Flexible Duct Performance & Installation Standards
ADC AIR DIFFUSION COUNCILAIR DIFFUSION COUNCILManufacturers of Flexible Air DuctFlexible Duct Performance& Installation StandardsFifth EditionADC AIR DIFFUSION COUNCIL, SCHAUMBURG, ILLINOIS
Flexible DuctPerformance andInstallation StandardsFifth EditionCopyright 2010Air Diffusion CouncilAIR DIFFUSION COUNCIL1901 N. Roselle Rd. Suite 800Schaumburg, IL 60195Telephone: (847) 706-6750 Fax: (847)706-6751Email: info@flexibleduct.org Web: www.flexibleduct.orgMission Statement of The Air Diffusion CouncilThe purpose for which the Air Diffusion Council was formed, as stated in its Certification ofIncorporation, is to promote and further the interests of manufacturers of air distribution equipment, more specifically, flexible air ducts and related products, and the interests of the generalpublic in the areas of safety, quality, efficiency and energy conservation, and to this end,develop programs approved and supported by the membership that legally promote and furtherthese interests, such as: To encourage, assist and support the maintenance and development of credible andeffective industry standards for the installation, use and performance of flexible ductproducts; to promote the use of those standards by various code bodies, governmentagencies; architects, engineers, heating and air conditioning contractors, etc. so thatthe best interests of the public may be served. To collect and disseminate lawful information of value to members of the Council, thegeneral public and others and to act as a clearing house for all such information, aswell as providing a means by which the interests of the individual members of theCouncil can be protected, defended, supported more vigorously and effectively inlegal association with others who share those interests.ADC Bylaws, Article 1, Section 2 (1996)
Table of ContentsForeword . iiiReferences . iiiGlossary of Terminology . iv1Introduction . 11.1Purpose . 11.2Scope . 11.3Units of Measurement . 11.4Classification . 12Characteristics of Flexible Duct . 22.1Description . 22.2Typical Styles - Figures 1-5 . 23Testing, Listing, Reporting & Certifying . 33.1General Requirements . 33.2Listing Requirements - Table 1 . 33.3Performance Values - Table 2 . 43.4Performance Requirements . 5, 63.5Material Characteristics . 73.6Methods of Test . 73.7Product Marking . 83.8Product Certification . 83.9Product Packaging . . . 8Installation Requirements . 94.1Code Reference . 94.2Installation Restrictions and Use Limitations . 94.3General . . 94.4Installation and Usage - Figures 6-9 . 104.5Duct Sizing and Routing - Figures 10-18 . 11 to 144.6Supporting Flexible Duct - Figures 19-26 . 15, 164.7Connecting, Joining, and Splicing . 174.7.1 Installation Instructions - Nonmetallic . 184.7.2 Alternate Installation Instructions - Nonmetallic . 194.7.3 Installation Instructions - Metallic . . 205Typical Accessories - Figures 27-37 . 21, 226General Commentary .6.1Fire Safety .6.2Duct Leakage .6.3Thermal Resistance (R-value Rating) .6.4Certification of Thermal Performance . .6.5Field Alterations .6.6Exposure to UV Radiation and Sunlight .Notes . .2323232424242425ADC Flexible Duct Performance & Installation Standards, 5th Edition4ii
ForewordThis standard was developed by the Air Diffusion Council.It is intended for use by the HVAC industry, includingmanufacturers, designers, installers, contractors, codebodies, inspectors and end users.The Flexible Duct Performance and Installation Standard isto be used as a comprehensive document in evaluating,selecting, specifying and installing flexible duct in heating,air conditioning and ventilating systems.no responsibility nor accepts any liability for theapplication or techniques contained in thestandard.This standard is subject to review and revision asthe art of the industry advances or experience inthe industry may dictate.Authorities considering adoption and/or reference of thisstandard should review all federal, state, local and otherapplicable regulations. The Air Diffusion Council assumesAIR DIFFUSION COUNCIL1901 N. Roselle Rd., Suite 