Plastic and Polymer Manufacturing HVAC Duct Guide — Injection Moulding, Blow Moulding, Extrusion, Thermoforming, Compounding and Plastic Recycling

Why plastic and polymer plant HVAC is its own discipline

Plastic and polymer manufacturing is one of the broadest manufacturing categories in Australian industry. A modern plant can be a small captive injection moulder running PP automotive trim, a 24-line PET stretch blow plant serving the beverage majors, a polymer compounding operation feeding masterbatch into the regional supply chain, a PVC profile extrusion plant serving the window and door market, a polyurethane PU rigid panel line for insulation, or one of the new plastic recycling plants now scaling across the eastern seaboard under the National Plastics Plan and the state-level container deposit and kerbside reform programmes. Each of these facilities sits at the intersection of process engineering, occupational hygiene, fire safety and energy efficiency — and the HVAC ductwork is the engineering control that ties all four together.

An HVAC specification that treats a plastic plant as a generic industrial workshop will fail compliance audit, fail worker exposure monitoring, or fail at the first overload event on a polymer dust extraction line. We have walked through plastic plant HVAC commissioning programmes with operators across Melbourne, Sydney, Brisbane, Adelaide and Perth, and the recurring lessons are consistent. Plastic plant HVAC is its own discipline. There are six characteristics that distinguish it from general industrial HVAC.

Polymer dust is combustible. Polyethylene, polypropylene, ABS, PS and a range of other thermoplastic dusts have NFPA 660 dust deflagration index Kst values in the St-1 to St-2 range. Any plastic plant that handles dry polymer dust above the 1/32 inch layer threshold across more than 5 percent of the building footprint triggers a dust hazard analysis and downstream design changes including explosion-rated dust collectors, spark-resistant fans, bonded grounding and hazardous area zoning to AS 3957. The two facility types where this is non-negotiable are polymer compounding plants and plastic recycling shredding lines.

Hygroscopic resin drying is a process load that the HVAC system has to support. PET, polyamide nylon, polycarbonate, ABS and PMMA acrylic absorb water from atmospheric humidity and have to be dried at 80-120°C through adsorption desiccant wheel dryers before moulding or extrusion. The dryer exhaust is hot, can carry dust shedding from the resin pellets, and on PET in particular can carry oligomer breakdown products. The HVAC designer needs to handle the dryer exhaust as a separate process duty, not a general supply and return zone.

Some polymer processes produce gases at strict workplace exposure limits. Polyurethane PU isocyanate (TDI and MDI) sits at a 0.005 ppm STEL — five thousand times stricter than the styrene STEL. PVC processing releases HCl at the die face when operating temperature drifts high, with a 5 ppm STEL on HCl. Phenolic moulding releases formaldehyde at 1 ppm STEL. These three duties — PU isocyanate, PVC HCl and phenolic formaldehyde — each require dedicated scrubber, 304L stainless ductwork, continuous gas monitoring and a negative pressure cascade across the entire zone. Treating them as part of general bay extract is a major compliance failure.

Plasticiser vapour and FR additive fume are a separate exposure route. PVC calendering releases plasticiser vapour (DOP, DEHP). Compounding with antimony trioxide flame retardant releases antimony at 0.5 mg/m³ WES. Older PVC lines using lead or tin stabilisers carry historical exposure routes that are now closing out but are still encountered on legacy plant. The HVAC engineer has to map each additive against the WES table and design source capture accordingly.

Plastic recycling adds wet-side duties that virgin plants do not face. The wash plant for PET bottle recycling uses sodium hydroxide and hot water with detergent — caustic mist scrubber and 304L stainless ductwork mandatory. The float-sink density separation and air classifier stages add dust and odour control. The crystallisation and solid-state polymerisation (SSP) reactors for food-grade rPET operate under vacuum or nitrogen with 180°C process temperature. Pyrolysis chemical recycling — the APR Plastics, Plastic Energy and similar plants now scaling in Australia — operates with hot pyrolysis gas at 350-450°C with Zone 1 hazardous area classification per AS/NZS 60079.

