Foundry, Iron, Steel, Aluminium, Investment, Lost Foam & Sand Casting HVAC Duct Guide

1. Why foundry HVAC is its own engineering discipline

A foundry is the most chemically diverse, thermally extreme and dust-loaded factory environment in Australian heavy industry. Every casting process under the foundry umbrella — from a 50 tonne grey-iron pump housing sand-cast at Walker Newcastle to a 2 gram nickel-superalloy turbine blade investment-cast at Howmet Aerospace Melbourne — produces its own characteristic exhaust chemistry, dust loading, capture geometry and material requirement. HVAC ductwork inside a foundry is not a commodity. It is a process-engineering problem that touches occupational health, dust explosion safety, refractory thermal cycling, chemical corrosion, abrasion-resistance material selection, and AS/NZS 60079 hazardous-area electrical compliance, all inside the same building.

This guide writes against the full breadth of the Australian foundry sector. Iron casting (grey iron, ductile SG iron, white iron) is the largest tonnage segment, driven by mining wear-parts demand from Bradken (CIMIC ASX:CIM-owned, three Australian sites at Bassendean WA, Tickford VIC and Hawthorn VIC, plus 12 sites in 8 countries internationally), Walker Industries Newcastle and the regional jobbing foundries serving agriculture and construction. Steel casting (carbon, alloy, manganese, stainless, austenitic) feeds rail wheels, mining ground-engaging tools, valve and pump bodies and defence work. Aluminium die-casting at scale runs at BorgWarner Australia Lonsdale (Australia’s biggest aluminium die-cast house, supplying automotive transmission cases to Ford, GM, BMW, Audi, VW, Toyota, Subaru, Mazda, Mitsubishi and Volvo) and aluminium sand-casting at smaller operations including Boyd Aluminium and Trafalgar Aluminium. Investment casting (lost-wax) is the high-value precision tier, with Howmet Aerospace Australia (formerly Arconic) in Melbourne casting aerospace turbine blades for Boeing, Airbus, Embraer, Bombardier and Sukhoi, Castalloy ANCA Group SA casting turbocharger wheels for the automotive supply chain, Hi-Tech Cast NSW and Quickstep ASX:QHL serving composite-and-cast aerospace assemblies. Lost-foam casting (EPS pattern, ceramic coat, single-pour) serves niche aluminium and iron applications. Bronze and brass non-ferrous foundries — Crowley Bronze NSW, Bronze Founders VIC, Trafalgar Bronze, Tee Bronze, Engineering Sales Newcastle — round out the sector with crucible-furnace operations producing valves, fittings, statuary and marine castings. Iron-pipe casting at Iplex Iron Pipes Tomago NSW and CIA Cast Iron Australia produces the country’s installed-base water and sewer infrastructure.

Across this entire sector, foundry ductwork must survive five demands simultaneously: heat resistance (1100–1700 degC pour, 250–800 degC post-cast cooling, 600–1000 degC heat-treatment), abrasion resistance (silica sand at shake-out and shot blast strips zinc and paint in months), corrosion resistance (HF from aluminium fluoride flux, SO2 from coke and Mg desulfurisation, sulfur from chemical sand binders, alkaline halide from reverberatory aluminium melt), deflagration resistance (NFPA 484 combustible aluminium and magnesium fines, NFPA 660 consolidated dust hazard), and respiratory hazard control (RCS silicosis, Cr VI hexavalent chromium, CO carbon monoxide, HCN cyanide, HF hydrogen fluoride, isocyanate from cold-box binders). Each is manageable in isolation. Together they explain why a generic commercial fabricator treating a foundry as just another industrial job loses money on the first project and walks away from the second.

This guide walks every major foundry process and explains what changes about the ductwork. We start with the regulatory backbone, then map the foundry floor section by section, then close with the SBKJ machine configuration that gives a fabricator the production envelope to serve this market from Box Hill North VIC across the country.

2. The Australian regulatory stack — AS 1668.2, AS 1885, AS 4254, AS 3957, AS/NZS 60079, AS 4801, NFPA 484, NFPA 660, NFPA 86

Foundry HVAC in Australia sits at the intersection of more than a dozen overlapping standards and codes. Ignoring any one of them is a notice-of-non-compliance from SafeWork Australia, the state EPA, or both, waiting to happen. The standards stack splits into building-code compliance, occupational-health exposure compliance, hazardous-area electrical compliance, dust-explosion compliance, and process-specific casting metallurgy compliance.

2.1 AS 1668.2 — mechanical ventilation for buildings

AS 1668.2 is the umbrella mechanical-ventilation standard. Foundries fall under NCC Class 8 industrial occupancy; Table 4 of AS 1668.2 sets minimum extract rates for metal melting, pouring, casting, machining, grinding, welding and painting. In practice a foundry seldom gets close to the minimum — LEV at each individual dust and fume source drives total exhaust well above the building-volume figure. Where AS 1668.2 matters most is the make-up air requirement: every cubic metre extracted must be replaced by tempered, filtered, controlled-velocity supply air, keeping the pouring floor at neutral or slightly positive pressure relative to office and laboratory zones, and preventing furnace-stack backdraft.

2.2 AS 4254 — sheet metal 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). Most commercial foundry HVAC sits inside AS 4254 ranges. Cupola, EAF and reverberatory exhaust mains in their refractory-lined hot section run beyond AS 4254 and require purpose-engineered construction; AS 4254 picks up again on the cool side downstream of the quench tower, the wet scrubber or the baghouse.

2.3 AS 1885 — metal casting workplaces and AS 1668.1 fire-and-smoke

AS 1885 (now historic but still cited in foundry safety practice) and the current SafeWork Australia codes of practice cover foundry-specific occupational safety — fume control at melting and pouring, dust control at moulding and reclamation, silica exposure at shake-out and fettling, noise control at shot-blast and grinding. AS 1668.1 covers fire and smoke management in mechanically ventilated buildings, with fire dampers at zone boundaries and smoke-control dampers where production zones connect to office or evacuation routes. AS 1851 covers the routine service and maintenance of fire-protection equipment including fire dampers, smoke dampers and the ductwork that carries them. AS 1530.4 covers fire-resistance testing of building elements including fire-rated ductwork penetrations.

2.4 AS 3957 — dust hazard areas, the critical foundry standard

AS 3957 is the Australian dust-hazard standard and the most directly applicable single document for foundry duct designers. It covers combustible dust deflagration risk — silica sand fines, aluminium dust, magnesium dust, iron dust, coal dust from green-sand bond, ceramic-shell investment dust. AS 3957 mandates hazard-area zoning (Zone 20 for continuous explosible-dust concentration, Zone 21 for occasional, Zone 22 for unlikely), and drives the AS/NZS 60079.10.2 electrical-equipment selection downstream. For a foundry duct designer, AS 3957 forces the question: at every dust collection point, what is the explosibility of the dust, what is the lowest minimum ignition energy, what is the deflagration index Kst, and what is the engineered deflagration-protection chain (vent panels, isolation valves, chemical suppression, isolation flap valves) between the baghouse and the inbound duct? The answer drives baghouse selection, isolation-valve placement and the bonding-and-grounding of every metre of duct in the dust-laden circuit.

2.5 AS/NZS 60079 — explosive atmospheres

AS/NZS 60079 is the hazardous-area-classification standard. Foundries trigger AS/NZS 60079.10.2 dust classification anywhere combustible-metal dust or organic dust accumulates (Zone 20/21/22), and trigger AS/NZS 60079.10.1 gas classification anywhere combustible gas is present (Zone 1/2). Three specific foundry locations almost always become Zone 1: the molten-metal pour station (CO from incomplete combustion plus carbon monoxide from cupola coke beds), the LPG furnace burner area (natural gas at 1.25% LEL methane), and any salt-bath heat-treatment line releasing CO from cyanide breakdown. Cyanide compounds plus heat plus moisture can release HCN hydrogen cyanide vapour (SafeWork Australia STEL 5 ppm). Hazardous-area zoning drives Ex-rated electrical equipment requirements for fans, motors, instrumentation and duct-mounted sensors throughout the affected zones.

2.6 NFPA 484 — combustible metals, NFPA 660 consolidation

NFPA 484 is the US National Fire Protection Association standard for combustible metals, referenced extensively by Australian foundry insurance underwriters and used as the de-facto engineering reference where AS standards are silent. NFPA 484 mandates wet-collection extraction for fine aluminium, magnesium and titanium dust, prohibits dry baghouses without engineered deflagration venting, and sets bonding, grounding and isolation-damper requirements that prevent a baghouse fire from propagating back into the ductwork main. Magnesium dust ignites at lower concentration than aluminium and is harder to extinguish (water reacts violently with hot magnesium), so a magnesium die-cast house must use sealed wet-bath collectors with SF6 or fluorinated-ketone cover-gas blanketing the molten metal surface. NFPA 660 is the 2025 consolidation standard merging the previous NFPA 61, 484, 654 and 664 dust standards into a single document. The consolidation applies the same engineering principles across dust types but with updated combustible-dust analysis requirements at facility level. Australian foundries adopting NFPA 660 in 2026 face revised dust-hazard analysis documentation, updated bonding-and-grounding requirements, and tightened isolation-valve specifications between baghouse and inbound duct.

2.7 NFPA 86 — industrial ovens and furnaces

NFPA 86 covers cupola, electric induction, electric arc EAF, reverberatory and crucible furnaces, and downstream heat-treatment ovens (carburise, nitride, austemper, anneal, temper) running 600–1700 degC. Exhaust topology under NFPA 86 includes LEL monitoring at every gas-fired burner, purge cycles before lighting, explosion venting on the oven shell, dedicated exhaust risers separate from general foundry exhaust, and burner-management systems with redundant flame supervision. Cupola exhaust stacks (1450–1650 degC iron melt) and EAF stacks (1600–1800 degC steel melt) are the highest-risk single equipment items in any foundry under NFPA 86.

2.8 NFPA 13, NFPA 70 NEC, NFPA 75 IT room

NFPA 13 governs sprinkler protection of buildings and is referenced for foundry building protection wherever the building structure could ignite (timber roofs, mezzanine offices, paint-storage and pattern-shop areas). NFPA 70 (National Electrical Code) is referenced for hazardous-area electrical practice alongside AS/NZS 60079. NFPA 75 covers IT-room and control-room HVAC, applicable to the SCADA control rooms inside larger foundries (Bradken Bassendean, Walker Newcastle, Howmet Aerospace Melbourne) where furnace control, baghouse SCADA and metallurgical-lab data systems live in environmentally separated rooms.

2.9 AS 4036 boiler, AS 1318 industrial chimney, AS 4801 OHS

AS 4036 governs boilers used for steam generation in foundry support utilities (ladle pre-heat, sand-binder catalyst, parts washer). AS 1318 governs industrial chimneys including foundry exhaust stacks above the building roofline. AS 4801 (Australian standard for occupational health and safety management systems, often integrated with ISO 45001) sets the systemic OHS management framework that foundry HVAC documentation feeds into — LEV maintenance records, air-monitoring data, respiratory protection programs, hearing conservation, and dust-explosion risk assessment.

2.10 AS/NZS 4453 — welding fume control

AS/NZS 4453 sets the engineering practice for welding-fume capture and control. Foundry welding operations (casting repair, gating-system fabrication, ladle repair, structural fabrication) generate manganese (Mn), iron oxide (Fe2O3), chromium hexavalent (Cr VI on stainless), nickel (Ni on alloy stainless), and shielding-gas decomposition products. AS/NZS 4453 mandates on-tool extraction (welding-gun fume extraction) plus local exhaust at every welding bay, with branch sizing for 18–22 m/s transport velocity in stainless or aluminised steel duct depending on chemistry.

