HVAC Equipment, Air Conditioner, Chiller, AHU, Fan-Coil, Fan, Cooling Tower & Evaporative Cooler Manufacturing HVAC Duct Guide

1. Why ventilating an HVAC-equipment factory is its own engineering discipline

There is a neat irony in the topic of this guide. The companies that build Australia’s air conditioners, chillers, air-handling units, fan-coils, fans, cooling towers and evaporative coolers are themselves running factories with some of the most demanding ventilation requirements in the country — and they know it better than anyone, because air movement is their trade. Yet the ventilation of the production hall is a different problem from the comfort or process air the equipment ultimately delivers. Inside a single HVAC-equipment plant — the Seeley International evaporative-cooler line at Lonsdale in Adelaide SA, the ActronAir ducted-AC assembly at Western Sydney NSW, the Smardt Chillers oil-free chiller hall in Melbourne VIC, or an AHU integrator’s casing shop in Dandenong VIC — you will find copper-aluminium coil brazing throwing copper and flux fume in one bay, polyurethane foam injection releasing isocyanate and pentane in the next, a refrigerant charging room handling flammable R32 and R290 a few metres away, a powder-coat booth and a 200 °C cure oven down the line, and a psychrometric test chamber rejecting the full heat of a unit under test in the back. Each process has its own characteristic fume chemistry, dust load, ignition risk, hazardous-area zoning requirement and duct-material specification.

Ductwork inside an HVAC-equipment factory is therefore not a commodity item. It is a process-engineering problem that touches coil-braze cadmium and copper-fume exposure control, flammable-refrigerant charge-limit and dilution design under AS/NZS 5149, isocyanate and pentane hazardous-area classification under AS/NZS 60079, combustible powder-coat dust deflagration safety under AS 3957, flammable-liquid spray-paint compliance under AS 1940 and NFPA 33, high-temperature cure-oven exhaust under AS 1375 and NFPA 86, and the occupational-health backbone of AS 1668.2 dilution ventilation tied to SafeWork Australia workplace exposure standards (WES). A generic commercial fabricator treating an HVAC-equipment plant as just another industrial job under-prices the first project and walks away from the second.

This guide writes against the full breadth of the Australian HVAC-equipment manufacturing sector as it exists in 2026. Evaporative cooling is an Australian export strength — Seeley International in Adelaide SA designs and builds Breezair, Braemar and Coolair evaporative coolers plus gas ducted heating, exporting to dozens of countries from a South Australian manufacturing base. Ducted and packaged air conditioning has a proud Australian-made presence in ActronAir (Sydney NSW), which engineers and assembles ducted, packaged and inverter systems for the Australian climate. The chiller end is led globally from Melbourne by Smardt Chillers, whose oil-free magnetic-bearing centrifugal chillers are exported worldwide. Air-handling units and ducted systems come from Temperzone, AustralAire and a set of AHU integrators; heat-recovery AHU specialist Air Change builds energy-recovery units; Fantech (Melbourne) is the dominant Australian fan manufacturer; Holyoake builds air distribution, diffusers and grilles; Polyaire (Adelaide) supplies flexible ducting, components and zoning; and Stoddart and Aolan fabricate AHU and casing product. Daikin Australia and Mitsubishi Electric Australia run national assembly, distribution and charging operations. Water-heating and combustion-adjacent names such as Dux, Rheem, Vulcan and Gason sit alongside on the same sheet-metal-and-combustion fabrication base, and the cooling-tower segment (Muller, BAC) adds plastic, FRP and water-treatment fabrication.

Across this entire sector, HVAC-equipment-factory ductwork must survive several simultaneous demands. Metal-fume capture and corrosion resistance (coil-braze copper and flux fume, cabinet weld fume). Flammable-atmosphere safety (A2L and A3 refrigerant charging, pentane foam blowing agent, spray-paint solvent, powder-coat combustible dust). High-temperature service (powder-coat and paint cure ovens at 180–200 °C). The lowest exposure standards in the plant (cadmium 0.001, isocyanate MDI 0.02, rosin solder fume as a no-threshold sensitiser). And cleanability and hygiene where evaporative-media, condensate or food-adjacent product demands it. Each is manageable in isolation. Together they explain why the cabinet shop, the coil shop, the charging room, the foam cell and the paint line each need a purpose-engineered duct circuit rather than a single generic exhaust system.

This guide walks every major process zone in an HVAC-equipment factory and explains what changes about the ductwork, then closes with the SBKJ machine configuration that gives an Australian fabricator — or an HVAC-equipment maker bringing fabrication in-house — the production envelope to serve this market from Box Hill North VIC across the country. And there is a natural affinity worth stating up front: the machines that fabricate ductwork are the same machines that fabricate AHU casings, condensing-unit cabinets, chiller frames and evaporative-cooler bodies. The HVAC-equipment manufacturer is, quite literally, SBKJ’s peer and customer in one.

2. The Australian regulatory stack — AS 1668, AS 4254, AS/NZS 5149, AS/NZS 1677, AS/NZS 60079, AS 3957, AS 1940, NFPA cross-references, ISO 9001/14001/45001

Factory ventilation in an Australian HVAC-equipment plant sits at the intersection of building-code mechanical-ventilation standards, occupational-health exposure compliance, refrigeration-safety standards, hazardous-area electrical compliance, combustible-dust and flammable-liquid safety, welding and oven standards, and the overarching quality and environmental management systems. Ignoring any one of them invites a notice from SafeWork Australia, the state EPA, or the certifying authority. The stack splits as follows.

2.1 AS 1668.1 and AS 1668.2 — the mechanical-ventilation backbone

AS 1668.2 is the umbrella mechanical-ventilation standard for buildings in Australia and the governing document for the factory’s general and process-driven ventilation. HVAC-equipment factories fall under NCC Class 8 industrial occupancy. AS 1668.2 sets the dilution ventilation rates that hold airborne contaminants below the relevant workplace exposure standard, and — just as importantly — the make-up air that must replace every cubic metre extracted from a braze hood, foam cell, paint booth, cure oven or charging room with tempered, filtered, controlled-velocity supply air. AS 1668.1 governs fire and smoke control in air-handling systems, relevant where the factory’s own HVAC interacts with the building’s fire-compartmentation. Where AS 1668.2 matters most in this sector is the interplay between localised exhaust ventilation (LEV) at each fume source and the building-volume dilution requirement: LEV at the coil-braze, foam, paint and solder stations drives total exhaust well above the building dilution figure, and the make-up-air plant must keep production zones at neutral or slightly negative pressure relative to clean assembly and office zones so that fume, solvent and refrigerant do not migrate.

2.2 AS 4254.1 and AS 4254.2 — sheet-metal and flexible duct construction

AS/NZS 4254.1 (sheet metal) and AS/NZS 4254.2 (flexible) govern duct construction across the normal pressure ranges — low pressure (up to 500 Pa), medium pressure (up to 1000 Pa) and high pressure (up to 2500 Pa). The general supply, return and the bulk of the process-fume LEV in an HVAC-equipment factory sit inside AS 4254 ranges. The high-temperature cure-oven exhaust in its hot section runs beyond AS 4254 and needs purpose-engineered construction; AS 4254 picks up again on the cool side downstream of the dilution and cooling zone. Crucially, AS 4254 is also the construction standard for the sheet-metal product the factory makes — the AHU casing, the connecting duct, the plenum — so the same construction discipline applies to the equipment and to the building services around it.

2.3 AS 1530.4 and fire-rated penetrations

AS 1530.4 covers fire-resistance testing of building elements, including fire-rated ductwork penetrations through fire compartments. In an HVAC-equipment factory this matters at every wall and floor penetration between a hazardous process zone (the foam cell, the paint line, the charging room, the flammable-store) and adjacent office, laboratory, test or evacuation zones. The penetration must meet the fire-resistance level (FRL) called by the building’s approval, with fire dampers complying with AS 1682 and the surrounding assembly meeting its rating — a 250 °C/2-hour integrity rating is typical at the boundary between a foam or paint hazard zone and an occupied space.

2.4 AS/NZS 1677 and AS/NZS 5149 — refrigeration safety and refrigerant charge limits

AS/NZS 1677 (refrigerating systems) and AS/NZS 5149 (refrigerating systems and heat pumps — safety and environmental requirements) are the dominant standards for the refrigerant-handling parts of the plant, and they have been transformed by the refrigerant transition. AS/NZS 5149.1 sets refrigerant safety classifications — A1 (non-flammable, e.g. R410A, R134a), A2L (mildly flammable, e.g. R32), A3 (flammable, e.g. R290 propane, R600a isobutane), B-group toxic (e.g. ammonia R717, classed B2L) — and the maximum permissible charge for a system as a function of the occupied-space volume and the refrigerant’s flammability. For the factory’s own charging room, this drives three things: the charge-and-volume calculation, the continuous dilution ventilation sized to keep any credible leak below 25% of the lower flammable limit (LEL), and the requirement for fixed leak detection interlocked to boost ventilation. AS/NZS 5149.3 (the installation site) and AS/NZS 5149.4 (operation, maintenance and recovery) round out the framework. ASHRAE 15 and ASHRAE 34 are the parallel international references that Australian manufacturers building for export also design to.