800Schaumburg, IL 60195Telephone (847)706-6750Fax: (847) 706-6751Email: info@flexibleduct.orgReferencesACCA Manual D - Residential Duct DesignACCA Manual Q - Commercial Low Velocity, Low Pressure, Duct DesignADC Standard FD 72-R1 - Flexible Duct Test CodeASHRAE 120 - Method of Testing to Determine Flow Resistance of HVAC Ducts and FittingsiiiASHRAE Handbook - Fundamentals and Equipment VolumesASTM E84 - Test for Surface Burning Characteristics of Building MaterialsADC Flexible Duct Performance & Installation Standards, 5th EditionASTM E96 - Water Vapor Transmission of Materials in Sheet FormASTM C167 - Thickness and Density of Blanket or Batt Thermal InsulationsASTM C177 - Thermal Conductivity of Materials by Means of the Guarded Hot PlateASTM E477 - Duct Liner Materials and Prefabricated Silencers for Acoustical and Airflow PerformanceASTM C518 - Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow MeterNFPA Standard 90A - Installation of Air Conditioning and Ventilating SystemsNFPA Standard 90B - Warm Air Heating and Air Conditioning SystemsNFPA Standard 255 - Method of Test of Surface Burning Characteristics of Building MaterialsNAIMA - Fibrous Glass Duct Construction StandardsSMACNA - HVAC Duct Construction Standards, Metal and FlexibleUL Heating, Cooling, Ventilating and Cooking Equipment DirectoryUL Standard 181 - Factory-Made Air Ducts and Air ConnectorsUL Standard 181B - Closure Systems for Use With Flexible Air Ducts and Air ConnectorsUL Standard 723 - Tests for Surface Burning Characteristics of Building Materials
Glossary of Terminologyare in accordance with the listing.Listing Mark/Label A printing, tag or other markingdevice of the listing agency permanently and prominently affixed to the listed product that certifies compliance to the applicable Standard UL 181/UL 181B andcontains recommendations relating to installation andmaximum physical conditions of use.Lot A collection of units of a product of a single category, style, class and type manufactured under essentially the same conditions and from which a sample isto be drawn and inspected for conformance to specification.Permeance The time rate of water vapor transmissionthrough the vapor barrier expressed in U.S. perms[ng/(s·m2·Pa)].Pressure The positive or negative static pressureexpressed in inches of water gauge (in. w.g.) [Pa].Radiated Noise The sound power level transmittedthrough the duct wall, expressed in decibels (dB).Sag The distance deviation, expressed in inches perlineal foot [mm/m] of flexible duct, from a horizontal orinclined plane between suspension points on installedflexible duct.Snaking Unnecessary directional change in any plane(horizontal, vertical, inclined) that produces excesspressure drop.Sound Attenuation (Insertion Loss) The extent towhich sound power level is reduced (attenuated) as ittravels through a flexible duct, expressed in decibels(dB).Sound Generation The sound power level which isgenerated by the movement of air through a flexibleduct, expressed in decibels (dB).Thermal Conductivity (k) The time rate of heat flowthrough unit thickness of an infinite slab ofhomogeneous material in a direction perpendicular tothe surface, induced by unit temperature difference.Expressed in BTU-in./hr.-ft.2- F [W/(m - C)].Thermal Resistance (R) The mean temperaturedifference, at equilibrium, between two definedsurfaces of material or a construction that induces aunit heat flow rate through unit area. Expressed inhr.-ft.2- F/BTU [(m2 - C)/W].Total Equivalent Length The sum of actual ductlength and the equivalent length of fittings, bends, etc(see Equivalent Length).Ultraviolet (UV) Light Invisible radiation in the electromagnetic spectrum lying between visable light (380nm)and x-rays (100nm). UV is arbitrarily categorized intoshort, medium and long wavelength bands: UV-A (315380nm), UV-B (280-315nm) and UV-C (100-280nm).UV radiation occurs naturally in sunlight or can beartificially generated.Vapor Barrier/Retarder The outer membrane of aninsulated flexible duct.Velocity The average time rate of air flow expressedin feet per minute (fpm) [m/s].ivADC Flexible