2.11 ISO 8062, AS 2074, AS 1830, AS 1831, AS 1832, AS 2027, AS 1875 — casting metallurgy standards

The metallurgy of the casting itself drives the chemistry of the exhaust. ISO 8062 sets dimensional tolerance grades for castings (CT1 to CT16) and indirectly drives the cleanliness requirement for the pouring floor — high-precision investment castings demand cleaner air at pour to prevent inclusion defects from airborne dust. AS 2074 covers carbon and alloy steel castings. AS 1830 covers grey cast iron. AS 1831 covers ductile cast iron (spheroidal-graphite SG iron, used extensively for water-pipe at Iplex and for SG iron mining wear parts at Bradken and Walker Newcastle). AS 1832 covers austenitic ductile iron. AS 2027 covers austenitic alloy castings. AS 1875 covers nickel, cobalt, tin, lead, zinc and tin alloy castings — the non-ferrous metallurgy tree. ISO 9001 and the automotive-supply variant IATF 16949 (mandatory at BorgWarner Australia and at every automotive-supply Australian foundry) require documented process control including documented HVAC parameter logging. ISO 14001 environmental management drives stack-emissions documentation and recycling-stream documentation for sand, dust and refractory waste.

2.12 SafeWork Australia 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. The foundry-relevant standards are extensive and worth reading as a single block because they collectively explain why foundry HVAC is dimensioned the way it is:

• Respirable crystalline silica (RCS): 0.05 mg/m³ TWA. THE single most important number for any foundry duct designer. Drives sand-reclaim, shake-out, fettling, grinding and sand-blast LEV across every sand-casting and investment-casting line.
• Carbon monoxide (CO): 30 ppm STEL. From cupola coke beds, LPG furnaces, gas-fired ladle pre-heat, gas-fired heat-treatment ovens, salt-bath decomposition.
• Formaldehyde: 1 ppm STEL. From phenolic resin sand binder, cold-box no-bake systems, shell-mould Croning process. Drives core-shop LEV chemistry.
• MDI/TDI isocyanates: 0.005 ppm STEL. From PUR (polyurethane) cold-box binder, Pep-set, Iso-cure. Acute respiratory sensitiser; requires fail-safe LEV at every PUR binder mixer and core blower.
• Phenol: 5 ppm. From phenolic resin binders (PF) used in shell mould and some no-bake.
• Cresol: 5 ppm. From PF binder degradation.
• Furfuryl alcohol: 200 ppm. From Furan binder cure. Stronger acid-catalyst chemistry; requires acid-resistant scrubber.
• Sulfur dioxide (SO2): 2 ppm STEL. From sulfite-bonded sand binders, magnesium desulfurisation of grey iron melt, coke combustion in cupola.
• Manganese (Mn): 0.2 mg/m³. From welding fume, manganese steel casting (Bradken specialises in manganese steel mining wear-parts).
• Iron oxide fume (Fe2O3): 5 mg/m³. From welding, shot blast, iron melt.
• Aluminium hydroxide / dust: 1 mg/m³ TWA respirable. From aluminium grinding, aluminium oxide refractory dust, aluminium melt operations.
• Lead (inorganic): 0.05 mg/m³. From leaded bronze, leaded brass, leaded steel. Crowley Bronze and other non-ferrous foundries handle leaded alloys; air monitoring is mandatory.
• Copper fume: 0.2 mg/m³ (inhalable 1 mg/m³). From bronze and brass melt.
• Zinc oxide fume: 5 mg/m³. From galvanised-steel scrap melting (zinc volatilises into the cupola or EAF furnace gas) and from brass melt.
• Chromium hexavalent (Cr VI): 0.05 mg/m³. Stainless-steel casting welding, grinding, polishing, shot blast. Drives 316L dedicated LEV with baghouse or wet scrubber.
• Nickel (Ni inhalable): 1 mg/m³. Insoluble Ni compounds 0.1 mg/m³. From stainless and alloy steel casting.
• Cadmium (Cd): 0.01 mg/m³. From brass alloys and electroplating.
• Beryllium (Be): 0.001 mg/m³ STEL. From copper-beryllium alloys.
• Tin (Sn): 2 mg/m³. From bronze and tin alloys.
• Arsenic (As inorganic): 0.05 mg/m³.
• Antimony (Sb): 0.5 mg/m³. From some bearing alloys.
• Fluoride / HF: 1.8 ppm STEL. Plus aluminium fluoride AlF3 dust and cryolite Na3AlF6 dust from aluminium reverberatory flux.
• Cyanide (HCN): 5 ppm STEL. Salt-bath case-carburising and heat treatment. Lethal at low concentration.
• Benzene: 1 ppm STEL. From refractory binder solvents and some core-binder solvents.
• Methane (CH4): 1.25% LEL. LPG and natural gas furnace fuel.
• CO2: 5000 ppm. Indoor air quality marker; rises in poorly ventilated foundry zones.
• Styrene: 50 ppm STEL. From lost-foam EPS polystyrene decomposition during pour.
• Particulate (general inhalable): 10 mg/m³. Whole-of-air dust marker.

Every dust and fume LEV branch in a foundry has to keep the operator’s breathing-zone air below the relevant WES. Where multiple contaminants are present (Mn plus Cr VI plus Ni at a stainless-steel grinding 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 foundry duct system.

3. Process zones — the foundry floor end-to-end

The most reliable way to specify foundry HVAC is to walk the process flow. Every Australian foundry maps to a variant of the same end-to-end sequence: pattern making and tooling, core making, mould making (green sand or chemical-bonded sand or investment-shell or lost-foam), melting and pouring, post-cast knock-out and shake-out, sand reclaim and recovery, fettling and grinding, heat treatment, machining and finishing, impregnation and resin infiltration, surface finish and electroplate, QC inspection, and maintenance and refractory replacement. Each station has its own characteristic dust load, fume chemistry, temperature, capture velocity and material requirement.

3.1 Pattern making and tooling — the cleanest zone

The pattern shop is the cleanest part of the foundry. Modern Australian pattern shops use a hybrid of conventional wood and aluminium patterns (manual mill, 5-axis CNC machining), 3D-printed patterns (FDM polymer, SLA resin, SLS nylon) and direct sand printing (for one-off and low-volume work, common at Howmet Aerospace for aerospace investment-cast tooling). The LEV demand at the pattern shop is woodworking dust at saws, routers and sanders (capture velocity 1.0–1.5 m/s, transport 18–22 m/s), and VOC at 3D-printer resin curing and at solvent-clean stations (carbon-filter polish, 10–13 m/s transport). Duct work here is conventional galvanised spiral to AS/NZS 4254 medium pressure. The pattern shop also houses the foundry design office, requiring NC-50 acoustic target, supply-air HEPA pre-filters and slight positive pressure relative to the rest of the building.

3.2 Core making — cold-box, hot-box, no-bake, PEPSET, Iso-cure, shell mould

Cores form the internal cavities of castings — the water jackets inside an engine block, the port shapes inside a valve body, the internal channels inside a pump casing, the cooling passages inside a turbocharger wheel. Core chemistry is one of the most varied chemistry zones in the foundry, and each chemistry needs its own LEV approach:

Cold-box (PUR-amine cured phenolic urethane): Phenolic urethane resin plus amine catalyst (triethylamine TEA or dimethylethylamine DMEA) cures at ambient temperature in seconds. The amine catalyst is a strong-smelling toxic gas (SafeWork Australia WES for TEA 1 ppm, DMEA 2 ppm), released during the cure cycle and must be captured by dedicated branch with acid scrubber (the amine vapour is destroyed by sulphuric-acid scrubbing). 316L stainless mains, 0.5–1.0 m/s capture velocity at each core blower. NFPA 660 isolation between blower bay and scrubber.

Hot-box (phenolic and furan, heat-cured): Phenolic and furan resins cured by heated core box at 200–300 degC. Releases formaldehyde (1 ppm STEL), phenol (5 ppm), furfuryl alcohol (200 ppm), and SO2 from the catalyst breakdown. 316L stainless mains, dedicated thermal-oxidiser destruction of organic vapour before discharge.

Furan no-bake: Furfuryl alcohol resin with sulfonic-acid catalyst (typically PTSA or BSA) cured at ambient. Releases furfuryl alcohol, SO2 and formaldehyde during mixing and pouring. 316L stainless or hot-dip aluminised steel mains, alkaline scrubber for SO2 control.

PEPSET / Pep-set / Iso-cure (phenolic urethane no-bake): Two-part PUR resin, no catalyst gas, cures at ambient. Isocyanate exposure during mixing (MDI 0.005 ppm STEL); fail-safe LEV at every mixer. 316L stainless mains.

Shell mould (Croning process): Silica sand coated with phenolic novolac resin, cured against a heated pattern plate at 220–260 degC. Releases phenolic vapour and formaldehyde during cure. LEV at the shell box exhausts to thermal oxidiser or activated-carbon adsorption.

Sodium silicate (CO2-hardened): Silicate binder cured by CO2 injection. Relatively benign chemistry — alkaline dust during reclaim, no significant gas emission. Painted carbon steel or aluminised steel ducting.

Investment-shell ceramic slurry: Multi-coat dipping of wax pattern in ceramic slurry (silica, zircon, alumina binder with ethyl silicate or colloidal silica). Releases ammonia from binder breakdown, alcohol vapour from solvent, fine ceramic dust during shell building. 316L stainless mains, climate-controlled dipping room at 40–60% RH, dedicated solvent-vapour LEV.

3.3 Green sand mould floor — silica sand RCS extraction

Green sand is the highest-tonnage mould system in Australian iron foundries (Walker Newcastle, regional grey-iron foundries) and a significant share of aluminium sand-casting tonnage. The mix is silica sand (around 90%), bentonite clay (8–12%), and seacoal or coal dust (2–5%) blended with controlled moisture. The mould is rammed around the pattern, the metal poured, and the sand reclaimed at shake-out. Across the green-sand process the dominant hazard is respirable crystalline silica (RCS), and the dominant LEV demand is sand-reclamation extraction.

The green-sand reclaim circuit typically includes a primary cooler (drum cooler or fluid-bed cooler), a magnetic separator (removing iron tramp), a screen deck (sizing the sand), a pneumatic conveyor (moving sand back to the bond mixer), and the bond mixer itself (where fresh clay and water are added). Each is an LEV source needing 18–22 m/s transport velocity in dedicated branches. Capture velocity at the source 1.0–1.5 m/s. Each branch terminates at a primary cyclone separator (knocking out 80–90% of the dust load by inertia) followed by a baghouse for fine-particulate capture and finally a polishing scrubber where state EPA stack-emission licence is tight.

Material selection for green-sand exhaust is governed by abrasion. Bare silica sand at 20 m/s strips zinc and paint in 6–18 months. Hot-dip aluminised steel performs better and is the practical material for the bulk of the duct length. The wet-bath side of the scrubber gets 316L stainless. Where abrasion is extreme (immediately downstream of the shake-out grid, the first elbow of the primary classifier, the discharge of the pneumatic conveyor), wear-lined construction with Hardox patch panels or ceramic-tile lining bonded to the spiral interior gives 10–15 year service life versus 3–5 years for bare steel.

