Paint, Coatings, Printing Ink, Resin, Adhesive & Sealant Manufacturing HVAC Duct Guide

1. Why paint, coatings, ink and resin manufacturing HVAC is its own engineering discipline

The factory that makes paint is a different animal from the workshop that sprays it. Spray-booth ventilation — overspray capture, paint-arrestor filtration, booth balance — is a well-trodden field covered elsewhere. This guide is about the upstream plant: the manufacturing site where raw solvents, resins, pigments, fillers, monomers and additives arrive by tanker and bulk bag and are combined, reacted, dispersed, let down, tinted, filled and shipped as finished paint, coating, printing ink, resin, adhesive or sealant. The HVAC inside those plants is a process-engineering discipline in its own right, sitting at the intersection of flammable-liquid safety, occupational-hygiene exposure control, combustible-dust deflagration safety, hazardous-area electrical compliance and high-temperature furnace engineering — frequently all inside the same building.

Consider what coexists on a single integrated Australian coatings site. In one bay, a bank of high-speed dispersers shears titanium dioxide and extender into a solvent-and-resin millbase, flashing off xylene, toluene and white-spirit vapour. In the next, a tank farm of bulk solvent feeds a thinner make-up station and a drumming line that decants Class IB and IC flammable liquids into 20 L pails and 200 L drums. Across the yard, a resin plant cooks alkyds at 240 degC under nitrogen blanket, venting hot solvent and acrolein through a condenser to a thermal oxidiser. In the adhesives building, a sealant line cures silicone and releases acetic acid, while a two-pack polyurethane line meters MDI and TDI isocyanate at exposure limits two orders of magnitude below the solvents next door. Down the corridor, a pigment store dumps carbon black and crystalline-silica-bearing extenders, and a QC laboratory runs fume cupboards full of solvents and curing agents. Each of these is a distinct ventilation problem with its own capture strategy, duct material, fan construction and regulatory driver, and the duct that serves them is anything but commodity sheet metal.

The Australian coatings, ink, resin and adhesive sector is concentrated and well-known. DuluxGroup — the owner of Dulux, Berger, British Paints, Cabot’s and Feast Watson decorative brands, plus Selleys adhesives and sealants and Yates — operates major manufacturing at Clayton and Dandenong in Melbourne’s south-east and at Rocklea in Brisbane. PPG Industries Australia runs decorative, industrial, automotive-refinish and aerospace coatings manufacturing including a long-established Clayton VIC presence. Wattyl, now part of Hempel, manufactures decorative and protective coatings with sites across the eastern states. Haymes Paint is the largest Australian family-owned paint manufacturer, headquartered and manufacturing in Ballarat VIC. Akzo Nobel Australia covers decorative and high-performance industrial and protective coatings; Resene and Taubmans (a PPG decorative brand) and Solver Paints cover the architectural market; Jotun Australia and International Paint serve the protective and marine sector; and Sherwin-Williams Australia covers industrial and protective lines. On the adhesives and sealants side, Bostik, Sika Australia and Parchem are the major construction-chemical and adhesive manufacturers. In resins, Allnex (the former Nuplex Resins) and Huntsman supply the alkyd, polyester, acrylic and epoxy resin intermediates that the paint makers buy in or make on site. In printing ink, Siegwerk, Flint Group and Sun Chemical Australia supply solvent-based, water-based and UV-curable inks. These operators cluster in known industrial precincts: Clayton, Dandenong and Ballarat in Victoria; Villawood, Wetherill Park and Padstow in western Sydney; Rocklea in Brisbane; Welshpool in Perth; and Beverley in Adelaide.

Across this sector, manufacturing HVAC duct must survive five simultaneous demands. Flammable-vapour safety: solvent dilution ventilation to hold workrooms below the explosive limit, conductive bonded duct, spark-resistant fans, and AS/NZS 60079 hazardous-area zoning around every release point, all under the AS 1940 flammable-liquid regime. Toxic-fume capture: local exhaust ventilation at source to hold every operator’s breathing zone below the workplace exposure standard, from xylene at 80 ppm down to isocyanate at 0.02 mg/m3. Combustible and respirable dust control: pigment and filler LEV and dust collection to hold respirable crystalline silica below 0.05 mg/m3 and to manage deflagration risk on combustible dusts under AS 3957 and NFPA 68/69. High-temperature service: resin-reactor and thermal-oxidiser vents at 250 to 850 degC needing high-temperature stainless and engineered expansion. And corrosion resistance: acetic-acid silicone-cure exhaust, acidic resin vapour and acid-handling streams needing stainless or plastic duct under AS 3780 corrosives logic. Each is manageable alone; together they explain why a generic commercial fabricator loses money on the first coatings-plant project and declines the second. This guide walks each zone and closes with the SBKJ machine configuration that lets an Australian fabricator serve this market from Box Hill North VIC.

2. The Australian regulatory stack — AS 1940, AS 1668.1/.2, AS/NZS 60079, AS 3957, AS 3780, NFPA 30/68/69, NCC Section J

HVAC for paint, coatings, ink, resin and adhesive manufacturing in Australia sits across two dozen overlapping standards. The stack divides into flammable-liquid safety (the spine), mechanical-ventilation design, occupational exposure control, hazardous-area electrical compliance, combustible-dust safety, corrosives handling, pressure and furnace safety, and energy and management-system overlays. Get any one wrong and a notice from SafeWork Australia or the state EPA follows. The sections below set out each standard and where it bites on the ductwork.

2.1 AS 1940 — storage and handling of flammable and combustible liquids (the spine)

AS 1940 is the central document for a solventborne plant. It classifies liquids by flash point and boiling point — Class IA, IB, IC flammable (flash below 60 degC) and Class II and IIIA combustible (flash 60 degC and above) — and sets quantity limits, separation distances, bunding, spill containment, electrical-area classification and the ventilation needed to prevent the accumulation of flammable vapour. For the HVAC engineer, AS 1940 is the source of the inventory and volatility data that drives the dilution-ventilation rate, the hazardous-area zoning under AS/NZS 60079, the bonding-and-earthing requirement on duct, and the spark-resistant-fan requirement. It governs the bulk solvent tank farm, the drum store, the decanting and drumming bay, the thinner make-up station and the in-process solvent at the disperser and let-down vessel. AS 1940 cross-references the ADG Code (Australian Dangerous Goods Code) for transport and GHS for classification and labelling.

2.2 AS 1668.1 and AS 1668.2 — fire and smoke control, and mechanical ventilation including dilution

AS 1668.1 covers fire and smoke control in buildings via the air-handling system. AS 1668.2 is the mechanical-ventilation standard and, critically for this sector, sets the basis for dilution ventilation of contaminants and references workplace exposure standards (WES) for the contaminant concentrations the ventilation must achieve. AS 1668.2 provides the dilution-airflow methodology — given a contaminant generation rate and a target concentration (a fraction of the WES for health, or a fraction of the LEL for fire safety), it yields the required dilution airflow. In a coatings plant the binding constraint is usually the LEL (keeping the general workroom below 10 percent of the lower explosive limit) rather than the WES, because the flammability limit is reached at a lower concentration than the health limit for most paint solvents. AS 1668.2 also mandates that extracted air be replaced by tempered, filtered make-up air, keeping process halls at neutral or slightly negative pressure relative to offices and laboratories so that vapour cannot migrate to occupied areas.

2.3 AS/NZS 4254.1 and .2 — sheet-metal and flexible duct construction

AS/NZS 4254.1 (sheet metal) and AS/NZS 4254.2 (flexible) govern duct construction across the low- (up to 500 Pa), medium- (up to 1000 Pa) and high-pressure (up to 2500 Pa) ranges. Most coatings-plant dilution supply, general extract and process LEV sit inside AS 4254 ranges and are fabricated to its gauge, joint and stiffening tables. The resin-reactor high-temperature riser, the thermal-oxidiser inlet and any refractory-lined section run beyond AS 4254 and are purpose-engineered; AS 4254 resumes downstream on the cooled side.

2.4 AS 1530.4 — fire-resistance of duct penetrations

AS 1530.4 covers fire-resistance testing of building elements, including fire-rated ductwork penetrations through fire compartments. In a coatings plant this matters at every penetration between a high-hazard process or solvent-storage zone and an adjacent office, laboratory, switchroom or evacuation route — the penetration must meet the fire-resistance level (FRL) called by the building’s NCC approval, with fire dampers to AS 1682 and continuously welded fire-rated risers where required.