Duct Performance & Installation Standards, 5th EditionAir Barrier The membrane of the flexible duct whichactually contains the air volume.Air Connector A category of flexible duct not meetingthe requirements of an Air Duct per UL 181 Standard(not tested for flame penetration, puncture and impact)and having limitations on use, length and location asdefined by NFPA 90A and 90B. Air Connectors areidentified by a “round shape” listing label of the listingagency.Air Duct A category of flexible duct tested andclassified as to the Surface Burning Characteristics inaccordance with the UL 181 Standard and identified bya “rectangular shape” listing label of the listing agency.Authority Having Jurisdiction The organization,office or individual responsible for and having finalapproval concerning use of flexible duct and itsinstallation.Classification For purposes of this standard, amethod of identifying, marking and specifying flexibleduct as related to listing category, physical style,positive pressure class and velocity type.Equivalent Length Additional length added to theactual duct length in duct sizing calculations to accountfor the frictional resistance of fittings, bends, etc (seeTotal Equivalent Length).Excess Length The difference between the fullystretched cut length and the measured, straight-line,entrance-to-exit span length.Flexible Duct A preformed, flexible, tubular passagefor supply, return and exhaust air in HVAC systems.For purposes of this document, the terms designatedAir Duct and Air Connector are used interchangeably,however not in their intended use and application.Friction Loss (Bends) The static pressure loss inbends of flexible duct, expressed as a dimensionlesscoefficient (Co) at a specified bend radius ratio. Co is adimensionless coefficient which represents the ratio ofthe total pressure loss to the dynamic pressure interms of velocity pressure.Friction Loss (Straight) The static pressure loss in astraight run of flexible duct, expressed in inches ofwater gauge (in. w.g.) per 100 feet [Pa/m].Inner Core/Liner That portion of insulated flexible ductwhich determines the internal dimensions and innerphysical form.Installation Instructions A manufacturers printedinstructions in accordance with the terms of their listingwhich advises the method and materials to install theflexible duct.Leakage The time rate of air volume loss expressed incubic feet per minute (cfm) [L/s].Listed A published list by a recognized approvingagency acceptable to the authority having jurisdictionstating that the flexible duct, tape, mastic, and clamphave been tested to and comply with the applicableStandard UL 181/UL 181B and maintains periodicinspection to assure production of the listed products
1Introduction1.1PurposeThis standard sets forth specific methods ofclassifying, testing and marking flexible air ducts forindoor comfort heating, ventilating and air conditioningapplications. This standard sets forth instructions forproperly installing flexible ducts in air distributionsystems.ClassificationFlexible ducts shall be categorized as either Air Ductsor Air Connectors in accordance with testing and listingrequirements in Table 1. Flexible ducts will appear inone of the following styles (see Figures 1 - 5):NM-ILNon Metallic, Insulated linedwith nonporous inner coreNM-UNNon Metallic, UninsulatedM-IMetallic, InsulatedSpecial considerations not covered by this standardmay be required when flexible ducts are used in:M-UNMetallic, Uninsulateda. Industrial applications; i.e. particulateconveying, corrosive atmospheres, excessivetemperatures, etc.NM-IPNon Metallic, Insulatedwith porous inner core1.2ScopeThis standard includes requirements for both insulatedand non-insulated flexible ducts. No attempt is made inthis standard to designate a specific material orconstruction.b. Outdoor applications; i.e. continuous exposureto direct sunlight, weathering elements etc.11.4Ducts shall be listed in conformance to NFPAStandards 90A and 90B.ADC Flexible Duct Performance & Installation Standards, 5th Editiona. They shall be tested in accordance withUnderwriters