Section 23 31 00- HVAC DUCTS AND CASINGS

SECTION 23 31 00

HVAC DUCTS and casings

SPEC WRITER NOTES:

1. Use this section only for NCA projects.

2. Delete between //// if not applicable to project. Also delete any other item or paragraph not applicable in the section and renumber the paragraphs.

3. References to pressure in this section are gage pressure unless otherwise noted.

4. DESIGNER’S NOTE: Coordinate Specification with applicable standard equipment details and schedules:

a. 23 31 00-01 Ductwork Square Vane Elbows

b. 23 31 00-02 Ductwork Radius Elbows

c. 23 31 00-03 Ductwork Transitions (with Equipment Mounted in Duct)

d. 23 31 00-04 Supply Ductwork Take-Offs

e. 23 31 00-05 Supply Duct Takeoff-Air Terminal Units

f. 23 31 00-06 Alternate Supply Duct Takeoff-Air Terminal Units

g. 23 31 00-07 Exhaust or Return Branch Ductwork

h. 23 31 00-08 Volume Damper Detail

i. 23 31 00-09 Access Panel and Door Detail

j. 23 31 00-10 Access Section Round/Oval Duct

k. 23 31 00-11 Flexible Duct Connections

l. 23 31 00-12 Section Thru Fire Damper Installation

m. 23 31 00-13 Flat Oval Duct Hangers/Reinforcement

n. 23 31 00-14 Round Duct Hangers

o. 23 31 00-24 Flexible Air Duct Connector

p. 23 31 00-26 Linear Slot Diffuser

PART 1 GENERAL

1.1 DESCRIPTION

A. Ductwork and accessories for HVAC including the following:

1. Supply air, return air, outside air, exhaust, roof hoods, goosenecks and relief systems.

B. Definitions:

1. SMACNA Standards as used in this specification means the HVAC Duct Construction Standards, Metal and Flexible.

2. Seal or Sealing: Use of liquid or mastic sealant, with or without compatible tape overlay, or gasketing of flanged joints, to keep air leakage at duct joints, seams and connections to an acceptable minimum.

3. Duct Pressure Classification: SMACNA HVAC Duct Construction Standards, Metal and Flexible.

4. Exposed Duct: Exposed to view in a finished room, // exposed to weather. //

1.2 RELATED WORK

A. Fire Stopping Material: Section 07 84 00, FIRESTOPPING.

B. Outdoor and Exhaust Louvers: Section 08 90 00, LOUVERS AND VENTS.

C. //Seismic Reinforcing: Section 13 05 41, SEISMIC RESTRAINT REQUIREMENTS FOR NON-STRUCTURAL COMPONENTS.//

D. General Mechanical Requirements: Section 23 05 11, COMMON WORK RESULTS FOR HVAC.

E. Noise Level Requirements: Section 23 05 41, NOISE AND VIBRATION CONTROL FOR HVAC PIPING AND EQUIPMENT.

F. Duct Insulation: Section 23 07 11, HVAC AND PLUMBING INSULATION

G. Air Flow Control Valves and Terminal Units: Section 23 36 00, AIR TERMINAL UNITS.

H. Duct Mounted Coils: Section 23 82 16, AIR COILS.

I. Return Air and Exhaust Air Fans: Section 23 34 00, HVAC FANS.

J. Air Filters and Filters' Efficiencies: Section 23 40 00, HVAC AIR CLEANING DEVICES.

K. //Duct Mounted Instrumentation: Section 23 09 23, DIRECT-DIGITAL CONTROL SYSTEM FOR HVAC.//

L. Testing and Balancing of Air Flows: Section 23 05 93, TESTING, ADJUSTING, AND BALANCING FOR HVAC.

M. Smoke Detectors: Section 28 31 00, FIRE DETECTION AND ALARM.

1.3 QUALITY ASSURANCE

A. Refer to article, QUALITY ASSURANCE, in Section 23 05 11, COMMON WORK RESULTS FOR HVAC.

B. Fire Safety Code: Comply with NFPA 90A.

C. Duct System Construction and Installation: Referenced SMACNA Standards are the minimum acceptable quality.

D. Duct Sealing, Air Leakage Criteria, and Air Leakage Tests: Ducts shall be sealed as per duct sealing requirements of SMACNA Standards for duct pressure classes shown on the drawings.

