SELECTION & DESIGN DATA REQUIREMENTS
Standards: AHRI 880 · ASHRAE 70 · ASHRAE 130 · SMACNA · AMCA 500-D · IEC 61537 · TCVN 10688
1.1 Product selection data
The manufacturer shall provide selection tables or a selection tool for each category below, so that the engineer can size and configure products for the design conditions. Every value shall state its source: measured (laboratory, report number, date), certified (certificate number, model / size scope) or calculated (marked "calculated – not tested" with the calculation basis).
VAV/CAV boxes: airflow range, pressure drop, sound, leakage, supply-air temperature limits; AHRI 880 certification for the models / sizes listed in the AHRI Directory (state the AHRI reference); K-factor and leakage reports per ASHRAE 130.
Air terminals / louvres: airflow, pressure drop, throw and sound for each configuration; ASHRAE 70 test report for the tested specimens.
Ductwork: pressure drop per 100 m by size and airflow, pressure class, sheet thickness; fabricated to SMACNA.
Seismic bracing: allowable loads, span lengths, brace angles; third-party certification / listing (FM Approvals, UL) for the exact models offered, with certificate numbers.
Fire dampers: materials, control mechanism, minimum / maximum sizes, EI fire rating with a test report to ISO 21925 (or equivalent), complying with QCVN 06:2023/BXD.
Control dampers (VCD / NRD / PRD): materials, maximum blade length for low / medium / high pressure ranges (SMACNA); leakage and pressure-drop test reports to the AMCA 500-D method, stating the laboratory and report number.
Cable trays: material, thickness, coating, safe working load (SWL); load test reports to TCVN 10688:2015 / IEC 61537:2006 and a valid certificate of conformity where the project requires one.
C-channel support systems: load, deflection and span tables for each channel size and each frame configuration.
1.2 Energy data
Provide data for energy assessment and specific fan power (SFP) checks to ASHRAE 90.1. Fan-powered equipment (fan-powered VAV, ERV, etc.) shall state electrical power (W) at the main operating modes / speeds.
1.3 Data for design verification by the consultant
Data shall be detailed enough for the consultant to verify the operating points independently, not only the manufacturer's "recommended" values. Example: VAV tables shall show the pressure drop at several airflows (25 %, 50 %, 75 %, 100 % of rated airflow) so that the whole operating range can be checked.
Related Starduct pages: Test reports & certificates
AIR OUTLETS / DIFFUSERS / LOUVRES / SILENCERS
Standards: ASHRAE 70 · AMCA 500-L · EN 13030 · ISO 7235 · ASTM E477 · ISO 10140-2 · ASTM B221 · ISO 12944-2
2.1 Grilles and diffusers (straight blade, T-bar, slot, egg-crate, perforated face, square, round, swirl, jet)
Material: extruded aluminium A6063-T5 (ASTM B221), galvanised steel or stainless steel 304 depending on the model; the manufacturer declares the material and thickness of frame, blades / face.
Finish: powder coating to P15.4; RAL colour to the architectural requirement.
Performance: airflow, pressure loss, throw and sound tested to ASHRAE 70 at an independent laboratory on a representative specimen; other sizes stated as calculated. Test reports provided on the consultant's request.
Selection: data tables of airflow (m³/h or L/s), pressure loss (Pa), throw (m) and sound (NC or dB(A)) for choosing size / configuration.
2.2 Volume control dampers and plenums
Opposed-blade volume control damper (OBD) in metal, adjustable from the outlet face; no plastic drive parts.
Plenum box in galvanised steel; sheet thickness and insulation (where fitted) declared; sealing gasket at the duct collar.
2.3 Square / round ceiling diffusers
Diffuser face and core without welds; core removable without tools, held by pins or spring clips against falling, for cleaning and damper access.
Documents: cross-section drawing showing construction, and the manufacturer's cleaning / maintenance instructions.
2.4 Displacement diffusers
Declare airflow against face velocity, sound and near-zone length (to 0.20 / 0.25 m/s); distributor and inner faces painted dark so they are not visible through the perforated face.
2.5 Fresh-air / exhaust louvres
Blades with water stops and drainage; declare material, blade and frame thickness and maximum module size; insect screen where the project requires.
Free area, pressure loss and beginning point of water penetration to AMCA 500-L; rain-defence class A–D to EN 13030 where the project requires; untested values marked "calculated – not tested".