2.5 AS/NZS 60079.10.1 and .10.2 — explosive gas and dust atmospheres

AS/NZS 60079.10.1 classifies gas and vapour hazardous areas (Zone 0/1/2) and AS/NZS 60079.10.2 classifies combustible-dust atmospheres (Zone 20/21/22). Together with the equipment-selection parts (AS/NZS 60079.0 general, .1 flameproof Ex d, .7 increased safety Ex e, .15 Ex nA, .31 dust Ex t) and the installation part (AS/NZS 60079.14, alongside AS/NZS 3000 wiring), this family dictates the Ex rating of every fan motor, instrument and electrical device in or near the affected zones, and requires that duct conveying an internally explosive atmosphere be conductive, continuously bonded and earthed. This is the dominant electrical-safety standard for the sector and is treated in detail in section 11.

2.6 AS 3957 — industrial dust hazard areas

AS 3957 addresses combustible-dust deflagration risk in industrial premises and, with AS/NZS 60079.10.2, drives the Zone 20/21/22 classification of pigment, filler and resin-powder handling. For the coatings-plant duct designer AS 3957 forces the question at every dust collection point: what is the explosibility and Kst of the dust, what is its minimum ignition energy, and what is the engineered deflagration-protection chain (venting to NFPA 68, inerting/suppression to NFPA 69, isolation between collector and inbound duct) protecting the system? The answer drives collector selection, isolation-valve placement and the bonding-and-earthing of every metre of dust duct.

2.7 AS 3780 and AS 4326 — corrosive substances

AS 3780 (the storage and handling of corrosive substances) governs the acids and bases used in a coatings, resin and adhesive plant — acetic acid liberated by silicone-sealant cure, the acids in resin esterification and catalysis, ammonia as a waterborne pH adjuster, and any pickling or cleaning acid. It drives the corrosion-resistant duct material selection (316L stainless or chemically inert plastic) for those streams and the segregation and bunding of corrosive storage. AS 4326 covers the storage of oxidising agents where peroxide initiators (for unsaturated polyester and acrylic systems) are held.

2.8 AS/NZS 2243.8 and .9 — laboratory fume cupboards and ventilation

AS/NZS 2243.8 (fume cupboards) sets the face-velocity (nominally 0.5 m/s across the open sash), containment, alarm and exhaust-discharge requirements for the QC and R&D laboratory fume cupboards that every coatings, ink, resin and adhesive manufacturer operates. AS/NZS 2243.9 covers broader laboratory ventilation, recirculation prohibition and make-up air. These are treated in section 13.

2.9 AS 1375 — industrial fuel-fired appliances and furnaces

AS 1375 (the SAA industrial fuel-fired appliances code) provides the furnace and combustion-safety context for the fired heating systems behind resin reactors, thermal oxidisers and regenerative thermal oxidisers (RTOs). It covers purge cycles, flame supervision and burner management on the gas-fired equipment that heats the reactor and destroys VOC in the oxidiser, complemented internationally by NFPA 86 industrial-oven logic.

2.10 AS 4024 machinery safety, AS 1692 tanks, and the supporting standards

AS 4024 (the machinery-safety series) governs guarding and access on the dispersers, mills, mixers and conveying equipment whose hoods the LEV serves, and informs the inspection-access and personnel-entry provisions on the ductwork. AS 1692 (the storage of flammable and combustible liquids in tanks) covers the bulk solvent tank-farm vessels whose vapour spaces and breather vents the tank-farm extract serves. AS/NZS 1715 (selection, use and maintenance of respiratory protective equipment) and AS/NZS 1716 (RPE performance) govern the air-supplied and full-face respirators that back up the engineering controls, particularly for isocyanate and crystalline-silica tasks.

2.11 NCC Section J, ASHRAE 62.1 and the energy/management overlays

NCC Section J (energy efficiency) governs the thermal performance and HVAC energy provisions of the building and drives the heat-recovery, fan-efficiency and economy-cycle decisions on the make-up-air and general-ventilation systems — weighed against the once-through, no-recirculation reality of a solvent-laden plant. ASHRAE 62.1 (ventilation for acceptable indoor air quality) provides the international benchmark for outdoor-air rates in the office and amenities portions of the site. ISO 9001 (quality), ISO 14001 (environmental) and ISO 45001 (occupational health and safety) management systems sit over the whole operation, and the HVAC and dust-collection records feed each of them.

2.12 NFPA 30, NFPA 68, NFPA 69 and NFPA 91 — international cross-references

Where Australian standards are silent on a specific detail, the US National Fire Protection Association documents are the de-facto engineering references used by Australian coatings-industry insurers and engineers. NFPA 30 (Flammable and Combustible Liquids Code) parallels and supplements AS 1940 for tank-farm, drumming and process-liquid handling. NFPA 68 (Standard on Explosion Protection by Deflagration Venting) and NFPA 69 (Standard on Explosion Prevention Systems) govern the deflagration venting, inerting and isolation of combustible-dust collection. NFPA 91 (Standard for Exhaust Systems for Air Conveying of Vapors, Gases, Mists, and Particulate Solids) governs the design of the conveying ductwork itself — transport velocity, material, cleanouts and construction — and is the closest international analogue to the duct-engineering practice this guide describes.

3. Solvent-vapour dilution ventilation and LEL control — the foundation of a solventborne plant

The single largest ventilation load in a solventborne paint, coatings, ink or adhesive plant is dilution ventilation to control flammable-solvent vapour. Across the millbase, let-down, tinting and filling areas, solvent evaporates from open vessels, transfer operations, sample-taking, spillage and the wetted surfaces of equipment. The aggregate evaporative load can run to tens of litres per hour of solvent across a busy production hall, and the ventilation system must dilute that vapour to a concentration that is safe on two counts: below a defined fraction of the lower explosive limit (LEL) for fire and explosion safety, and below the workplace exposure standard (WES) for health.

The solvents in question are well-characterised. Xylene (WES 80 ppm; LEL approximately 1.0 percent by volume) and toluene (WES 50 ppm; LEL approximately 1.1 percent) are the workhorse aromatic solvents. Methyl ethyl ketone (MEK, WES 150 ppm; LEL approximately 1.4 percent) and methyl isobutyl ketone (MIBK, WES 50 ppm) are the ketones; acetone (WES 500 ppm; LEL approximately 2.5 percent) is the most volatile and is also used as an exempt solvent in some low-VOC formulations. Ethyl acetate (WES 200 ppm; LEL approximately 2.0 percent) is the dominant ester. White spirit (mineral turpentine, WES 240 mg/m3) is the classic decorative-paint aliphatic hydrocarbon. Glycol ethers (a family with individual WES values) serve as coalescing and tail solvents in both solventborne and waterborne systems. Each solvent’s flash point sets its AS 1940 class and its autoignition temperature sets the AS/NZS 60079 temperature class — most of these solvents fall into Gas Group IIA, Temperature Class T3, though acetone and ethyl acetate push toward IIB.

The critical engineering insight is that the LEL constraint, not the WES, almost always governs the dilution airflow in a paint plant, and by a wide margin. The LEL of xylene at roughly 1.0 percent by volume is 10,000 ppm; the WES is 80 ppm. The accepted design target is to hold the general workroom below 10 percent of the LEL — for xylene, 1,000 ppm — which is still more than ten times the health WES. This means a workroom diluted to a safe-from-explosion concentration is nowhere near safe to breathe, and the difference is made up by local exhaust ventilation at source (section 4) plus, where residual exposure remains, respiratory protection. Dilution ventilation is a fire-safety control first and a coarse health control a distant second; it is never a substitute for capture at source. Some operators run continuous LEL monitoring on the general extract and on key local-exhaust streams, with the dilution fans and process interlocks driven by the LEL reading so that the system ramps up or trips before vapour approaches a dangerous concentration.

The duct serving the dilution and general-extract system is conductive galvanised sheet to AS 1397, fabricated to AS 4254, with every flanged joint bonded by a conductive gasket and the whole run earthed to under 10 ohms to the building grid — because the extract stream is, by definition, flammable-vapour-laden and the duct interior is a potential explosive atmosphere. The general-extract fan is spark-resistant (AMCA 99 Type B minimum) with an Ex-rated motor matched to the zone it serves. Make-up air is tempered and filtered, delivered low and at low velocity to sweep heavier-than-air solvent vapour toward the floor-level and source extracts, and balanced so the hall sits at slight negative pressure relative to offices and laboratories. The discharge stack is located and sized per AS/NZS 60079 and NFPA 91 to clear the building and any air intake, frequently after a carbon adsorber or thermal oxidiser for VOC and odour abatement.

4. High-speed disperser, let-down and mixing-vessel local exhaust ventilation

The heart of paint and ink manufacture is the dispersion and let-down operation. A high-speed disperser (a Cowles-type sawtooth blade running at high tip speed) shears pigment and filler into a millbase under a partial vacuum or open hatch, and a let-down vessel then dilutes that concentrated millbase with additional resin, solvent and additives to finished viscosity. Both operations flash off solvent at a high local rate — the disperser because of the energy input and large exposed surface, the let-down vessel because of the volume of solvent added and the agitation. Capturing that flash-off at source, before it reaches the operator’s breathing zone or disperses into the general hall, is the job of local exhaust ventilation (LEV), and it is the most cost-effective single intervention in the entire plant because it cuts both the health exposure and the dilution-ventilation burden at once.