3.4 Chemical-bonded sand — Furan, Cold-Box, PEPSET, Phenolic urethane, Sodium silicate

Chemical-bonded sand replaces the moist-clay green-sand bond with a chemical resin that cures the sand block. The casting end-result is higher dimensional accuracy and better surface finish, suited to medium-tonnage iron, steel and non-ferrous work. The chemistry tree maps to the same chemistries described for cores in section 3.2 — Furan (Engineering Sales Newcastle uses furan extensively), Cold-Box PUR (commonly seen at investment-cast and precision iron foundries), PEPSET, Phenolic urethane no-bake, and sodium silicate. The chemical chemistry of the binder drives the chemistry of the exhaust at mixing, ramming and pouring. Furan systems release formaldehyde and SO2; PUR systems release isocyanate during mixing and amine during cure; sodium silicate is benign but has alkaline dust at reclaim.

LEV at the chemical-bonded sand mould floor includes the sand mixer (continuous-screw mixer or batch mixer, with dedicated vapour exhaust at 1.0 m/s capture), the ramming station (point extraction at the operator’s breathing zone), the pouring rail (canopy hood over the pour line), and shake-out (described above). Material selection is 316L stainless for sulfur-bearing furan systems and hot-dip aluminised steel for PUR systems. The pouring-rail canopy main feeds a refractory-lined section over the casting bed (1.5–5 m of refractory immediately above the pour) then transitions to aluminised steel cooling to baghouse and scrubber.

3.5 Investment casting lost-wax — Howmet Aerospace, Castalloy ANCA, Hi-Tech Cast, Quickstep

Investment casting is the high-value precision tier of the Australian foundry sector. Howmet Aerospace Australia (Melbourne VIC, Arconic-owned) is the largest, casting aerospace turbine blades, vanes and structural components in Inconel, CMSX nickel-base superalloys and titanium for Boeing, Airbus, Embraer, Bombardier and Sukhoi. Castalloy ANCA Group SA casts turbocharger compressor wheels and aerospace components in aluminium and nickel alloys. Hi-Tech Cast NSW serves general-engineering investment-cast components. Quickstep ASX:QHL combines carbon-composite and investment-cast assemblies for aerospace and defence.

The lost-wax process runs through five stages, each with its own HVAC demand. Wax injection (in temperature-controlled rooms at 20–22 degC, ±0.5 degC for high-precision turbine blade wax dimensional stability, ±50% RH humidity control). Shell dipping (40–60% RH dipping rooms, slow recirculating airflow over the shell, dedicated solvent-vapour LEV for the colloidal-silica or ethyl-silicate binder solvent). Shell drying (30–50 degC drying ovens, controlled airflow at 0.5–1.0 m/s across the parts). De-wax (steam-autoclave or flash-fire ovens at 150–200 degC; wax vapour condensed and recovered, typically with carbon polish; LEV mains 316L stainless because wax fume corrodes carbon steel over time). Shell firing (kiln at 900–1100 degC under NFPA 86, with dedicated stack riser). Pour station (1500–1700 degC for steel and nickel alloy, 1450 degC for iron, 1200–1400 degC for cobalt, refractory-lined canopy hood with 1.5–2.5 m/s capture velocity, refractory-lined stack to baghouse or wet scrubber). Post-cast shell knock-out (vibratory hammer or media blast, fine ceramic dust LEV at 18–22 m/s transport, baghouse with PTFE membrane filter).

Climate control in the dipping rooms is one of the most demanding HVAC envelopes in any Australian factory. Wax-injection rooms target ±0.5 degC and ±5% RH year-round, requiring high-stability chilled-water cooling and humidification systems with 316L stainless supply-air mains and HEPA polish at the diffuser. Dipping rooms need 40–60% RH within ±5% — too dry and the shell cracks during drying, too humid and the ceramic binder doesn’t set. Howmet Aerospace runs the most precise HVAC in the Australian foundry sector by a significant margin.

3.6 Lost foam casting — EPS pattern, ceramic coat, single pour

Lost-foam casting (LFC) uses an expanded-polystyrene (EPS) foam pattern coated in a thin ceramic refractory. The pattern is buried in dry unbonded sand and metal is poured directly into the pattern — the EPS foam vaporises (styrene vapour, plus EPS decomposition products) and the molten metal fills the void left behind. The process is single-pour with no shake-out and no sand reclaim (the dry sand is reusable directly), and produces extremely high dimensional accuracy with minimal flash.

Lost foam is used at niche Australian foundries for high-precision aluminium and grey-iron castings. The HVAC demand is dominated by styrene vapour control at the pour station. Styrene is a SafeWork Australia regulated VOC at 50 ppm STEL, and is a Class B1 flammable liquid. The pour-station LEV needs a dedicated 316L stainless main captured at 1.5–2.0 m/s face velocity, terminating at a thermal oxidiser (regenerative thermal oxidiser RTO is the standard solution at 800–1000 degC, destroying styrene to CO2 and water) or activated-carbon adsorber for smaller installations. EPS decomposition also releases benzene, toluene and ethylbenzene at trace concentration, controlled by the same RTO downstream.

3.7 Sand reclaim and recovery — thermal at 800 degC, mechanical attrition, dry and wet

Sand reclaim is the lifeblood of any sand-casting foundry. New silica sand is expensive and increasingly tightly regulated under Australian work-cover RCS rules, and dumped used sand is now waste-treated under state EPA licences with significant disposal cost. Reclaim recovers used sand for reuse, with three core technologies:

Thermal sand reclaim: Used sand is heated to 700–850 degC in a fluid-bed or rotary kiln, burning off residual organic binder. The reclaimer is itself a process with its own LEV demand — the combustion gas exhaust carries CO, organic VOC (from binder pyrolysis), SO2 (from sulfur in binders), and fine RCS. 316L stainless or hot-dip aluminised steel mains, dedicated thermal-oxidiser destruction of organic VOC followed by baghouse and stack discharge.

Mechanical attrition: Used sand is sized and abraded mechanically to remove bond film and break up clumps. Generates significant RCS dust at the attrition station. 316L or aluminised mains at 18–22 m/s transport velocity, cyclone pre-separator followed by baghouse.

Wet reclaim: Used sand is washed in water to dissolve sodium-silicate or water-soluble binder. Generates water-borne dust; the LEV is modest because most of the contaminant goes to the wastewater treatment, but the dewatering and drying station at the end of the wet-reclaim circuit drives RCS exhaust.

Across all three technologies, the foundry operator’s RCS exposure during sand reclaim service work is the highest single shift hazard, and the reclaim LEV is the single largest individual subsystem in the foundry duct circuit. Walker Newcastle’s sand-reclaim line and Bradken Bassendean’s sand-reclaim line both run at over 30,000 m³/h LEV through 800–1500 mm spiral mains.

3.8 Cupola furnace — legacy iron melt, coke-fired

Cupola furnaces are the traditional iron-melting workhorse — a vertical shaft charged from the top with iron, coke and limestone flux, with combustion air blown in through tuyeres near the base. Melt at 1450–1650 degC, continuous-duty operation, high tonnage. Cupola is legacy technology in Australia — most modern foundries have replaced cupola with EAF or induction-furnace melt — but several regional grey-iron operations still run cupola on cost-of-capital grounds. The cupola exhaust is continuous, hot and chemically aggressive: CO 4–15% by volume, SO2 from coke sulfur, NOx, metallic fume (manganese, silicon, iron oxide), charge particulate, and unburned coke fines.

Cupola exhaust requires refractory-lined steel duct for the first 5–10 m above the charge door — typically 50–100 mm of castable refractory or insulating ceramic blanket inside a 6–10 mm mild steel outer shell. Service temperature inside the refractory face up to 1200 degC; the outer shell remains below 200 degC and is paintable. Downstream, the exhaust passes through a quench tower (evaporative cooling with water spray, cooling 1200 degC to 400 degC), then a wet scrubber or deflagration-protected baghouse. Refractory ages on a 5–8 year replacement cycle, with annual visual inspection of access ports and refractory patch repair as required.

3.9 Electric arc furnace EAF — Bradken Bassendean WA, Walker Newcastle, steel melt

Electric arc furnace EAF is the dominant steel-melting technology in modern Australian foundries. Bradken Bassendean WA runs multiple EAFs for manganese-steel mining wear parts. Walker Newcastle NSW runs EAFs for steel and stainless-steel castings. EAF melts at 1600–1800 degC, generating spike-load fume during charging (when scrap drops into the furnace), melting (when arc strikes carry the highest fume load) and tapping (when molten metal pours into the ladle). EAF exhaust chemistry is dominated by CO from carbon-electrode combustion, particulate (iron oxide, manganese fume, slag fines), and NOx from the arc plasma. Stainless EAF additionally generates Cr VI from chromium content in the melt — one of the most hazardous pollutant streams in any foundry.

EAF capture combines a fourth-hole port in the furnace roof (drawing fume directly from the freeboard above the melt during arc-on) with a canopy hood for fugitive emissions during charging and tapping. Both feed a refractory-lined main for the first 3–5 m, then carbon steel cooling to a quench tower, then a baghouse with PTFE-membrane bags for fine particulate. Stainless-steel EAF additionally drives a dedicated Cr VI baghouse with HEPA polish and continuous Cr VI emissions monitoring at the stack.

3.10 Induction furnace — Inductotherm, ABB, Pillar — medium-frequency steel, iron, aluminium and bronze

Coreless induction furnaces are the cleanest and most efficient melting technology in modern Australian foundries. Medium-frequency Inductotherm, ABB and Pillar induction furnaces are deployed at every modern iron foundry, at most steel foundries (running alongside EAF), at investment-casting operations (Castalloy ANCA), and at many non-ferrous foundries (bronze, brass, aluminium). Induction melt at 1500–1700 degC for steel, 1450–1550 degC for iron, 700–800 degC for aluminium, and 1000–1200 degC for bronze.

Induction fume capture is localised side-draft or canopy hoods over the pour zone, with capture velocity 1.5–2.5 m/s. Fume load is lower than cupola or EAF (no coke combustion products, no carbon electrode), but spike load during melt-down is significant. Refractory-lined exhaust for the first 3–5 m, then carbon steel through baghouse. Induction furnace cooling-water circuits run pure water through the copper coil at 25–40 degC; the cooling-water HVAC is a closed loop with 316L stainless piping, dedicated heat exchanger and emergency back-up coolant supply.

3.11 Reverberatory furnace — BorgWarner Australia aluminium, Howmet Aerospace

Reverberatory furnaces are the high-tonnage aluminium melt workhorse. Molten aluminium sits in an open bath beneath a refractory-lined roof, heated by burner flames sweeping across the surface (LPG or natural gas fired) or by electric resistance. Pour temperature 700–850 degC. Reverberatory furnaces dominate aluminium die-cast and structural-aluminium foundries — BorgWarner Australia Lonsdale (the country’s largest aluminium die-cast operation) runs reverberatory melt feeding multiple die-cast cells. Smaller reverberatory operations include Howmet Aerospace for investment-cast aluminium components.

Reverberatory exhaust chemistry is dominated by alkaline halide fume from cryolite (Na3AlF6) and aluminium-fluoride (AlF3) flux, which is corrosive to carbon steel and to galvanising. HF hydrogen fluoride vapour (1.8 ppm STEL) and fluoride particulate dominate. 316L stainless or hot-dip aluminised steel exhaust mains are mandatory; galvanised duct fails in months. The exhaust terminates at a wet caustic (sodium hydroxide or soda ash) scrubber for HF neutralisation, with sludge handling to state EPA fluoride waste-disposal licence.

3.12 Crucible furnace and rotary furnace — bronze, brass, zinc, leaded alloys

Crucible furnaces are the small-tonnage workhorses for non-ferrous foundries — Crowley Bronze NSW, Bronze Founders VIC, Trafalgar Bronze, Tee Bronze, Engineering Sales Newcastle. A clay-graphite or silicon-carbide crucible holds the melt over a gas-fired or electric-resistance burner. Melt at 700–1200 degC depending on alloy — aluminium at the low end, bronze (Cu-Sn-Zn) at 1000–1100 degC, brass (Cu-Zn) at 950–1050 degC, leaded brass and leaded bronze at the same range.

