Window Type Sash Lock

Door

Gasket

Gasket

Door

OriginalReinforcementLocation Spacing Per

Schedule Female Shiplap

*

4"(102 mm)

1

FIGURE 6-5-22 Access Door Location Interferingwith Reinforcement

DETAIL G Window-Type Sash Lock, FlangedDoor

FIGURE 6-5-24 Attachment to Fire DamperSleeves

#10 x 1-1/4" Sheet MetalScrews and 2-1/2" SquareWashers, 12" (Max.) O.C.,to attach duct board tosheet metal sleeve

Closure

FireDamper

1-1/2"(Nom.)

Closure

Sheet Metal SleeveThrough Fire Wall asspecified in fire dampermanufacturer's instructionsPP

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Sealing of fibrous glass duct board to the sheetmetal sleeve must be made with glass fabric andmastic, except where operating pressure is less thanone (1) inch W.G. (249 Pa) and the sheet metalsurfaces are carefully cleaned, in that case pressure-sensitive aluminum foil tape may be used. SeeSection 6.503 for methods.

A.6.506 Hangers and Supports(A) General. Fibrous glass ducts are light in weight, so

that they can be supported with a minimum of hangers if care is taken as to placement of thesupports.

The charts and examples illustrated in this section show that the hanger treatment and spacing required is dependent on duct dimensions. Trapeze-style channels, suspendedby twelve (12) gauge (2.8 mm) (minimum) hanger wire (see Figure 6-5-25) are the preferredmethod of support. Channel gauge and profile vary with duct size, but in no case should the supporting channel be less than two (2) inches (51 mm) wide. Channels may also be suspended by means of metal rods of one (1) inch-wide(25.4 mm) (minimum) galvanized steel straps.

When channel reinforcement members occur within maximum hanger spacing as shown in Table No. 6-5-5, sheet metal straps may be bolted to the channel reinforcement asshown in Figure No. 6-5-26. Support may also bemade with twelve (12) gauge (2.8 mm)(minimum) wire.

(B) Hanger Design. Occasionally, hanger channelsmust be extended considerably beyond the ductsides so that the supports will clear otherobstructions. The total extension (E + E’) of the supports beyond the duct sides (see Figure 6-5-27),governs the minimum dimensions (see Table 6-5-6) of the channel.

TABLE 6-5-5

Maximum HangerDuct Size, Inches Spacing, Feet(x 25.4 for mm) (x 304.8 for mm)

48" wide or greater 4Less than 48" wide and less than

12" deep 6Width between 24" and 48" and

greater than 24" deep 6Less than 48" wide and depth

between 12" and 24" 8Width 24" or less and depth greater

than 12" 8

TABLE 6-5-6 Channel Selection

If Total Extension is Min. Channel Min. Channel Not Greater than: Gauge Profile

6" 24 3" x 1.5"18" 22 3" x 2"30" 18 3" x 2"

STANDARD FOR INSTALLATION OFFACTORY-MADE AIR DUCTS

APPENDIX A, UMC STANDARD 6-5

347

Framing Access Door Opening:

1" x 1" x 3", 22 Gage(0.030 in) (0.76 mm)U-Channel FramingAround Door Opening

Framing Access Door:1" x 1" x 1", 22 Gage(0.030 in) (0.76 mm)Z-Channel FramingAround Access Door

Fibrous Glass Duct Board

1" x 2", 22 Gage Framing,Spot Welded or Pop Rivetedto Z-Channel 6" (Max.) O.C.to Secure Fibrous GlassDuct Board

Door Fastened to Opening Framingwith #10 Sheet Metal Screws, 6"(Max.) O.C., Min. 2 Per Side

#10 x 1-1/4" Sheet MetalScrews and 2-1/2" SquareWashers 6" O.C.

Duct Wall Door

Gasket

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Figure 6-5-28 is based upon three (3) inch (76 mm) -wide (minimum) channels.

For ducts not over forty-eight (48) incheswide by twenty-four (24) inches high (1219 mmby 610 mm), two (2) inch wide by 1-1/2 inch channels (51 mm by 38 mm), spaced not morethan four (4) feet (1219 mm) apart may beinstalled. The total extension of the hanger supports shall not exceed six (6) inches (152 mm).