Laboratories Standard for FactoryMade Air Ducts and Air Connectors, UL 181.b. Such ducts shall be installed in accordance withthe conditions of their listing.1.3Units of MeasurementThis standard is written in inch-pound (I-P) unitsfollowed by SI units in brackets [ ]. Metric symbolsand units are consistent with SI policy, however somedeviations have been taken in conversion values andrules-of-rounding. Examples of some deviations are:Diameter conversions are based on 25 mm/in. dia.A 12 in. duct diameter converts to 300 mm.Length conversions are rounded to the nearest 0.1 m.A 14 ft. duct length converts to 4.3 m.Linear dimensions are rounded to the nearest 1 mm.A 1½ in. duct strap converts to 38 mm.Pressure conversions use 250 Pa/inch w.g.A pressure of 6 in. w.g. converts to 1500 Pa.Note: When more precise conversions are required,follow ASHRAE Policy on SI Units.Flexible ducts, as part of this standard and for thepurpose of application use only, shall be one of thefollowing pressure classes and velocity types.Positive Pressure ClassVelocity TypePressureVelocity(Up to and including)(Up to and including)1/2 in. w.g. [125 Pa]1000 fpm [5.1 m/s]1 in. w.g. [250 Pa]2500 fpm [12.7 m/s]2 in. w.g. [500 Pa]4000 fpm [20.3 m/s]3 in. w.g. [750 Pa]Over 4000 fpm[20.3 m/s]4 in. w.g. [1000 Pa]6 in. w.g. [1500 Pa]10 in. w.g. [2500 Pa]
2Characteristics of Flexible Duct2.1 DescriptionFlexible ducts usually are packaged in compressedform in a variety of lengths with plain ends or as assemblies with special end fittings attached to either orboth ends. Diameters generally range from 2" [50 mm]through 12" [300 mm] in 1 in. [25 mm] increments and14" [350 mm] through 22" [560 mm] in 2 in. [50 mm]increments. Most flexible ducts are slightly over-sizedin diameter to fit over standard sheet metal fittings (see“Dimensions and Tolerances” in Section 3.5).2.2 Typical StylesFigure 3Style M-I - Metallic, Insulated2Figure 2Style NM-IL - Nonmetallic, Insulated,Lined (Non porous Inner Core)Figure 4Style M-UN - Metallic, UninsulatedFigure 5Style NM-IP - Nonmetallic Insulated,Perforated (Porous Inner Core)Style NM-UN Nonmetallic, UninsulatedADC Flexible Duct Performance & Installation Standards, 5th EditionFigure 1
3Testing, Listing, Reportingand Certifying3.1 General Instructions3.2 Listing RequirementsFlexible ducts conforming to this standard shall betested, listed, reported and certified as applicable, inaccordance with the requirements of this standard.Testing requirements by category are shown in Table1.Factory made air ducts and air connectors shall betested and listed in accordance with UnderwritersLaboratories Standard for Factory-Made Air Ducts andAir Connectors, UL 181. The UL Heating, Cooling,Ventilating and Cooking Equipment Directorypublishes such listings.Table 1Key to Table 1Test3Air DuctsAir ConnectorsXTest applicable-Test not applicableaApplicable to parts of metals not inherentlycorrosion resistant.bTest applicable for flexible air ducts and airconnectors that incorporate vapor barrierssupported by grommets or other means of fieldsupport.ADC Flexible Duct Performance & Installation Standards, 5th EditionSurface BurningCharacteristics 1xxFlame Penetrationx-BurningxxCorrosion axxMold Growthand HumidityxxFootnote 1TemperaturexxPuncturex-Static LoadxbxbTests for surface burning characteristics are to beconducted as specified for Surface BurningCharacteristics of Building Materials, UL 723 (ASTME84, NFPA 255).Impactx-Erosion 2xxPressure 2xxCollapse 2xxClass 1 Material: Shall have flame spread rating ofnot over 25 without evidence of continuedprogressive combustion and a smoke-developedrating of not over 50.TensionxxFootnote 2TorsionxxBendingxxLeakagexxThese three tests, Pressure, Erosion and Collapse,are run at 2.5 times the manufacturer’s stated ratingfor that property. For the erosion test, the variable isvelocity; for the pressure test the variable is positivepressure; for the collapse test, the variable isnegative pressure.ListingLabel ShapeRectangularRoundClass 0 Material: Shall have surface burningcharacteristics of zero (flame spread/smokedeveloped).