2.5 AS/NZS 60079 — explosive atmospheres, the dominant electrical-safety standard

AS/NZS 60079 is the hazardous-area-classification standard, and the refrigerant transition plus foam pentane plus spray-paint solvent plus powder-coat dust now trigger it at multiple points in an HVAC-equipment factory:

• Zone 1 (gas/vapour, likely in normal operation): the immediate vicinity of the refrigerant charging manifold for A2L/A3 refrigerants; the foam-injection mixing head and the pentane day tank; the spray-paint booth interior during spraying; the surface of any open solvent or IPA bath.
• Zone 2 (gas/vapour, unlikely in normal operation, short duration): the general refrigerant charging room; the general foam cell around the mixing head; the general spray-paint room outside the booth; the flammable-liquid store.
• Zone 21 / Zone 22 (combustible dust): the powder-coat spray booth and powder-recovery cartridge collector interior (Zone 21 in the booth, Zone 22 around it), where organic powder coat is an explosible dust.

AS/NZS 60079 drives Ex-rated electrical equipment for fans, motors, instrumentation, leak detectors, lighting and any device inside or near the affected zones. Ductwork in a flammable-gas or combustible-dust zone must be conductive throughout (316L stainless is the default for these circuits), continuously bonded with conductive flange gaskets at every joint, externally bonded with copper or stainless strap to the building earth grid, and verified at commissioning at less than 1 ohm to ground at every section — the static-discharge ignition path is the failure mode that bonding prevents.

2.6 AS 3957 — dust hazard areas for powder coat and combustible particulate

AS 3957 is the Australian dust-hazard standard, and in an HVAC-equipment factory its dominant application is the powder-coat line. Organic powder coat is a combustible dust with a deflagration index Kst typically in the St1 range (up to about 200 bar·m/s) and a minimum ignition energy low enough that an electrostatic discharge can ignite a suspended cloud. AS 3957 mandates dust-hazard zoning (Zone 21 for the booth where an explosible cloud occurs in normal operation, Zone 22 around it), driving the AS/NZS 60079.10.2 electrical-equipment selection, and forcing a dust hazard analysis (DHA): at the powder-recovery collector, what is the Kst, what is the minimum ignition energy, and what is the engineered deflagration-protection chain (vent panels to NFPA 68, isolation to NFPA 69) between the cartridge collector and the inbound duct? Where the plant also handles fine plastic dust from rotomould trimming or grinding, AS 3957 applies there too.

2.7 AS 1940 — storage and handling of flammable and combustible liquids

AS 1940 governs flammable and combustible liquids in Australian workplaces, and an HVAC-equipment factory triggers it at several stations. The spray-paint line stores solvent-borne paint, thinners and two-pack hardener (Class IB and IC flammable liquids). The foam line stores the polyol and isocyanate components and the pentane or cyclopentane blowing agent (pentane is a Class IA flammable liquid with a flash point well below ambient). Any solvent wipe-down or degreasing station adds Class IB liquids. Each storage and handling point requires bunded containment, a dedicated LEV branch, segregated storage and AS/NZS 60079 zoning around the immediate work area. AS 1940 sits alongside NFPA 33 (spray application using flammable materials) as the engineering reference for the paint booth.

2.8 AS/NZS 1554 — structural and sheet-metal welding

AS/NZS 1554 (structural steel welding) and the associated welding-fume guidance govern the cabinet, frame and casing welding throughout the plant. Light spot-welding and seam-welding of galvanised, Zincalume and stainless casing release manganese (WES 0.2 mg/m³), iron oxide (5 mg/m³) and, on stainless, hexavalent chromium (Cr VI, 0.05 mg/m³ and an IARC Group 1 carcinogen) and nickel. On-tool or captor-hood extraction at the weld, into a fume main, is the control. Coil brazing and soldering, though metallurgically distinct from welding, sit under the same fume-control philosophy.

2.9 AS 1375 and NFPA 86 — industrial cure ovens

AS 1375 (the SAA industrial fuel-fired appliances code) and the international reference NFPA 86 (industrial ovens and furnaces) govern the powder-coat and wet-paint cure ovens running 160–220 °C. The exhaust topology includes LEL monitoring at every gas-fired burner, a purge cycle before light-off, explosion relief on the oven shell, a dedicated exhaust riser separate from general facility exhaust, and a burner-management system with redundant flame supervision. The cure oven volatilises trace VOC and, for blocked-isocyanate powders, decomposition products that the dedicated oven exhaust must carry to atmosphere or to a thermal oxidiser.

2.10 AS 4024, AS/NZS 2243.8, AS/NZS 1715/1716 — machinery safety, fume cupboards and RPE

AS 4024 (safety of machinery) governs the guarding, interlocking and emergency-stop design of the fabrication and assembly machinery — including the duct-fabrication line itself. AS/NZS 2243.8 (fume cupboards) is relevant in the plant’s chemistry and quality laboratory and at any small chemical handling station. AS/NZS 1715 (selection, use and maintenance of respiratory protective equipment) and AS/NZS 1716 (RPE performance) set the respiratory protection backup behind engineering controls — powered air-purifying respirators (PAPR) for foam and isocyanate work, particulate respirators for coil-braze and weld fume, and organic-vapour cartridges for spray paint.

2.11 NCC Section J, ASHRAE 62.1 and the energy overlay

NCC Section J (energy efficiency) governs the factory building’s thermal performance and the efficiency of its own HVAC plant, including the make-up-air and heat-recovery systems that serve the heavily-exhausted production hall. ASHRAE 62.1 (ventilation for acceptable indoor air quality) is the international reference for the clean assembly and office portions of the plant. Because an HVAC-equipment factory exhausts large volumes from braze, foam, paint and charging circuits, the make-up-air energy penalty is significant, and heat recovery on the exhaust (where the stream is clean enough) is both an energy and a Section J compliance lever.

2.12 ISO 9001, ISO 14001 and ISO 45001 — the management-system overlay

ISO 9001 (quality), ISO 14001 (environmental) and ISO 45001 (occupational health and safety) are the management systems under which most Australian HVAC-equipment manufacturers operate, and each touches the factory ventilation. ISO 45001 requires documented LEV maintenance records and periodic breathing-zone air sampling against the WES for every operator-occupied zone. ISO 14001 requires control and monitoring of stack emissions to the state EPA licence. ISO 9001 requires the fabrication and commissioning documentation that ties every duct run to its mill certificate, pressure test and bonding verification — the same paperwork an exporter needs for its CE, UL or AHRI product approvals.

2.13 SafeWork Australia workplace exposure standards — the chemistry-driven sizing inputs

SafeWork Australia’s workplace exposure standards (WES) are the regulatory inputs that drive LEV capture velocity and ductwork sizing across the HVAC-equipment factory. The sector-relevant standards are extensive:

• Cadmium and cadmium compounds: 0.001 mg/m³ (1 µg/m³) — among the lowest in the standard. From legacy cadmium-bearing silver-braze filler at the coil-braze station. THE reason cadmium-free filler is mandated; an acute kidney and lung carcinogen.
• Copper fume: 0.2 mg/m³. From copper-tube brazing and soldering at the coil station — the dominant routine coil-braze metal fume.
• Fluoride (as F): 2.5 mg/m³. From the fluoride-bearing brazing flux that wets the copper joint; borate compounds accompany it.
• Isocyanate (MDI, methylene diphenyl diisocyanate): 0.02 mg/m³. From polyurethane foam injection and from two-pack polyurethane spray-paint hardener — THE killer of the foam and paint zones. A potent respiratory sensitiser; once sensitised, occupational asthma is triggered by trace exposure for life.
• Pentane / cyclopentane: simple asphyxiant; flammable with an LEL around 1.4% by volume. The low-GWP foam blowing agent. Drives AS/NZS 60079 hazardous-area zoning around the foam cell.
• Manganese (fume): 0.2 mg/m³. From cabinet and frame welding (steel). Neurotoxic.
• Iron oxide (fume): 5 mg/m³. From cabinet and frame welding.
• Chromium VI (hexavalent): 0.05 mg/m³. From stainless casing welding and stainless coil work. IARC Group 1 human carcinogen.
• Nickel (inhalable): 1 mg/m³; insoluble compounds 0.1 mg/m³. From stainless and nickel-bearing alloy welding.
• Lead: 0.05 mg/m³. From leaded solder where still used in controls/PCB assembly — favouring lead-free alloys.
• Rosin / colophony solder-flux fume: a recognised respiratory sensitiser treated as having no safe threshold. From PCB and controls soldering. Control is engineering (tip extraction), not dilution.
• Xylene: 80 ppm. From solvent-borne spray paint and thinners. Toluene 50 ppm, MEK 200 ppm, ethyl acetate 200 ppm accompany it.
• Ozone (O3): 0.1 ppm STEL. From arc welding plasma and from any UV process.
• Ammonia (R717): 25 ppm TWA, 35 ppm STEL. From industrial ammonia refrigeration charging and service (B2L toxic and mildly flammable).
• Hydrogen fluoride (HF): 1.8 ppm. The decomposition product if an A2L/A3 fluorinated refrigerant burns — the reason fire risk in a charging room is more than just the flammability.
• Carbon monoxide (CO): 30 ppm STEL. From gas-fired cure ovens and combustion-test rigs.
• Carbon dioxide (CO2): 5000 ppm. Indoor-air-quality marker; also the refrigerant R744 (asphyxiant at high concentration in a leak).
• Propane (R290) / isobutane (R600a): simple asphyxiants; flammable, LEL around 1.7–2.1% by volume. The A3 flammable refrigerants. Heavier than air; pool at floor level.