Hanger design and spacing for fibrous glass ducts is based upon extensive testing with loadsexceeding twice the duct weight located betweensupports to assure the integrity of the duct system. Recommended hanger spacing is shown in Figure 6-5-28. Caution should be taken withother types of hanger systems to assure that excessive stress is not placed on the hanger or thefibrous glass duct system.

(D) Fittings. Proper support of duct fittings mayrequire that additional hangers be installed.

For an elbow, hangers should be on each leg, within twelve (12) inches (305 mm) of thethroat. If the width of the duct is greater thaneighteen (18) inches (457 mm), an additionalhanger must be installed (see Figure 6-5-29) sothat it is approximately two-thirds of thediagonal distance from throat to heel.

Tees require support on the trunk as shownin Figure 6-5-30. If a tee runout hanger falls where the trunk duct is located, add hangers on

either side of trunk. Do not exceed maximum hanger spacing.

Branch ducts are treated in a similar mannerwith hanger spacing on the trunk duct in accordance with Figure 6-5-28.

For diffuser drops, hangers are installedwithin three (3) inches (76 mm) of each side ofthe drop. The connection of the drop to the duct is reinforced in accordance with Figure 6-5-31.

If the drop assembly, including the diffuser,weighs more than twenty-five (25) pounds (11.3kg), the diffuser must be separately supported.

(E) Hanging Rigid Round Duct. Preformed round fibrous glass duct should be hung so the hanger will not damage the duct facing.

Straps or saddles in contact with the ductmust be not less than 5/8 inch (15.9 mm) wide.Avoid sharp edges and burrs.

Space hangers at a maximum of six (6) feet (1829 mm) on center. Where practical, hangersshould be located at circumferential joints. Provide hanger support at all fittings.

Part B — Flexible Ducts

A.6.507 Suitable Installations

(A) General

(1) The routing and length of flexible duct, thenumber of bends, the number of degrees of each

UNIFORM MECHANICAL CODE

348

APPENDIX A, UMC STANDARD 6-5

FIGURE 6-5-23 Duct Opening Frame

FIGURE 6-5-27 Hanger Spacing and ExtensionUsing 3-Inch (76 mm) Wide Channels

TotalHanger

Extension(E + E')

See Table No. 6-5-6

E

E'3" (76 mm)

MaximumHanger Spacing

See Table No. 6-5-5

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bend and the amount of sag allowed betweensupport joints will have serious effects on systemperformance due to the increased resistance eachintroduces. Use the minimum length of flexibleduct to make connections. It is not re-commended that excess lengths of ducts beinstalled to allow for possible future relocationsof air terminal devices.(2) Avoid installations where exposure to direct

or indirect sunlight can occur, e.g., turbine vents,skylights, canopy windows, etc. Prolongedexposure to sunlight will cause degradation of thevapor barrier. Direct exposure to UV light from asource lamp installed within the HVAC systemwill cause degradation of some inner core/linermaterials.(3) Terminal devices shall be supportedindependently of the flexible duct.(4) Repair torn or damaged vapor barrierjackets with approved duct tape listed andlabeled to Standard UL 181B. If the internal coreis penetrated, replace the flexible duct or treat itas a connection.

(B) Installation(1) Install duct fully extended. Do not install inthe compressed state or use excess lengths. Thiswill noticeably increase friction losses.(2) Avoid bending ducts across sharp corners orplacing in incidental contact with metal fixtures,pipes, or conduits. The radius at the centerlineshall not be less than one duct diameter.(3) Do not install near hot equipment (e.g.,furnaces, boilers, steam pipes, etc.) that is abovethe recommended flexible duct use temperature.

A.6.508 Connecting, Joining, and SplicingFlexible Duct

(1) All connections, joints, and splices shall bemade in accordance with the manufacturer’sinstallation instructions.(2) Unless specified by the manufacturer,adhesives are not recommended for use withnonmetallic flexible duct as they will chemically

STANDARD FOR INSTALLATION OFFACTORY-MADE AIR DUCTS

APPENDIX A, UMC STANDARD 6-5

349

Hanger Wire, 12 Gauge

(2.8 mm) (Min.)

