with a tenable environment. These systems (lBC) utilized for building construction in the United must meet minimum standards of performance States. This code dictates duct systems that pass and set by the building code for both through fire rated horizontal assemblies shall be

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located in shafts; transfer open­ Example of duct with ings in shafts are to be protected insufficient space to with fire or combination construct a shaft fire/smoke dampers; and special­ enclosure ized ventilation systems such as ducts serving smokeproof enclo­ sures and exit enclosures shall be enclosed in construction as required for shafts or ductwork enclosed by 2 Hour fire barriers. Despite these prescriptive I requirements, unique job site conditions arise where "alterna­ tives" to shafts (often referred to as fire rated duct enclosures) offer potential solutions and therefore are given considera­ tion. These conditions can include but are not limited to: • Insufficient space to construct a shaft enclosure • Inadequate access to fire dampers for maintenance, requiring the shaft enclosure be "extended" to the new dam per location The building code does not define shaft alterna­ • Fire rated enclosure of ducts that pass through tive requirements for an air distribution system exit enclosures and exit passageways (except for commercial kitchen grease ducts). There­ • Penetrations of shafts where steel subducts are fore, Section 104.11 of the IBC can be utilized, installed but lack continuous vertical air flow which permits "An alternative materials, design or • Penetrations of shafts by kitchen, clothes method of construction to be approved, where the dryer, bathroom and toilet room exhaust building official finds the proposed design is openings, where steel subducts are installed satisfactory and complies with the intent of the pro­ but the exhaust lacks continuous power in visions of this code, and that the material, method, Group B (Business) and Group R (Residential) or work offered, is for the purpose intended, is at . least the equivalent of that prescribed in this code For these situations and others, there are in quality, strength, effectiveness, fire resistance, numerous benefits to using fire rated duct durability, and saftety"1 This option is further enclosures including flexible duct wrap systems . defined in Chapter 7 on Fire Resistance Rated The most common include: Construction, Section 703 .3 Alternate methods ./ Uses less space than shaft construction, thin for determining Fire Resistance . Approvals for installed profile Alternative Materials and Methods are typically ./ Potential for more effective space utilization granted for project specific requests . Applications ./ Contours to fit complex configurations should include supporting documentation, prefer­ ./ Easy material handling ably with Listed and Labeled systems tested at an ./ Lower installed cost lAS accredited testing lab & inspection agency, ./ Listed and labeled systems which are recognized by ICC. Accreditation Existing and potential fire rated duct applica­ Listings can be found at www.iasonline.org or tions that could benefit from shaft alternatives 562-699-0541 . Intertek Testing Services and include: Underwriters Laboratories are examples of accred­ • Smoke control, including stairwell & vestibule ited companies. pressurization ducts • Exit enclosures and passageways Shaft alternative: performance criteria • Bathroom and toilet exhaust One guideline for defining shaft alternative perfor­ • Commercial dryer exhaust mance criteria is the International Mechanical • Trash & linen chutes Code (IMC), Section 506.3.10 Enclo­ • Hazardous ducts sures . For this specific air distribution system application, the code states, "Duct enclosures shall Shaft alternative: approval using have a fire resistance rating not less than that of alternate materials and methods the assembly penetrated, but need not Fire rated duct enclosures, including flexible fire exceed two hours." Enclosure protection can be rated duct wrap systems are increasingly being uti­ provided via IBC requirements for shaft con­ lized by design professionals and accepted by struction, a field-applied grease duct enclosure or Authorities Having Jurisdiction (AHJ's) as a shaft a factory-built grease duct assembly. Section alternative for unique job site conditions. 506.3.10.2 Field Applied Grease Duct Enclosure,

INTERNATIONAL FIRE PROTECTION 89 FIRE RATED DUeTING FIRE RATED DUCT ENCLOSURES

Duct enclosure system being prepared for testing per ISO 6944 under full scale duct application conditions

defines the criteria that must be met for it to be and temperature ratings (T) equal to the duct used as an alternate to a shaft. This includes: enclosure and assembly penetrated (per ASTM E 1 Listed and labeled material, system, product 814 criteria). Results are reported as F Ratings and or method of construction specifically T Ratings. Temperature rise limitations are a evaluated for such purpose (as a duct enclosure mandatory component of ASTM E119, used to configuration) define a shaft. Therefore, T Ratings that are equiv­ 2 Fire tested per ASTM E2336 (under full scale alent to the F Ratings are mandatory for application conditions, including ASTM E119 installed on grease duct enclosure systems used as engulfment ) shaft "a Iternatives" . See Table 1 . 3 Duct continuously covered on all sides from the origin to the outlet terminal Extension of performance criteria to 4 Duct penetrations sealed with system ADS ducts tested per ASTM E 814 or UL 1479 It is logical that the shaft alternative performance 5 Firestop system shall have an F and T rating criteria for grease duct enclosures defined in the equal to the fire resistance rating of the IMC can be used as a model for other type air assembly being penetrated. 2 distribution system (ADS) duct enclosures. Since In this example, the fire rated duct enclosure the IBC requirements for fire protection of ducts is demonstrates equivalency to a shaft by limiting based on enclosure in shafts, then a shaft alterna­ fire and temperature rise to the next tive for ADS would have the same performance compartment (per ASTM E119 criteria). Both objectives and components as grease ducts, using criteria must be met and results are reported as an engulfment fire exposure test conditions the Fire Resistance Rating of the system. Meeting appropriate for ADS duct application. Using this the passlfail criteria of the standard verifies philosophy, the ADS fire rated duct enclosure stability, integrity and insulation capabilities of the system must provide equal fire and temperature duct enclosure system and its ability to provide ratings to demonstrate equivalent performance to equivalent fire resistance to the code prescribed a shaft. shaft. In addition, a through-penetration firestop ISO 6944-1985 (BS 476: Part 24) "Method for system must be utilized to seal the duct penetra­ Determination of the Fire Resistance of Ventilation tion opening, which shall provide fire ratings (F) Ducts" is utilized extensively in Europe and other