Louvres installed outdoors use an outdoor coating system to P15.4.
2.6 Duct silencers and acoustic louvres
Material: casing, frame and blades in galvanised, Zn-Al-Mg or aluminium-zinc coated steel (ASTM A653 / A792), aluminium or stainless steel; infill of perforated sheet, mineral wool / glass wool and a fibre-retaining facing; no bare wool exposed to the airstream. Declare casing thickness, wool density and thickness, and facing weight.
Fire behaviour of the absorbent: declare reaction to fire (EN 13501-1 / BS 476-6/7 / ASTM E84) when a report exists; otherwise state that it is not tested.
Duct silencers: insertion loss, self-generated noise and pressure loss to ISO 7235 or ASTM E477 per octave band; casing leakage to EN 1507 / EN 12237 where the project requires.
Acoustic louvres: sound reduction index to ISO 10140-2 (or ASTM E90); aerodynamics to AMCA 500-L.
State whether each value is measured or calculated; pressure class and velocity to SMACNA / ASHRAE.
Related Starduct pages: Air outlets · Silencers & acoustic louvres
AIR CONTROL DAMPERS (VCD / NRD / PRD)
Standards: AMCA 500-D · EN 1751 · SMACNA · ASTM A653 / JIS G3302
Materials
• Casing and blades in galvanised steel with coating of at least Z180 (180 g/m²), Zn-Al-Mg coated steel or stainless steel 304 to suit the environment; casing and blade thickness declared by size and pressure class.
• Blades ribbed or profiled for stiffness, with overlapping or interlocking edges; low-leakage dampers have blade-edge seals and blade-end seals; seal material (rubber, silicone, stainless spring strip) chosen for the operating temperature.
• Blade length per module not more than 900 mm; reinforced high-pressure dampers up to 1 000 mm per the manufacturer's table; larger sizes are built from modules. Plated steel or stainless shafts, bronze or self-lubricating polymer bearings, fixed rigidly in the casing.
Performance
• Casing leakage and closed-blade leakage tested to AMCA 500-D or EN 1751; declare leakage flow against pressure difference, or casing class (A–C) and blade class (0–4) to EN 1751; reports state laboratory, report number and specimen size. Results from the manufacturer's in-house laboratory are accepted when clearly marked as in-house.
• Pressure loss against face velocity and blade angle; untested sizes stated as calculated. State an AMCA 511 leakage class only when the product holds the corresponding AMCA certification.
• Data tables: airflow, pressure loss at blade angles, closed leakage.
NRD (non-return damper): opens / closes with the airflow direction, light or spring-loaded blades.
PRD (pressure relief damper): opening pressure set at the factory or adjusted on site; airflow – pressure difference curve.
Related Starduct pages: Control dampers
FIRE DAMPERS
Standards: ISO 21925-1:2018 · TCVN 9311-1:2012 · EN 1366-2 / EN 15650 · QCVN 06:2023/BXD
Types and fire classification
• Single- or multi-blade dampers, fire class E / EI by duration (30 / 45 / 60 / 90 / 120 / 180 min) not less than the requirement of the fire-separating element where installed.
• Fire tested to ISO 21925-1 (superseding ISO 10294-1), or EN 1366-2 where the project follows European standards, at an accredited laboratory; submit the test report (report number, date, specimen, test wall / floor construction) and the inspection file under QCVN 06:2023/BXD where the law requires.
• Smoke class (S) stated only when a corresponding classification document exists.
• Sizes larger than the specimen: within the field of application stated in the test report (modular assembly…).
Materials and installation
• Materials, thickness and density of casing, blade, insulation, shaft and bearings identical to the specimen described in the test report; inorganic insulation, non-combustible, non-absorbent, mould resistant.
• Installation, gap-sealing materials and supporting construction per the tested configuration in the test report; other configurations must fall within the report's field of application.
• The manufacturer declares how far the blade projects beyond the casing when open, so that the design leaves duct length or clearance.
Actuation
• Motorised dampers: spring-return electric actuator closing on power loss or fire alarm signal; declare voltage, closing time and 2 auxiliary switches for closed / open status; actuator rated for elevated temperature or housed in a heat-protection enclosure as tested.
• Thermal-fuse dampers: fusible link with nominal operating temperature 72 °C (or as designed); control box outside the damper casing for manual open / close during periodic testing; fuse replaceable from outside without removing damper or duct; status contacts where required.