E. Duct accessories exposed to the air stream, such as dampers of all types (except smoke dampers) and access openings, shall be of the same material as the duct or provide at least the same level of corrosion resistance.

1.4 SUBMITTALS

A. Submit in accordance with Section 01 33 23, SHOP DRAWINGS, PRODUCT DATA, AND SAMPLES.

B. Manufacturer's Literature and Data:

1. Rectangular ducts:

a. Schedules of duct systems, materials and selected SMACNA construction alternatives for joints, sealing, gage and reinforcement.

b. Duct liner.

c. Sealants and gaskets.

d. Access doors.

2. Round and flat oval duct construction details:

a. Manufacturer's details for duct fittings.

b. Duct liner.

c. Sealants and gaskets.

d. Access sections.

e. Installation instructions.

3. Volume dampers, back draft dampers.

4. Upper hanger attachments.

5. Fire dampers, fire doors, and smoke dampers with installation instructions.

6. Sound attenuators, including pressure drop and acoustic performance.

7. Flexible ducts and clamps, with manufacturer's installation instructions.

8. Flexible connections.

9. Instrument test fittings.

10. Details and design analysis of alternate or optional duct systems.

C. Coordination Drawings: Refer to article, SUBMITTALS, in Section 23 05 11, COMMON WORK RESULTS FOR HVAC.

1.5 APPLICABLE PUBLICATIONS

A. The publications listed below form a part of this specification to the extent referenced. The publications are referenced in the text by the basic designation only.

B. American Society of Civil Engineers (ASCE):

ASCE/SEI 7-05 Minimum Design Loads for Buildings and Other Structures

C. American Society for Testing and Materials (ASTM):

A653/A653M-08 Standard Specification for Steel Sheet, ZincCoated (Galvanized) or Zinc-Iron Alloy coated (Galvannealed) by the Hot-Dip process

B20907 Standard Specification for Aluminum and AluminumAlloy Sheet and Plate

C1071-05e1 Standard Specification for Fibrous Glass Duct Lining Insulation (Thermal and Sound Absorbing Material)

E84-09 Standard Test Method for Surface Burning Characteristics of Building Materials

D. National Fire Protection Association (NFPA):

90A-09 Standard for the Installation of Air Conditioning and Ventilating Systems

E. Sheet Metal and Air Conditioning Contractors National Association (SMACNA):

3rd Edition – 2005 HVAC Duct Construction Standards, Metal and Flexible

1st Edition, 1985 HVAC Air Duct Leakage Test Manual

F. Underwriters Laboratories, Inc. (UL):

UL 33 Heat Responsive Links for Fire-Protection Service

UL 181 FactoryMade Air Ducts and Connectors

UL 555 Fire Dampers

UL 555S Smoke Dampers

PART 2 PRODUCTS

2.1 DUCT MATERIALS AND SEALANTS

A. General: Except for systems specified otherwise, construct ducts and accessories of galvanized sheet steel, ASTM A527, coating G90; or, aluminum sheet, ASTM B209, alloy 1100, 3003 or 5052.

B. Joint Sealing:

1. Sealant: Elastomeric compound, gun or brush grade, maximum 25 flame spread and 50 smoke developed (dry state) compounded specifically for sealing ductwork as recommended by the manufacturer. Generally provide liquid sealant, with or without compatible tape, for low clearance slip joints and heavy, permanently elastic, mastic type where clearances are larger. Oil base caulking and glazing compounds are not acceptable because they do not retain elasticity and bond.