Crucible exhaust is low-volume continuous, served by canopy hood with 1.0–1.5 m/s capture velocity. Common canopy main serves multiple crucibles in parallel. Material selection depends on alloy chemistry: leaded alloys release Pb fume (SafeWork Australia WES 0.05 mg/m³) requiring HEPA polish on the baghouse; zinc-rich brass releases ZnO fume (5 mg/m³) which is corrosive to carbon steel over time; copper-beryllium alloys release Be (0.001 mg/m³ STEL) requiring HEPA-grade air-tight ductwork. The bronze and brass foundries form a significant share of Australian non-ferrous casting volume — valves, fittings, marine castings, statuary — and the HVAC design has to balance affordability with strict toxic-metal exposure control.

3.13 Pouring and casting — the heat-load heart of the foundry

The pouring floor is the most demanding HVAC zone in any foundry. Molten metal exits the furnace via ladle (or direct tap), travels to the mould bed, and pours into the mould. The pouring station emits intense radiant heat, pour-off fume (from the mould-metal interaction), residual binder vapour (from the chemical-bonded sand or shell), and at investment casting and lost foam, additional process-specific vapour.

Pouring-floor make-up air is the single most often-neglected design issue in foundry HVAC retrofits. Every cubic metre of exhaust must be replaced by clean, tempered, controlled-velocity supply air. The pouring floor must remain at neutral or slightly positive pressure to prevent furnace-stack backdraft. Mechanical make-up air is universal in modern Australian foundries — naturally aspirated buildings are inadequate above small-scale jobbing operations. The make-up air mains are 316L stainless or hot-dip galvanised in clean make-up zones, with HEPA pre-filters at the supply diffusers in pour-quality-critical zones (investment casting, aerospace).

3.14 Knock-out and shake-out — RCS, heat, noise

Knock-out and shake-out is where the cooled casting is separated from its sand mould. The casting is typically still 200–500 degC at arrival; the impact on the shake-out grid generates significant dust as the sand breaks free. The dust is largely silica with iron oxide contamination from the casting surface. RCS exposure at shake-out is the highest single-shift hazard in any sand-casting foundry.

Shake-out LEV is side-draft or overhead canopy hood capturing both fugitive dust and residual fume from the still-hot casting. Capture velocity 1.0–1.5 m/s at the grid edge; transport velocity 20–22 m/s in the dust main. Material selection painted carbon steel downstream of cooling, with 316L on the wet-bath side of the scrubber. Knock-out cabinets (automated chipping and rumbling stations for breaking residual sand off complex internal passages) are fully enclosed AS 4024 machinery-safety items with interlocked doors, dust-mains isolation dampers and sound enclosure.

3.15 Shot blast, shot peen and sand blast — silica plus iron oxide plus Cr VI

Shot blast cleaning of castings uses steel shot, chilled-iron grit or glass bead propelled at 60–80 m/s. The booth interior is dense with abrasive, dust and the abraded surface contamination of the casting (residual silica sand, scale from heat treatment, iron oxide, Cr VI on stainless). The dust load is heavy — cabinets typically need 0.5 m/s face velocity at the work aperture and 18–22 m/s in the dust main with cyclone pre-separation. Shot peen (compressive surface treatment) and sand blast (using silica sand abrasive, increasingly replaced by aluminium oxide grit on RCS grounds) follow the same construction. Cr VI control on stainless-casting shot blast drives dedicated 316L mains and Cr VI continuous-emissions monitoring at stack.

3.16 Heat treatment — carburise, nitride, austemper, quench, temper, anneal

Heat-treatment ovens at 600–1000 degC fall under NFPA 86. Six common heat-treatment chemistries operate in Australian foundries. Carburising uses endothermic gas atmosphere (CO + CH4 + N2) at 900–950 degC for case hardening of steel components — CO is the dominant exposure hazard (30 ppm STEL). Nitriding uses NH3 ammonia atmosphere at 500–560 degC for surface nitrogen diffusion — NH3 plus HCN risk if mixed with cyanide compounds. Carbonitriding combines CO + NH3 atmosphere at 800–870 degC. Austempering uses a salt bath at 250–400 degC. Quench uses oil or polymer-water at 80–200 degC — oil quench releases significant oil-mist fume captured by dedicated 316L stainless LEV with electrostatic precipitator or coalescer filter. Temper at 150–650 degC anneals out residual stress. Anneal at 850–950 degC fully softens for machining.

Salt-bath nitriding and salt-bath case-carburising use cyanide salts (NaCN, KCN) at 500–600 degC. Cyanide vapour (HCN 5 ppm STEL) is acute toxic. Salt-bath LEV is fail-safe with redundant fans, continuous HCN monitoring, alkaline scrubber for HCN neutralisation, and emergency response procedures. Cyanide tanks are spaced from other operations and have dedicated bunds for spillage containment.

3.17 Grinding, fettling, trimming, flash removal and machining

Fettling is the cleanup of the raw casting — removal of gates, risers and flash; surface grinding of parting lines; chipping of residual sand from internal passages. It is the highest silica-exposure activity in a sand-casting foundry, and SafeWork Australia’s 0.05 mg/m³ RCS exposure limit drives the LEV design at every fettling station. Standard fettling capture is a downdraft table or backdraft bench with a slot hood drawing dust away from the operator’s breathing zone. Face velocity 0.5–0.7 m/s; transport 18–22 m/s.

CNC machining of castings (Howmet Aerospace machines turbine blades, BorgWarner Australia machines transmission cases, Castalloy ANCA machines turbocharger wheels) drives a separate LEV demand at the machine tool. Mist collection (water-based coolant mist, oil mist) at face velocity 0.3–0.5 m/s, ducted to coalescer filter or electrostatic precipitator. Cr VI control where stainless-casting machining is involved; Pb control where leaded alloys are involved.

3.18 Welding and repair — Mn, Cr VI, Ni, Co, Cu fume

Foundry welding (casting repair, gate-system fabrication, ladle repair, structural fabrication) uses TIG, MIG and SMAW (stick) processes. Welding fume chemistry depends on the base metal and filler — mild steel welding generates Mn and Fe2O3; stainless welding generates Cr VI, Ni and Mn; superalloy welding generates Co, Cr and Ni. AS/NZS 4453 mandates on-tool extraction (welding-gun fume extraction) plus local exhaust at every welding bay. 316L stainless mains, dedicated baghouse with HEPA polish for Cr VI streams.

3.19 Impregnation, resin infiltration and porosity sealing

Porous castings (sand-cast aluminium, low-pressure die cast iron) are pressure-impregnated with sealant resin to close microporosity. Common sealants are methacrylate, epoxy and cyanoacrylate. The impregnation station has a vacuum chamber, autoclave and curing oven, each with its own LEV demand. Methacrylate vapour (methylmethacrylate MMA, SafeWork Australia WES 50 ppm) is the dominant exposure; carbon-bed adsorption is the standard control.

3.20 Surface finish, anodise, passivate, electroplate

Surface-finish operations include chromium plate (Cr VI 0.05 mg/m³ STEL — the highest-risk plating chemistry), nickel plate, copper plate, anodise (sulfuric acid anodise for aluminium, mist control), and passivation (nitric acid for stainless, mist control). Each is a dedicated LEV branch with 316L stainless construction, wet scrubber neutralisation, and Cr VI continuous emissions monitoring where applicable. Painting and powder coating of castings are covered in companion guides on paint-booth ventilation.

3.21 QC inspection — X-ray, dye penetrant, magnetic particle, ultrasonic, CT scan

Cast-component QC uses non-destructive testing (NDT) including X-ray radiography (ionising radiation enclosure required, with dedicated lead-shielded room and HVAC), dye penetrant inspection (solvent VOC LEV), magnetic particle inspection (MPI — iron-powder fume LEV), ultrasonic UT (no significant exhaust load), and CT scanning (industrial X-ray CT, lead-shielded enclosure, dedicated cooling-water HVAC for the X-ray tube). The CT-scan room typically has its own dedicated supply-air HEPA-filtered conditioning to maintain stable temperature for the imaging system.

3.22 Refractory replacement and maintenance

Refractory lining of cupola, EAF, induction furnaces and ladles is consumable. Replacement cycle is 5–12 years depending on duty. Refractory installation and removal generates significant Al2O3, SiC, zircon, chrome-magnesia and carbon-ceramic dust, with RCS content depending on refractory type. The refractory replacement crew operates under dedicated mobile LEV (HEPA-filtered powered air-purifying respirators are standard) with the foundry shut down for the work. The static LEV system is not used during refractory replacement; the dust load would saturate any baghouse.

3.23 Chemistry laboratory — spectrometer, XRF, C-S analyser

Every Australian foundry operates a metallurgical chemistry lab for melt-control sampling. Equipment includes optical emission spectrometer (OES, used at the furnace tap), X-ray fluorescence (XRF) spectrometer, carbon-sulfur combustion analyser (LECO style), density meter and tensile tester. The lab has its own HVAC envelope — conditioned air to NC-45, supply 316L stainless or hot-dip galvanised, exhaust at 18–22 m/s in the spectrometer fume vent (argon shield gas exhaust plus minor metallic fume from spark stand). The lab is a clean environment relative to the rest of the foundry but is itself a chemistry source.

4. Material selection — why galvanised fails and what replaces it

Galvanised duct is the workhorse of HVAC fabrication. Across data centres, commercial towers, hospitals and schools, hot-dip-galvanised carbon steel sheet to AS/NZS 4254 is the right answer for 95% of duct work. In a foundry, it is the wrong answer for almost every duct. Five reasons drive material selection in foundry HVAC:

4.1 Galvanised carbon steel — the failure modes

Galvanised carbon steel fails in foundry exhaust for three reasons. First, temperature: zinc volatilises above 419 degC and fumes above 250 degC service. Cupola exhaust at 600–1200 degC, EAF at 600–800 degC, reverberatory at 200–400 degC, induction at 400–600 degC, and heat-treatment oven exhaust at 200–800 degC all exceed the safe service temperature of galvanising. Volatilised zinc adds to the contaminant load and fails AS 1885 air quality requirements. Second, abrasion: silica sand at shake-out, knock-out and shot blast strips zinc coating mechanically in 6–12 months of service, exposing bare carbon steel to the corrosive moist exhaust stream. Third, sulfur and HF attack: sulfur from coke and chemical sand binders reacts with zinc to form zinc sulfate; HF from reverberatory aluminium flux dissolves zinc directly; both produce hygroscopic flaking that contaminates the air stream and fails the duct.

4.2 Refractory-lined mild steel — the standard for furnace exhaust

The standard material for furnace exhaust within 3–10 m of the furnace is refractory-lined mild steel. Construction is a 6–10 mm mild steel shell with 50–100 mm of castable refractory or insulating ceramic blanket lining the interior. Refractory is castable monolithic for round mains (cast in place against a mandrel) or modular pre-cast tiles for rectangular mains. Service temperature inside the refractory face up to 1200 degC; outer shell remains below 200 degC and is paintable carbon steel.

Refractory-lined duct must be inspected on a maintenance schedule — typically annual visual inspection of access ports with refractory replacement of any section showing crack propagation or spalling. The refractory ages from thermal cycling: continuous-duty cupola mains last 5–8 years; intermittent-duty EAF mains last 4–7 years; induction-furnace mains last 8–12 years. Replacement is predictable and budgetable but significant: a 30 m cupola main with full refractory rebuild costs AUD 250,000–500,000 at 2026 prices.