• Tunnel dampers: see P12.
Performance at ambient temperature
• Open-damper pressure loss and closed leakage at ambient temperature (EN 1751 / AMCA 500-D), stated as measured or calculated; these values lie outside the fire classification.
• Where the project requires: closing against airflow, opening against working pressure difference and number of open / close cycles tested.
Related Starduct pages: EI fire dampers
VAV / CAV BOXES (AIR TERMINAL UNITS)
Standards: AHRI 880 · AHRI 885 · ASHRAE 130 · ASHRAE Guideline 36 · UL 1996 / UL 1995 / IEC 60335-2-40 (electric heaters)
5.1 Configuration and material
• Single-duct, dual-duct and fan-powered VAV/CAV, delivered with factory-mounted controller.
• Casing, body and damper blade in corrosion-protected coated steel (Zn-Al-Mg or equivalent); sheet thickness and coating mass declared; no black or uncoated steel.
• Damper blade with seal; multi-point airflow sensor with K-factor measured to ASHRAE 130.
5.2 Performance
• Airflow, pressure loss and sound tested to AHRI 880 (sound to AHRI 885 to estimate room NC); models / sizes listed in the AHRI Directory carry their AHRI reference number, other sizes stated as calculated; the model name in the AHRI Directory matches the order code.
• Minimum operating pressure (MOP) at rated airflow.
• Casing and damper leakage tested to ASHRAE 130, leakage flow declared at several static pressures, and EN 1751 leakage class where the project requires; reports included in the technical submittal.
5.3 Fan-powered units
High-efficiency EC motor with stepless speed control; publish power, current, airflow, pressure and sound at each speed step.
5.4 Acoustic lining
Sealed boxes: closed-cell, fibre-free, dust-free foam lining. Fan-powered boxes: mineral wool / glass wool behind perforated sheet with a fibre-retaining facing is allowed. No bare fibres exposed to the airstream.
Declare fire behaviour (UL 94 / ASTM D635 / BS 476-6/7) and mould resistance (UL 181 / ASTM G21) of the lining, with test reports.
5.5 Controls
Digital controller, set-up / balancing by NFC or software; BMS interface (BACnet MS/TP, Modbus RTU or 0–10 V); full integration documents.
5.6 Reheat
Hot-water coil: selection data (air / water flow, entering / leaving temperatures, air- and water-side pressure drop, capacity) to the AHRI 410 / ASHRAE 33 method, stating measured or calculated; coil leak-tested at not less than 1.5 × working pressure; 2- / 3-way control valve and discharge-air sensor, discharge temperature limited per ASHRAE Guideline 36.
Electric heater: electrical safety to UL 1996 or IEC 60335-2-40, installed to the electrical code; minimum-airflow interlock (airflow / pressure switch) and two thermal cut-outs (one automatic reset, one manual reset). Duct downstream of the heater in non-combustible material for at least 1 m; maintenance clearance on the control-box side.
PTC heater: self-limiting ceramic PTC elements, insulated from the casing and the airstream; over-temperature / over-current protection.
Related Starduct pages: VAV boxes · Electric heater table
METAL DUCTWORK (GI / ZAM)
Standards: SMACNA HVAC Duct Construction Standards – Metal and Flexible · TCVN 5687:2024
Design standard
• Metal ductwork fabricated to SMACNA "HVAC Duct Construction Standards – Metal and Flexible"; pressure class, sheet thickness, reinforcement and hangers selected from the SMACNA tables for each pressure range and size.
Material
• Hot-dip galvanised steel, minimum coating Z180 (or Zn-Al-Mg / as the environment requires); no uncoated black steel for supply / return ductwork.
• Sheet thickness from the SMACNA tables by pressure class and longest side; reference values:
— Low pressure (< 750 Pa): 0.60 – 1.20 mm
— Medium pressure (750–1,500 Pa): 0.80 – 1.50 mm
— High pressure (1,500–2,500 Pa): 0.90 – 2.00 mm
Air tightness
• Seams and joints sealed to the leakage class required by SMACNA / TCVN 5687, using duct sealant, tape or gaskets. FIRE-RATED DUCTWORK (EI)
Standards: QCVN 06:2023/BXD · ISO 6944-1 · EN 1366-1
Testing and classification
• Fire-rated ductwork for smoke extraction, emergency ventilation, etc. tested and classified to ISO 6944-1 / EN 1366-1 (or equivalent), complying with QCVN 06:2023/BXD; covering fire outside and fire inside the duct where the design requires; E / EI rating not less than the design requirement.