2. Tape: Use only tape specifically designated by the sealant manufacturer and apply only over wet sealant. Pressure sensitive tape shall not be used on bare metal or on dry sealant.

3. Gaskets in Flanged Joints: Soft neoprene.

C. Approved factory made joints such as DUCTMATE SYSTEM may be used.

2.2 DUCT CONSTRUCTION AND INSTALLATION

A. Follow SMACNA HVAC Duct Construction Standards.

SPEC WRITER NOTES: Verify that appropriate duct pressure classes as required by SAMCNA are shown on the drawings and in paragraph 2.2B below.

B. Duct Pressure Class: // 500 Pa // 750 Pa // 1000 Pa // (2 inch // 3 inch // 4 inch //) W.G.

C. Seal Class: As shown on the drawings and in accordance with SMACNA Standards.

D. Round Ducts: Furnish duct and fittings made by the same manufacturer to insure good fit of slip joints. When submitted and approved in advance, round and flat oval duct, with size converted on the basis of equal pressure drop, may be furnished in lieu of rectangular duct design shown on the drawings.

1. Elbows: Diameters 150mm through 200 mm (6 through 8 inches) shall be two sections die stamped, all others shall be gored construction, maximum 18 degree angle, with all seams continuously welded or standing seam. Coat galvanized areas of fittings damaged by welding with corrosion resistant aluminum paint or galvanized repair compound.

2. Provide bell mouth, conical tees or taps, laterals, reducers, and other low loss fittings as shown in SMACNA HVAC Duct Construction Standards.

E. Volume Dampers: Single blade, opposed blade, or multilouver type as detailed in SMACNA Standards.

F. Duct Hangers and Supports: Refer to SMACNA Standards. Avoid use of trapeze hangers for round duct.

SPEC WRITER NOTES: For Outside air ducts, duct liner is not permitted. Provide exterior insulation only.

2.3 DUCT LINER (Where indicated on drawings)

A. Duct sizes shown on drawings for lined duct are clear opening inside lining.

B. Rectangular Duct Liner: ASTM C1071, Type I (flexible), or Type II (board), 25 mm (one inch) minimum thickness, applied with mechanical fasteners and 100 percent coverage of adhesive in conformance with SMACNA HVAC Duct Construction Standards.

C. Round and Oval Duct Liner: Factory fabricated doublewalled with // 25 // 50 // 75 // mm (// one // two // three // inch //) thick sound insulation and inner perforated galvanized metal liner. Construction shall comply with flame and smoke rating required by NFPA 90A. Metal liner shall be 1.0 to 0.60 mm (20 to 24 gage) having perforations not exceeding 2.4 mm (3/32 inch) diameter and approximately 22 percent free area. Metal liner for fittings need not be perforated. Assemblies shall be complete with continuous sheet Mylar liner, 2 mil thickness, between the perforated liner and the insulation to prevent erosion of the insulation. Provide liner couplings/spacer for metal liner. At the end of insulated sections, provide insulation end fittings to reduce outer shell to liner size. Provide liner spacing/concentricity leaving airway unobstructed.

2.4 DUCT ACCESS DOORS, PANELS AND SECTIONS

A. Provide access doors, sized and located for maintenance work, upstream, in the following locations:

1. Each duct mounted coil.

2. Each fire damper (for link service), smoke damper and automatic control damper.

3. Each duct mounted smoke detector.

B. Openings shall be as large as feasible in small ducts, 300mm by 300mm (12 inch by 12 inch) minimum where possible. Access sections in insulated ducts shall be double-wall, insulated.

1. Refer to SMACNA HVAC Duct Construction Standards.

2.5 FIRE DAMPERS

A. Galvanized steel, interlocking blade type, UL listing and label, 11/2 hour rating, 70 degrees C (160 degrees F) fusible link, 100 percent free opening with no part of the blade stack or damper frame in the air stream.