Table 1. Grease Duct Enclosure Shaft Alternative Performance Criteria

Criteria Duct Enclosure (ASTM E119) Penetration Opening (ASTM E814) Fire Resistance Rating Fire Penetration No collapse of duct support F Rating - no openings through firestop No passage of flame throughout Temperature Rise Temperature rise limit on T Rating - temperature rise limit on unexposed side of firestop

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Through-penetration firestop system with thermocouples measuring unexposed surface temperature of duct enclosure and to determine compliance with requirement for equal F and T ratings (

parts of the world to evaluate the fire resistance blies (duct plus enclosure materials) shall be tested rating of ventilation air ducts and duct enclosure per ISO 6944, ASTM E814 and ASTM E84. Mini­ systems. This standard evaluates full scale duct mum F and T Ratings for the assembly are man­ systems under application conditions, which is dated and defined in the bulletin. Similar criteria representative of the configuration they will be are being considered for adoption by many other installed in the field . Performance per ISO 6944 is cities, indicating a growing trend of acceptance for reported with the following Ratings: ADS duct shaft alternatives. • Stability Rating - no duct collapse (of duct An ASTM Test Standard for fire rated ventilation support system) ducts is under development. Once published, this • Integrity Rating - no passage of flames standard can then be considered for inclusion in (through duct or opening) appropriate sections of Building Codes that cover • Insulation Rating - temperature rise limit duct fire protection requirements. Testing and (through duct or opening to unexposed side) Listing of duct enclosure systems per this new Testing per this standard is conducted by North ASTM standard can then be conducted at national American laboratories (including those with lAS testing laboratories providing additional evidence Accreditations and recognized by ICC). Listed and of compliance with shaft alternative criteria. Labeled systems are available on line in each lab's Listing Directory. Design listings reflect the individ­ Evolution from project solver to design ual ratings achieved for each criteria. However the option equivalent fire resistance rating for the system is The use of fire rated duct enclosures as shaft the lowest rating achieved of the three. Manufac­ alternatives have provided designers, installers and turers of fire rated duct systems under considera­ code officials with solutions to unique project tion for approval should produce evidence of an conditions. There is no doubt the benefits associated Insulation Rating that is at least equal to the fire with flexible duct wrap systems are evolving this resistance rating of the assembly penetrated. technology from project solver to design option, Approvers should be cautious, as not all systems creating the potential to value engineer solutions have achieved an insulation rating that matches as the building is being designed. The culmination the assembly, which demonstrates equivalency to of industry activities already underway aim to Sarah Brewer is a Group a shaft. provide AHJ's with a code defined criteria for shaft Product Manager for Unifrax alternatives beyond grease duct systems. In the I LLC with over 20 years meantime, existing Listed and Labeled fire resistive experience in various Acceptance by local jurisdictions Some jurisdictions are developing acceptance duct enclosure systems are available as supporting engineering and marketing criteria for fire rated duct enclosures for ventilation evidence for local project submittals and accept­ positions supporting the air ducts or ADS. This permits broader approval of ance criteria . North AmeriCan passive fire lIm the systems and elimination of the need to apply protection business. She is for approval of Alternate Methods and Materials member of the ASTM E05 Footnotes on an individual project basis. Support documenta­ Task Group on Duct 1. International Code Congress, 2006 International tion typically includes Fire Resistant Duct Design Enclosures, UL Standards Building Code (IBC), Section 104.11 . Listings provided by lAS accredited labs as Technical Committee on 2. International Code Congress, 2009 International evidence of successful fire testing. Grease Ducts and current Mechanical Code (IMC), Sections 506.3.10 and One example of a major metropolitan area and President of the International 506.3 .10.2 jurisdiction that has developed acceptance criteria Firestop Council (IFC) and for the ADS application is the New York City Chairperson of its Duct References Buildings Department. Their Office of Technical Committee. She is also a 1. International Building Code 2006, International Certification and Research (OTCR) has defined the member of the National Fire Code Council, Inc., 2006 acceptance criteria for Fire Rated Flexible Duct Protection Association 2. International Mechanical Code 2009, International Wrap Insulation as an Alternate Material in the (NFPA) and Society of Fire Code Council, Inc., 2009 2008 NYC Construction Codes under Building Protection Engineers (SFPE). 3. BS 476: Part 24 (ISO 6944-1985), British Standards Bulletin OTCR 2009-028. Fire rated duct assem- Institution, 1987

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