• Submit the test report (laboratory, report number, specimen configuration) for the exact duct system offered.
Field of application
• Duct construction, insulation, joints and hangers shall fall within the field of application of the tested system; no ad-hoc material combinations without a corresponding tested system.
Insulation
• Non-combustible or limited-combustibility material, with thickness, density and installation details confirmed by the test report.
FLEXIBLE DUCTWORK
Standards: SMACNA · ASHRAE Handbook · EN 13180 · UL 181 / EN 13501-1 (where the project requires)
Product
• Factory-made flexible duct: aluminium / polyester core reinforced with a steel-wire helix; insulated type with glass-wool insulation and an aluminium or reinforced-film jacket.
• State the operating temperature range, maximum working pressure and the heat / cold resistance test reports (laboratory, report number); pressure drop calculated to the ASHRAE Handbook and marked "calculated – not tested".
• Insulated types: declare insulation thickness, density and thermal conductivity (or thermal resistance to ASTM C518); dimensions, mechanical strength and air-tightness to EN 13180; pressure loss including the correction factor for duct not fully extended.
• Reaction to fire to UL 181 or EN 13501-1 / BS 476-7 where the project requires, with a report for the exact product offered.
Limits of use
• Only for short final connections to terminals or equipment; section length and bend radius as recommended by SMACNA / the manufacturer; not for main duct runs.
Related Starduct pages: Ductwork
FLEXIBLE CONNECTORS
Standards: SMACNA
Standard flexible connectors
• Rubber- / PVC-coated technical fabric or equivalent, suitable for the system temperature and pressure; galvanised steel frames to SMACNA / manufacturer details.
Heat-resistant flexible connectors (smoke-extraction systems)
• State the temperature and duration of heat resistance from the test report (laboratory, report number, specimen).
• Galvanised frame thickness declared; temperature and duration of heat resistance not less than the smoke-extract system requirement (for example 300 °C – 120 min).
• Where an EI fire separation must be maintained, use a solution tested within the corresponding fire-rated duct / damper system; no site-made connectors.
Related Starduct pages: Ductwork
CABLE TRAYS & LADDERS
Standards: TCVN 10688:2015 / IEC 61537:2006
Design and testing
• Designed, tested and manufactured to TCVN 10688:2015 / IEC 61537:2006: safe working load (SWL), deflection, electrical continuity, corrosion resistance and mechanical safety.
• Submit load test reports to TCVN 10688 / IEC 61537 (laboratory, report number, specimen size) and a valid certificate of conformity where the project requires; loads for untested sizes are marked as calculated.
• Impact resistance, electrically conductive / non-conductive classification and non-flame propagation to IEC 61537, with test records.
Construction
• Cold-formed (punched, roll-formed, folded); no thermal cutting, no welding.
• Integral section joints or matching couplers; hooked / rolled stiffening edges; curved tees, bends, risers / drops and reducers.
Material
• Galvanised steel (coating at least Z180), Zn-Al-Mg coated steel, stainless steel 304 / 316 or powder coated, chosen by ISO 12944-2 corrosivity category (P15.4); uniform coating, no peeling.
• Sheet thickness declared per size; joint bolts of property class at least 8.8 with a coating equivalent to the tray.
Related Starduct pages: Cable trays
SEISMIC SWAY BRACING
Standards: NFPA 13 · ASCE 7 · TCVN 9386 · FM 1950 · UL 203A · SMACNA Seismic Restraint Manual
General requirements
• Seismic bracing for piping, ductwork, cable trays and suspended equipment uses braces, structure attachments and pipe clamps with third-party certification / listing (FM Approvals to FM 1950, UL to UL 203A) for the exact models offered; submit certificate numbers and how to verify them (FM Approval Guide, UL Product iQ).
• Each certification / listing applies only to the models named in it; brace angle within the model's listed range and not less than 30° from vertical; design force to NFPA 13 §18.5.9 or the project standard.
• Design seismic force, lateral / longitudinal brace layout, brace angles and spacing per the standards applicable to the project.
• The supplier submits allowable-load tables, installation instructions and bracing layout calculations consistent with the project's seismic design drawings.