B. Fire dampers shall be galvanized steel.

1. The damper frame may be of design and length as to function as the mounting sleeve, thus eliminating the need for a separate sleeve, as allowed by UL 555. Otherwise provide sleeves and mounting angles, minimum 1.9mm (14 gage), required to provide installation equivalent to the damper manufacturer's UL test installation.

2. Submit manufacturer's installation instructions conforming to UL 555 rating test.

2.6 COMBINATION FIRE AND SMOKE DAMPERS

A. Type: Static and dynamic; rated and labeled according to UL 555 and UL 555S.

B. Closing rating in ducts up to //1 kPa (4-inch wg)// static pressure class and minimum 20 m/s (4000-fpm) velocity.

C. Fire Rating: //1-1/2// and 3// hours.

D. Frame: Multiple-blade type; fabricated with roll-formed, 0.85mm (0.034 inch) thick galvanized steel; with mitered and interlocking corners.

E. Heat-Responsive Device: Replaceable, //74 deg C (165 deg F)// 100 deg C (212 deg F)// rated, fusible links.

F. Smoke Detector: Integral, factory wired for single-point connection.

G. Blades: Roll-formed, horizontal, interlocking, 0.85mm (0.034 inch) thick, galvanized sheet steel. In place of interlocking blades, use full-length, 0.85mm (0.034 inch thick, galvanized-steel blade connectors.

H. Leakage: //Class I//Class II//.

I. Rated pressure and velocity to exceed design airflow conditions.

J. Mounting Sleeve: Factory-installed, 1.3mm (0.052 inch) thick, galvanized sheet steel; length to suit wall or floor application.

K. Damper Motors: Two-position action.

L. Comply with NEMA designation, temperature rating, service factor, enclosure type, and efficiency requirements for motors specified in Section 23 05 12 GENERAL MOTOR REQUIREMENTS FOR HVAC EQUIPMENT.

1. Spring-Return Motors: Equip with an integral spiral-spring mechanism where indicated. Enclose entire spring mechanism in a removable housing designed for service or adjustments. Size for running torque rating of 17 Nm (150 in. x lbf) and breakaway torque rating of 17 Nm (150 in. x lbf).

2. Outdoor Motors and Motors in Outdoor-Air Intakes: Equip with O-ring gaskets designed to make motors weatherproof. Equip motors with internal heaters to permit normal operation at minus 40 deg F (minus 40 deg C).

2.7 SMOKE DAMPERS

A. Maximum air velocity, through free area of open damper, and pressure loss: Low pressure and medium pressure duct (supply, return, exhaust, outside air): 450 m/min (1500 fpm). Maximum static pressure loss: 32 Pa (0.13 inch W.G.).

B. Maximum air leakage, closed damper: 0.32 cubic meters /min/square meter (4.0 CFM per square foot) at 750 Pa (3 inch W.G.) differential pressure.

C. Minimum requirements for dampers:

1. Shall comply with requirements of UL 555S, except for the Fire Endurance and Hose Stream Test.

2. Frame: Galvanized steel channel with side, top and bottom stops or seals.

3. Blades: Galvanized steel, parallel type preferably, 300 mm (12 inch) maximum width, edges sealed with neoprene, rubber or felt, if required to meet minimum leakage. Airfoil (streamlined) type for minimum noise generation and pressure drop are preferred for duct mounted dampers.

4. Shafts: Galvanized steel.

5. Bearings: Nylon, bronze sleeve or ball type.

6. Hardware: Zinc plated.

7. Operation: Automatic open/close. No smoke damper that requires manual reset or link replacement after actuation is acceptable. See drawings for required control operation.

D. Motor operator (actuator): Provide electric as required by the automatic control system, externally mounted on stand-offs to allow complete insulation coverage.

2.8 FLEXIBLE AIR DUCT

A. General: Factory fabricated, complying with NFPA 90A for connectors not passing through floors or buildings. Flexible ducts shall not penetrate any fire or smoke barrier which is required to have a fire resistance rating of one hour or more. Flexible duct length shall not exceed 1.5 m (5 feet). Provide insulated flexible air duct connectors in supply air duct systems and elsewhere as shown.