The capture strategy depends on the vessel geometry. For an open-top disperser or mixing vessel, a rim-extract ring or a hinged canopy hood pulls vapour off the liquid surface and the charging aperture; for a closed disperser with a charging hatch, the LEV is captured at the hatch and at the millbase transfer points. Capture velocity at the working aperture is the design parameter — for solvent vapour evaporating from a still or gently agitated surface, 0.25 to 0.5 m/s at the face is typical, rising toward 1.0 m/s where the operation is vigorous or the aperture is large and exposed to cross-draughts. The LEV branch is conductive duct sized for a transport velocity that prevents condensation and dropout, ducted back to the general solvent extract main and thence to abatement. Because the captured stream is concentrated solvent vapour, the LEV duct and fan are treated to the full hazardous-area standard: conductive, bonded, earthed, spark-resistant fan, Ex-rated motor.

Cross-draught control is decisive. A disperser hood that captures perfectly in still air loses containment when a roller door opens, a forklift drives past, or a poorly placed make-up-air diffuser blows across the working face. The make-up-air design (section 3) and the LEV design are therefore a single coupled problem — supply air must be delivered so that it does not destroy capture at the hoods, which usually means low-level, low-velocity supply rather than high-level diffusers throwing air across the hall. For let-down vessels handling the volatile end of the solvent range (acetone, MEK, ethyl acetate), the capture velocity and the hazardous-area zoning step up accordingly. The principle throughout is capture-at-source: it is always cheaper, safer and more effective to catch the vapour at the hatch than to dilute it after it has filled the room.

5. Pigment, filler and extender powder dust control

Before the dispersion step comes the powder-handling operation: weighing and charging the pigments, fillers and extenders that give paint its colour, opacity and body. This is a dust problem, and a serious one. The dominant white pigment is titanium dioxide (TiO2), handled in bulk by every decorative-paint maker; its inhalable WES is 10 mg/m3, and while not acutely toxic it is a respiratory irritant and a category of concern at high exposure. The dominant black pigment is carbon black, with an inhalable WES of 3 mg/m3 and a category 2 carcinogen classification that mandates control to as low as reasonably practicable. The bulk extenders — talc, calcium carbonate, kaolin clay, barytes (barium sulfate) and silica flour — are handled in far larger tonnages than the pigments, and the critical hazard among them is respirable crystalline silica (RCS). The Australian WES for RCS was halved to 0.05 mg/m3 (eight-hour TWA) and is now among the most rigorously enforced exposure standards in the country, with mandatory air monitoring and health surveillance for exposed workers. Any extender or filler containing free crystalline silica — and many natural minerals do — forces RCS-grade dust control on the powder-handling operation.

Capture is by local exhaust ventilation engineered at source. A ventilated weigh booth, bag-dump station or bulk-bag (FIBC) discharge station presents a controlled working aperture across which a back-draught or down-draught hood pulls 0.5 to 1.0 m/s capture velocity, drawing the liberated dust away from the operator and into the ductwork. The duct is sized for a transport velocity of 18 to 23 m/s — high enough that pigment and filler particles never settle out in the duct, because settled dust is both a housekeeping and (for combustible dusts) a deflagration hazard. The duct runs to a cartridge filter or baghouse dust collector with a HEPA polishing stage on the clean side to meet emission limits and protect the recirculated or discharged air. Reverse-pulse cleaning keeps the filter media clear; the captured dust is collected for disposal or, where economic and clean, reprocessing.

The duct geometry for dust service is round spiral wherever the layout allows, because the streamlined circular cross-section holds transport velocity through elbows and branches without the flat-panel dropout pockets that rectangular duct creates. Where the dust is combustible — some organic pigments, aluminium-flake and other metallic effect pigments, and resin powders in adjacent powder-coatings operations — the AS 3957 dust-hazard zoning (Zone 20 inside the collector and high-concentration duct, Zone 21/22 around the equipment) and the NFPA 68/69 deflagration-protection chain apply: the duct is bonded and earthed, the collector carries explosion venting or chemical suppression, and an isolation device sits between the collector and the inbound duct to stop a deflagration propagating back. For the inert mineral dusts (TiO2, calcium carbonate, talc, barytes) the deflagration risk is low but the respirable-dust health control is paramount, and the LEV is designed around the RCS and carbon-black limits regardless.

6. Resin reactors and cookers — alkyd, polyester, acrylic and epoxy synthesis venting

Resin manufacture is the most demanding process zone in the coatings supply chain and a discipline distinct from the let-down and tinting that consumes the resin. Allnex (formerly Nuplex Resins) and Huntsman are the major Australian resin manufacturers, and several paint makers run captive resin plants. The chemistry runs hot, exothermic and hazardous, and the venting reflects it.

An alkyd cook is the archetype. Esterification of a polyol, a polyacid (or anhydride) and a fatty acid or oil proceeds at 220 to 260 degC under a nitrogen blanket that keeps the reactor headspace below the LEL and excludes oxygen that would discolour and gel the product. The reaction liberates water, which must be removed to drive the esterification to completion; the classic technique is the azeotrope or solvent process, in which a small charge of xylene refluxes and carries the water of reaction overhead. The reactor vent therefore carries hot xylene vapour, water vapour, entrained monomer and a cocktail of thermal partial-oxidation products including acrolein (a severe respiratory irritant and lachrymator), other aldehydes and low-molecular-weight organics that give resin plants their characteristic odour. The vent runs first through a primary condenser — a water-cooled or glycol-cooled heat exchanger — that recovers the xylene and water; the xylene is decanted from the water in a separator and returned to the reactor, and the water of reaction is sent to treatment. The non-condensable vapour and odour stream that escapes the condenser goes to a thermal oxidiser (TO) or regenerative thermal oxidiser (RTO) that destroys the residual VOC and odour at 760 to 850 degC, frequently the difference between a compliant site and an EPA odour complaint.

The duct engineering follows the temperature and chemistry. The reactor-to-condenser vent line is high-temperature stainless — 304 or 316 at the lower end, 309/310S where temperatures climb — because the vapour is hot and the organic-acid and water content is corrosive. The condenser-to-oxidiser line is stainless because the stream is still solvent-laden and acidic, though cooler. The oxidiser inlet, combustion chamber and the first section of its outlet sit under NFPA 86 industrial-oven and AS 1375 furnace logic, with purge cycles, flame supervision, burner management and explosion relief on the fired equipment. Bellows expansion joints absorb the thermal growth of the hot vent runs — a 30 m stainless run at 250 degC grows roughly 75 mm from ambient, and high-temperature riser sections grow proportionally more, so engineered expansion-joint sizing is critical. The reactor itself, being nitrogen-inerted, carries an asphyxiation consideration at any point where the nitrogen-rich vent could discharge into an occupied space, and the reactor hall is a hazardous area under AS/NZS 60079 with spark-resistant fans and Ex-rated electricals throughout.

Polyester and acrylic resin synthesis follow similar high-temperature, inerted, condenser-and-oxidiser logic. Unsaturated polyester adds styrene as a reactive diluent (styrene WES 50 ppm, a strong-odour irritant) and peroxide initiators (stored to AS 4326 oxidiser logic). Epoxy resin manufacture adds epichlorohydrin (a carcinogen and severe irritant) and bisphenol-A handling, each requiring dedicated capture beyond the general reactor vent. Across all of them the common thread is a hot, corrosive, solvent-and-odour-laden vent that must be condensed, recovered and then thermally or catalytically abated, conveyed in high-temperature corrosion-resistant duct with engineered expansion and full hazardous-area compliance.

7. Isocyanate and two-pack polyurethane — the dedicated extract that saves lives

If there is a single ventilation system in a coatings, adhesive or sealant plant that must never fail, it is the isocyanate extract. Two-pack (2K) polyurethane coatings, polyurethane adhesives and PU sealants are formulated and manufactured by reacting a polyol with an isocyanate hardener, and the isocyanate monomers — MDI (methylene diphenyl diisocyanate), TDI (toluene diisocyanate), and the aliphatic HDI and IPDI in light-stable systems — are the most dangerous routine chemical exposure in the entire sector. Isocyanates are potent respiratory sensitisers. Once a worker becomes sensitised, any subsequent exposure, even at concentrations far below the exposure standard, can trigger an asthmatic response, and for a sensitised individual there is effectively no safe re-exposure level. They are the leading cause of occupational asthma in coatings manufacture.