Every dust and fume LEV branch in an HVAC-equipment factory has to keep the operator’s breathing-zone air below the relevant WES. Where multiple contaminants are present (Cr VI plus Ni plus Mn at a stainless-casing weld station), the additive-mixture rule applies and the LEV must be sized to the lowest practical fraction. This is the calculation that drives capture velocity, transport velocity, branch sizing and main sizing across every process duct in the plant — covered in detail in the WES dilution-calculation section below.

3. Process zones — the HVAC-equipment factory end-to-end

The most reliable way to specify HVAC-equipment-factory ventilation is to walk the process flow. A typical plant maps to a variant of the same sequence: incoming sheet metal, tube and component; coil manufacturing (tube expansion, fin press, braze, leak test); sheet-metal cabinet and AHU casing fabrication; sub-assembly; refrigerant charging and run test; foam injection and panel insulation (evaporative, AHU, fridge); rotomould or thermoform plastic parts (evaporative tanks); powder coat and spray paint; controls and PCB assembly; final assembly; performance and psychrometric test; motor and fan balancing; and pack-out. Each station has its own characteristic fume chemistry, temperature, capture velocity and duct-material requirement.

4. Coil manufacturing — brazing fume LEV, cadmium-free filler and the copper-aluminium heart of the plant

The coil is the thermodynamic heart of every air conditioner, chiller, AHU, fan-coil and condenser made in Australia, and the coil shop is the single most important LEV zone in the factory. The heat-exchanger coil is built by expanding copper tube into a stack of pressed aluminium fins, forming the U-bends and return bends, and then joining the tube ends to return bends and to the distributor and header by brazing — and where dissimilar metals or lower temperatures are involved, by soldering. Brazing copper to copper uses copper-phosphorus filler (which is self-fluxing on copper) at roughly 700–760 °C; brazing copper to brass or steel, or where a stronger silver joint is needed, uses silver-bearing filler with a fluoride-borate flux at 620–750 °C.

The braze station produces the most concentrated and the most hazardous routine fume in the plant. The fume cocktail has three parts. First, copper fume (WES 0.2 mg/m³) from the heated copper tube and filler. Second, flux decomposition products — fluoride (WES 2.5 mg/m³ as F) and borate compounds from the flux that wets the silver-braze joint, which are both an inhalation hazard and corrosive to galvanised duct. Third, and historically the killer, cadmium. Older silver-braze alloys included cadmium to depress the melting point and improve flow, and cadmium oxide fume has a WES of just 0.001 mg/m³ (1 µg/m³), an acute renal and pulmonary toxin and a recognised carcinogen. The unequivocal modern Australian practice — across Seeley International, ActronAir, Smardt Chillers, Temperzone, and every coil shop that feeds them — is cadmium-free filler, and the plant must specify cadmium-free and verify it on the filler certificate, because legacy stock and some imported filler can still contain cadmium. We emphasise this because it is the single highest-consequence specification error a coil plant can make: brazing with cadmium-bearing filler under inadequate LEV has killed brazers.

The ventilation response is dedicated LEV at every braze and solder position. The practical arrangement is a captor hood positioned within 150–300 mm of the joint, or on-torch/at-the-tip extraction, drawing the fume away from the brazer’s breathing zone at a capture velocity of 0.5–1.0 m/s at the joint. Because braze fume is a fine fume and not an abrasive dust, the branch and main run at a moderate 8–12 m/s transport velocity into a cartridge or baghouse collector with a HEPA polishing stage. The duct material is 316L stainless or aluminised steel, not galvanised, because the fluoride-borate flux fume attacks zinc. On a multi-station coil line — some Australian coil shops run a dozen or more braze positions in parallel — each position feeds a branch into a trunk main sized for the coincident braze load (rarely 100%, since not every position brazes simultaneously). After braze, the coil is pressure-and-leak tested (dry nitrogen or helium trace gas), which adds an inert-gas handling consideration but a minor ventilation load. AS 1668.2 sets the dilution and make-up air behind the LEV; AS/NZS 1715/1716 set the particulate-respirator backup.

5. Refrigerant charging and handling — A2L/A3 flammable refrigerants, charging-room ventilation and leak dilution

The refrigerant transition is the single biggest change to HVAC-equipment-factory safety in a generation, and it has turned the refrigerant charging room from a low-hazard area into a hazardous-area-classified zone. The global-warming-potential (GWP) phase-down has pushed the industry off high-GWP non-flammable HFCs (R410A, R134a, R404A) and onto lower-GWP refrigerants that are, by chemistry, flammable. R32, the A2L (mildly flammable) refrigerant, is now the dominant charge in Australian split systems and many packaged units. R290 (propane, A3 flammable) is used in some chillers, heat pumps and commercial refrigeration. R600a (isobutane, A3 flammable) is used in small sealed systems. On the industrial side, ammonia (R717, B2L toxic and mildly flammable, WES 25 ppm TWA / 35 ppm STEL) and CO2 (R744, a high-pressure asphyxiant) appear in large refrigeration plant. The flammable A3 hydrocarbons have an LEL around 1.7–2.1% by volume; R32 around 14% but still classed A2L; and a leak in an enclosed charging room can build an explosible or oxygen-displacing mixture.

The ventilation engineering response under AS/NZS 5149 and AS/NZS 1677 has three layers. First, the charge-limit and room-volume calculation per AS/NZS 5149.1 — the maximum permissible charge for an A2L or A3 system is a function of the occupied-room volume and the refrigerant’s flammability class, and the charging room must satisfy this for the largest charge handled. Second, continuous mechanical dilution ventilation sized so that any credible leak (a charging-hose disconnection, a relief-valve lift, a brazed-joint failure on a charged unit) stays below 25% of the LEL. Because R32, propane, isobutane and CO2 are all heavier than air, the extract is taken at low level where these gases pool; the supply air is introduced high to sweep the room downward. Third, fixed refrigerant leak detection — catalytic-bead or infrared sensors mounted at low level — interlocked to boost the extract fan to a high-rate purge and to alarm before the concentration approaches the LEL. The charging manifold and its immediate surrounds are classified Zone 1 under AS/NZS 60079, the general charging room Zone 2, driving Ex-rated extract fans, motors, leak detectors and light fittings, and conductive bonded ductwork.

The fire-decomposition hazard adds a further consideration: if a fluorinated A2L refrigerant burns, it decomposes to hydrogen fluoride (HF, WES 1.8 ppm) and carbonyl halides, so the charging-room emergency response and the ventilation purge are designed to clear not just the flammable gas but the toxic decomposition products of a fire. Ammonia charging (industrial plant) has its own toxic-gas envelope — the ammonia WES of 25 ppm and its sharp odour threshold drive a dedicated ammonia detection and scrubbed-exhaust system, with the charging area treated as a toxic-and-flammable zone. ActronAir, Daikin Australia, Mitsubishi Electric Australia and every Australian split-system, packaged-unit and chiller assembler has rebuilt charging-room ventilation around the A2L/A3 reality, and the charging-room extract duct is now a bonded, conductive, low-level-extract 316L circuit rather than a simple wall fan.