B. Flexible ducts shall be listed by Underwriters Laboratories, Inc., complying with UL 181. Ducts larger than 200 mm (8 inches) in diameter shall be Class 1. Ducts 200 mm (8 inches) in diameter and smaller may be Class 1 or Class 2.

C. Insulated Flexible Air Duct: Factory made including mineral fiber insulation with maximum C factor of 0.25 at 24 degrees C (75 degrees F) mean temperature, encased with a low permeability moisture barrier outer jacket, having a puncture resistance of not less than 50 Beach Units. Acoustic insertion loss shall not be less than 3 dB per 300 mm (1 foot) of straight duct, at 500 Hz, based on 150 mm (6 inch) duct, of 750 m/min (2500 fpm).

D. Application Criteria:

1. Temperature range: -18 to 93 degrees C (0 to 200 degrees F) internal.

2. Maximum working velocity: 1200 m/min (4000 feet per minute).

3. Minimum working pressure, inches of water gage: 2500 Pa (10 inches) positive, 500 Pa (2 inches) negative.

E. Duct Clamps: 100 percent nylon strap, 80 kg (175 pounds) minimum loop tensile strength manufactured for this purpose or stainless steel strap with cadmium plated worm gear tightening device. Apply clamps with sealant and as approved for UL 181, Class 1 installation.

2.9 FLEXIBLE CONNECTIONS

A. Where duct connections are made to fans and air handling units, install a noncombustible flexible connection of 822g (29 ounce) neoprene coated fiberglass fabric approximately 150 mm (6 inches) wide. For connections exposed to sun and weather provide hypalon coating in lieu of neoprene. Burning characteristics shall conform to NFPA 90A. Securely fasten flexible connections to round ducts with stainless steel or zinccoated iron draw bands with worm gear fastener. For rectangular connections, crimp fabric to sheet metal and fasten sheet metal to ducts by screws 50mm (2 inches) on center. Fabric shall not be stressed other than by air pressure. Allow at least 25 mm (one inch) slack to insure that no vibration is transmitted.

2.10 SOUND ATTENUATING UNITS

A. Casing, not less than 1.0 mm (20 gage) galvanized sheet steel, or 1.3 mm (18 gage) aluminum fitted with suitable flanges to make clean airtight connections to ductwork. Soundabsorbent material faced with glass fiber cloth and covered with not less than 0.6mm (24 gage) or heavier galvanized perforated sheet steel, or 0.85 mm (22 gage) or heavier perforated aluminum. Perforations shall not exceed 4 mm (5/32inch) diameter, approximately 25 percent free area. Sound absorbent material shall be long glass fiber acoustic blanket meeting requirements of NFPA 90A.

B. Entire unit shall be completely air tight and free of vibration and buckling at internal static pressures up to 2000 Pa (8 inches W.G.) at operating velocities.

C. Pressure drop through each unit: Not to exceed indicated value at design air quantities indicated.

D. Submit complete independent laboratory test data showing pressure drop and acoustical performance.

E. Cap open ends of attenuators at factory with plastic, heavy duty paper, cardboard, or other appropriate material to prevent entrance of dirt, water, or any other foreign matter to inside of attenuator. Caps shall not be removed until attenuator is installed in duct system.

2.11 PREFABRICATED ROOF CURBS

A. Galvanized steel or extruded aluminum 300 mm (12 inches) above finish roof service, continuous welded corner seams, treated wood nailer, 40 mm (11/2 inch) thick, 48 kg/cubic meter (3 pound/cubic feet) density rigid mineral fiberboard insulation with metal liner, builtin cant strip (except for gypsum or tectum decks). For surface insulated roof deck, provide raised cant strip (recessed mounting flange) to start at the upper surface of the insulation. Curbs shall be constructed for pitched roof or ridge mounting as required to keep top of curb level.