Energy and operating cost are dominated by process heat rejection. A 200-tonne injection moulder rejects 25-35 kW of cooling water heat continuously, plus radiated heat from the barrel, plus hydraulic system heat. A 5-tonne-per-hour extrusion line rejects 80-120 kW. These thermal loads accumulate across a busy bay and dominate the HVAC sensible load. Designing for the rejection rate at peak production rather than the manufacturer's nameplate is the difference between a 28°C bay summer working temperature and a 38°C summer working temperature that pushes maintenance and operator turnover.

This guide walks through every one of these characteristics by zone and process, with material selection, sizing guidance and commissioning notes. The standards baseline is AS 1668.2 for general dilution ventilation, AS/NZS 4254 for ductwork construction, NFPA 660 for combustible polymer dust analysis, AS/NZS 60079 for hazardous area classification, and Safe Work Australia Workplace Exposure Standards for the binding contaminant limits. ASHRAE Applications Chapter 33 industrial ventilation and Chapter 38 industrial drying are the international design references for the process exhaust and dryer calculations.

Australian plastic and polymer industry context

Plastic and polymer manufacturing has been one of the most quietly resilient Australian manufacturing categories through the last two decades. Aggregate production has shifted from a focus on commodity virgin moulding to a more sophisticated mix of premium converters, technical compounders and a rapidly expanding plastic recycling base. The 2025 ASX-listed packaging and plastics segment — Amcor, Orora, Pact Group and Cleanaway — represents over A$20 billion of market capitalisation and underpins a network of more than 200 manufacturing sites across all states and territories.

The major Australian operators sit in five segments and the HVAC implications of each segment are materially different.

Rigid plastic packaging — Pact Group, Amcor Rigid, Orora and ALPLA

Pact Group ASX:PGH, headquartered in Melbourne, is the largest rigid plastic packaging operator in Australasia with more than 60 manufacturing sites across Australia and New Zealand. Pact runs injection moulding, blow moulding and thermoforming lines for food, beverage, dairy, personal care and industrial product packaging. Amcor PLC Rigid Packaging — Australia's largest packaging group with sites across Botany New South Wales, Scoresby Victoria, Welshpool Western Australia, Kew Victoria and Eaglehawk Victoria — runs the largest PET stretch blow operations in the country, plus injection moulding for closures and HDPE bottles. Orora Limited ASX:ORA, headquartered in Box Hill Victoria, runs the Australian wine bottle, can and adjacent plastic packaging operations as a partial spin-off from Amcor. ALPLA Australia is an Austrian PET and HDPE bottle subsidiary with a continuing build-out of dedicated beverage majors capacity.

Flexible plastic packaging — Amcor Flexibles, Sealed Air, Pro-Pac

Amcor Flexibles operates film extrusion and printing for food contact and pharmaceutical packaging across multiple sites. Sealed Air Australia, headquartered at Dandenong Victoria, operates film and bubble extrusion plus protective packaging for the industrial market. Pro-Pac Packaging operates a mix of converter and printer operations. The HVAC profile is dominated by extrusion line heat extract, printing solvent VOC and ink mist capture, and general ACH control.

Injection moulding and industrial converters — Empire, AIP, Cobden, IPL

Empire Plastics, Aussie Plastics and Australian Industrial Plastics AIP are representative independent injection moulding operations serving automotive, white goods, building products and industrial OEM markets. Cobden Industries operates injection moulding for agricultural and industrial products. Aussie Mould Tech operates moulds and injection moulding for white goods. IPL Plastics operates a converter network. Linewell operates technical injection moulding for medical and electronics products. The HVAC profile is dominated by process heat rejection, mould storage and try-out room conditioning, and general bay ventilation.

PVC pipe and profile — Iplex, Vinidex, Plasson, HG Smith

Iplex Pipelines (legacy ASX:IPL, now within Fletcher Building) operates large-scale PVC, PP and HDPE pipe extrusion for water and gas reticulation, sewerage and stormwater. Vinidex operates PVC pipe extrusion for the building services and infrastructure market. Plasson Australia operates PVC profile and fittings. HG Smith operates a smaller PVC profile operation. PVC processing brings the HCl scrubber duty into scope.