6. Foam injection — polyurethane isocyanate (MDI) and pentane blowing agent

Foam injection is where the lowest practical exposure standard in the plant meets a flammable blowing agent, and it is the most chemically dangerous single process in an evaporative-cooler, insulated-panel or refrigeration-cabinet line. Polyurethane (PU) foam is formed by reacting a polyol (the “A” side) with an isocyanate (the “B” side) at a high-pressure mixing head, injecting the reacting mix into the cavity of an evaporative-cooler body, an AHU sandwich panel, or a fridge/freezer cabinet, where it expands and cures. The isocyanate is methylene diphenyl diisocyanate (MDI), with a SafeWork Australia WES of 0.02 mg/m³ and a potent respiratory-sensitiser action: MDI is released as aerosol and vapour at the mixing head, at the injection ports, during overspill and flash, and during demould, and once a worker is sensitised, occupational asthma can be triggered by trace exposure for the rest of their working life. There is no “safe” casual exposure to isocyanate; the control is rigorous engineering plus PAPR.

The second hazard is the blowing agent. The foam needs a blowing agent to expand, and the low-GWP choice is pentane or cyclopentane — a hydrocarbon that is both a simple asphyxiant and flammable, with an LEL around 1.4% by volume and a flash point well below ambient (a Class IA flammable liquid under AS 1940). Pentane is present in the blowing-agent storage, the day tank, the metering system and the mixing head, and a leak can build an explosible atmosphere.

So the foam cell needs two engineering responses simultaneously. First, dedicated LEV at the mixing head, the injection fixture and the demould station at 0.5–1.0 m/s capture velocity to hold MDI below 0.02 mg/m³ in the breathing zone, into a 316L stainless branch (amine catalyst off-gas is corrosive) at 8–12 m/s transport to a collector or scrubber. Second, hazardous-area classification under AS/NZS 60079 around the pentane source — the blowing-agent store and day tank Zone 2, the mixing head and metering skid Zone 1 — with Ex-rated extraction fans and fixed flammable-gas detection interlocked to the extract, and the duct continuously conductive and bonded to ground. Seeley International’s Breezair and Braemar evaporative-cooler bodies, the AHU sandwich-panel lines at the AHU integrators, and every fridge/freezer cabinet foam line in Australia run this dual MDI-plus-pentane envelope. It is, with the coil-braze cadmium hazard and the spray-paint isocyanate hazard, one of the three places in the plant where getting the ventilation wrong has the highest human consequence.

7. Sheet-metal cabinet and AHU casing fabrication — the SBKJ affinity zone

Every air conditioner, chiller, AHU, fan-coil, condensing unit and evaporative cooler has a sheet-metal cabinet, and the cabinet shop is exactly where SBKJ duct-fabrication machinery belongs — because the casing, the internal baffles, the condensate trays and the connecting duct are formed from the same galvanised, Zincalume, aluminium and stainless coil, on the same machines, as the ductwork SBKJ’s traditional customers fabricate. An AHU maker, a packaged-AC maker or an evaporative-cooler maker that brings cabinet fabrication in-house is buying the SBKJ machine set; this is the natural affinity that runs through this whole guide.

The fabrication ventilation in the cabinet shop is moderate but not nil. Light spot-welding and seam-welding of the casing releases manganese (0.2 mg/m³) and iron oxide (5 mg/m³) on steel and, on stainless casing, Cr VI (0.05 mg/m³) and nickel; AS/NZS 1554 weld practice drives captor-hood or on-tool extraction at 0.5–1.0 m/s into an 8–12 m/s fume main. Punching, notching, lock-seam forming and rollforming produce noise and a little metallic dust but a minor ventilation load. The dominant HVAC consideration in the cabinet shop is actually general dilution, weld-fume capture and make-up air, not a high-hazard chemistry.

The SBKJ machine fit in the cabinet shop is direct and complete. The SBAL-V auto duct line forms the cabinet panels, internal baffles, condensate trays and connecting duct in 0.5–1.6 mm galvanised, Zincalume, aluminised and 304/316L stainless in a continuous decoil-level-notch-fold-flange line. The SBAL-III heavy-gauge line handles the AHU frames, condensing-unit base frames and chiller structural casing in 1.6–2.0 mm. The SBPC1500 Pittsburgh-lock former and the SBLR-600 rollformer close the casing longitudinal seam (Pittsburgh lock, snap-lock or rollformed standing seam). The SBFB-1500 TDF flange line and the SBTF-1500/1602/2020 TDF flange formers produce the bolted section-to-section flange connections between AHU modules and to the site ductwork. The SB-ZF1500 plasma line cuts the coil, fan, filter, access-panel and service-penetration openings from CAD files. And the SBSF-1525 longitudinal stitch welder lays a continuous hermetic TIG seam where a coastal-grade stainless casing, a hygienic plenum or a stainless condensate tray demands a welded joint rather than a lock seam. This is the exact machine set an Australian HVAC-equipment maker installs to bring cabinet and connecting-duct fabrication in-house — identical to the set SBKJ supplies to dedicated ductwork fabricators, which is precisely why the HVAC-equipment manufacturer is SBKJ’s natural peer and customer.

8. Powder coating and wet spray paint — combustible dust, solvent overspray and cure-oven exhaust

HVAC cabinets, chiller frames, AHU casings, condensing-unit covers and evaporative-cooler bodies are finished for outdoor weather resistance, predominantly by powder coating and, where colour or substrate demands, by wet spray paint. The two finishing routes have different ventilation envelopes.

Powder coating has two LEV demands. First, the spray booth, where electrostatically-charged organic powder is sprayed at the part and the overspray is recovered. Organic powder coat is a combustible dust — an explosible cloud with a deflagration index Kst typically in the St1 range and a minimum ignition energy low enough that a static discharge can ignite it — so the booth and the powder-recovery cartridge collector fall under AS 3957 (dust hazard area, Zone 21 in the booth, Zone 22 around it) and AS/NZS 60079.10.2, and the cartridge collector needs NFPA 68 deflagration venting and NFPA 69 isolation between the collector and the inbound duct, sized from the dust hazard analysis. Second, the cure oven, where the powder is cross-linked at 180–200 °C; the oven releases trace VOC and, for blocked-isocyanate powders, decomposition products, and needs a dedicated NFPA 86 / AS 1375 oven exhaust with burner management, LEL monitoring and a purge cycle.

Wet spray paint adds an organic-solvent overspray load. Solvent-borne topcoats release xylene (WES 80 ppm), toluene (50 ppm), MEK (200 ppm) and, critically, the isocyanate hardener in two-pack polyurethane topcoats — the same MDI 0.02 mg/m³ respiratory-sensitiser hazard as the foam line. The overspray and solvent are captured in a water-wash or dry-filter spray booth designed to AS 1940 flammable-liquid practice and NFPA 33 spray-application practice, with the booth and its immediate surrounds classified Zone 1 (interior, during spraying) and Zone 2 (surrounds) under AS/NZS 60079. The booth extract is sized for the design face velocity across the booth opening — typically 0.4–0.6 m/s for an open-front booth, higher for a cross-draft or down-draft booth — and the booth plenum and stack are 316L stainless to resist the solvent and two-pack overspray. The cure oven after wet paint runs the same NFPA 86 / AS 1375 envelope as the powder cure oven. Across both routes, the LEV mains are 316L for the high-solvent and overspray sections and aluminised steel for the warm cure-oven exhaust downstream of the hot transition.

9. Rotomould and thermoform plastic parts — evaporative-cooler tanks and plastic fume

Evaporative coolers, cooling-tower components and some AHU and fan-coil parts use moulded plastic — the water sump and tank of an evaporative cooler, the casing of some residential units, fan scrolls and impellers, and cooling-tower fill and basins. Rotational moulding (rotomould) is the dominant process for large hollow plastic parts such as evaporative-cooler tanks: powdered polyethylene is loaded into a closed mould, the mould is rotated bi-axially in an oven at 250–300 °C until the polymer melts and coats the cavity, then cooled and demoulded. Thermoforming and injection moulding cover smaller and thinner parts.

The ventilation hazard from rotomould is plastic-decomposition fume at the oven and at demould. Heated polyethylene releases low-molecular-weight hydrocarbons, aldehydes and, if overheated, acrolein and other irritants; pigment and additive packages add their own off-gas. The control is oven exhaust (the rotomould oven runs an NFPA 86 / AS 1375 envelope, with the products of combustion from a gas-fired oven plus the plastic-decomposition fume carried to atmosphere) and a captor hood at the demould/de-flash station where the hot part releases residual fume. The plastic-trimming, drilling and grinding of moulded parts produces plastic dust, which — if fine enough — is a combustible dust under AS 3957 and needs dust-collection LEV with the same deflagration-protection thinking as the powder-coat collector. The duct material here is generally aluminised steel or 316L for the warm oven exhaust and galvanised or stainless for the dust circuits. Cooling-tower fabricators (Muller, BAC) and evaporative specialists add FRP and plastic-welding fabrication with their own light-fume LEV.