Channel(See Table No. 6-5-6 for sheetmetal gage and dimensions.)

Hanger Rodor

FIGURE 6-5-25 Attachment to Fire DamperSleeves

6" (152 mm) max.

Channel Reinforcement

Hanger Strap,1" (25.4 mm)Wide (min.)

FIGURE 6-5-26 Hanging from ChannelReinforcement

UNIFORM MECHANICAL CODE

350

APPENDIX A, UMC STANDARD 6-5

48

44

40

36

32

28

24

20

16

12

8

4

08 16 24 32 40 48 56 64 72 80 88 96

8 ft. Max.

Duct Width, Inside (Inches)

6 ft. Max.

4 ft. Max.

Duc

t Wid

th, I

nsid

e (I

nche

s)

in. x 25.4 = mmft.. x 304.8 = mm

6 ft. Max.

2/3 of the diagonaldistance from throatto heel (approx.)

Required only whenduct is greater than18" (457 mm) in width

45°(.79 rad)

12" (305 mm) Max.

FIGURE 6-5-29 Elbow Support

Figure 6-5-28 Minimum Hanger Spacing, Straight Duct, 3 Inch Wide (76 mm) Channel

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FIGURE 6-5-32 Hanging Round Duct with Saddleand 12 Gauge Wires

Wire, 12 Gauge (2.1 mm)

5/8" (16 mm) (min.),26 gage (0.019 in)(0.48 mm)

3" x 3"(76 mm x 76 mm)

Angle

Tap Trunk Duct

ScrewsWashersDiffuser

Sheet Metal AngleBrackets, 3" x 3"(76 mm x 76 mm),22 Gage (0.030 in) (0.76 mm)to Attach Diffuser Dropto Trunk Duct

#10 x 1-1/4" (32 mm)Sheet Metal Screws and2-1/2" (64 mm) SquareSteel Washers, Min. 2 PerSide, 12" (305 mm)(Max.) O.C.

FibrousGlass Drop

Diffuser or Grille

3" (76 mm)(Max.) Both

Sides of Drop

Hangers toSupport

Weight ofDiffuser

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1 x D

WRONG

RIGHT

FIGURE 6-5-31 Diffuser Connection

STANDARD FOR INSTALLATION OFFACTORY-MADE AIR DUCTS

APPENDIX A, UMC STANDARD 6-5

351

react with the duct materials, causingdeterioration and degradation. Tapes, mastics,and non-metallic clamps used with flexible airducts shall be listed and labeled to Standard UL181B.(3) Sheet metal collars fittings to that the whichthe flexible ducts with plain ends are attachedshall be beaded and have a minimum of two (2)inches (51 mm) in collar length. Beads areoptional for fittings when attaching metallicflexible ducts.(4) Sheet metal sleeves used for joining twosections of flexible duct shall be a minimum offour (4) inches (102 mm) in length and beaded oneach end. Beads are optional for sleeves whenjoining metallic flexible ducts.(5) Flexible ducts secured with non-metallicclamps shall be limited to six (6) inches w.g. (1500Pa) positive pressure.

Installation Instructions for Nonmetallic AirDucts with Plain Ends

(A) Connections

(1) After the desired length is determined, cutcompletely around and through duct with aknife. Cut the wire with snips or side cutters.(2) Pull back the jacket and insulation from thecore. Slide at least one (1) inch (25.4 mm) of coreover collar, pipe, or fitting. Tape with at least twowraps of approved duct tape. Secure withapproved clamp.(3) Pull the jacket and insulation back over thecores. Tape the jackets together with two wrapsof approved duct tape.

(B) Splices.

(1) Peel back the jacket and insulation from thecore. Butt the two cores together on a minimumfour (4) inch wide (102 mm) collar.