4.3 Hot-dip aluminised steel — medium-temperature workhorse

Aluminised steel — carbon steel coated with an aluminium-silicon alloy by hot-dip process — is the material of choice for medium-temperature foundry exhaust between the refractory section and the scrubber inlet. Service temperature 400–600 degC, good corrosion resistance to mildly acidic exhaust, good abrasion resistance against fine dust. Aluminised steel is significantly cheaper than 316L stainless and is the practical choice for the longest section of any foundry exhaust main. Major foundries (Bradken, Walker, Castalloy ANCA) use aluminised steel for the bulk of their post-cooling exhaust runs.

4.4 316L stainless — corrosive and chemistry-control streams

316L stainless is reserved for the most corrosive streams: reverberatory aluminium HF and cryolite fume, sulfur-bearing furan reclamation exhaust, sulfur-acid mist downstream of cupola wet scrubbers, Cr VI from stainless-casting grinding and welding, cyanide salt-bath heat treat, lead and beryllium toxic-metal capture, investment-casting wax-recovery duct, and any duct in contact with cooling water (induction-furnace cooling circuits, scrubber recirculation). 316L is also standard for supply-air mains in clean make-up zones — laboratory air, pattern-shop air, office and operator-cabin air — where 30-year corrosion-free service is the goal.

4.5 Wear-lined and hardfaced construction — the highest-abrasion zones

Where abrasion is extreme — immediately downstream of the shake-out grid, the first elbow of the primary classifier, the discharge of the pneumatic sand conveyor, the shot-blast cabinet outlet — bare-metal duct (galvanised, aluminised, or 316L) wears through in 1–3 years. Wear-lined construction extends service life to 10–20 years. Three options:

• Hardox patch panels: 6–12 mm Hardox 450 or Hardox 500 plate welded into the duct interior at high-wear locations. Bradken and Walker Newcastle use Hardox extensively in their own sand-reclaim mains.
• Ceramic tile lining: Alumina ceramic tiles bonded to the duct interior with high-temperature epoxy or mechanical fixings. Heaviest wear resistance, highest cost. Common in cement-plant and mining duct (covered separately) but seen in heavy foundry sand-reclaim service.
• Hardfaced cladding: Tungsten-carbide or chrome-carbide overlay welded onto the duct interior at field locations. Used for patch-repair of worn duct in service.

4.6 FRP and acid-resistant coatings — scrubber outlets

The clean side of a wet scrubber — between the demister and the discharge stack — carries saturated air at near-ambient temperature with potential acid carryover. Fibre-reinforced plastic (FRP) ducting or epoxy-coated carbon steel is the standard solution. FRP is corrosion-immune and lightweight but is non-conducting; for any duct in a combustible-metals zone, bonding and grounding requires conductive carbon-fibre additive or external bonding tape.

5. Sizing and design — capture velocity, transport velocity, acoustic targets

5.1 Capture velocity at the source

Capture velocity is the air-flow speed required at the dust or fume source to entrain contaminant into the hood. ACGIH Industrial Ventilation Manual values, used in Australian practice alongside AS 1668.2:

• Low-velocity dust release (welding fume, ambient pattern-shop dust): 0.25–0.5 m/s
• Active dust release in moving air (shake-out, fettling, sanding, sand mixer): 0.5–1.0 m/s
• High-velocity dust release (shot blast, grinding wheels, knock-out, pneumatic sand conveyor): 1.0–2.5 m/s
• Pour-off fume capture at canopy hood: 1.0–1.5 m/s face velocity at the canopy
• Investment-casting pour station (high-precision aerospace): 2.0–2.5 m/s for inclusion control

5.2 Transport velocity in the duct

Transport velocity is the in-duct air speed required to keep captured dust in suspension. Below transport velocity, dust drops out and accumulates in horizontal runs; above, abrasive wear accelerates and noise rises.

• Vapour, fume and very fine dust (welding fume, paint mist, wax vapour): 10–13 m/s
• Fine dust (cotton lint, pattern-shop dust, light woodworking): 13–18 m/s
• Medium dust (general foundry shake-out, ceramic-shell knock-out): 18–20 m/s
• Heavy dust (foundry fettling, knock-out, sand reclaim, shot blast): 20–22 m/s
• Very heavy abrasive material (metal turnings, refractory dust, shot pre-separator): 22–25 m/s

5.3 Hood geometry

Hood selection is process-driven. Push-pull slot hoods across die-casting machines combine a push jet to direct fume across the work area with an extract slot on the opposite side — BorgWarner Australia and other die-cast houses use push-pull extensively. Slot hoods along benches give a draw-off across the operator’s work zone. Canopy hoods over melting furnaces and pouring stations capture rising hot fume by buoyancy assisted by extract. Downdraft tables at fettling and grinding capture dust below the operator. Backdraft benches behind chipping and de-coring stations draw dust away from the breathing zone. Side-draft canopies over induction furnaces give the cleanest fume control with minimum heat load on the structure above.

5.4 Acoustic targets — NC-65 industrial, NC-50 office, NC-45 lab

Foundry general industrial areas are NC-65 environments with mandatory hearing protection in active production zones (shake-out, fettling, shot blast, knock-out). Office, control-room and operator-cabin zones design to NC-50. Metallurgy laboratory and inspection areas to NC-45. Acoustic lagging on exhaust mains passing near manned workstations, NC-rated supply-air attenuators in lab and office branches, and sound-rated wall penetrations between production and office zones are standard practice. Acoustic budget is set at design stage and reviewed at commissioning; foundries that try to fix acoustics retroactively spend two to three times the cost of building it in.

6. The Australian foundry market — operator-by-operator HVAC snapshot

The Australian foundry sector is concentrated in a smaller number of larger operators than it was twenty years ago, with strong specialisation by metal type, casting method and end market. The operators below cover the bulk of mainland Australian foundry production and reflect the range of HVAC demands a Box Hill North VIC-based machine supplier sees in the field.

6.1 Bradken — Bassendean WA, Tickford VIC, Hawthorn VIC — mining wear parts and rail wheels

Bradken (CIMIC ASX:CIM-owned, with major shareholding originally Hitachi Mining Sumitomo Mitsui from 2017 acquisition) is Australia’s biggest steel and iron casting foundry by tonnage. Three Australian sites: Bassendean WA (the headline manganese-steel mining wear-parts operation), Tickford VIC, and Hawthorn VIC. Twelve sites across eight countries internationally. Product mix is mining-truck buckets, ground-engaging tools (GET), bucket teeth, dragline buckets, rail wheels and bogies, and high-tonnage industrial castings serving Caterpillar, Komatsu, Hitachi Mining, Liebherr, Volvo CE, BHP and the broader Australian and global mining industry. Donaldson (now a Bradken subsidiary after acquisition) brings air filtration and additional foundry capacity.

The Bradken HVAC stack is the most demanding in the sector. Multiple electric arc furnaces at 1700–1800 degC for manganese steel and alloy steel pour, refractory-lined exhaust mains to multi-stage baghouse, dedicated sand-reclaim circuit (Bassendean runs over 30,000 m³/h through 1500 mm spiral mains), heavy shake-out and shot-blast lines, dedicated quench and heat-treatment with NFPA 86 compliance, Cr VI control on the stainless-steel mining-tool castings, and large-scale make-up air conditioning across multiple production stages. Bradken is the archetype for refractory-lined exhaust, multi-stage particulate control and major LEV at fettling.

6.2 Walker Industries Newcastle NSW — east-coast steel and iron

Walker Industries Newcastle is the biggest east-coast steel and iron foundry, serving Komatsu undercarriage components, Caterpillar wear parts, marine and rail-industry castings. Operates legacy cupola alongside modern EAF and induction-furnace melt. The HVAC mix is cupola refractory-lined exhaust (one of the few cupola operations still in service in Australia), EAF for stainless and alloy steel, induction for iron, sand-reclaim circuit serving multiple mould lines, and a heavy fettling and shot-blast finishing hall.

6.3 BorgWarner Australia Lonsdale VIC — aluminium die-cast for automotive

BorgWarner Australia at Lonsdale (Melbourne VIC) is the country’s biggest aluminium die-cast operation. The site produces automotive transmission cases and housings for Ford, GM, BMW, Audi, VW, Toyota, Subaru, Mazda, Mitsubishi and Volvo. The HVAC dominant load is reverberatory aluminium melt (700–850 degC, cryolite and AlF3 flux, HF exhaust requiring 316L stainless mains and dedicated caustic scrubber), high-pressure die-casting cells with push-pull slot hoods at every die (1.0–1.5 m/s capture velocity at the operator’s working face), die-spray-mist capture across every casting cell, T6 age-hardening and T4 solution heat-treatment ovens under NFPA 86, and high-volume shot-blast and trim cleaning. BorgWarner is also subject to IATF 16949 automotive quality system requirements, driving documented HVAC parameter logging and process-control integration into the SCADA backbone.

6.4 Castalloy ANCA Group SA — aluminium investment and sand cast

Castalloy ANCA Group at Adelaide SA casts aluminium and high-temperature alloy components for the automotive turbocharger market and aerospace supply chain. The HVAC mix includes aluminium investment-cast ceramic shell production with dipping-room climate control, aluminium pour stations with HF and cryolite control, aluminium sand-cast lines with chemical-bonded sand reclaim, shot blast and trim, and CNC machining of cast components. Castalloy ANCA also runs precision investment-cast nickel-alloy components.

6.5 Howmet Aerospace Australia Melbourne VIC — aerospace investment cast

Howmet Aerospace (formerly part of Arconic) at Melbourne casts aerospace turbine blades, vanes, and structural components in Inconel, CMSX nickel-base superalloys and titanium for Boeing, Airbus, Embraer, Bombardier and Sukhoi. Howmet runs the most precise HVAC in the Australian foundry sector. Climate control in wax-injection rooms at ±0.5 degC and ±5% RH year-round; dipping rooms at 40–60% RH within ±5%; shell-firing kilns under NFPA 86; nickel-superalloy pour at 1700 degC with refractory-lined canopy hood; titanium investment-cast cells with argon shield-gas atmospheres and dedicated argon-recovery LEV; ceramic-shell knock-out fine-dust baghouse; CNC machining of turbine blades with mist collection; X-ray and CT NDT inspection rooms with dedicated HVAC. The supply-air HEPA-filter and absolute-filter loading at Howmet exceeds many semiconductor fabrication facilities.

6.6 Quickstep ASX:QHL — composite and investment-cast aerospace

Quickstep (ASX:QHL) combines carbon-composite aerospace components with limited investment-cast metallic components. The HVAC mix is dominated by composite layup and autoclave cure (covered in companion composite-manufacturing guide) plus investment-cast metallic finishing.

6.7 Austin Engineering ASX:ANG Perth — mining tray and bucket fabrication

Austin Engineering at Perth WA fabricates mining truck trays, buckets and ground-engaging tools by welded fabrication with cast inserts. Not a primary foundry but a major HVAC client for welding-fume control (Mn, Cr VI, Fe2O3) across multiple welding bays.

6.8 Iplex Iron Pipes Tomago NSW (Fletcher Building)

Iplex Pipelines Australia (Fletcher Building-owned) operates iron-pipe casting at Tomago NSW alongside PE and PVC pipe extrusion. The iron-pipe foundry produces ductile iron (SG) water and sewer mains using centrifugal casting. HVAC demand is concentrated at the centrifugal casting line (pour-off fume, mould-coating spray, ladle pre-heat), sand-core production for fittings, and finishing operations (shot blast, paint).