10. Controls, PCB and solder assembly — rosin solder fume

Every modern HVAC unit carries control electronics — inverter and variable-speed drives, ECM motor controllers, building-management-system interface boards, thermostats, expansion-valve controllers and sensor boards — and many Australian HVAC manufacturers assemble, configure or rework these PCBs in-house. Soldering electronics releases rosin (colophony) solder-flux fume, a recognised respiratory sensitiser and one of the leading causes of occupational asthma in electronics assembly. SafeWork Australia treats colophony solder fume as a sensitiser without a safe threshold, so the control is engineering, not dilution: tip extraction or a benchtop captor hood at every hand-solder position and at every wave-solder or reflow machine, at 0.5–1.0 m/s capture into a small-diameter branch at 8–10 m/s transport to a dedicated solder-fume filter (HEPA for the particulate plus activated carbon for the gas-phase rosin acids).

Where leaded solder is still in use, lead fume (WES 0.05 mg/m³) is an additional concern, favouring lead-free alloys (which, however, solder hotter and can generate more flux fume). The solder-fume LEV is small in volume compared with the coil-braze, foam or paint circuits, but it is non-negotiable for worker health and is kept on a separate clean circuit so that the fine solder-fume filtration is not loaded with metal-shop dust. The controls assembly area also has ESD-control and clean-air requirements (anti-static flooring, controlled humidity) that sit alongside the solder-fume LEV.

11. Performance and psychrometric test — heat load, refrigerant and run test

Air conditioners, chillers, AHUs and evaporative coolers are performance-tested and run-tested before shipment, and the test facility imposes a distinct HVAC and safety load on the factory. A psychrometric test chamber — used by ActronAir, Smardt Chillers, Temperzone and any manufacturer rating capacity to AHRI 210/240 and 340/360, EN, ISO or AS standards — holds tightly controlled temperature and humidity on both the indoor and outdoor side of the unit under test, while rejecting the full heat of the operating unit. This requires a large dedicated cooling and reheat plant, precise air-temperature and humidity control on the chamber supply, an air-measuring code-tester (nozzle bank) on the airflow side, and a substantial sensible-and-latent heat-rejection path to outside. The chamber HVAC is engineered separately from the production-floor general ventilation but shares the same make-up-air and energy-recovery philosophy, and the heat rejected from continuous capacity testing is itself a significant facility load.

The refrigerant in the unit under test is a hazard. A charged unit that develops a leak inside a sealed test chamber can build a refrigerant concentration — oxygen displacement for any refrigerant, and an explosible mixture for an A2L/A3 charge — so the chamber needs fixed refrigerant leak detection and a high-rate purge-ventilation interlock, with low-level extract for the heavier-than-air refrigerants, mirroring the charging-room design. The run-test and electrical burn-in area, where units are soaked under power to verify motors, compressors and controls, adds a heat load and a small amount of motor and bearing off-gas, plus the general requirement to manage the rejected heat. For combustion product (gas ducted heaters from Seeley, Braemar, Vulcan, Gason; gas water heaters from Dux, Rheem), the combustion test rig adds a flue-gas exhaust with CO (30 ppm STEL) and NOx monitoring.

12. Motor and fan balancing — rotational test and bearing handling

Fans, fan-coils, condensing units and AHUs contain rotating assemblies — fan impellers, motor rotors, compressor sets — that are dynamically balanced and run-tested. Fantech (Melbourne) and the AMCA-aligned fan makers fabricate, balance and test fan impellers at scale; every AHU and fan-coil maker balances its fan sets. The balancing and rotational-test area is not a high-fume zone, but it carries its own considerations: the noise of high-speed rotational test (an acoustic, not an air-quality, control); a small amount of bearing-grease and motor-varnish off-gas during run-in; metallic swarf and grinding dust from any in-balance material removal (drilling balance holes, grinding); and the general make-up air and comfort ventilation for an area with significant motor heat rejection. The grinding and material-removal LEV is a conventional metal-dust circuit; the rest is general dilution and comfort ventilation under AS 1668.2. Impeller and scroll fabrication itself is sheet-metal work — another zone where the SBKJ machine set forms the rollformed and welded components.

13. Hazardous-area classification — flammable refrigerant, pentane, solvent and combustible dust

Pulling the flammable hazards together, an HVAC-equipment factory now carries a hazardous-area map that did not exist a generation ago, driven by AS/NZS 60079 (gas and dust). The gas/vapour zones (AS/NZS 60079.10.1) are: the refrigerant charging manifold and immediate surrounds (Zone 1 for A2L/A3 refrigerants) within the general charging room (Zone 2); the foam mixing head and pentane day tank (Zone 1) within the foam cell (Zone 2); the spray-paint booth interior during spraying (Zone 1) within the paint room (Zone 2); the flammable-liquid and blowing-agent stores (Zone 2); and the psychrometric test chamber during a charged-unit test (a transient Zone 2 on leak). The dust zones (AS/NZS 60079.10.2) are: the powder-coat booth (Zone 21) and powder-recovery collector interior (Zone 21) within the powder-coat area (Zone 22); and any fine-plastic-dust collection from rotomould trimming.

Hazardous-area classification drives three things for the ductwork. First, material and bonding: duct in a gas or dust zone must be conductive (316L stainless) and continuously bonded with conductive flange gaskets and external bonding strap to the building earth, verified below 1 ohm to ground at every section at commissioning — the static-discharge ignition path is the failure mode. Second, fan and electrical selection: every fan, motor, leak detector, light and instrument in or near a zone must be the correct Ex protection type and temperature class for AS/NZS 60079.0–.31. Third, deflagration protection on the dust circuits: NFPA 68 venting and NFPA 69 isolation between the powder-coat collector and the inbound duct. The hazardous-area dossier — a zone map, an equipment schedule and a verification record — is part of the factory’s safety case and is maintained under ISO 45001.

14. Combustible dust — powder coat, plastic fines and the dust hazard analysis

The combustible-dust risk in an HVAC-equipment factory is real and concentrated in two places: the powder-coat line and any fine-plastic-dust generation from rotomould or thermoform trimming and grinding. AS 3957 and the international reference NFPA 660 (the 2025 consolidation of the former combustible-dust standards) require a written dust hazard analysis (DHA) that maps every point of dust generation, accumulation, ignition source and propagation path, with engineering controls for each. For organic powder coat, the DHA quantifies the deflagration index Kst (St1 range, up to about 200 bar·m/s), the minimum ignition energy and the explosibility, and from that sizes the deflagration venting (NFPA 68) and the isolation (NFPA 69) on the powder-recovery cartridge collector so that a deflagration in the collector cannot propagate back through the duct into the booth.

The duct-design consequences are: keep the powder-coat overspray main at a transport velocity high enough to prevent powder dropout and accumulation in horizontal runs (powder coat is a fine solid, so 12–18 m/s in the laden main, higher than a clean-fume main), route with minimum horizontal dead legs, fit the duct with clean-out access at intervals, bond the duct to ground throughout, and place the isolation device between the collector and the duct so the flame front is arrested. The same discipline applies to a fine-plastic-dust collector. Good housekeeping — preventing dust layers from accumulating on duct, beams and surfaces where a primary deflagration could loft them into a far more destructive secondary explosion — is the other half of combustible-dust safety and is documented in the DHA.

15. WES dilution and LEV sizing — the calculation that drives the ductwork

Two velocity calculations dominate HVAC-equipment-factory LEV design: capture velocity at the source and transport velocity in the main. Capture velocity is the air velocity, measured at the point of contaminant release, needed to draw the contaminant into the hood faster than thermal buoyancy, mechanical disturbance and cross-drafts can carry it past the operator’s breathing zone. The practical capture-velocity ranges in this sector are: coil-braze and solder joint 0.5–1.0 m/s; cabinet and frame weld 0.5–1.0 m/s at the arc; foam mixing head and demould 0.5–1.0 m/s; PCB solder tip 0.5–1.0 m/s at the iron; spray-paint booth 0.4–0.6 m/s face velocity across the opening; rotomould demould 0.5–0.7 m/s; refrigerant-charging-room and foam-cell general dilution sized from the leak/LEL calculation rather than a capture velocity.

Transport velocity is the minimum velocity in the branch and main that keeps the contaminant entrained without dropout. For fine fume (braze, weld, solder, paint solvent) 8–12 m/s is adequate — there is no heavy particulate to settle. For powder-coat overspray and plastic dust (a fine solid) 12–18 m/s. For metal-grinding swarf and dust 18–22 m/s. For vapour-only streams (solvent vapour with no aerosol) 5–10 m/s. Each branch is sized at its design transport velocity; the trunk main is sized for the simultaneous load of all branches at their design coincidence factor (a coil shop rarely brazes at every position at once; a paint booth runs continuously during a spray batch).