Related Starduct pages: Hangers & seismic sway bracing
TUNNEL DAMPERS
Reference standards: UL 555S · BS 476-20 · AMCA 500-D
Requirements
• For tunnel, station and large car-park ventilation and smoke extraction: high airflow, high pressure and high temperature in a fire.
• Steel airfoil blades and reinforced steel frame; electric or pneumatic actuation with a fail-safe position as designed.
• Frame, blade and coating materials chosen for the environment (Zn-Al-Mg coated steel, stainless steel 304 / 316); heat-resistant blade seals; limit switches for status; declare maximum working pressure, module size and assembly method.
• Heat resistance (temperature / duration), leakage and pressure drop: the manufacturer submits test reports to the standards specified for the project (e.g. UL 555S or BS 476-20 for heat resistance; AMCA 500-D for aerodynamics) or states the testing status and the calculated data.
Related Starduct pages: Tunnel damper
ENERGY RECOVERY VENTILATORS (ERV)
Reference standards: ASHRAE 62.1 · ASHRAE 90.1 · TCVN 5687:2024 · EN 308 (heat-exchanger test method)
Components
• Supply and exhaust fans, sensible or enthalpy (total) heat-exchanger core, filters and integrated controller.
Performance
• State the sensible / total recovery efficiency at rated airflow, fan curves and electrical power (W) at the main operating modes for ASHRAE 90.1 checks; state whether measured (laboratory, report number) or calculated.
• Outdoor-air flow per ASHRAE 62.1 / TCVN 5687.
• Cross-leakage between supply and exhaust air, sound level and external static pressure (ESP) at the design airflow.
Related Starduct pages: Energy recovery ventilator (ERV)
C-CHANNEL SUPPORT SYSTEM
Standards: SMACNA · manufacturer's MEP support design guidelines
14.1 Material and construction
• Roll-formed C-channel with stiffening ribs; serrated inner lips for positive engagement with spring nuts / channel nuts, no slipping under design load or vibration.
• Coating: galvanised steel (minimum Z120) or Zn-Al-Mg coating; for highly corrosive environments (coastal, outdoor) hot-dip galvanising or an enhanced paint system.
• Matching accessories: spring nuts, bolts and nuts, gusset plates, clamps, threaded rod, etc. in the same material and coating as the channel.
14.2 Loads
• The manufacturer publishes allowable loads for each channel size and configuration (simply supported beam, cantilever, single suspension, composite frame) with the corresponding spans; deflection tables / charts at design load and the allowable deflection limit; state measured or calculated.
• The contractor uses only configurations and spans within the published load range; anything beyond requires a separate verification calculation or written technical approval.
Related Starduct pages: Hangers & seismic sway bracing
GENERAL REQUIREMENTS FOR ALL PRODUCTS
15.1 Data sources, test reports and certificates
• Every performance value states its source: measured (laboratory, report number, date), certified / listed (certificate number, model / size scope) or calculated (marked "calculated – not tested" with the calculation basis).
• "Complied" statements without supporting documents are not accepted. Test reports are issued by independent accredited laboratories; results from the manufacturer's in-house laboratory are clearly identified as in-house.
• Logos and certification statements apply only to the models / sizes named in the certificate; expired certificates are not presented as valid.
15.2 Warranty
• Warranty period and scope as stated in the contract / warranty card; the manufacturer provides a written warranty policy.
15.3 Mandatory technical documentation
• Detailed drawings
• Installation instructions
• Operation and maintenance manual
• Cleaning instructions
• Spare parts list
• In Vietnamese and English (or translated as the project requires)
15.4 Surface finish and corrosion protection
• Coating chosen for the ISO 12944-2 atmospheric corrosivity category of the installation; the manufacturer declares the coating system for each category.
• Coated steel: declare coating mass (for example Z180, ZM275); coating thickness measured to ISO 2178 / ISO 1460.
• Powder coating: multi-stage line pretreatment before coating; average dry film thickness not less than 60 µm (ISO 2808); adhesion ISO 2409, impact ISO 6272-1, bend ISO 1519, gloss ISO 2813.
• Outdoor, coastal or corrosivity C3 and above: coating system certified to AAMA 2603 / Qualicoat class 1 or AAMA 2604 / Qualicoat class 2, or UV durability to ISO 16474-3.
• Written coating warranty: duration, applicable environment category and assessment criterion (for example colour difference ΔE*ab measured to ASTM D2244).
Related Starduct pages: Test reports & certificates