The numbers explain the engineering. The SafeWork Australia workplace exposure standard for TDI and MDI is 0.02 mg/m3 as an eight-hour time-weighted average and 0.005 ppm as a short-term limit — roughly 50 micrograms per cubic metre, two orders of magnitude below the common solvents handled a few metres away. No general dilution system can reliably hold an exposure at that level near an active source; only capture-at-source with full enclosure can. Accordingly, isocyanate handling gets a dedicated, segregated extract that is never combined with the general solvent dilution system, for two reasons: the isocyanate stream must be held under tight negative pressure and discharged through its own treated stack, and combining it would contaminate the general system and complicate abatement. The isocyanate charging vessel, reaction vessel and transfer points are fully enclosed; local exhaust captures at every hatch and transfer point at a face velocity of 0.5 to 1.0 m/s; the duct is 316L stainless or chemically inert polypropylene held under negative pressure relative to the workroom; and the extract discharges through a dedicated stack, commonly via a chemical scrubber or activated-carbon adsorber, well clear of any air intake.

The system is interlocked as a life-safety control. Loss of extract airflow trips the isocyanate charging and reaction sequence; the extract fan is on essential power; airflow and pressure are continuously monitored and alarmed. Continuous or frequent breathing-zone air monitoring verifies that the engineering controls are holding, and respiratory protection to AS/NZS 1715/1716 — air-supplied or, at minimum, full-face with an appropriate isocyanate-rated cartridge — is mandatory for any task with potential for exposure, explicitly as the last line of defence behind the enclosure and extract, never the first. Australian operators handling 2K PU at manufacturing scale — Sika Australia and Bostik in construction adhesives and sealants, Parchem in construction chemicals, and the industrial- and protective-coatings lines at PPG, DuluxGroup, Akzo Nobel and Jotun — treat the isocyanate extract with the same rigour as a gas-detection or fire-suppression system. Isocyanate is also progressively being engineered out of new formulations, but the installed base and the high-performance applications mean it remains a defining hazard, and the dedicated extract is non-negotiable.

8. Adhesive and sealant manufacturing — silicone acetic acid, PU, acrylic and hot-melt

Adhesive and sealant manufacture — the domain of Selleys (DuluxGroup), Bostik, Sika and Parchem in Australia — spans several chemistries, each with its own ventilation signature. The common solventborne contact adhesives and the solvent-cement products carry the same flammable-solvent dilution and capture demands as a solventborne paint line (toluene, MEK, acetone, ethyl acetate), handled under AS 1940 with conductive bonded duct and spark-resistant fans. But three chemistries add distinctive hazards.

Silicone sealant is the standout. The most common one-part silicone sealants are acetoxy-cure systems that release acetic acid as the cure by-product — the sharp vinegar smell of fresh silicone. During manufacture, mixing and filling of acetoxy silicone, acetic acid vapour is liberated (WES 10 ppm; corrosive and a strong irritant to eyes and airways), and the capture duct and fan for this stream must be corrosion-resistant: 316L stainless or an inert plastic such as polypropylene or PVC, never plain galvanised, because acetic acid attacks zinc and carbon steel rapidly. The LEV captures at the mixing and filling heads, and the extract is treated (scrubbed) before discharge. Neutral-cure (alkoxy and oxime) silicones release methanol or oxime by-products instead and shift the capture chemistry accordingly.

Polyurethane adhesives and sealants carry the isocyanate hazard of section 7 and get the same dedicated, enclosed, interlocked extract. Acrylic and water-based sealants are lower-hazard on the flammability front but still off-gas ammonia (a common pH adjuster and preservative aid, WES 25 ppm, corrosive and irritant) and residual monomer, needing capture and a corrosion-resistant duct. Hot-melt adhesives (EVA, polyolefin and reactive PUR hot-melts) are applied molten at 120 to 180 degC and off-gas thermal-decomposition fumes and, for reactive PUR hot-melts, trace isocyanate; the manufacturing and compounding of hot-melts needs thermal-fume capture over the melt and compounding vessels. Across the adhesives and sealants building, the ventilation engineer must map each line to its chemistry, segregate the isocyanate streams, specify corrosion-resistant duct for the acetic-acid and ammonia streams, and apply the flammable-vapour controls to the solvent-based lines.

9. Printing ink manufacturing — solvent, water-based and UV-cure ozone

Printing-ink manufacture — Siegwerk, Flint Group and Sun Chemical Australia are the major players — mirrors paint manufacture in its dispersion-and-let-down structure but splits into three technology streams with distinct ventilation profiles. Solvent-based inks (for flexographic and gravure printing) use volatile solvents — ethyl acetate, ethanol, MEK, toluene and aliphatic hydrocarbons — at high loadings, so a solvent-ink plant carries the full AS 1940 flammable-vapour regime: dilution ventilation for LEL control, capture-at-source at the dispersers and let-down vessels, conductive bonded duct, spark-resistant fans, AS/NZS 60079 zoning and frequently solvent recovery (the volatile esters and alcohols are economically worth recovering by carbon adsorption or condensation). Water-based inks reduce the flammable-vapour load but still carry coalescing solvents, glycol ethers and ammonia (pH adjuster, WES 25 ppm), needing capture and corrosion-resistant duct on the ammonia stream.

The distinctive ink stream is UV-curable ink. UV inks contain acrylate and methacrylate monomers and oligomers and photoinitiators, and they cure under intense ultraviolet light rather than by solvent evaporation. The manufacturing hazards are the acrylate monomers themselves (skin sensitisers and irritants requiring capture and skin protection) and, where the inks are test-cured or where UV lamps are used in process, ozone. UV lamps in the relevant wavelength range generate ozone from atmospheric oxygen, and ozone is acutely toxic (WES 0.1 ppm, a powerful oxidant and respiratory irritant). Any UV-curing or UV-testing station needs dedicated ozone extract captured at the lamp housing, ducted in ozone-resistant material (316L stainless or appropriate plastic, because ozone degrades many elastomers and some plastics) and either vented high and clear or passed through an ozone-destruct catalyst. Some UV systems are now LED-based at wavelengths that generate little or no ozone, but mercury-lamp UV remains common and the ozone extract is essential where it is used. As with paint, the ink-plant pigment and dust handling (section 5) is identical regardless of the carrier technology, and the carbon-black and crystalline-silica controls apply to ink manufacture exactly as they do to paint.

10. Waterborne versus solventborne lines — how the carrier reshapes the HVAC envelope

The defining trend of the last two decades in Australian coatings is the migration from solventborne to waterborne technology, driven by VOC-emission regulation, the National Pollutant Inventory reporting regime, Green Building Council Green Star and product-stewardship pressure, and consumer demand for low-odour, low-VOC product. DuluxGroup, Resene, Taubmans, Haymes and Akzo Nobel all market extensive low-VOC and water-based decorative ranges, and the architectural market is now predominantly waterborne. This shift dramatically reshapes — but does not eliminate — the manufacturing HVAC demand, and a plant running both carriers (the common Australian reality) must design each hall to its own envelope.

A fully waterborne let-down and tinting line carries far less flammable-vapour hazard. The hazardous-area classification shrinks — the general process hall may fall out of Zone 2 entirely, the dilution-ventilation rate set by LEL control drops sharply, and fans in the let-down area may no longer require spark-resistant construction. This is a real capital and energy saving and a genuine safety improvement. But three ventilation demands persist regardless of the carrier. First, even waterborne paint contains coalescing solvents and glycol ethers as film-formation aids — white spirit (WES 240 mg/m3) and various glycol ethers off-gas VOC that still requires capture and still carries a health limit, so local exhaust at the disperser and let-down vessel remains necessary even when the headline product is water-based. Second, pigment and filler dust handling (section 5) is completely independent of the carrier — the same titanium dioxide, carbon black, talc and crystalline-silica-bearing extenders are weighed and charged whether the paint is solvent- or water-based, so the powder LEV and dust collection are unchanged. Third, waterborne systems add their own contaminants: ammonia as a pH adjuster (WES 25 ppm, corrosive), biocides and preservatives, and residual monomer from the acrylic and vinyl-acrylic emulsion polymers, each needing capture and, for the ammonia stream, corrosion-resistant duct.

The practical design consequence is segregation. On a dual-carrier site, the solventborne hall is built to the full AS 1940 / AS/NZS 60079 envelope — conductive bonded duct, spark-resistant Ex-rated fans, dilution ventilation for LEL control, hazardous-area zoning — while the waterborne hall is built to a reduced envelope reflecting its lower flammable-vapour load. Critically, the two halls must be ventilated and pressurised so that solvent vapour from the solventborne hall can never migrate into the waterborne hall in a way that would invalidate the reduced controls there. As the industry continues to reformulate toward lower VOC, including high-solids solventborne and powder technologies as well as waterborne, the HVAC engineer’s task is increasingly to right-size each hall to its actual chemistry rather than apply a blanket worst-case envelope to the whole site — which is exactly the kind of process-specific judgement that distinguishes a coatings-experienced fabricator from a generalist.