The dilution calculation that ties it together comes from the WES. For a general-dilution requirement — for example, holding a charging room below 25% of the refrigerant LEL, or a foam cell below the pentane LEL fraction, or a weld bay below the manganese WES — the required ventilation rate is the contaminant generation rate divided by the allowable concentration (the WES, or the LEL fraction, minus the supply-air background), with a mixing-efficiency factor (K-factor) applied because real rooms do not mix perfectly. Where several contaminants act on the same target organ (Cr VI, Ni and Mn at a stainless weld; xylene and toluene at a paint booth), the additive-mixture rule sums the fractions of each WES and the ventilation is sized so the sum stays below one. This calculation — generation rate, allowable concentration, mixing factor, additive mixture — is the quantitative basis for every branch and main in the plant, and it is the engineering content behind the AS 1668.2 and AS/NZS 5149 numbers.

16. Material selection — why galvanised fails and what replaces it in the process circuits

Galvanised carbon steel is the workhorse of general HVAC duct and the right answer for the factory’s clean supply and return air. In the process-exhaust circuits of an HVAC-equipment plant, it is the wrong answer for most duct, for four reasons:

16.1 Galvanised carbon steel — the failure modes

First, chemistry: coil-braze fluoride-borate flux fume, foam amine-catalyst off-gas, and spray-paint solvent overspray all attack zinc directly. Second, temperature: zinc fumes above about 250 °C service and volatilises above 419 °C, so the powder-coat and wet-paint cure-oven exhaust at 180–200 °C (and hotter at the oven shell) approaches or exceeds safe galvanising service. Third, conductivity and bonding: the flammable-refrigerant, pentane and combustible-dust circuits must be continuously conductive to ground (below 1 ohm at every flange) to prevent static-discharge ignition, and the surface oxide on galvanising raises contact resistance at joints. Fourth, cleanability and hygiene: where evaporative-media hygiene, condensate or food-adjacent product matters, galvanising’s white-rust under washdown contaminates the stream.

16.2 316L stainless — the process-circuit workhorse

316L stainless (Cr 16–18%, Ni 10–14%, Mo 2–3%, C ≤0.03%) is the dominant material for the high-hazard process circuits: the coil-braze flux-fume main, the foam MDI-and-pentane main, the spray-paint and powder-coat overspray mains, the flammable-refrigerant charging-room extract, the PCB solder-fume circuit, and any condensate or hygiene-critical run. It resists flux, amine and solvent; it runs well above the cure-oven temperature; it gives consistent earth-bonding conductivity for the hazardous-area circuits; and it is cleanable. The SBAL-V stainless option produces 316L rectangular duct, the SBFB-1500 produces 316L spiral round duct, and the SBSF-1525 lays a continuous TIG bead for a hermetic, conductive, bonded envelope.

16.3 Aluminised steel — the warm-and-mild middle ground

Hot-dip aluminised steel (carbon steel with an aluminium-silicon coating) serves the warm, mildly-corrosive sections: the powder-coat and wet-paint cure-oven exhaust downstream of any high-temperature transition, and the general process-fume mains. Service temperature 400–600 °C, good resistance to mildly acidic exhaust, and significantly cheaper than 316L — the practical choice for the bulk length of cure-oven exhaust between the hot section and the collector.

16.4 Aluminium, coated steel and FRP — the specialty cases

Aluminium duct appears where weight or specific corrosion resistance favours it and temperature is low. Coated (epoxy or PVC-laminated) steel serves moderately corrosive cool streams. FRP (fibreglass-reinforced plastic with a vinyl-ester or furan resin) is the choice for any strongly acidic mist — relevant where the plant runs a chemical pre-treatment or passivation line ahead of paint, or a water-treatment chemistry station for cooling-tower and evaporative product. FRP duct is built to AS/NZS 4254 with a conductive interior coating where AS/NZS 60079 zoning applies.

17. Australian operator deep dives

17.1 Seeley International — Adelaide SA, evaporative cooling and gas heating

Seeley International, headquartered in Adelaide SA with manufacturing at Lonsdale, is Australia’s evaporative-cooling champion and a substantial exporter — Breezair and Coolair evaporative coolers, Braemar evaporative coolers, ducted gas heating and add-on cooling, shipped to dozens of countries. From a factory-ventilation perspective, Seeley carries one of the heaviest hazard stacks in the sector: foam injection for the insulated cooler bodies (isocyanate MDI plus pentane blowing agent — the dual hazardous-area-plus-isocyanate envelope), rotomould plastic tanks (plastic-decomposition oven fume and demould fume), powder coat (combustible-dust booth plus 180–200 °C cure oven), sheet-metal cabinet fabrication, and gas-heater combustion test (CO/NOx flue exhaust). The SBKJ machine fit at an operation like Seeley centres on the SBAL-V (cabinet and chassis panels in Zincalume and stainless), the SBPC1500 and SBLR-600 (lock-seam and rollformed casing), the SBFB-1500 (TDF-flanged connecting duct and round LEV mains for the foam, paint and rotomould circuits), and the SBSF-1525 (hermetic stainless seam for hygiene-critical water-side components).

17.2 ActronAir — Sydney NSW, Australian-made ducted and packaged AC

ActronAir, based in Western Sydney NSW, engineers and assembles ducted, packaged and inverter air conditioning purpose-designed for the Australian climate, with a strong “Australian-made” market position. The dominant factory hazards are coil-braze fume (copper, fluoride flux, cadmium-free filler verification), sheet-metal cabinet and chassis fabrication, A2L refrigerant (R32) charging with the full AS/NZS 5149 charging-room ventilation envelope, and performance/psychrometric testing of finished units to AHRI and AS rating standards. The SBKJ machine fit centres on the SBAL-V and SBAL-III (cabinet, chassis and base-frame fabrication), the SBPC1500 and SBLR-600 (casing seams), the SBFB-1500 (coil-braze and general LEV mains, plus connecting duct), and the SBSF-1525 (stainless condensate-tray and hermetic-seam work).

17.3 Smardt Chillers — Melbourne VIC, oil-free magnetic-bearing chillers

Smardt Chillers, headquartered in Melbourne VIC, designs and builds oil-free magnetic-bearing centrifugal chillers and is a global exporter of high-efficiency chiller technology. The factory is dominated by large-frame sheet-metal and structural fabrication (the chiller frame, the evaporator and condenser shells’ cladding, the cabinet), large-coil and shell-and-tube brazing/welding, and refrigerant charging including the lower-pressure and A2L refrigerants used in high-efficiency centrifugal machines. The scale of the fabrication is larger than a residential-unit plant, which puts the SBAL-III heavy-gauge line and the SBTF-1500/1602/2020 large TDF flange formers at the centre of the SBKJ fit, alongside the SBPC1500, SBLR-600 and the SB-ZF1500 plasma line for the heavier structural cutting and the SBSF-1525 for welded stainless and structural seams.

17.4 Temperzone, Air Change and the AHU integrators

Temperzone builds AHU and ducted systems; Air Change specialises in heat-recovery AHU (energy-recovery ventilation units); AustralAire, Stoddart, Aolan and the AHU integrators fabricate air-handling casings and modules. The dominant factory work here is AHU casing fabrication (double-skin insulated panels, frames, access doors), coil brazing, and the foam or insulation injection for the sandwich-panel casing. This is the purest SBKJ-affinity segment in the sector: an AHU casing is a sheet-metal box with bolted TDF flanges between modules, fabricated on exactly the SBAL-V, SBAL-III, SBPC1500, SBLR-600, SBFB-1500 and SBTF machine set that SBKJ supplies, with the SBSF-1525 for welded-seam and hygienic-casing variants. The foam-insulated double-skin panel adds the MDI-and-pentane LEV envelope.

17.5 Fantech and the fan makers — Melbourne, AMCA-aligned

Fantech (Melbourne) is the dominant Australian fan manufacturer, with AMCA-aligned product across axial, centrifugal and inline fans. The factory work is fan-impeller and scroll fabrication (rollformed and welded sheet metal), motor assembly, dynamic balancing and aerodynamic/acoustic test. The dominant ventilation is weld-fume capture at impeller and scroll welding, grinding-dust LEV at balance material-removal, and general dilution for motor heat. The impeller and scroll fabrication is sheet-metal work on the SBLR-600 rollformer and the SBAL-V/SBAL-III lines, with the SB-ZF1500 plasma line cutting the impeller blanks and scroll profiles.