Run-Out Run-Out

12" Max(304.8 mm)

Do Not ExceedStandard Hanger

Spacing per TablesNos. 6-5-5 and 6-

5-6

Trunk

FIGURE 6-5-30 Tee Support

FIGURE 6-5-33 Extend Duct Fully

SteamPipes

FIGURE 6-5-34 Wrong Method of Support

UNIFORM MECHANICAL CODE

352

APPENDIX A, UMC STANDARD 6-5

FIGURE 6-5-35A End Connectors

FIGURE 6-5-35B

FIGURE 6-5-35C

FIGURE 6-5-36A

FIGURE 6-5-36B

FIGURE 6-5-36CPPRR

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STANDARD FOR INSTALLATION OFFACTORY-MADE AIR DUCTS

APPENDIX A, UMC STANDARD 6-5

353

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Connections1. After desired length is determined, cutcompletely around and through duct with knife orscissors. Cut wire with wire cutters. Fold backjacket and insulation.

2. Slide at least 1” (25 mm) of core over fitting andpast the bead. Seal core to collar with at least 2wraps of duct tape. Secure connetion with clampplaced over the core and tape and past the bead.

3. Pull jacket and insulation back over core. Tapejacket with at least 2 wraps of duct tape. A clampmay be used in place of or in combination with theduct tape.

Splices

1. Fold back jacket and insulation from core. Butttwo cores together on a 4'' (100mm) length metalsleeve.

2. Tape cores together with at least 2 wraps of ducttape. Secure connection with 2 clamps placed overthe taped core ends and past the beads.

3. Pull jacket and insulation back over cores. Tapejackets together with at least 2 wraps of duct tape.

Note:1. For uninsulated air ducts and air connectors, disregard references to insulation and jacket.2. Use beaded sheet metal fittings and sleeves.3. Use tapes listed and labeled in accordance with Standard UL 181B and marked “181B-FX”.4. Nonmetallic clamps shall be listed and labeled in accordance with Standard UL 181B and marked “181B-

C”. Use of nonmetallic clamps shall be limited to 6 in. w.g. (1500 Pa) positive pressure.

UNIFORM MECHANICAL CODE

354

APPENDIX A, UMC STANDARD 6-5

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Alternate Installation Instructions for Air Ducts and Air Connectors – Nonmetallic with Plain Ends

Connections and SplicesStep 1: After desired length is determined, cutcompletely around and through duct with knife orscissors. Cut wire with wire cutters. Pull back jacketand insulation from core.

Step 2: Apply mastic approximately 2'' (50 mm)wide uniformly around the collar of the metal fittingor over the ends of a 4'' (100 mm) metal sleeve.Reference data on mastic container for applicationrate, application thickness, cure times and handlinginformation.

Step 3: Slide at least 2'' (50 mm) of core over thefitting or sleeve ends and past the bead.

Step 4: Secure core to collar with a clamp appliedpast the bead. Secure cores to sleeve ends with 2clamps applied past the beads.

Step 5: Pull jacket and insulation back over coreends. Tape jacket(s) with at least 2 wraps of ducttape. A clamp may be used in place of or incombination with the duct tape.

Notes:1. For uninsulated air ducts and air connectors, disregard references to insulation and jacket.2. Use beaded sheet metal fittings and sleeves.3. Use mastics listed and labeled in accordance with Standard UL 181B and marked “181B-M” on container.4. Use tapes listed and labeled in accordance with Standard UL 181B and marked “181B-FX”.5. Nonmetallic clamps shall be listed and labeled in accordance with standard UL 181B and marked “181B-

C”. Use of nonmetallic clamps shall be limited to 6 in. w.g. (1500 Pa) positive pressure.

STANDARD FOR INSTALLATION OFFACTORY-MADE AIR DUCTS

APPENDIX A, UMC STANDARD 6-5

355

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Installation Instruction for Air Ducts and Air Connectors – Metallic with Plain Ends

Connections and Splices1. After cutting duct to desired length, fold backjacket and insulation exposing core. Trim core endssquarely using suitable metal shears. Determineoptional sealing method (step 2 or 5) beforeproceeding.

2. When mastics are required and for pressure 4''w.g. (1000 Pa) and over, seal joint with masticapplied uniformly to the outside surface ofcollar/sleeve. (Disregard this step when not usingmastics and proceed to step 3).

3. Slide at least 1'' (25mm) of core over metal collarfor attaching duct to take off or over ends of a 4'' (100mm) metal sleeve for splicing 2 lengths of duct.