11. Hazardous-area classification of duct and fans — AS/NZS 60079 Zone 0/1/2 gas and Zone 20/21/22 dust

Hazardous-area classification is the discipline that ties the whole coatings-plant HVAC design together, and it is worth setting out the zones explicitly because they dictate duct material, fan construction, bonding and instrument selection across the entire facility. AS/NZS 60079.10.1 classifies gas and vapour atmospheres; AS/NZS 60079.10.2 classifies combustible-dust atmospheres.

On the gas and vapour side, the zones are defined by the probability and persistence of an explosive atmosphere:

• Zone 0: An explosive gas atmosphere is present continuously or for long periods. The vapour space inside a solvent storage tank, inside a closed solvent-containing process vessel, and inside the solvent-laden extract duct itself in the limit.
• Zone 1: An explosive gas atmosphere is likely to occur in normal operation. The immediate envelope around an open disperser charging hatch, a let-down vessel manway during charging, a solvent decanting nozzle, a drum-filling head, and a sample-taking point.
• Zone 2: An explosive gas atmosphere is not likely in normal operation and, if it occurs, will persist only briefly. The general solventborne process hall, the area around pump seals and flanged joints, and the periphery of the Zone 1 envelopes.

On the combustible-dust side (where the pigment, filler or resin dust is combustible), the parallel zones under AS/NZS 60079.10.2 and AS 3957 are:

• Zone 20: A combustible-dust cloud is present continuously or for long periods. The interior of a dust collector, the interior of a high-concentration dust duct, the interior of a closed powder hopper.
• Zone 21: A combustible-dust cloud is likely in normal operation. The immediate area around a bag-dump or FIBC-discharge aperture, around an open weigh-booth charging point.
• Zone 22: A combustible-dust cloud is not likely in normal operation and, if it occurs, persists briefly. The general powder-handling room around the equipment.

The extent of each gas zone is determined by the AS/NZS 60079.10.1 source-of-release method — the release rate, the solvent volatility, the ventilation effectiveness and the gas density together fix how far the zone extends from each source. Effective ventilation (good dilution plus capture-at-source) shrinks the zones; poor ventilation expands them. This is the formal link between the ventilation design and the electrical-area classification: better HVAC literally reduces the extent and severity of the hazardous areas, which in turn reduces the cost and complexity of the Ex-rated electrical installation.

For the ductwork and fans the consequences are concrete. Any duct conveying a flammable-vapour or combustible-dust stream is treated as containing an explosive atmosphere internally, regardless of where it runs, so it is built conductive (galvanised or 316L stainless), continuously bonded across every flanged joint with a conductive gasket or external bonding strap, and earthed to the building grid — under 10 ohms to earth for vapour duct, with tighter limits and verification on combustible-dust mains. Any fan handling that stream is spark-resistant to AMCA 99 (Type B minimum, Type A where the zone and gas group demand), with the impeller, casing and inlet cone in non-sparking material combinations, and the motor Ex-rated to the zone: Ex d (flameproof) or Ex de for Zone 1, Ex e (increased safety) or Ex nA for Zone 2, Ex t for dust zones, each selected to the gas group (IIA for most hydrocarbon solvents, IIB for acetone/ethyl-acetate-dominant atmospheres) and temperature class (T3 typical for paint solvents, T4 where lower-autoignition materials are present). Every duct-mounted instrument — LEL sensor, damper actuator, flow switch, pressure transmitter — is Ex-rated to AS/NZS 60079.0 and wired per AS/NZS 60079.14 and AS/NZS 3000. A documented hazardous-area dossier, with a verification dossier per AS/NZS 60079.17, accompanies the installation.

12. Bulk solvent tank farm, drum store and decanting/drumming bay

The solvent supply infrastructure — the bulk tank farm, the drum store and the decanting and drumming bay — is where the largest single inventory of flammable liquid sits and where AS 1940 (with AS 1692 for the tanks and the ADG Code for delivery) governs most tightly. Each part carries a distinct vapour-management and ventilation requirement.

The bulk tank farm holds the high-volume solvents — xylene, toluene, white spirit, MEK, ethyl acetate — in fixed tanks built and located to AS 1692, within bunds sized to contain the largest tank plus rainfall allowance per AS 1940. The tank vapour spaces are Zone 0; the tank breather vents, through which vapour is displaced on filling and drawn in on emptying, discharge to atmosphere through flame arresters at a safe height and location, or to a vapour-recovery or vapour-balancing system on the larger installations. The area around the breather vents and fill points is Zone 1, stepping out to Zone 2. Tanker offloading at the fill point is a Zone 1 operation with bonding of the tanker to the installation before the hose is connected (to dissipate the static charge that solvent flow generates) and an interlocked overfill-protection system.

The drum and IBC store holds packaged solvent and is ventilated to prevent vapour accumulation in the event of a leak or spill — natural or mechanical ventilation sized so that the store cannot build a flammable atmosphere, with the store classified Zone 2 and bunded for spill containment. The decanting and drumming bay is the highest-activity vapour source: here bulk solvent is metered into drums, pails and process totes, and finished solventborne product is filled into retail and trade containers. Every filling head is a vapour-release point — Zone 1 at the nozzle — and the bay carries dedicated capture-at-source LEV at the filling heads plus general dilution ventilation, with the whole bay classified and ventilated to hold the general space below 10 percent LEL. Drum and container filling generates static, so bonding and earthing of the container to the fill head before flow begins is mandatory, and the fill nozzles, level sensors and pumps are Ex-rated. The captured vapour goes to recovery or abatement; the dilution discharge clears the building per NFPA 91 and AS/NZS 60079.

The duct serving the tank-farm breather collection, the drum-store ventilation and the drumming-bay capture is conductive, bonded and earthed throughout, fabricated in galvanised sheet for the hydrocarbon-solvent streams and 316L stainless where the stream is corrosive or where the solvent attacks zinc. Heavier-gauge trunk duct on these high-volume extract systems is well suited to the SBAL-III heavy-gauge line (section 14). Every fan is spark-resistant with an Ex-rated motor matched to the zone it draws from.

13. Deflagration and explosion protection — NFPA 68 venting, NFPA 69 inerting, isolation

Wherever a combustible dust or a flammable-vapour atmosphere can form inside the HVAC system — primarily the pigment, filler and resin-powder dust collection, and any solvent-vapour stream that could reach the explosive range — the system must be protected against deflagration, the rapid subsonic combustion that generates a damaging pressure wave. The Australian framework (AS 3957, AS/NZS 60079) sets the requirement; the detailed engineering practice follows NFPA 68 (deflagration venting) and NFPA 69 (explosion prevention systems), which Australian coatings-industry engineers and insurers use as the working references.

Three protection strategies, used alone or in combination, apply. Deflagration venting (NFPA 68) provides a deliberately weak relief path — a vent panel or door on the dust collector or vessel that opens at low overpressure and discharges the deflagration to a safe location, limiting the peak pressure to below the equipment’s strength. The vent area is sized from the dust’s deflagration index Kst and maximum pressure Pmax, the vessel volume and strength. Explosion prevention by inerting or suppression (NFPA 69) either keeps the oxygen concentration below the limiting oxygen concentration (inerting with nitrogen, used on some powder-handling systems) or detects an incipient explosion and injects a suppressant within milliseconds to quench it before it develops (chemical suppression, used where venting to a safe location is impractical). Explosion isolation prevents a deflagration in one part of the system (typically the dust collector) from propagating through the connecting duct into other equipment or back into the building — achieved with fast-acting isolation valves, chemical-suppression isolation barriers, flap (backdraught) valves, or rotary valves, selected by duct size and dust Kst.

The standard topology for a combustible-pigment or resin-powder dust collector in a coatings plant is therefore: a dust collector fitted with NFPA 68 explosion vents (or NFPA 69 suppression where vent location is constrained), an explosion-isolation device on the dirty-air inlet duct between the collector and the upstream process, and a bonded-and-earthed conductive duct system throughout so that no electrostatic ignition source can develop. The isolation device is interlocked to the explosion-detection system so that on detection of a pressure rise or flame in the collector it acts to seal the duct and prevent flame travel. For the inert mineral dusts (TiO2, calcium carbonate, talc, barytes) that dominate paint manufacture the deflagration risk is low and the protection is correspondingly lighter, but the dust-hazard analysis under AS 3957 / NFPA 660 logic must still be performed and documented to confirm it, and any combustible dust in the mix (organic pigments, metallic effect pigments, resin powders) forces the full protection chain. The duct fabricator’s contribution is the conductive, hermetically welded, fully bonded spiral main that gives the isolation and suppression systems an envelope they can rely on — a leaking or poorly bonded duct undermines the entire protection scheme.