2.12 FIRESTOPPING MATERIAL

Refer to Section 07 84 00, FIRESTOPPING.

2.13 //SEISMIC RESTRAINT FOR DUCTWORK

Refer to Section 13 05 41, SEISMIC RESTRAINT REQUIREMENTS FOR NON-STRUCTURAL COMPONENTS.//

2.14 THERMOMETER (AIR)

Refer to Section 23 09 23, DIRECT-DIGITAL CONTROL SYSTEM FOR HVAC.

2.15 INSTRUMENT TEST FITTINGS

A. Manufactured type with a minimum 50 mm (two inch) length for insulated duct, and a minimum 25 mm (one inch) length for duct not insulated. Test hole shall have a flat gasket for rectangular ducts and a concave gasket for round ducts at the base, and a screw cap to prevent air leakage.

B. Provide instrument test holes at each duct mounted temperature sensor or transmitter, and at entering and leaving side of each heating coil, cooling coil, and heat recovery unit.

2.16 ROOF HOODS AND GOOSENECKS

A. Factory or shop fabricate according to SMACNA's "HVAC Duct Construction Standards - Metal and Flexible," Figures 6-5 and 6-6.

B. Materials: Galvanized-steel sheet, minimum 1.62-mm (0.064-inch) thick base and 1.0-mm (0.040-inch) thick hood. //Aluminum sheet, minimum 1.6-mm (0.063-inch) thick base and 1.27-mm (0.050-inch) thick hood//; suitably reinforced.

C. Roof Curb: Galvanized steel or extruded aluminum 300mm (12 inches) above finish roof service, continuous welded corner seams, treated wood nailer, 40mm (11/2 inch) thick, 48 kg/cubic meter (3 pound/cubic feet) density rigid mineral fiberboard insulation with metal liner, builtin cant strip (except for gypsum or tectum decks). For surface insulated roof deck, provide raised cant strip (recessed mounting flange) to start at the upper surface of the insulation. Curbs shall be constructed for pitched roof or ridge mounting as required to keep top of curb level.

D. Bird Screening: Flattened, expanded aluminum, 19 by 1.27 mm (3/4 by 0.050 inch) thick.

E. Galvanized-Steel Sheet Finish:

1. Surface Preparation: Clean surfaces of dirt, grease, and other contaminants. Clean welds, mechanical connections, and abraded areas.

2. Field-Painted Finish: Apply an air-dried primer immediately after cleaning.

part 3 - execution

3.1 INSTALLATION

A. Comply with provisions of Section 23 05 11, COMMON WORK RESULTS FOR HVAC , particularly regarding coordination with other trades and work in existing buildings.

B. Fabricate and install ductwork and accessories in accordance with referenced SMACNA Standards:

1. Drawings show the general layout of ductwork and accessories but do not show all required fittings and offsets that may be necessary to connect ducts to equipment, boxes, diffusers, grilles, etc., and to coordinate with other trades. Fabricate ductwork based on field measurements. Provide all necessary fittings and offsets at no additional cost to the government. Coordinate with other trades for space available and relative location of HVAC equipment and accessories on ceiling grid. Duct sizes on the drawings are inside dimensions which shall be altered by Contractor to other dimensions with the same air handling characteristics where necessary to avoid interferences and clearance difficulties.

2. Provide duct transitions, offsets and connections to dampers, coils, and other equipment in accordance with SMACNA HVAC Duct Construction Standards. Provide streamliner, when an obstruction cannot be avoided and must be taken in by a duct. Repair galvanized areas with galvanizing repair compound.

3. Provide bolted construction and tierod reinforcement in accordance with SMACNA HVAC Duct Construction Standards.

C. Install duct hangers and supports in accordance with SMACNA HVAC Duct Construction Standards.

D. Install fire dampers in accordance with the manufacturer's instructions to conform to the installation used for the rating test.