4. Secure to collar/sleeve using #8 sheet metalscrews spaced equally around circumference. Use 3screws for diameters under 12'' (300mm) and 5screws for diameters 12'' (300mm) and over.

5. For pressure under 4'' w.g. (1000 Pa) seal jointusing 2 wraps of duct tape applied over screw headsand spirally lapping tape to collar/sleeve.(Disregard this step when using mastics per Step 2).

6. Pull jacket and insulation back over core. Tapejacket with 2 wraps of duct tape. A clamp may beused in place of or in combination with the ducttape.

Notes:1. For uninsulated air ducts and air connectors, disregard references to insulation and jacket.2. Use mastics listed and labeled to Standard UL 181B and marked “181B-M” on container.3. Use tapes listed and labeled to Standard UL 181B and marked “181B-FX”.4. Nonmetallic clamps shall be listed and labeled in accordance with Standard UL 181B and marked “181B-C”.

Ceiling Joists

6'(1829 mm)

Max.

UNIFORM MECHANICAL CODE

356

APPENDIX A, UMC STANDARD 6-5

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Sag 1/2" Per Foot(42 mm/m) ofSupport Spacing

Wire

1-1/2"(38 mm)Min.

1-1/2" (38 mm) Min.

Wire

4'-0" (1219 mm) Max.

(2) Tape together with at least two wraps ofapproved duct tape. Secure with two approvedclamps.(3) Pull the jacket and insulation back over thecores. Tape the jackets together with two wrapsof approved duct tape.Notes:(a) For uninsulated duct/connector, disregardreference to insulation and jacket.(b) See manufacturer’s installation instructionsfor approved tapes and clamps.(c) Use beaded fittings for pressures exceedingfour (4) inches W.G. (995 Pa) and for diameterstwelve (12) inches (305 mm) and larger.

A.6.509 Supporting Flexible Duct(A) Flexible duct shall be supported at manufacturer’s

recommended intervals, but at no greater distance than four (4) five (5) feet (1219 1524mm).Maximum permissible sag is 1/2 inch per foot(42 mm/m) of spacing between supports.

A connection to rigid ducting or equipmentshall be considered a support joint.

Long horizontal duct runs with sharp bendsshall have additional supports before and after the bend approximately one duct diameterdistance from the centerline of the bend.

(B) Hanger or saddle material in contact with the flexible duct shall be of sufficient width to prevent any restriction of the internal diameter of the duct when the weight of the supported section rests on the hanger or saddle material. In no case will the material contacting the flexibleduct be less than 1-1/2 inches (38 mm) wide.

(C) Factory-installed suspension systems integral tothe flexible duct are an acceptable alternativehanging method when manufacturer’s recommended procedures are followed.

(D) Flexible ducts may rest on ceiling joists or trusssupports. Maximum spacing between supportsshall not exceed the maximum spacing per manufacturer’s installation instructions.

(E) Support the duct between a metal connectionand a bend by allowing the duct to extend straight for a few inches before making the bend.This will avoid possible damage of the flexibleduct by the edge of the sheet metal collar.

(F) Vertically installed duct shall be stabilized by support straps at a maximum of six (6) feet (1829mm) on center.

Note: Factory-made air ducts may not be used forvertical risers in air duct systems serving more thantwo stories. See Section 604.2 of this code.

FIGURE 6-5-37

FIGURE 6-5-38 Proper Support

STANDARD FOR INSTALLATION OFFACTORY-MADE AIR DUCTS

APPENDIX A, UMC STANDARD 6-5

356A

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A.6.510 Checklist

The following checklist is provided for the benefit ofthe inspector, as well as the installer. It is designed sothat the correct answer to all questions is yes.General Yes No

____ Have all tears or punctures to facingmaterial been repaired using theproper technique? ( ) ( )

____ Are all sheet metal accessory items galvanized? ( ) ( )

Product

____ Is the UL label present? (Although ( ) ( )each board is labeled, each sectionmay not be, since there is only onelabel per sheet.)