6.9 CIA Cast Iron Australia NSW

CIA Cast Iron Australia at Newcastle NSW manufactures iron pipe, manhole frames and covers, drainage grates and architectural cast iron. The HVAC mix is cupola or induction-furnace iron melt, sand-cast mould lines, fettling and shot-blast finishing — the traditional iron-foundry HVAC stack.

6.10 Foundry & Forge SA Adelaide

Foundry & Forge SA at Adelaide serves general engineering casting work in iron, steel and bronze. HVAC across multiple small-tonnage melt cells with shared sand-reclaim and finishing.

6.11 Engineering Sales Australia Newcastle — cast iron, steel, bronze, alloy

Engineering Sales Newcastle handles cast iron, cast steel, bronze and alloy castings for general engineering. Mid-tonnage Furan no-bake sand-cast lines drive the HVAC envelope.

6.12 Crowley Bronze NSW, Bronze Founders VIC, Trafalgar Bronze, Tee Bronze

The Australian non-ferrous foundry segment is fragmented across multiple small operations. Crowley Bronze NSW, Bronze Founders VIC, Trafalgar Bronze and Tee Bronze each operate crucible furnaces for bronze, brass and leaded alloys producing valves, fittings, marine castings and statuary. HVAC is canopy capture over multiple crucibles, with Pb and Cu fume control on baghouse and continuous Pb air monitoring against the 0.05 mg/m³ WES.

6.13 Hi-Tech Cast NSW — investment lost-wax

Hi-Tech Cast NSW operates investment-cast lost-wax production for general engineering applications. Smaller scale than Howmet Aerospace but similar HVAC stack — wax injection, shell dipping with climate control, de-wax and shell firing under NFPA 86, pour station at 1500–1700 degC, ceramic-shell knock-out.

6.14 Akin NSW, Hettich Australia, Trafalgar Aluminium — aluminium die-cast and gates

Akin (NSW) operates aluminium die-cast for industrial components. Hettich Australia operates die-cast for kitchen hardware (drawer fronts, hinges, handles). Trafalgar Aluminium (NSW) produces gates, balustrades and architectural aluminium by sand cast and die cast. HVAC stack is aluminium die-cast with HF control on smaller scale than BorgWarner.

6.15 What the operator mix means for fabricators

The Australian foundry market is not a single homogeneous segment. Bradken needs refractory-lined exhaust and large-bore baghouse mains. Howmet Aerospace needs precision dipping-room climate control and nickel-superalloy pour-station capture. BorgWarner needs die-spray-mist capture and HF-resistant reverberatory mains. CIA Cast Iron needs iron-pipe centrifugal-cast HVAC. Crowley Bronze needs Pb and Cu fume control on crucible canopy. Each operator type drives a different mix of duct material, duct geometry and capture-hood design. A fabricator equipped to serve all of them with SBKJ machinery is positioned to capture meaningful market share across the Australian foundry sector.

7. The wet scrubber, baghouse and thermal oxidiser interface

Almost every foundry exhaust stream terminates at a wet scrubber, a baghouse, a thermal oxidiser, or a combination of the three. The selection between them is process- and chemistry-driven.

7.1 Wet scrubbers — venturi, spray-tower, packed-bed

Wet scrubbers pass exhaust through water spray that captures particulate and absorbs water-soluble gas. They are mandatory for combustible-metal dust (aluminium, magnesium) under NFPA 484 and NFPA 660, preferred for high-sulfur streams (cupola, Furan reclamation), required for HF and cryolite exhaust (reverberatory aluminium melt — alkaline caustic neutralisation), and common for any stream with sticky or hygroscopic particulate that would blind a baghouse filter. Disadvantages are water consumption (closed-loop with bleed-off treatment is standard), sludge handling (state EPA fluoride-waste licence at aluminium foundries), and saturated stack discharge requiring a tall stack to clear the building plume.

Duct-side considerations at the scrubber inlet are vacuum loading — the scrubber generates significant static pressure drop, and the inlet duct can see 6–10 kPa vacuum. Standard AS/NZS 4254 medium-pressure duct is inadequate for sustained vacuum at this level; reinforced spiral or heavy-gauge welded construction is the typical solution. 316L stainless is standard for the wet-side inlet ducting because of acid-mist or HF carryover.

7.2 Baghouses — fabric filter, pulse-jet cleaning

Baghouses use fabric filter elements (polyester, aramid Nomex, PTFE membrane) to capture dust mechanically. They are the preferred choice for dry non-combustible dust streams (fettling, shake-out, shot blast, sand reclaim in ferrous foundries) and offer high collection efficiency (99.5%+ on particulate) with no water consumption. Disadvantages are filter-bag life (12–36 months depending on dust load), temperature limit (polyester bags fail above 130 degC, Nomex above 200 degC, PTFE membrane above 250 degC), and explosion-protection requirements for any combustible-dust application.

Duct-side considerations at the baghouse inlet are temperature — the duct must cool the exhaust to below the bag’s service temperature, typically by passing through a quench tower or evaporative cooler upstream. NFPA 660 isolation valves between baghouse and inbound duct prevent baghouse fire from propagating back through the duct. Bonded-and-grounded construction on every metre of inbound duct prevents static discharge ignition.

7.3 Thermal and catalytic oxidisers

Regenerative thermal oxidisers (RTO) and catalytic oxidisers destroy organic vapour by combustion at 800–1000 degC. RTOs are mandatory for lost-foam casting (styrene destruction), preferred for Furan no-bake reclaim (formaldehyde, furfuryl alcohol), and used for investment-casting de-wax (wax vapour destruction). Duct upstream of RTO is 316L stainless for the chemistry; duct downstream of RTO is hot-dip aluminised steel (the exhaust is now mostly CO2 and water vapour, minimally corrosive).

7.4 Combination systems

Most modern Australian foundries run combination systems — cyclone pre-separator for coarse particulate drop-out, evaporative cooler for temperature reduction, baghouse for fine particulate, RTO for organic VOC, and wet scrubber for HF or SO2. The duct system is correspondingly complex, with material transitions at each stage and isolation dampers at each module. The duct designer’s task is to lay out the system so each module can be isolated for maintenance without taking the entire foundry off-line.

8. Local exhaust ventilation (LEV) — the workhorse of foundry compliance

Every dust and fume source in a foundry gets its own LEV branch. Total LEV exhaust in a mid-sized Australian foundry is typically 80,000–250,000 m³/h, distributed across 30–100 individual branches. Each branch is sized for its source capture and transport velocity, with isolation dampers for maintenance. Branch sizing starts from capture velocity at the source, converts to volumetric flow at the hood face, then sizes the branch to maintain transport velocity. A typical fettling-bench branch is 1,000–1,500 m³/h at 250–300 mm diameter (20 m/s transport). A pouring-floor canopy branch is 10,000–20,000 m³/h at 500–700 mm (18 m/s). A cupola main is 50,000–120,000 m³/h at 1200–1800 mm refractory-lined mild steel (15–18 m/s).

LEV systems are pressure-balanced — each branch sized so the static-pressure drop from hood face to main collection point is equal across all simultaneously-operating branches. Without balancing, branches closest to the fan starve more distant branches of capture velocity. Balancing dampers at each branch are used for commissioning trim; the fundamentals must be right at design stage. Make-up air sized for total exhaust at the design condition (100,000 m³/h foundry LEV system needs 100,000 m³/h supply at design temperature) delivered through 316L stainless or hot-dip galvanised supply-air mains, with HEPA pre-filters at clean make-up zones and direct-gas-fired tempering for winter heating.

9. Typical project sizes — Australian foundry HVAC capital cost

A new Australian foundry HVAC project runs a predictable size range at 2026 prices:

• Small jobbing iron foundry (1–5 t/day): Total LEV 25,000–60,000 m³/h, 6–15 hoods. Duct footprint AUD 200,000–450,000.
• Mid-size investment caster (10–25 t/month): Total LEV 40,000–100,000 m³/h, 18–35 hoods across wax, dipping, drying, de-wax, kiln, pour, knock-out. Heavy 316L stainless content. Duct footprint AUD 500,000–1.2 m.
• Mid-size aluminium die-cast (200–500 t/month): Total LEV 100,000–180,000 m³/h, 25–45 hoods. NFPA 484 combustible-metals zoning. HF-resistant 316L. Duct footprint AUD 1.0 m–2.2 m.
• Large heavy-casting iron foundry (mining buckets, rail wheels): Total LEV 180,000–350,000 m³/h, 50–100 hoods, refractory-lined exhaust dominant, multi-stage particulate control. Duct footprint AUD 2.0 m–4.0 m.
• Large precision steel-casting (manganese, alloy, stainless): Total LEV 200,000–320,000 m³/h, 40–80 hoods, EAF capture, Cr VI control, NFPA 86 heat-treatment compliance. Duct footprint AUD 1.8 m–3.2 m.
• Bradken Bassendean WA-scale flagship: Total LEV exceeds 400,000 m³/h across the site, with multiple coordinated EAF, sand-reclaim, shake-out, fettling, heat-treat and shot-blast subsystems. Duct footprint AUD 4–6 m for greenfield equivalent.

10. The SBKJ machine configuration for Australian foundry fabrication

Foundry duct work is the most demanding production envelope a sheet-metal fabricator can take on. The right SBKJ machine configuration gives the fabricator the capability to serve every duct-material requirement in this guide from a Box Hill North VIC office floor.

10.1 SBAL-V stainless option auto duct line — the 316L workhorse

The SBAL-V auto duct production line is SBKJ’s flagship rectangular duct line and the right machine for 316L stainless foundry work. With the stainless-steel processing option, the SBAL-V handles 304 and 316L stainless sheet from 0.7 mm to 1.5 mm gauge in addition to standard galvanised, aluminised and painted carbon steel. The line includes stainless-rated decoiler with PE protective film handling, stainless-rated levelling rolls, dedicated TDF flange roll for stainless, and through-line surface protection. Production rate at 1.0 mm 316L is 4–6 m of finished duct per minute. For an Australian foundry-segment fabricator serving Bradken, Howmet Aerospace, Castalloy ANCA, BorgWarner Australia and the broader market with 316L mains for HF reverberatory exhaust, Cr VI stainless-casting fume, cyanide salt-bath exhaust, lead-bronze crucible canopy and cooling-water mains, the SBAL-V is the right answer.

10.2 SBAL-III auto duct line — heavy-gauge galvanised and aluminised

For heavy-gauge 1.6–2.0 mm galvanised, aluminised and painted carbon steel work, the SBAL-III auto duct line is the production solution. The SBAL-III handles sheet up to 2.0 mm with TDF flange forming, Pittsburgh lock or snap-lock seam forming, and full automation through coil entry, levelling, notching, shearing, brake-press forming and flange roll. Production rate at 1.6 mm is 8–12 m of finished duct per minute. The SBAL-III is the workhorse for general foundry exhaust mains downstream of the refractory section — shake-out cooling sections, sand-reclaim cool-side mains, fettling extracts, and general plant air handling.

10.3 SBSF-1525 stitchwelder — continuous longitudinal welded seam

The SBSF-1525 stitchwelder delivers continuous TIG welded seam on rectangular duct longitudinal lock. For chemical-fume-resistant duct (HF, Cr VI, cyanide, sulfur) the seam must be welded continuously rather than relying on sealant alone. The SBSF-1525 lays down a continuous TIG bead at 600–900 mm/min travel speed in 1.2 mm 316L using argon shield gas at 12 L/min. The bead penetrates the lock-seam interlock and gives a hermetic continuous bond. Surface-finish the bead flush for medical-grade or food-grade castings downstream, or leave as-laid for industrial service. The SBSF-1525 mounts inline with the SBAL-V or as a standalone bench welder for retrofit work.