Plastic recycling — Cleanaway, Veolia, APR Plastics, Pact Recycling, Replas, Plastic Forests

Plastic recycling has become one of the fastest growing manufacturing segments in Australia under the National Plastics Plan, the state-level container deposit programmes and the National Packaging Targets co-ordinated by the Australian Packaging Covenant Organisation (APCO). The major operators sit in three groups. First, the kerbside collectors and Material Recovery Facility operators — Cleanaway Waste Management ASX:CWY, Veolia Environmental Services Australia, iQ Renew and the council-tendered MRF operators across each state. Second, the dedicated plastic recyclers — APR Plastics with PET wash and repelletise plants in Sydney and Melbourne, Pact Recycling operating kerbside hard plastics into rPET and rHDPE, Replas Australia in Ballarat Victoria turning recycled plastic into outdoor furniture and lumber, and Plastic Forests in Yass New South Wales focused on soft plastic recycling. Third, the new pyrolysis chemical recyclers — the Plastic Energy, Licella Hot Bottle and similar facilities now in construction at multiple Australian sites turning mixed end-of-life plastic into pyrolysis oil for cracker feedstock and fuel.

Industry bodies and the standards reference set

The Plastics Industry Pipeline Association (PIPA) is the peak body for the plastic pipe segment in Australasia. The Vinyl Council of Australia represents the PVC value chain. The Australian Packaging Covenant Organisation (APCO) co-ordinates the National Packaging Targets and the Australasian Recycling Label programme. The Polyolefins Association and the Bio-Plastics Council cover the broader thermoplastic and bio-based plastic segments. The annual Australian Plastics Recycling Survey is the most cited reference on aggregate recycling tonnage and end-market splits. ARRT (Australian Recycling and Resource Technology) is one of the more recent industry research and standards organisations. The Plastics New Zealand body covers the regional supply chain across the Tasman.

Standards and exposure limits — the binding reference set

Plastic plant HVAC design sits at the intersection of mechanical, electrical, occupational hygiene and fire safety standards. The HVAC engineer should have working familiarity with each of the following and should know which is the binding compliance reference for the project's jurisdiction.

AS 1668.2 — The use of ventilation and airconditioning in buildings — Mechanical ventilation in buildings. The Australian general dilution ventilation framework. Sets minimum outside air rates and contaminant control approach. The binding document for general ventilation in Australian plastic plants but does not replace source-capture velocities required to hit Safe Work Australia WES at the worker breathing zone.

AS/NZS 4254 — Ductwork for air-handling systems in buildings. The Australian and New Zealand HVAC ductwork construction standard. Sets pressure classes, materials, sealing classes, support and access. Equivalent to SMACNA HVAC Duct Construction Standards in the US and DW/144 in the UK. Plastic plant general supply and return ducts are typically Pressure Class 500 Pa, sealing class C. Process exhaust ducts typically Class 1000 Pa, sealing class A or B depending on toxicity.

AS 1530.4 — Methods for fire tests on building materials, components and structures, Part 4: Fire-resistance tests for elements of construction. The Australian fire-rated ductwork test framework. Applies where ductwork penetrates fire-rated walls, slabs or compartments. Plastic plant fire-rated ductwork is typically encountered at the boundary between the production hall and the office or amenity blocks, and at the boundary into a pyrolysis or PU casting zone with elevated fire load.

AS 1530.3 — Methods for fire tests on building materials, components and structures, Part 3: Simultaneous determination of ignitability, flame propagation, heat release and smoke release. Reference for the ignitability ranking of fabric and other duct interior finishes — relevant where fabric diffusers are used in clean process areas adjacent to a plastic processing hall.

AS 1851 — Routine service of fire protection systems and equipment. Sets the routine maintenance interval framework for fire dampers, fire-rated duct, smoke control duct and the broader fire safety system. Plastic plants typically have multi-zone fire damper installations because of the process heat and the polymer fire load.

AS/NZS 60079 — Explosive atmospheres. The Australian and New Zealand hazardous area classification framework. Applies to PE/PP/ABS combustible polymer dust zones, to solvent-handling areas in compounding and decoration lines, to pyrolysis chemical recycling reactors (Zone 1), and to the broader chemical zones in PU, PVC and phenolic processing. AS/NZS 60079 works with AS/NZS 3000 Electrical Wiring Rules for the electrical equipment selection in the classified zone.

AS 1940 — The storage and handling of flammable and combustible liquids. Applies to compounding solvent storage, ink and printing solvent storage in the decoration line, pyrolysis condensate handling and the broader flammable liquid storage on a plastic plant.