14. QC laboratory and R&D fume cupboards — AS/NZS 2243.8 and .9

Every paint, coating, ink, resin, adhesive and sealant manufacturer runs a quality-control and R&D laboratory in which solvents, monomers, isocyanate curing agents, pigments and finished products are handled in small quantities for batch release testing, formulation development and instrumental analysis. The laboratory ventilation is governed by AS/NZS 2243.8 (fume cupboards) and AS/NZS 2243.9 (laboratory ventilation and the broader safety-in-laboratories series), and it is a distinct system from the production-hall ventilation.

The fume cupboard is the primary control. AS/NZS 2243.8 sets a face velocity nominally at 0.5 m/s measured across the open sash (within a defined tolerance band, neither so low that containment fails nor so high that turbulence pulls contaminant back out), a containment-tested envelope, sash-position and low-airflow alarms, and an exhaust that discharges through a stack sized and located per the standard to clear the building roofline and any air intake. The fume-cupboard exhaust duct is selected for the dominant chemistry — 316L stainless or a chemically resistant plastic (polypropylene or uPVC) where acids, isocyanate or aggressive solvents are routinely handled — and the exhaust fan is spark-resistant where flammable solvents are a regular part of the lab work, which in a coatings lab they invariably are. Critically, laboratory exhaust is once-through and never recirculated; the make-up air is tempered and controlled, and the system holds each cupboard’s face velocity steady regardless of how many cupboards are open, typically through variable-air-volume control with a fast face-velocity controller on each cupboard so that closing one sash does not over-speed the others.

Beyond the cupboards, the laboratory runs general dilution ventilation for fugitive vapour and is held at slight negative pressure relative to adjoining corridors and offices so that solvent vapour and odour cannot migrate to occupied non-laboratory areas. Where the lab handles isocyanate hardeners for 2K formulation work, the same dedicated-extract and monitoring philosophy of section 7 applies at lab scale. Where it handles open solvents for viscosity, solids and colour testing, the work is done in the cupboards under the 0.5 m/s capture. The duct fabrication for the laboratory — stainless or galvanised cupboard exhaust risers, conductive and bonded where solvent-laden — sits comfortably within the SBKJ machine envelope, with the SBSF-1525 stitch welder producing the hermetic stainless risers for acidic and isocyanate-bearing lab exhaust.

15. Worked WES and LEL dilution calculation — sizing the ventilation

It is worth setting out the dilution arithmetic explicitly, because it shows why the LEL constraint dominates and how the airflow is sized. The principle, drawn from AS 1668.2 and standard industrial-ventilation practice, is a steady-state mass balance: the dilution airflow required to hold a contaminant at a target concentration equals the contaminant generation rate divided by the target concentration (with a mixing-efficiency safety factor applied because real rooms do not mix perfectly).

Take a worked example. Suppose a let-down area evaporates xylene at a generation rate of 2 litres per hour (a moderate figure for an active vessel). Xylene has a density of about 0.86 kg/L and a molar mass of 106 g/mol, so 2 L/hr is roughly 1.72 kg/hr, or about 16.2 mol/hr, which at 24.5 L/mol (25 degC) is about 0.397 m3/hr of xylene vapour, equivalent to roughly 6.6 litres per minute of pure vapour entering the room air.

To hold the room at the health WES of 80 ppm (80 parts per million by volume, i.e. a vapour-to-air ratio of 0.00008), the dilution airflow is the vapour rate divided by the target fraction: 6.6 L/min divided by 0.00008 equals roughly 82,500 L/min, or about 1,375 litres per second, or close to 5,000 m3/hr — before any mixing-efficiency factor. Apply a typical mixing factor of 3 to 5 for an imperfectly mixed industrial space and the WES-based requirement rises to the order of 15,000 to 25,000 m3/hr for that single source.

Now compare the LEL constraint. The LEL of xylene is about 1.0 percent by volume (10,000 ppm); the design target is 10 percent of LEL, i.e. 1,000 ppm (a vapour-to-air ratio of 0.001). The dilution airflow to hold 1,000 ppm is 6.6 L/min divided by 0.001 equals 6,600 L/min, about 110 L/s, or under 400 m3/hr before the mixing factor — roughly one-twelfth of the WES-based figure. This is the crucial result and it appears counter-intuitive at first: the airflow to keep the room safe from explosion (below 10 percent LEL) is far smaller than the airflow to keep the room safe to breathe (below the WES), because the flammability limit sits at a far higher concentration than the health limit. It confirms the principle of section 3 — dilution ventilation sized for LEL control is a fire-safety measure that does not come close to achieving the health WES, and the health protection must come from capture-at-source LEV plus, where residual exposure remains, respiratory protection. In practice the engineer sizes the general dilution system for LEL control (often with continuous LEL monitoring), sizes the local exhaust to capture the bulk of the vapour at source so the room generation rate is a fraction of the open-evaporation figure, and verifies the residual breathing-zone concentration against the WES by air monitoring. The same arithmetic, run for each solvent at its own WES and LEL, drives the whole-of-plant ventilation balance.

16. The SBKJ machine line for coatings, ink, resin and adhesive plant duct fabrication

Fabricating the ductwork described in this guide — conductive galvanised dilution and LEV duct, 316L stainless corrosion-resistant and isocyanate extract, high-temperature reactor and oxidiser vents, hermetically welded combustible-dust spiral mains — demands a machine line that spans light galvanised through heavy stainless and from rectangular TDF duct to large round spiral. The SBKJ Product Catalog 2026 lines give an Australian fabricator that envelope from Box Hill North VIC.

The SBAL-V auto duct line is the core machine: it takes galvanised coil from 0.5 to 1.2 mm, levels, notches, forms the integral TDF transverse flange and rollforms the body in a continuous automated line at up to 10 m/min on lighter gauges, producing the conductive galvanised rectangular duct that makes up the bulk of a coatings plant’s dilution ventilation and general solvent extract. Its 304/316 stainless option produces the corrosion-resistant duct for acetic-acid silicone-cure exhaust, acidic resin vapour and isocyanate extract. The SBAL-III heavy-gauge auto duct line handles the thicker 1.0 to 2.0 mm galvanised and stainless gauges that the high-temperature reactor and oxidiser mains, the tank-farm and drumming-bay extract trunks, and the large general-extract systems demand.

The SBFB-1500 spiral tubeformer produces round spiral duct from roughly 80 to 1500 mm diameter in galvanised, aluminised or stainless coil at 0.6 to 1.5 mm — the correct geometry for pigment and filler dust mains, holding 18 to 23 m/s transport velocity through bends without dropout pockets. The SBTF-1500/1602/2020 spiral family extends the same geometry to 2000 mm for trunk dust and large-volume mains. The SB-ZF1500 longitudinal stitch welder runs in-line with the spiral former to deposit a continuous TIG bead along the spiral seam, giving the hermetic, bonded, conductive combustible-dust main that AS 3957 and NFPA 68/69 service requires. The SBSF-1525 longitudinal stitch welder produces continuously TIG-welded hermetic seams on rectangular and round sections for solvent-laden, acidic, isocyanate-bearing and fire-rated duct to AS 1530.4. The SBLR-600 lock former forms the Pittsburgh and snap-lock longitudinal seams for standard rectangular sections. The SBPC1500 plasma cutter cuts the custom transitions, tapered cones, mitred elbows and bellows-flange plates in 316L and high-temperature 309/310S stainless up to 25 mm thickness for the reactor, oxidiser and scrubber connections.

The decisive point for a coatings-plant fabricator is that this is one integrated, locally supported machine line covering every duct type the sector needs — galvanised and stainless, rectangular and spiral, lock-seamed and continuously welded, light and heavy gauge. A fabricator equipped with the SBAL-V, SBAL-III, SBFB-1500, SBSF-1525, SB-ZF1500, SBLR-600 and SBPC1500 can quote and deliver the full duct scope for a DuluxGroup, PPG, Haymes, Sika or Allnex project without subcontracting the difficult stainless and spiral work, which is exactly where the margin and the repeat business sit.

17. Commissioning, measurement and verification (M&V)

A coatings-plant ventilation system is only as good as its commissioning, and the commissioning of a flammable-vapour and combustible-dust system is a regulated, documented exercise, not a quick balance check. Commissioning proceeds in a defined sequence and produces a dossier that the operator integrates into its AS 1940, AS/NZS 60079, ISO 14001 and ISO 45001 records.