17.6 Polyaire, Holyoake and the air-distribution makers — Adelaide and national

Polyaire (Adelaide) manufactures flexible ducting, rigid-duct components, zoning systems and air-distribution product; Holyoake builds air distribution, diffusers, grilles and registers. The factory work spans sheet-metal fabrication, aluminium extrusion finishing and assembly. Polyaire’s flexible-duct manufacture adds an insulation and film-handling envelope; Holyoake’s diffuser fabrication is sheet-metal and extrusion work. The SBKJ fit is the SBAL-V, SBFB-1500 and SBTF lines for the rigid sheet-metal and TDF-flanged components, with the SBPC1500 and SBLR-600 for the seams.

17.7 Daikin Australia, Mitsubishi Electric Australia and the assembly/charging operators

Daikin Australia and Mitsubishi Electric Australia run national assembly, distribution and charging operations for split, ducted and VRF systems. The dominant factory hazard at the assembly/charging end is A2L (R32) refrigerant charging with the full AS/NZS 5149 charging-room ventilation envelope, plus coil and sub-assembly handling and controls work. The SBKJ relevance here is the connecting duct, the charging-room low-level-extract stainless circuit, and any in-house sheet-metal and casing fabrication.

17.8 Dux, Rheem, Vulcan, Gason and the combustion-adjacent makers

Dux and Rheem (water heating, including heat-pump water heaters), Vulcan and Gason (gas heating and combustion appliances) sit on the same sheet-metal-and-combustion fabrication base as the HVAC-equipment makers, and several build heat-pump product that overlaps directly with the refrigerant-charging and coil-braze envelopes described above. The combustion test rig adds a flue-gas exhaust with CO/NOx monitoring; the heat-pump lines add A2L/A3 refrigerant charging. The sheet-metal cabinet and tank fabrication is SBKJ machine territory.

17.9 Cooling-tower and evaporative specialists — Muller, BAC and water-treatment chemistry

Cooling-tower makers Muller and BAC (Baltimore Aircoil) and the evaporative specialists fabricate steel and stainless tower structures, FRP and plastic fill, basins and casings, plus the water-treatment chemistry that controls scale, corrosion and Legionella in the product. The factory work adds FRP and plastic fabrication (with light plastic-fume LEV) and a water-treatment chemistry handling station (AS/NZS 2243.8 fume-cupboard and AS 1940 chemical-handling envelope). The structural and casing steel/stainless fabrication is SBKJ machine territory, with the SBSF-1525 for the stainless welded basins and casings.

18. Cleanability, hygiene and the evaporative/condensate water side

A distinct demand in this sector — absent from a pure metal-fabrication plant — is the hygiene of the water-side components: evaporative-cooler sumps and media, condensate trays, cooling-tower basins and the connecting drains. These components, and any duct serving a washdown or steam-clean station around them, must resist repeated wet cleaning and must not harbour biofilm. 316L stainless with continuous TIG-welded seams (SBSF-1525) is the right material for hygiene-critical trays, basins and the connecting duct, because lock seams sealed with silicone degrade under repeated washdown and become biofilm traps. The water-treatment chemistry handling for cooling-tower and evaporative product (biocide, scale and corrosion inhibitor dosing) is an AS 1940 and AS/NZS 2243.8 chemical-handling station with its own dedicated LEV. Legionella control on the product is a public-health obligation (state public-health regulations and AS/NZS 3666 for the installed product) that flows back into the factory’s hygienic-fabrication and test practice.

19. Energy, heat recovery and the make-up-air penalty

An HVAC-equipment factory exhausts large volumes — coil-braze LEV, foam-cell extract, paint booth, cure ovens, charging-room dilution, weld fume — and every cubic metre extracted must be replaced by tempered, filtered make-up air. In the Australian climate this make-up-air conditioning is a major energy load and an NCC Section J compliance factor. The levers are: heat recovery on the cleaner exhaust streams (run-around coils, plate or rotary heat exchangers where the stream is clean enough to pass through a recuperator without fouling); demand-controlled ventilation that modulates braze, weld and paint LEV to actual occupancy and process state rather than running flat-out continuously; variable-speed drives on the extract and make-up fans; and heat recovery from the psychrometric-test-chamber heat rejection and the run-test soak area. There is a pleasing symmetry here: the same heat-recovery and energy-efficiency technologies the factory sells in its products (heat-recovery AHU from Air Change, high-efficiency chillers from Smardt, inverter systems from ActronAir and Daikin) are the technologies the factory itself should apply to its own make-up-air plant. Green Star and NABERS ratings (below) increasingly reward this.

20. Electrification, heat pumps and the refrigerant-transition demand trend

The structural trends shaping Australian HVAC-equipment manufacturing all feed back into factory ventilation and fabrication demand. First, electrification and the heat-pump boom — the shift from gas heating and gas water heating to heat-pump systems (reverse-cycle AC, heat-pump water heaters, heat-pump hydronic) is expanding production at ActronAir, Daikin, Mitsubishi Electric, Dux, Rheem and the heat-pump entrants, every one of which adds refrigerant-charging and coil-braze capacity. Second, the refrigerant transition — the GWP phase-down is driving the wholesale move to A2L (R32) and A3 (R290, R600a) refrigerants, which is exactly what has rebuilt charging-room ventilation around hazardous-area design. Third, the “Australian-made” demand trend — supply-chain resilience, local-content procurement and the marketing value of local manufacture are favouring Australian assemblers (ActronAir, Seeley, Smardt) and, with them, in-house fabrication capacity. Fourth, the data-centre and electrification load growth — the explosion of data-centre cooling and grid-scale battery thermal management is expanding chiller, AHU and fan demand. Every one of these trends increases the demand for coil-braze LEV, A2L/A3 charging-room ventilation, sheet-metal cabinet fabrication and the connecting ductwork — and for the SBKJ machine set that fabricates the casing and the duct.

21. Green Star, NABERS, DDA AS 1428.1 and the building overlay

The factory building itself, and the products it makes, sit inside a sustainability and accessibility overlay. Green Star (the Green Building Council of Australia rating) and NABERS (the National Australian Built Environment Rating System, energy and indoor-environment ratings) increasingly govern both the factory premises and the buildings the factory’s products are installed in — an efficient make-up-air and heat-recovery system on the production hall contributes to the factory’s own rating, while the efficiency of the AC, chiller, AHU and fan product determines its contribution to the rating of the buildings it serves. The Disability Discrimination Act and AS 1428.1 (design for access and mobility) govern accessibility of the factory’s office, amenities and public areas. NCC Section J ties the energy thread through both. These overlays do not change the process-LEV engineering, but they shape the make-up-air, heat-recovery and building-services design around it, and they are part of the commercial story an Australian manufacturer tells its customers.

22. Industry bodies and standards organisations

The Australian HVAC-equipment sector is supported by an active set of industry bodies and standards organisations. AIRAH (the Australian Institute of Refrigeration, Air Conditioning and Heating) is the peak professional body for HVAC&R practitioners and a major technical-publication and CPD source. AMCA (the Air Movement and Control Association) sets fan and air-movement performance standards that Fantech and the fan makers certify to. AREMA (the Air Conditioning and Refrigeration Equipment Manufacturers Association of Australia) represents equipment manufacturers. Refrigerants Australia and the Australian Refrigeration Council (ARC) administer the refrigerant-handling licensing and the refrigerant-transition policy framework that drives the A2L/A3 charging changes. The AMCA, ASHRAE (the international body whose 62.1, 15, 34 and equipment-rating standards Australian exporters design to) and AHRI (the US certification body for equipment performance ratings) round out the technical framework. Standards Australia publishes the AS/NZS standards; SafeWork Australia publishes the WES; the state EPAs administer the stack-emissions and environmental licences; and the state work-health-and-safety regulators enforce the hazardous-area, combustible-dust and flammable-liquid obligations.

23. Competitive positioning — why the HVAC-equipment maker is SBKJ’s natural customer

The thread running through this entire guide is an affinity that is worth stating plainly. The machines that fabricate HVAC ductwork — the auto duct line, the Pittsburgh-lock former, the rollformer, the TDF flange line, the plasma line and the stitch welder — are the same machines that fabricate the sheet-metal product the HVAC-equipment manufacturer builds: the AHU casing, the condensing-unit cabinet, the chiller frame, the evaporative-cooler body, the fan scroll, the connecting plenum and the very ductwork the factory ships with its product. An Australian HVAC-equipment maker that brings cabinet and duct fabrication in-house — for cost control, lead-time control, quality control and the “Australian-made” story — is buying exactly the SBKJ machine set. And the mechanical contractors who install that equipment, who fabricate the site ductwork that connects to it, are SBKJ’s established customers too. SBKJ therefore sits at the intersection of two markets that are really one: the people who build HVAC equipment and the people who install it both fabricate sheet metal, and both need the SBAL-V, SBAL-III, SBSF-1525, SB-ZF1500, SBFB-1500, SBPC1500, SBLR-600 and SBTF lines to do it.

