saving lives and property through fire and smoke containment ©2004 ifc flexible fire resistive duct...

Saving Lives and PropertyThrough Fire and Smoke Containment ©2004 IFC

Flexible Fire Resistive Duct Enclosures


Fires related to cooking equipment

represent the largest category of eating and

drinking establishment fires in

the U.S.


During the period from 1992-1996,

there have been an average of 11,200

fires and $164 million in property

losses per year.


Approximately 4,600 of those fires were traced to kitchen equipment

such as stoves, deep fat fryers, open fired grills and GREASE HOODS

and DUCTS.


Grease and Air Duct Enclosures


• What is Grease and Air Duct Insulation?

• Traditional, Generic Materials

• Flexible Wraps• Product Information• Installation procedures • Codes and approvals• Summary


What is a Fire Resistive Grease and Air Duct Enclosure?


Grease and Air Duct Flexible Fire Resistive Enclosure

A high temperature insulation enclosure system designed to provide 1 and 2 hour fire rated shaft alternative and zero clearance to combustibles protection for commercial kitchen exhaust grease ducts. In HVAC air ventilation ducts, the insulation enclosure system provides a 1 or 2 hour shaft alternative to rigid board systems.


Previously Used Systems

• Factory built enclosures

• Field flexible wrap or rigid board built enclosures

• Drywall enclosures


Commercial Kitchen Grease & Air Ventilation Duct Enclosure Materials

• Factory Built Enclosure

– A listed and labeled factory-built self contained grease duct enclosure system evaluated for reduced clearance to combustibles.

• Field Built Flexible Wrap or Board Enclosure

– A listed and labeled field fabricated system for reduced clearances to combustibles and an alternative to a 1 or 2 hour fire resistance rated shaft enclosures for commercial kitchen grease and HVAC air ventilation ducts.


Why is an Enclosure Necessary?

Grease: Flammable Grease Vapors+ High Temperature Operation= Hot, Fast Moving Fire

Air:External Fire Attack

(Room Fire Conditions)


Performance Requirements

• Contain Internal Duct Fires and prevent heat transfer to nearby combustibles

• Repel External Fires from entering the duct and becoming a conduit of rapid fire spread

• Block Fire Prorogation through through penetration openings

• Limit Enclosure Material’s Surface Flammability


Laboratory Listing Categories

• UL Classification – Grease (YYET)– Air Duct (HNLJ)– Fire Stop (XHEZ)– Product Flammability (BHWV)

• Omega Point Laboratories– Grease Duct (GD)– Air Duct (VAD)– Fire Stop (FS)– Product Flammability (Division 7)


Grease Duct Enclosure Tests

Grease Duct• Fire Resistance - Internal (UL1978)• Fire Resistance - Internal (AC101)• Fire Resistance - External (ASTM E-119/UL263)• Through-Penetration Fire stop (ASTM E-814/UL1479)• Surface Flammability (ASTM E-84/UL723)• Hot Surface (ASTM C411)• Combustion Behavior (ASTM E 136)• Thermal Conductivity “Aging” (ASTM C 518)


Air Ventilation Duct Enclosure Tests

• External Engulfment Air Duct Test (ISO 6944)

– Test representative of maximum width to height ratio intended for use

• Fire Stop Test (ASTM E814/UL 1479)

– Establishes F & T rating

• Surface Flammability (ASTM E-84/UL723)


Grease Duct Enclosure Internal Grease Duct Fire Test (UL 1978)

500°F (260°C) for 4 hours

Max. Single TC rise is 117°F (65°C) if not in contact with duct or 90°F if enclosure is in contact with duct

2000°F (1093°C) for 1/2 hour; Max. single TC rise is 250°F (121°C)

Accepted by ICCES (BOCA, SBCCI) in East and Mid-West U.S.


Grease Duct EnclosureInternal Grease Duct Fire Test (AC101)

500°F (260°C) gasses into duct for 4 hours; max. temperature on surface under insulating pad is 117°F (65°C) above ambient

2000°F (1093°C) at duct test area for 1/2 hour; max. average temperature rise surface under insulating pad is 250°F (121°C), max individual temperature rise 325°F (198°F)

Accepted by ICBO in Western U.S.


Grease Duct EnclosureExternal Grease Duct Test – Full Engulfment

ASTM E-119

• 2 Hour engulfment plus hose stream test for integrity of duct

ASTM E 814

• 2 Hour through-penetration firestop test


Grease Duct Enclosure Tests

ASTM E84 Surface Burning Characteristics

• Flame Spread Rating must be < 25

• Smoke Developed Rating must be < 450

• Covers Core Insulation and Covering Material


Performance Tests for Air Ducts

• ISO 6944 – Full engulfment test with a negative pressure on the duct. Duct must resist collapse during the test.

• ASTM E814 – Through Penetration Firestop Test

• Surface Flammability (ASTM E84/UL723)


Flexible Wraps Review


• High Temperature Insulation Blanket

• One or Two Layers Required

• 1 ½” or 2” Material Thickness

• Applied directly to Duct Surface

• Joints Overlapped 3” or alternate installation techniques available

• Filament Tape / Banding Attachment

Design Features


Available Product Forms

Total Aluminum Foil

Encapsulated

Un-encapsulated Blanket

Aluminum Foil Faced Blanket One Side


Flexible Wrap Features

• Durable Aluminum Foil Scrim Covering

• Resists Tearing

• Resists Grease or Water Condensation Absorption

• Minimizes Fiber Exposure

Total Foil Encapsulated:


Installation Details



Backing Material:Un-faced Flexible Wrap Blanket Scrap or 3 pcf Mineral Wool

Two Layers Flexible Duct Insulation

Fire Stop Sealant


Installation DetailsMeasure to include overlaps


Installation DetailsAluminum taped exposed cut edges



• 1 or 2 Layers

• 3” Overlap at seams or approved alternate installation techniques

• Tape exposed cut blanket edges


Installation DetailsBlanket thickness should not be compromised


Installation DetailsBanding snug, but not to cut into blanket


Installation DetailsAccess Doors


Codes & Approvals


Code Language –”Exception”

Requirement Code

• Must be Listed & Labeled System NFPA 96, IMC

• Material Covers All Sides of Duct NFPA 96, IMC

• Firestop = F&T Rating NFPA 96, IMC

• Zero Clearance Option Identified NFPA 96


Other Wrap Opportunities

• Plenum Wrap– Plastic Pipe, Concealed Spaces

• Conduit Wrap– Emergency Feeder Lines

• Cable Tray Wrap– Industrial Control Systems


About the IFCFounded in 1990, the IFC is a nonprofit organization of industry experts committed to making buildings safer through passive fire containment. With membership composed of manufacturers, firefighters, distributors, and users of passive fire protective materials and systems, IFC aims to promote passive fire containment through awareness, education and development of codes and standards.

Website - www.firestop.org

Email - [email protected]

Voting Members


Available educational seminars on our website include…..• Firestop 101 – An introduction to firestopping

• Curtain Wall Protection

• Firestop System Selection

• Flexible Duct Wrap Systems

• Fire Protection of Construction Joints

• Commonly Made Mistakes

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