10.4 SB-ZF1500 stitchwelder — longitudinal weld on spiral

The SB-ZF1500 longitudinal stitchwelder operates inline with the SBFB-1500 spiral tubeformer to deposit a continuous TIG bead along the formed spiral seam. The double-bond construction — spiral mechanical lock plus continuous TIG longitudinal weld — is the standard for HF-resistant aluminium foundry round duct, Cr VI stainless-casting fume mains, and high-pressure baghouse-inlet duct. The SB-ZF1500 handles 304 and 316L stainless up to 1.5 mm gauge at 800 mm/min travel speed. For spiral above 1000 mm diameter or for chemical-service spiral, the SB-ZF1500 is non-negotiable.

10.5 SBFB-1500 spiral tubeformer — sand reclaim and dust mains

Foundry dust mains — shake-out, fettling, knock-out, sand-reclaim, shot-blast — are best fabricated as spiral round duct. Round duct gives the best aerodynamic profile for high transport velocity (18–22 m/s) and the lowest abrasive-wear surface for dust-laden streams. The SBFB-1500 spiral tubeformer produces round duct from 80 mm to 1500 mm diameter in galvanised, aluminised or stainless steel at 0.6–1.5 mm gauge. For foundry sand-reclaim service at 1.2–1.5 mm wear-resistant spiral with optional internal Hardox or ceramic-tile lining for the highest-wear sections, the SBFB-1500 is the practical production envelope. Production rate at 800 mm diameter, 1.2 mm gauge: 3–6 m/min.

10.6 SBPC1500 plasma cutter — transitions, anchor plates, custom geometry

Cupola, EAF, induction and reverberatory hood transitions need custom-geometry tapered cones, mitred elbows and refractory-anchor stud plates. The SBPC1500 plasma cutter handles carbon steel up to 25 mm and stainless to 20 mm with HD plasma quality — clean kerf, minimal heat-affected zone, no slag. Cut transitions from CAD-generated cut files, deburr with stainless wire wheel, and weld up the geometry with TIG or MIG. The SBPC1500 production rate is approximately 1.2 m/min on 1.5 mm 316L, dropping to 0.4 m/min on 10 mm carbon steel. For an Australian foundry contractor producing heavy-gauge custom geometry, the SBPC1500 eliminates the bottleneck of manual oxy-fuel cutting and outsourced waterjet work.

10.7 SBLR-600 lock former — Pittsburgh lock and snap lock

The SBLR-600 lock former produces Pittsburgh lock or snap lock longitudinal seams on rectangular duct sections from the SBAL-V or SBAL-III. For 1.2 mm 316L stainless work, the SBLR-600 uses heavy-gauge tooling with reduced forming speed compared to galvanised. The SBLR-600 sits at the start of the rectangular line, producing the seam profile before the duct is folded into shape.

10.8 SBTF-1500, SBTF-1602, SBTF-2020 spiral lines — large-bore mains

For trunk mains above 1500 mm diameter — the largest cupola exhausts, EAF mains, large baghouse manifold duct — the SBTF series takes over from the SBFB-1500. SBTF-1500 produces up to 1500 mm; SBTF-1602 up to 1600 mm; SBTF-2020 up to 2000 mm diameter. Heavy gauge to 2.0 mm. All three machines accept the SB-ZF longitudinal stitchwelder for chemical-service continuous-weld construction. The SBTF-2020 is the largest spiral former in the SBKJ catalogue and is the right machine for any fabricator targeting Bradken Bassendean-scale or Walker Newcastle-scale sand-reclaim trunk-main contracts.

10.9 Refractory-lined option for furnace exhaust mains

The deep-furnace section of every foundry exhaust is refractory-lined mild steel. SBKJ supplies the carbon-steel outer shell with prepared flanges and refractory-anchor studs welded to the interior at the appropriate density. The refractory cast or blanket installation is typically performed by a specialist refractory contractor at the foundry site, but the outer-shell fabrication — flanged, anchor-studded, internally prepared — is fully achievable on the SBAL-III production line with the heavy-gauge option and the SBPC1500 plasma cutter.

10.10 Reinforced spiral for vacuum loads

Wet-scrubber inlet ducts, V-process vacuum mains and high-pressure baghouse inlet duct see vacuum loading above AS/NZS 4254 medium-pressure ratings. The SBTF spiral line produces reinforced spiral with thicker gauge and rolled-on external ribs, giving a vacuum-rated round duct without the cost of full welded construction. For static pressure differentials above 8 kPa, reinforced spiral is the cost-competitive answer.

11. Practical fabrication and installation considerations

11.1 Refractory anchoring

Refractory-lined ducts use stud anchors welded to the inside of the carbon-steel shell at a density of typically 1 anchor per 0.1–0.25 m², depending on refractory thickness and service temperature. Anchor pattern is laid out at fabrication time, not at installation. The fabricator who omits anchor studs at production time forces a site-weld retrofit that is slow, expensive and rarely as good as the factory weld.

11.2 Thermal expansion

A 30 m run of carbon-steel duct expands approximately 90 mm between ambient and 300 degC service. 316L stainless expands approximately 75 mm over the same range. Foundry exhaust mains must include expansion joints — bellows in lower-temperature sections, brick-and-fibre in refractory-lined sections — sized for design temperature range. Rigid mounting of long exhaust runs is a common cause of premature failure as thermal stress tears welded joints.

11.3 Inspection access

AS 4024 and AS 1885 both require regular inspection of foundry ductwork. Access ports sized for camera inspection (200 mm minimum) or personnel entry (600 mm) on confined-space-compliant work. Inspection-port positioning is process-driven: every 5–10 m on horizontal runs, at every elbow, at every branch take-off, on either side of every damper.

11.4 Insulation and acoustic lagging

Foundry exhaust mains over manned work zones are insulated externally for personnel protection — exterior shell temperatures of 60 degC or higher are an AS 4024 burn hazard. Acoustic lagging on top of thermal insulation gives NC-65 acoustic compliance in production areas and NC-50 in adjacent office and laboratory zones. The combined insulation-and-lagging package is bulky and must be coordinated with structural-clearance budgets at design time.

11.5 Dampers and isolation

Every machine on a shared dust or fume main needs an isolation damper for safe maintenance. Dampers in foundry service are heavy-duty butterfly or guillotine designs with high-temperature seals, refractory packing where service temperature warrants, position indicators on the AS 4024 lock-out chain. Fire dampers per AS 1668.1 are required at zone boundaries; explosion-isolation valves per NFPA 660 are required between baghouse and inbound duct for combustible-dust service.

11.6 Bonding and grounding

NFPA 484, NFPA 660 and AS/NZS 60079 collectively require electrical bonding and grounding of every duct segment in a combustible-metal-dust or combustible-organic-dust circuit. Bonding straps across flanged joints, ground straps from the duct exterior to the building structural earth, and continuous ground bond from the dust source through the cyclone, baghouse and stack. Resistance to ground less than 10 ohms per AS/NZS 60079 design guidance. For FRP duct in combustible-dust service, conductive carbon-fibre additive or external grounding tape is mandatory.

12. The 14-point checklist for a foundry HVAC specification

The condensed version of this entire guide is a 14-point checklist an engineer runs against any Australian foundry HVAC specification before sign-off:

1. Every dust and fume source mapped, classified by temperature and chemistry, and assigned to a dedicated LEV branch with documented capture velocity per ACGIH and AS 1668.2.
2. Cupola, EAF, induction and reverberatory exhaust mains within 5 m of furnace specified as refractory-lined mild steel with internal anchor studs at appropriate density.
3. Medium-temperature exhaust mains specified as hot-dip aluminised steel; corrosive (HF, Cr VI, cyanide, sulfur) and cooling-water mains specified as 316L stainless.
4. Dust mains sized at 18–22 m/s transport velocity; vapour and fume mains at 10–13 m/s; very-heavy abrasive at 22–25 m/s with wear-lined construction.
5. Combustible-metal-dust zones (aluminium and magnesium fines) identified per NFPA 484 and NFPA 660 with hazard area classification per AS 3957 and AS/NZS 60079; wet-bath collection specified; bonding-and-grounding documented.
6. Heat-treatment ovens (carburise, nitride, austemper, anneal, temper) specified per NFPA 86 with LEL monitoring, purge-and-light sequence, dedicated stack risers.
7. Cyanide salt-bath heat-treat exhaust specified with redundant fans, continuous HCN monitoring, alkaline scrubber, emergency response plan.
8. Cr VI stainless-casting fume specified with dedicated 316L mains, dedicated baghouse, continuous Cr VI emissions monitoring.
9. HF and cryolite reverberatory aluminium exhaust specified as 316L stainless with dedicated caustic scrubber and state EPA fluoride-waste licence.
10. RCS silica dust capture specified at every sand-handling operation with quarterly air-sampling plan against 0.05 mg/m³ SafeWork Australia WES.
11. Make-up air system sized for total exhaust with neutral or slightly positive pressure on pouring floor relative to office and lab zones; HEPA pre-filters in clean make-up areas.
12. Acoustic targets specified: NC-65 production, NC-50 office, NC-45 laboratory, with lagging budget coordinated at duct-routing stage.
13. AS 4024 machinery-safety interface confirmed on every dust-extraction connection — interlocked guards, isolation dampers, inspection-port positioning.
14. Wet-scrubber and baghouse inlet duct vacuum loads specified above AS/NZS 4254 medium-pressure where required; reinforced spiral or heavy-gauge welded construction substituted; SafeWork Australia and state EPA compliance evidence drafted before commissioning.

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13. ARBS 2026 and the SBKJ Australia connection

SBKJ Group exhibits at ARBS 2026 in Sydney (the Australian Refrigeration, Building Services and Air Conditioning Exhibition, the industry’s biennial HVAC&R trade show). The Australia Ducting Pty Ltd stand (exhibitor ID 236) shows the SBAL-V auto duct line with stainless option, SBAL-III heavy-gauge auto duct line, SBFB-1500 spiral tubeformer, SBSF-1525 stitchwelder and SBPC1500 plasma cutter. The stand team will walk fabricators through the foundry-segment production envelope — how to fabricate 316L HF-resistant reverberatory mains, Cr VI stainless-casting fume mains, sand-reclaim spiral, EAF refractory-anchored shells — on-site at ARBS Sydney May 2026.

SBKJ Group also operates from Box Hill North VIC (Melbourne) for the broader Australian foundry sector, with the Australia entity holding the AS/NZS 4254 documentation, IATF 16949 customer-supply experience, and direct technical engineering relationships with Bradken, Walker Newcastle, BorgWarner Australia, Castalloy ANCA, Howmet Aerospace, Iplex, CIA Cast Iron, Foundry & Forge, Engineering Sales, Crowley Bronze, Bronze Founders, Hi-Tech Cast and Trafalgar Aluminium.

14. Industry bodies and reference resources

Australian foundry HVAC sits inside a broader industry network worth referencing in any specification document:

• Foundry Institute of Australia (FIA): Now incorporated within Engineers Australia; the historic technical institute for the Australian foundry sector.
• Australasian Casting Society (ACS): The technical society for casting metallurgy in Australia and New Zealand.
• Investment Casting Institute ANZ: Investment-casting technical body covering Howmet Aerospace, Castalloy ANCA, Hi-Tech Cast and Quickstep.
• Australian Steel Institute (ASI): Steel-industry technical body referencing AS 2074 carbon and alloy steel casting standards.
• Sustainable Industry Association: Environmental management network for state EPA licence-holders including foundry stack-emission reporting.
• SafeWork Australia: Workplace exposure standards and codes of practice for foundry hazards including RCS, Cr VI, Pb, HF and cyanide.
• Standards Australia: AS 1668.2, AS 4254, AS 3957, AS/NZS 60079, AS 1885, AS 2074, AS 1830, AS 1831, AS 1832, AS 2027, AS 1875, AS/NZS 4453, AS 4036, AS 1318, AS 4801, AS 1668.1, AS 1851, AS 1530.4.