24. SBKJ machine application checklist for HVAC-equipment-factory fabrication

For an Australian fabricator — or an HVAC-equipment maker fabricating in-house — the practical SBKJ machine envelope to cover the full cabinet-and-duct demand is:

• SBAL-V with 316L stainless option — the core auto duct line for AHU casing panels, condensing-unit cabinets, evaporative-cooler bodies, condensate trays, internal baffles and connecting duct, plus the 316L process-LEV mains. Production envelope 0.5–1.6 mm galvanised, Zincalume, aluminised and 304/316L stainless.
• SBAL-III — heavy-gauge 1.6–2.0 mm work for chiller structural frames, condensing-unit base frames, large AHU frames and heavy fume/oven-exhaust mains.
• SBSF-1525 — continuous TIG longitudinal seam for hermetic stainless casing, hygienic condensate trays and basins, the foam MDI-and-pentane main, the flammable-refrigerant charging-room extract and the chemical-fume mains.
• SB-ZF1500 — plasma cutting line for coil/fan/filter/access openings in casings, service penetrations, frame profiles and custom transition geometry in galvanised, aluminised and stainless plate.
• SBFB-1500 — TDF flange line for spiral round and rectangular TDF-flanged duct 80–1500 mm for the coil-braze, foam, paint-booth and general process-fume mains, plus connecting duct. The single most-used machine for the LEV circuits.
• SBPC1500 — Pittsburgh-lock former for the casing and rectangular-duct longitudinal seam, with heavy-gauge tooling for 1.2 mm stainless casing and chemical-fume duct.
• SBLR-600 — rollformer for standing-seam and snap-lock casing joints, fan scroll and impeller profiles, and rectangular-duct seams.
• SBTF-1500/1602/2020 — TDF flange formers for the large AHU section-to-section flanges, the chiller and large-cabinet flanges, and the large booth-extract and cure-oven-exhaust trunk mains up to 2000 mm.

The combined machine fit delivers the production envelope to cover every cabinet and duct requirement across every Australian HVAC-equipment operator — from Seeley International in Adelaide SA, ActronAir in Sydney NSW and Smardt Chillers in Melbourne VIC, through Temperzone, Air Change, Fantech, Polyaire, Holyoake, Daikin Australia, Mitsubishi Electric Australia, Dux, Rheem, Vulcan, Gason, Stoddart, Aolan and the cooling-tower makers Muller and BAC.

25. Commissioning, monitoring and measurement & verification (M&V)

Commissioning HVAC-equipment-factory ductwork is more demanding than commissioning conventional comfort HVAC, because the hazardous-area and process-LEV circuits carry a safety case. The documentation required at handover includes: pressure-test records (1.5× design pressure for 30 minutes per AS 4254) on every duct branch; earth-bonding verification at every flange on the hazardous-area circuits (resistance below 1 ohm to ground); conductivity verification on every conductive flexible connection; NATA-certified airflow balance against the design schedule; the AS 3957 dust hazard analysis tied to the powder-coat zoning; the AS/NZS 60079 hazardous-area zone-classification dossier; the AS/NZS 5149 charge-limit-and-dilution basis for the charging room; and the AS 1940 flammable-liquid basis for the paint and foam stores.

Ongoing monitoring and measurement & verification run on daily, weekly, monthly, quarterly and annual cycles. Daily: refrigerant and flammable-gas leak-detector status and alarm test on the charging room and foam cell; LEL monitoring on the cure ovens; differential pressure across each collector. Weekly: visual inspection of LEV hood capture, condition of bonding straps and conductive gaskets, and duct-interior accumulation at access ports on the powder-coat and braze mains. Monthly: airflow balance verification at key LEV branches, isolation-valve actuation test on the powder-coat collector, fan-vibration measurement. Quarterly: NATA-certified breathing-zone air sampling against the WES for every operator-occupied zone — coil-braze (copper, fluoride, cadmium confirmation), foam (MDI), paint (xylene, isocyanate), weld (manganese, Cr VI), solder (rosin) — fed into the ISO 45001 OHS management system. Annual: full system pressure test, full bonding-resistance re-verification, AS/NZS 60079.17 Ex-equipment inspection on the hazardous-area circuits, cure-oven burner-management and explosion-relief inspection, and collector deflagration-protection inspection. The M&V data is the bridge between the fabricated ductwork and the manufacturer’s ongoing regulatory and ISO obligations.

26. AS/NZS compliance checklist for HVAC-equipment-factory duct fabrication and commissioning

A short-form compliance checklist for HVAC-equipment-factory ductwork commissioning, suitable for inclusion in handover documentation:

• AS 1668.1 / AS 1668.2 mechanical ventilation — design extract, dilution and make-up-air calculations documented for every process zone.
• AS 4254.1/.2 sheet-metal and flexible duct construction — pressure-test certificates at 1.5× design pressure for 30 minutes on every branch.
• AS 1530.4 fire resistance — fire-rated penetrations certified at the required FRL at every fire-compartment boundary (foam, paint, charging, store).
• AS/NZS 1677 / AS/NZS 5149 refrigeration safety — charge-limit-and-room-volume calculation and charging-room dilution-to-25%-LEL documented for A2L/A3 refrigerants.
• AS/NZS 60079.10 hazardous-area classification — documented Zone 1/2 (gas) and Zone 21/22 (dust) maps with Ex-equipment selection per AS/NZS 60079.0–.31.
• AS 3957 dust hazard areas — documented dust hazard analysis for the powder-coat and plastic-dust collectors (Kst, MIE, deflagration-protection chain).
• AS 1940 flammable and combustible liquids — paint solvent, two-pack hardener and pentane blowing-agent storage documented and segregated.
• AS/NZS 1554 welding — documented on-tool/captor extraction at cabinet, frame and impeller welding.
• AS 1375 / NFPA 86 industrial ovens — LEL monitoring, purge cycle and burner management on every cure and rotomould oven.
• NFPA 33 spray application — spray-booth design and face-velocity documented for the wet-paint line.
• NFPA 68 deflagration venting and NFPA 69 isolation — documented for the powder-coat and plastic-dust collection systems.
• AS/NZS 1715 / AS/NZS 1716 respiratory protective equipment — PAPR and cartridge-respirator selection documented for foam, paint, braze and weld tasks.
• AS/NZS 2243.8 fume cupboards — documented capture and exhaust for the chemistry lab and water-treatment chemical handling.
• AS 4024 machinery safety — guarding, interlocking and emergency-stop on the fabrication and assembly machinery.
• ISO 9001 / ISO 14001 / ISO 45001 — documented LEV maintenance records, stack-emission monitoring and quarterly breathing-zone air sampling against the WES.
• NCC Section J / ASHRAE 62.1 — make-up-air energy and indoor-air-quality compliance for the production hall and assembly/office zones.
• NATA certification — final commissioning balance and breathing-zone sampling certified by a NATA-accredited laboratory.

Compliance documentation forms the bridge between the fabricated ductwork and the manufacturer’s ongoing regulatory obligation. Every length of ductwork SBKJ supplies to an Australian HVAC-equipment fabricator is delivered with mill certificate, fabrication date, pressure-test record, earth-bonding verification at every flange on the hazardous-area circuits, and AS/NZS-compliant labelling — the foundation paperwork the manufacturer integrates into its ISO 9001, ISO 14001, ISO 45001 and product-certification audit packs.

27. Closing — SBKJ engineering support for Australian HVAC-equipment makers

The Australian HVAC-equipment manufacturing sector is in a period of fast change — electrification and the heat-pump boom, the wholesale refrigerant transition to flammable A2L and A3 refrigerants, the data-centre cooling load, and a renewed “Australian-made” demand trend — and every one of these changes increases the demand for coil-braze LEV, flammable-refrigerant charging-room ventilation, foam and paint hazardous-area exhaust, and the sheet-metal cabinet and connecting-duct fabrication that underpins it all. The SBKJ Group engineering team in Box Hill North VIC is positioned to support Australian HVAC-equipment manufacturers — SBKJ’s natural peers and customers — and their mechanical contractors with machine supply (SBAL-V, SBAL-III, SBSF-1525, SB-ZF1500, SBFB-1500, SBPC1500, SBLR-600, SBTF-1500/1602/2020), engineering documentation, commissioning support and ongoing technical advisory across every process zone described in this document.

We will be exhibiting at ARBS 2026 in Sydney in May with the full SBKJ machine portfolio plus reference samples covering AHU casing fabrication, coil-braze and foam-cell LEV duct, flammable-refrigerant charging-room stainless extract, powder-coat and paint-booth overspray mains, and hygienic stainless condensate-tray work. Pre-show meetings with Australian HVAC-equipment manufacturers, AHU integrators, fan makers, evaporative and chiller builders, and their mechanical contractors are scheduled across the week.