Fabrication and Installation

____ When metal parts are attached, are2-1/2 inch (64 mm) minimumsquare steel washers used on 16-inch(406 mm) maximum centers? ( ) ( )

____ When staples cannot be used, are8 inch (203 mm) cross-tabs of approvedclosure being used in place of staples?

____ Are tab spacing requirements12 inches, (305 mm) on center minimum one per side. ( ) ( )

____ Are all system joints tight, free frombulges, with taped joints showing good workmanship? ( ) ( )

____ Have offsets been installed so duct sections are not forced to bendaround obstructions? ( ) ( )

Yes NoFire Dampers—See Section A. 6.505

____ Is sheet metal sleeve present? Is duct properly attached to sleeve withscrews and washers 16 inches (406 mm)on center? (Fibrous glass ducts must not penetrate assemblies required to have afire damper.) ( ) ( )

Access Doors

____ Is installation in accordance with Section A. 6.504(E)6? ( ) ( )

Grills, Diffusers, Registers—See Section A. 6.506

____ Is the extra weight of the item beingseparately supported and not dependent on the duct alone forsupport? (Exception: Registers notgreater than 150 square inches(96.7 x 103 mm2) in area may beattached to the duct with metal channel, without other support.) ( ) ( )

Connection to Units

____ Are sheet metal screws and washersused to secure the duct system to flange extensions? (Securing the duct to theunit flange without mechanical fastenersis sufficient.) ( ) ( )

Closures—See Section A. 6.503

____ Are all joints in the system properlysealed? ( ) ( )

____ Are closure materials for rigid duct systemsof a listed type as evidenced by presence of UL instruction sheet in duct board carton or imprinted UL 181A on the tape? ( ) ( )

Yes No

____ Are closure materials for flexible duct systems of a listed type as evidenced by presence of UL instruction sheet in the duct carton and imprinted UL 181B on the tape, mastic, and nonmetallic clamps?

____ Are there staples or cross-tabs, properlyspaced, on circumferential joints? ( ) ( )

____ Are all pressure-sensitive tape closuresrubbed down adequately, with staplesor scrim infacing clearly visible through the tape? ( ) ( )

____ If heat-sealable tape closure was used,was it applied correctly, as evidencedby dot color change? ( ) ( )

____ If glass fabric and mastic are used, is the mesh of the glass fabric completely filled with mastic? ( ) ( )

Reinforcement—See Section A. 6.504

____ Is the reinforcement system in accordance with Section A. 6.504? ( ) ( )

____ Is the tie rod spacing correct accordingto duct span, board type, and staticpressure? ( ) ( )

____ Are tie rod washers 2-1/2 inches(64 mm) square? ( ) ( )

____ Do tie rod washers have turned edges facing away from duct board so theywill not cut into it? ( ) ( )

____ If tie rods reinforce a butt joint, arerods used on both sides of the butt joint?( ) ( )

____ Is wire termination one of those documented in Section 6.504(B)? ( ) ( )

Yes No

____ Are anti-sag devices used on ducts48 inch (1219 mm) span or greater to support top panel of ducts? ( ) ( )

____ Are heels of tees, elbows, and end caps reinforced (formed sheet metal channel, tie rod, or combination)? ( ) ( )

____ When formed sheet metal channelreinforcement is used, are sheet metal gauges, dimensions, and spacing correct? ( ) ( )

____ For return ducts, are sheet metal channel reinforcements attached toducts with screws and 2-1/2 inch(64 mm) square washers or 2 inch by6 inch (51 x 152 mm) clips? ( ) ( )

Hangers and Supports—See Sections A. 6.506 and A.6.509

____ Are hangers installed in accordancewith Section 6.506? ( ) ( )

Are hanger designs in accordance withTable 6-5-6? ( ) ( )

____ Are accessories that add weight to the duct system separately supported so as not to stress the system? (See Section A. 6.506(4).) ( ) ( )

____ If formed sheet metal reinforcementsare used as hangers, are attachments within 6 inches (152 mm) of duct sides? ( ) ( )

____ Are all fittings supported by hangers? ( ) ( )

UNIFORM MECHANICAL CODE

356B

APPENDIX A, UMC STANDARD 6-5

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