Testing, Listing, Reporting and Certifying . . . continued3.3 Performance ValuesTable 2 lists the required tests and units ofmeasurement and recommended values of minimumperformance where applicable.Table 2For comparison purpose only. Not for design. For detailed design data, refer to manufacturer’s product engineeringdata.PropertyThermal Loss*All diametersFriction Loss12" [300 mm]diameterStatic Press./Temp12" [300 mm]diameterLeakageAll diametersLeakageAll diametersPermeance*All diametersTest - Section 3.4 - Thermal Performance4.2 [0.74](minimum) @ 75 F [24 C] mean temperatureTest - Section 3.4 - Friction LossStraight:(in.w.g. per 100 ft. [Pa/m]of duct @ 1000 fpm [5.1 m/s])0.3 [2.5] (maximum)490 bend loss coefficient (Co)@ R/D 21.0 (maximum)Sound AttenuationSound GenerationRadiated NoiseTest - Section 3.4 - Acoustical PerformanceDue to complexity of data, no recommended value ofperformance is stated. Refer to Manufacturer’s Data.At Recommended OperatingPositive Pressure (in. w.g.) [Pa]Test - Section 3.4 - Static Press./Temp. Performance140 F [60 C] Continuous180 F [82 C] Intermittentcfm/in. (dia.)·ft. (length)[L/s/mm (dia.)·m (length)Test - Section3.4 - Leakage (Duct Only)0.03[1.7 x 10 4]cu.ft./hr. [L/s]U.S. Perms [ng/(s·m2·Pa)]* Not applicable to uninsulated ducts.Test - Section 3.4 - Leakage (Including Connections)0.87 [1.1 x 10 5] D2 (maximum) where D isinternal duct diameter in inches [mm].Test - Section 3.6Water Vapor Transmission Rates of Vapor Barriers1.0 [57.5] (maximum)ADC Flexible Duct Performance & Installation Standards, 5th EditionAcoustical(dB)R: hr·ft2· F/BTU [(m2· C/W]Recommended Performance Value
Testing, Listing, Reporting and Certifying . . . continued3.4Performance RequirementsThermal Performance. Thermal loss properties ofinsulated flexible duct shall be based on flat sections ofinsulation only at in
ASTM C167 - Thickness and Density of Blanket or Batt Thermal Insulations ASTM C177 - Thermal Conductivity of Materials by Means of the Guarded Hot Plate ASTM E477 - Duct Liner Materials and Prefabricated Silencers for Acoustical and Airflow Performance ASTM C518 - Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter NFPA Standard 90A - Installation of .
installed as described in the TDC or TDF addendum to the SMACNA Duct Construction Standards except the corners may not be bolted. Standard 5" metal clips may be used with spacing as shown in diagram. SLEEVE DUCT TYPICAL TDC/TDF JOINT DUCT 60" Duct 3 REQ'D. 48" Duct 3 REQ'D. 36" Duct 3 REQ'D. 24" Duct 2 REQ'D. 18" DUCT and .
Duct Sizing Tools OR Duct Sizing Chart Ductulator (Manual/Digital) AIRAH DA3 Duct Design Manual Manufacturers/Programs . Duct Sizing Methods . More available in the ASHRAE Handbook or SMACNA Obtain other duct fittings pressure losses from manufacturers such as duct heaters, dampers, filters, grilles, coils, etc
Air Duct Design & Sizing Duct sizing methods Static regain method Normally used with a computer package for high velocity systems (e.g. in main duct) Size air duct so that static pressure nearly offset the pressure loss of succeeding duct section along main duct T me
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The Flexible Duct Performance and Installation Standard is to be used as a comprehensive document in evaluating, selecting, specifying and installing flexible duct in heating, air conditioning and ventilating systems.