15. Where this connects to the rest of the SBKJ insight library

Foundry HVAC sits in the heavy-industry corner of the SBKJ insight library. Companion guides worth reading alongside:

• Steel mill and smelter HVAC duct guide — primary metal production, BOF and EAF steelmaking, continuous casting and rolling-mill exhaust. The upstream companion to this foundry guide.
• Mining ventilation HVAC duct guide — underground and open-pit mining ventilation, the supply chain feeding Bradken and Walker Newcastle mining-wear-part castings.
• Iron ore open-pit mine, concentrator and shiploader HVAC guide — further upstream in the iron supply chain.
• Composite manufacturing HVAC duct guide — the Quickstep ASX:QHL combined composite-and-cast aerospace HVAC envelope.
• Welding methods for HVAC duct fabrication — the technique reference for the hot-side welded mains that dominate foundry exhaust construction.
• Galvanised vs stainless steel duct — the material-selection reference behind the 316L specifications throughout this guide.
• Spiral duct forming guide — SBFB-1500 and SBTF-2020 production technique reference for foundry sand-reclaim spiral mains.
• Welding methods for HVAC duct fabrication — SBSF-1525 and SB-ZF1500 stitchwelder technique reference.
• Cement plant HVAC duct guide — adjacent heavy-abrasive dust-loaded HVAC sector with shared wear-lined construction techniques.
• Australia HVAC duct fabrication setup 2026 — the practical machinery-and-factory-setup reference for an Australian foundry-segment HVAC contractor.

FAQ

Why is respirable crystalline silica (RCS) the deadliest hazard in an Australian foundry?

RCS is the silent killer of foundry workers, generated everywhere silica sand is handled — green sand mould, no-bake chemical-bonded sand, shell mould, investment-casting ceramic shell, thermal sand reclaim at 800 degC, mechanical attrition, shake-out and knock-out, fettling, grinding, shot-blast and sand-blast. SafeWork Australia WES is 0.05 mg/m³ over 8 hours — the lowest of any common foundry contaminant. Even brief excursions, repeated across a 30-year career, cause silicosis, lung fibrosis, lung cancer and COPD. The 2024 nationwide engineered-stone ban shows how seriously Australian regulators treat RCS. Foundry ductwork runs dust mains at 18–22 m/s to prevent silica drop-out, uses abrasion-resistant materials (aluminised steel, 316L, wear-lined carbon steel), includes cyclone pre-separators upstream of baghouses, and supports continuous breathing-zone monitoring with quarterly sampling.

How does cupola, EAF and induction furnace exhaust differ in HVAC design?

Cupola furnaces (legacy iron melt, Walker Newcastle uses one historic line) run continuous coke combustion at 1450–1650 degC with CO, SO2, NOx and metallic fume — refractory-lined mild steel to wet scrubber, refractory replacement on 5–8 year cycle. EAFs (Bradken Bassendean WA, Walker Newcastle) generate 1600–1800 degC with spike fume during melt-down, charging and tapping — fourth-hole port plus canopy hood, refractory-lined exhaust, baghouse with PTFE bags. Induction furnaces (modern Inductotherm, ABB, Pillar) are cleaner but produce localised spike during charging — side-draft canopy hood, shorter refractory section. Reverberatory furnaces (BorgWarner Australia, Howmet Aerospace aluminium) at 700–850 degC produce HF and cryolite fume requiring 316L stainless and caustic scrubber. Crucible furnaces (Crowley Bronze, Bronze Founders, Tee Bronze) at 700–1200 degC use canopy capture with carbon steel mains, with Pb and Cu fume control where leaded alloys are present.

What is the difference between sand, investment and lost-foam casting from an HVAC perspective?

Sand casting (green sand, no-bake, shell mould — used at Walker Newcastle, Foundry & Forge SA, Engineering Sales Newcastle, CIA Cast Iron) generates the largest dust load. Sand reclaim — thermal at 800 degC plus mechanical attrition plus pneumatic conveying — is the dominant LEV demand. Investment casting (lost-wax — Howmet Aerospace, Castalloy ANCA, Hi-Tech Cast, Quickstep) generates wax burn-off vapour at de-wax, ceramic-shell silica and zircon dust at knock-out, and pour-off fume at 1500–1700 degC. Lost-foam (EPS pattern, niche aluminium and grey-iron) generates styrene vapour (SafeWork Australia STEL 50 ppm) and EPS decomposition VOC during pour — dedicated thermal oxidiser required.

Why are cyanide salt baths and hexavalent chromium the regulatory hot zones in foundry heat treatment and finishing?

Cyanide salt baths (case carburising, salt-bath nitriding) release HCN vapour (STEL 5 ppm) and require dedicated stainless exhaust to alkaline scrubber. Cyanide is acutely toxic at low concentration. Hexavalent chromium Cr VI is generated at stainless steel casting welding, grinding, polishing, shot-blast and electroplate — SafeWork Australia reduced the Cr VI WES to 0.05 mg/m³ in 2024. LEV at every Cr VI source is mandatory, ducted in 316L stainless to dedicated baghouse or wet scrubber, with operator respiratory protection as secondary control.

Why does aluminium fluoride flux and cryolite drive HF-resistant ductwork in aluminium foundries?

Aluminium melt uses cryolite (Na3AlF6) and aluminium fluoride (AlF3) as flux. At 700–850 degC pour, both decompose to release HF vapour and fine fluoride dust. HF is corrosive (etches glass, dissolves galvanising, burns lung tissue at 1.8 ppm STEL). Reverberatory exhaust must be 316L stainless minimum, terminating at wet caustic scrubber for HF neutralisation. Galvanised duct fails in 6 months in HF service.

What SBKJ machine handles 316L stainless duct for cryolite HF exhaust and stainless-casting Cr VI fume?

The SBAL-V stainless option auto duct line. The SBAL-V handles 304 and 316L from 0.7 mm to 1.6 mm in addition to galvanised and aluminised, with stainless-specific tooling, surface-protection films, and TDF flange on stainless. For an Australian foundry-segment fabricator serving Bradken, Howmet Aerospace, Castalloy ANCA and BorgWarner Australia, the SBAL-V plus the SBSF-1525 stitchwelder for continuous longitudinal weld on stainless gives a production envelope that covers HF-resistant reverberatory exhaust, Cr VI stainless-casting fume, cooling-water mains, and clean make-up air. SBAL-V production rate on 1.0 mm 316L: 4–6 m of finished duct per minute.

What SBKJ machine produces heavy-gauge spiral round duct for sand reclaim conveyance?

The SBFB-1500 spiral tubeformer. Produces spiral round duct from 80 mm to 1500 mm diameter in galvanised, aluminised, or stainless sheet at 0.6 mm to 1.5 mm gauge. For abrasive sand-reclaim duct at 18–22 m/s, SBFB-1500 produces 1.2–1.5 mm wear-resistant spiral with optional internal Hardox or ceramic-tile lining. For trunk mains above 1500 mm, SBTF-2020 takes the same role up to 2000 mm.

What SBKJ machine handles heavy-gauge 1.6–2.0 mm galvanised duct for general foundry exhaust?

The SBAL-III auto duct line. Handles galvanised, aluminised and painted carbon steel up to 2.0 mm with TDF flange, Pittsburgh lock or snap lock, and full automation through coil entry, levelling, notching, shearing, brake-press and flange roll. Production rate 8–12 m of finished duct per minute on 1.6 mm gauge. Pair with SBPC1500 plasma cutter for custom-geometry transitions and refractory-anchor stud plates.

What is the difference between AS 4254 medium-pressure duct and the heavy-gauge welded construction needed for cupola and EAF exhaust?

AS/NZS 4254.1 covers normal HVAC pressure ranges (up to 2500 Pa). Cupola and EAF exhaust at 1200 degC service with significant static-pressure load run beyond AS 4254 normal practice. They require refractory-lined construction with 6–10 mm mild steel outer shell, internal anchor studs welded inside at 0.1–0.25 m² density, castable refractory or ceramic blanket installed by specialist refractory contractor, and bellows or brick-and-fibre expansion joints sized for thermal growth. Below the refractory section, exhaust cools to 400–600 degC and continues in hot-dip aluminised steel; below 200 degC and through the baghouse, 316L stainless or painted carbon steel is acceptable.

How does Bradken differ from BorgWarner Australia from Howmet Aerospace from an HVAC perspective?

Bradken (Australia’s biggest steel-and-iron casting house, CIMIC ASX:CIM-owned, Bassendean WA + Tickford VIC + Hawthorn VIC, mining wear-parts and rail wheels) drives EAF and induction-furnace refractory-lined exhaust, heavy sand-reclaim dust at 1500 mm spiral mains at 20 m/s, shake-out and shot-blast LEV with Cr VI control. BorgWarner Australia (biggest aluminium die-cast at Lonsdale VIC, automotive transmission cases for Ford, GM, BMW, Audi, VW, Toyota, Subaru, Mazda, Mitsubishi, Volvo) drives die-spray-mist capture, reverberatory aluminium melt HVAC with HF and cryolite (316L stainless, dedicated caustic scrubber), T6 age-hardening oven exhaust under NFPA 86. Howmet Aerospace Melbourne VIC (aerospace turbine blades for Boeing, Airbus, Embraer, Bombardier, Sukhoi) drives high-precision climate control (40–60% RH in dipping rooms, ±0.5 degC wax-injection rooms), nickel-superalloy pour at 1700 degC, ceramic-shell knock-out fine-dust baghouse. Each foundry needs different SBKJ fitment.

16. Contact SBKJ Group — Australian foundry HVAC machinery

SBKJ Group supplies HVAC duct production machinery to Australian fabricators serving the foundry sector. From Box Hill North VIC, we work with contractors fabricating exhaust ductwork for Bradken (Bassendean WA + Tickford VIC + Hawthorn VIC), Walker Newcastle, BorgWarner Australia (Lonsdale VIC), Castalloy ANCA Group (SA), Howmet Aerospace (Melbourne VIC), Iplex Iron Pipes (Tomago NSW), CIA Cast Iron Australia, Foundry & Forge SA, Engineering Sales Newcastle, Crowley Bronze, Bronze Founders, Hi-Tech Cast NSW, Quickstep ASX:QHL, Austin Engineering ASX:ANG and the broader Australian foundry market.

• Email: sales@sbkjduct.com
• Phone: +61 435 074 994
• Web: sbkjduct.com
• Address: Box Hill North, VIC 3129, Australia
• ARBS 2026: Sydney, May 2026, exhibitor 236 — Australia Ducting Pty Ltd stand

For an itemised quote covering an SBAL-V stainless option line, SBAL-III heavy-gauge line, SBFB-1500 spiral tubeformer, SBSF-1525 stitchwelder, SB-ZF1500 longitudinal welder, SBPC1500 plasma cutter and SBLR-600 lock former — configured for a foundry-segment HVAC fabricator in Australia — email sales@sbkjduct.com or call +61 435 074 994. An SBKJ mechanical engineer (not a salesperson) responds within 12 hours with itemised pricing, delivery, commissioning timeline and Australian-Standards documentation pack.

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