The fabrication-side verification comes first: every duct length is delivered with its mill certificate, gauge, flange specification and a pressure-test record at 1.5 times design pressure held for 30 minutes, and every flanged joint and every isolation valve in a hazardous-area circuit is earth-bonding-verified with a hand-held resistance meter (under 10 ohms to earth for vapour duct, with tighter limits and full documentation on combustible-dust mains), with every flexible connection conductivity-tested. The airflow commissioning follows: each LEV hood is verified at its design capture velocity (0.25 to 1.0 m/s at the working aperture depending on the source) with a calibrated anemometer; each fume cupboard is verified at 0.5 m/s face velocity across the sash per AS/NZS 2243.8; the general dilution airflow is measured and confirmed against the LEL-control design; and the make-up-air balance is set so the process halls sit at the intended slight negative pressure relative to offices and laboratories. The hazardous-area verification confirms that every fan, motor and instrument matches its zone, gas group and temperature class, with the AS/NZS 60079.17 inspection dossier completed. The deflagration-protection verification confirms vent areas, suppression-system arming and isolation-valve interlock function on the dust collectors.

The measurement-and-verification phase closes the loop on health and emissions: breathing-zone air sampling at the disperser, let-down, drumming, isocyanate and powder-handling stations confirms residual exposures against the WES (xylene 80 ppm, toluene 50, MEK 150, MIBK 50, acetone 500, ethyl acetate 200, white spirit 240 mg/m3, isocyanate 0.02 mg/m3, RCS 0.05, carbon black 3, acetic acid 10 ppm, ammonia 25, ozone 0.1), and stack monitoring confirms VOC, particulate and (where relevant) abatement-efficiency emission limits against the EPA licence. A NATA-accredited laboratory certifies the air-sampling and balance results. The final commissioning report ties every duct branch back to its AS/NZS 60079 zone, its AS 3957 dust-hazard rating, its AS 1940 liquid class and its WES dilution basis — the audit-ready package that an Australian coatings, ink, resin or adhesive manufacturer needs to demonstrate compliance to SafeWork Australia, the state EPA and its own management system.

18. Energy, solvent recovery, thermal oxidiser economics and the low-VOC trend

The ventilation system of a solventborne coatings plant is an energy sink — large volumes of tempered make-up air are extracted once-through and discharged, and the abatement equipment (thermal oxidisers, carbon adsorbers) consumes fuel and power. NCC Section J energy provisions, rising energy costs, and corporate net-zero commitments push operators to recover as much of that energy and solvent as economically possible, and the HVAC engineer is central to the trade-offs.

Solvent recovery is the first lever. The high-value, low-water-solubility solvents in solventborne paint and ink — ethyl acetate, MEK, toluene, the alcohols — are economically worth recovering from the extract stream by carbon adsorption (with steam or nitrogen regeneration and condensation) or by direct condensation on the more concentrated streams. Recovered solvent is purified and returned to process, offsetting raw-material cost and reducing the VOC load on the atmosphere. The resin-plant condenser that recovers azeotrope xylene (section 6) is a solvent-recovery system in its own right. Recovery is most attractive where the extract stream is concentrated (capture-at-source LEV produces a richer, smaller stream than dilution ventilation, which is another argument for good capture) and where the solvent value is high.

Thermal oxidation is the destruction lever where recovery is uneconomic or where odour and trace-VOC abatement is the driver. A straight thermal oxidiser burns the VOC at 760 to 850 degC; a regenerative thermal oxidiser (RTO) recovers most of the combustion heat through ceramic media, achieving thermal efficiencies above 95 percent and slashing the natural-gas burden; a catalytic oxidiser operates at lower temperature (300 to 450 degC) over a catalyst, saving fuel where the stream is catalyst-compatible. The choice is an energy-and-capital optimisation against the VOC concentration, the airflow and the abatement-efficiency target set by the EPA licence. Heat recovered from the oxidiser can preheat make-up air or process feed, closing part of the energy loop. The duct between the process and the abatement plant, and between the abatement plant and the stack, is part of this energy system — insulated where heat is to be conserved, stainless where the stream is hot and corrosive.

The low-VOC reformulation trend (section 10) is the structural backdrop to all of this: as the industry moves to waterborne, high-solids and powder technologies, the absolute solvent load falls, the recovery and abatement duty shrinks, and the energy and emissions profile of the plant improves. But the transition is gradual and incomplete — high-performance industrial, protective, marine and automotive-refinish coatings remain substantially solventborne, and the resin synthesis that underpins even waterborne paint still runs solvent-assisted high-temperature chemistry. The HVAC engineer’s job through the transition is to right-size each system to its actual current load while leaving headroom and flexibility for reformulation, rather than locking in a worst-case solventborne envelope that the plant will grow out of.

19. Australian industry bodies, accreditation and the broader compliance context

The Australian coatings sector operates within a framework of industry bodies and accreditation schemes that intersect with the HVAC and emissions story. The Australian Paint Approval Scheme (APAS), administered by CSIRO, is the dominant product-specification and approval scheme for paints and coatings used by government and major specifiers in Australia — APAS specifications define performance requirements, and the manufacturing facilities producing APAS-approved product operate under documented quality systems that encompass the manufacturing environment. The Australasian Corrosion Association (ACA) is the peak body for corrosion-protection knowledge and certification, central to the protective and marine coatings segment (Jotun, International Paint, Akzo Nobel protective, PPG protective and marine), where the coatings are engineered to protect steel infrastructure and the manufacturing quality is paramount. The Surface Coatings Association Australia and the broader chemicals-industry bodies provide technical and regulatory coordination.

On the regulatory side, the National Pollutant Inventory (NPI) requires reporting of VOC and other emissions above threshold quantities, directly tied to the abatement-efficiency performance of the ventilation and oxidiser systems. State EPA licensing (EPA Victoria, NSW EPA, Queensland DES, WA DWER, SA EPA) sets site-specific emission limits, monitoring obligations and odour requirements that the HVAC and abatement design must meet. SafeWork Australia and the state work-health-and-safety regulators enforce the WES and the hazardous-area, dust and flammable-liquid obligations described throughout this guide. The Australian Industrial Chemicals Introduction Scheme (AICIS) regulates the introduction of industrial chemicals, and GHS classification and labelling under the WHS regulations governs how the hazards are communicated. For the HVAC fabricator, the practical upshot is that the ductwork is one documented link in a long compliance chain — from raw-material introduction through manufacturing emissions to product approval — and the fabrication, commissioning and verification records must be robust enough to stand up within that chain.

20. Competitive positioning — why coatings-plant duct is a specialist fabrication market

The coatings, ink, resin, adhesive and sealant manufacturing sector is a specialist HVAC fabrication market, and that specialisation is the opportunity. A generic commercial sheet-metal fabricator can produce galvanised office-building ductwork all day, but a coatings plant demands conductive bonded duct to a hazardous-area dossier, 316L stainless for corrosive and isocyanate streams, hermetically welded combustible-dust spiral mains with deflagration isolation, and high-temperature stainless for reactor and oxidiser vents — each with fabrication, material-traceability and commissioning documentation that feeds an AS 1940, AS/NZS 60079, APAS and EPA compliance chain. A fabricator that cannot weld stainless spiral, cannot produce a bonding-verification dossier, or does not understand why the isocyanate extract must be segregated will lose the job or, worse, deliver non-compliant work.

This is precisely where an Australian fabricator equipped with the full SBKJ machine line holds the advantage. The combination of the SBAL-V and SBAL-III auto duct lines (galvanised and stainless, light through heavy gauge), the SBFB-1500 and SBTF spiral formers (round dust mains to 2000 mm), the SB-ZF1500 and SBSF-1525 stitch welders (hermetic conductive welded seams), the SBLR-600 lock former and the SBPC1500 plasma cutter (custom high-temperature transitions) lets a single fabricator self-perform the entire duct scope for a coatings, ink, resin or adhesive project — the easy galvanised dilution duct and the difficult stainless, spiral and welded work alike. Subcontracting the difficult work erodes margin and control; bringing it in-house captures both. For an Australian fabricator or mechanical contractor serving DuluxGroup at Clayton and Rocklea, PPG at Clayton, Haymes at Ballarat, Sika and Bostik in construction chemicals, Allnex and Huntsman in resins, or the Siegwerk, Flint Group and Sun Chemical ink plants, the SBKJ line is the production base that turns a specialist, documentation-heavy, hazardous-area market from a risk into a defensible niche.

21. Standards and exposure reference table

The table below consolidates the standards, codes and workplace exposure standards referenced throughout this guide for paint, coatings, ink, resin, adhesive and sealant manufacturing HVAC.