E. Seal openings around duct penetrations of floors and fire rated partitions with fire stop material as required by NFPA 90A.

F. Flexible duct installation: Refer to SMACNA HVAC Duct Construction Standards. Ducts shall be continuous, single pieces not over 1.5m (5 feet) long, as straight and short as feasible, adequately supported. Centerline radius of bends shall be not less than two duct diameters. Make connections with clamps as recommended by SMACNA Standards. Clamp per SMACNA Standards with one clamp on the core duct and one on the insulation jacket. Flexible ducts shall not penetrate floors, or any chase or partition designated as a fire or smoke barrier, including corridor partitions fire rated one hour or two hour. Support flexible ducts per SMACNA HVAC Duct Construction Standards.

G. Control Damper Installation:

1. Provide necessary blankoff plates required to install dampers that are smaller than duct size. Provide necessary transitions required to install dampers larger than duct size.

2. Install all damper control/adjustment devices on stand-offs to allow complete coverage of insulation.

H. //Air Flow Measuring Devices (AFMD): Install units with minimum straight run distances, upstream and downstream as recommended by the manufacturer.//

I. Low Pressure Duct Liner: Install in accordance with SMACNA HVAC Duct Construction Standards.

J. Protection and Cleaning: Adequately protect equipment and materials against physical damage. Place equipment in first class operating condition, or return to source of supply for repair or replacement, as determined by RE/COTR. Protect equipment and ducts during construction against entry of foreign matter to the inside and clean both inside and outside before operation and painting. When new ducts are connected to existing ductwork, clean both new and existing ductwork by mopping and vacuum cleaning inside and outside before operation.

3.2 DUCT LEAKAGE TESTS AND REPAIR

A. Leak testing company shall be independent of the sheet metal company employed by General Contractor.

B. //Ductwork leak test shall be performed for the entire air distribution supply, return, exhaust system Section by Section including fans, coils and filter Section designated as static pressure class 750 Pa (3 inch W.G.) and above. All supply ductwork less than 500 Pa (3 inch W.G) shall also be tested where there is no air terminal unit employed in the system.//

C. Test procedure, apparatus and report shall conform to SMACNA HVAC Air Duct Leakage Test Manual. The maximum leakage rate allowed is 4 percent of the design air flow rate.

SPEC WRITE NOTES: SMACNA requires the system designer to show pressure classes for establishing leakage test requirements for duct systems. Refer to SMACNA HVAC Duct Construction Standards for pressure classes, associated operating pressure ranges and for seals and normal leakage classification. Verify pressure classes are shown on the drawings.

D. All ductwork shall be leak tested first before enclosed in a shaft or covered in other inaccessible areas.

E. All tests shall be performed in the presence of the RE/COTR and the Test and Balance agency. The Test and Balance agency shall measure and record duct leakage and report to the RE/COTR and identify leakage source with excessive leakage.

F. If any portion of the duct system tested fails to meet the permissible leakage level, the Contractor shall rectify sealing of ductwork to bring it into compliance and shall retest it until acceptable leakage is demonstrated to the RE/COTR.

G. All tests and necessary repairs shall be completed prior to insulation or concealment of ductwork.

H. Make sure all openings used for testing flow and temperatures by TAB Contractor are sealed properly.

SPEC WRITER NOTES:

Specify wind velocity as per ASCE Minimum Design Loads for Buildings and Other Structures 7-05 where wind velocity exceeds 90 mph in coastal areas.

// 3.3 ductwork exposed to wind velocity

A. Provide additional support and bracing to all exposed ductwork installed on the roof or outside the building to withstand wind velocity of____km/h (__mph). //

3.4 testing, adjusting and balancing (tab)

Refer to Section 23 05 93, TESTING, ADJUSTING, AND BALANCING FOR HVAC.

3.5 operating and performance tests

Refer to Section 23 05 11, COMMON WORK RESULTS FOR HVAC

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