21.1 Standards and codes

• AS 1940 — The storage and handling of flammable and combustible liquids. The spine of solventborne-plant ventilation: liquid classification, quantities, bunding, ventilation and hazardous-area trigger.
• AS 1668.1 — Fire and smoke control in buildings via the air-handling system.
• AS 1668.2 — Mechanical ventilation in buildings, including dilution-ventilation methodology and reference to workplace exposure standards.
• AS/NZS 4254.1 and .2 — Sheet-metal and flexible duct construction across low/medium/high pressure ranges.
• AS 1530.4 — Fire-resistance testing of building elements including fire-rated duct penetrations.
• AS/NZS 60079.10.1 — Classification of explosive gas atmospheres (Zone 0/1/2).
• AS/NZS 60079.10.2 — Classification of combustible-dust atmospheres (Zone 20/21/22).
• AS/NZS 60079.0/.1/.7/.14/.15/.17/.31 — Ex equipment general, flameproof Ex d, increased safety Ex e, installation, Ex nA, inspection, dust Ex t.
• AS 3957 — Industrial dust hazard areas; combustible-dust deflagration risk and zoning.
• AS 3780 — The storage and handling of corrosive substances (acetic acid, acids, ammonia).
• AS 4326 — The storage and handling of oxidising agents (peroxide initiators).
• AS/NZS 2243.8 and .9 — Laboratory fume cupboards and laboratory ventilation.
• AS 1375 — Industrial fuel-fired appliances and furnaces (reactor heating, thermal oxidisers).
• AS 4024 — Safety of machinery (dispersers, mills, mixers, conveying).
• AS/NZS 3000 — Wiring rules, including Ex-area wiring.
• AS/NZS 1715 / 1716 — Selection, use and maintenance of respiratory protective equipment, and RPE performance.
• AS 1692 — The storage of flammable and combustible liquids in tanks (bulk solvent tank farm).
• ADG Code — Australian Dangerous Goods Code (transport of solvents and dangerous goods).
• GHS / AICIS — Globally Harmonised System classification and labelling; industrial-chemicals introduction.
• NCC Section J — Energy efficiency provisions of the building and HVAC.
• ASHRAE 62.1 — Ventilation for acceptable indoor air quality (office and amenities benchmark).
• ISO 9001 / 14001 / 45001 — Quality, environmental and occupational-health-and-safety management systems.
• NFPA 30 (cross-ref) — Flammable and Combustible Liquids Code.
• NFPA 68 (cross-ref) — Explosion protection by deflagration venting.
• NFPA 69 (cross-ref) — Explosion prevention systems (inerting, suppression, isolation).
• NFPA 91 (cross-ref) — Exhaust systems for air conveying of vapours, gases, mists and particulate solids.

21.2 Workplace exposure standards (SafeWork Australia)

• Xylene — 80 ppm (8-hour TWA). Gas Group IIA, Temperature Class T3.
• Toluene — 50 ppm (8-hour TWA).
• Methyl ethyl ketone (MEK) — 150 ppm (8-hour TWA).
• Methyl isobutyl ketone (MIBK) — 50 ppm (8-hour TWA).
• Acetone — 500 ppm (8-hour TWA). Volatile; Gas Group IIA/IIB.
• Ethyl acetate — 200 ppm (8-hour TWA).
• White spirit (mineral turpentine) — 240 mg/m3 (8-hour TWA).
• Isocyanate (TDI / MDI) — 0.02 mg/m3 (8-hour TWA), 0.005 ppm short-term. Respiratory sensitiser — the killer.
• Titanium dioxide (TiO2) — 10 mg/m3 inhalable (8-hour TWA).
• Respirable crystalline silica (RCS) — 0.05 mg/m3 (8-hour TWA).
• Carbon black — 3 mg/m3 inhalable (8-hour TWA). Category 2 carcinogen.
• Acetic acid — 10 ppm (8-hour TWA). Silicone (acetoxy) cure by-product.
• Ammonia — 25 ppm (8-hour TWA). Waterborne pH adjuster.
• Formaldehyde — 1 ppm (8-hour TWA).
• Ozone — 0.1 ppm (8-hour TWA). UV-cure ink and lamp by-product.

22. Compliance documentation checklist for coatings, ink, resin and adhesive plant duct

The following checklist captures the documentation that an Australian coatings, ink, resin, adhesive or sealant manufacturer should hold for its manufacturing HVAC ductwork, and that SBKJ-equipped fabricators deliver as standard with every project:

• AS 1940 flammable-liquid register — liquid classification, quantities, bunding and ventilation basis documented for tank farm, drum store, drumming bay and in-process solvent.
• AS 1668.2 dilution-ventilation design — airflow calculations to LEL and WES targets with mixing-efficiency factors, and make-up-air balance.
• AS/NZS 4254 duct construction — pressure-test certificates at 1.5x design pressure for 30 minutes on every branch.
• AS 1530.4 fire resistance — fire-rated penetrations certified at every fire-compartment boundary, fire dampers to AS 1682.
• AS/NZS 60079.10.1 and .10.2 hazardous-area classification — documented Zone 0/1/2 (gas) and Zone 20/21/22 (dust) maps with Ex equipment selection and the AS/NZS 60079.17 verification dossier.
• AS 3957 dust-hazard analysis — Kst, minimum ignition energy and deflagration-protection chain documented for every combustible-dust collection point.
• AS 3780 / AS 4326 corrosives and oxidisers — acetic-acid, acid, ammonia and peroxide-initiator storage and capture documented and segregated.
• AS/NZS 2243.8 and .9 laboratory ventilation — fume-cupboard face-velocity (0.5 m/s) and containment certificates, once-through exhaust documented.
• AS/NZS 1715 / 1716 RPE — respirator selection documented for isocyanate, crystalline-silica and high-exposure tasks.
• Isocyanate extract life-safety documentation — enclosure, capture velocity, negative-pressure verification, airflow interlock and breathing-zone monitoring records.
• Spark-resistant fan certification — AMCA 99 construction grade and Ex-rated motor zone/gas-group/temperature-class records for every fan on a flammable or combustible stream.
• NFPA 68 / 69 deflagration protection — vent-area sizing, suppression-system arming and isolation-valve interlock documented for every combustible-dust collector.
• Bonding and earthing verification — resistance-to-earth records (under 10 ohms for vapour duct) at every flange and isolation valve, conductivity test on every flexible connection.
• Material traceability — mill certificate and gauge for every duct length, galvanised to AS 1397 and stainless to AS 1449.
• Breathing-zone air monitoring — NATA-certified results against every relevant WES at disperser, let-down, drumming, isocyanate and powder-handling stations.
• Stack emission monitoring — VOC, particulate and abatement-efficiency results against the EPA licence and NPI reporting.
• ISO 9001 / 14001 / 45001 integration — HVAC and dust-collection maintenance records folded into the management systems.
• NATA-certified commissioning balance — final airflow, capture-velocity and pressure-balance report tying every branch to its zone, dust rating, liquid class and WES basis.

Compliance documentation is the bridge between the fabricated ductwork and the operator’s ongoing regulatory obligation. Every length SBKJ supplies to an Australian fabricator is delivered with mill certificate, gauge, flange specification, pressure-test record and earth-bonding verification — the foundation paperwork the coatings, ink, resin or adhesive manufacturer integrates into its AS 1940, AS/NZS 60079, APAS, EPA and management-system audit pack.

23. Closing — SBKJ engineering support for Australian coatings, ink, resin and adhesive manufacturers

The Australian paint, coatings, printing ink, resin, adhesive and sealant manufacturing sector runs some of the most demanding industrial HVAC in the country — flammable-solvent dilution and capture, isocyanate life-safety extract, pigment and crystalline-silica dust control, high-temperature resin-reactor and thermal-oxidiser venting, acetic-acid and ammonia corrosion resistance, and combustible-dust deflagration protection, frequently all on one site. Every one of those demands lands on the ductwork, and every one carries a standard, an exposure limit and a documentation obligation. Generic commercial fabrication does not meet this brief; purpose-engineered, conductive, bonded, corrosion- and temperature-appropriate, fully documented ductwork does.

The SBKJ Group engineering team in Box Hill North VIC supports Australian fabricators and mechanical contractors serving this sector with machine supply (SBAL-V, SBAL-III, SBSF-1525, SB-ZF1500, SBFB-1500, SBPC1500, SBLR-600, SBTF-1500/1602/2020), engineering and commissioning documentation, and ongoing technical advisory across every process zone described in this guide — from solvent dilution and disperser capture through resin-reactor venting, isocyanate extract and pigment dust mains to QC laboratory fume cupboards. The line is the production base that lets a fabricator self-perform the galvanised and the difficult stainless, spiral and welded work alike, and serve DuluxGroup, PPG, Wattyl/Hempel, Haymes, Akzo Nobel, Resene, Taubmans, Solver, Jotun, Sherwin-Williams, Bostik, Sika, Parchem, Allnex/Nuplex, Huntsman, Siegwerk, Flint Group and Sun Chemical from a local base.

We will be exhibiting at ARBS 2026 in Sydney in May with the full SBKJ machine portfolio plus process-specific reference samples covering conductive galvanised dilution duct, 316L stainless corrosive and isocyanate extract, hermetically welded combustible-dust spiral, and high-temperature reactor and oxidiser transitions. Pre-show meetings with Australian coatings, ink, resin and adhesive fabricators, OEM partners and existing customers are scheduled across the week.