AS 3957 — Industrial fuel-fired appliances — Construction and use. Older but still cited Australian dust hazard standard. Plastic plant dust hazard areas are now typically classified to AS/NZS 60079 with reference to the NFPA 660 dust framework.

NFPA 660 — Standard for the Fundamentals of Combustible Dust. The 2024-effective consolidation of NFPA 484, 654, 655, 664 and 61 into a single combustible dust standard. The reference framework for combustible polymer dust analysis on PE, PP, ABS and other thermoplastic dust streams. Plastic plant dust hazard analysis is run to NFPA 660 then translated to AS/NZS 60079 hazardous area zoning for the Australian electrical equipment specification.

NFPA 68 — Standard on Explosion Protection by Deflagration Venting. The reference for deflagration venting on dust collectors and silos. Polymer dust collectors serving NFPA 660 classified zones are deflagration vented per NFPA 68.

NFPA 69 — Standard on Explosion Prevention Systems. The reference for explosion prevention by inerting, suppression or oxygen reduction. Some PU and pyrolysis applications use NFPA 69 explosion prevention rather than NFPA 68 deflagration venting.

ASHRAE Applications Handbook Chapter 33 Industrial Ventilation. The international design reference for industrial general dilution and source-capture ventilation. Chapter 33 is the working reference for plastic plant bay ventilation and source capture sizing.

ASHRAE Applications Handbook Chapter 38 Industrial Drying. The international design reference for industrial drying systems including the desiccant wheel dryers used for hygroscopic resin drying.

AS 4801 and the Work Health and Safety Acts. The Australian occupational health and safety legislative framework, with the binding obligation on plant operators to provide and maintain a working environment that is safe and without risk to health, including engineering control through HVAC.

AS 1657 — Fixed platforms, walkways, stairways and ladders. Sets requirements for access platforms — relevant on duct routes that pass over plant rooms and on roof-mounted plant access.

Safe Work Australia Workplace Exposure Standards (WES). The binding contaminant limits for Australian workplaces. The plastic plant relevant subset includes styrene 50 ppm 8-hour TWA and 100 ppm STEL (polystyrene and GRP), formaldehyde 1 ppm STEL (phenolic and urea moulding), polyurethane isocyanate TDI/MDI 0.005 ppm STEL (PU casting), HCl 5 ppm STEL (PVC overheated), chlorine 0.5 ppm (PVC processing), VCM 1 ppm STEL (legacy PVC), lead 0.05 mg/m³ (legacy PVC stabilisers), tin 2 mg/m³ (PVC stabilisers), antimony 0.5 mg/m³ (FR additive), hexavalent chromium 0.005 mg/m³ (chrome plating mould), inhalable dust 10 mg/m³ and respirable dust with separate fraction limits. The TVOC less than 1 mg/m³ figure is aspirational for clean room and quality-critical zones.

ISO 14001 — Environmental Management Systems and ISO 14021 — Environmental claims. The voluntary environmental standards adopted by most major plastic plant operators. ISO 14001 drives the documentation of HVAC operating energy, exhaust monitoring and emissions reporting. ISO 14021 governs the use of environmental claims on recycled content and on the Australasian Recycling Label that APCO co-ordinates.

WEEE Directive and APR plastic recycling. The Waste Electrical and Electronic Equipment framework drives end-of-life plastic flows into the recycling chain. APR (Association of Plastic Recyclers) test methodology is widely used in plastic recycling plant commissioning, particularly for PET wash and repelletise.

Polymer families and the HVAC implications of each

The HVAC duty profile of a plastic plant is determined by the polymer mix being processed. A plant running pure PP moulding has a fundamentally different HVAC profile from a plant running PVC profile extrusion, and both differ from a plant running PU foam casting. The major polymer families and their HVAC implications are summarised below.

Polyethylene (PE) — LDPE, LLDPE, HDPE

The largest volume thermoplastic globally. Processed by extrusion (film, pipe), blow moulding (HDPE bottles), injection moulding (closures, industrial parts) and rotational moulding (tanks). PE is not hygroscopic and does not require drying. PE dust is combustible per NFPA 660 with Kst typically in St-1 range. Processing emissions are minor — light hydrocarbon and aldehyde release at the die face at trace level. HVAC profile is dominated by process heat extract and general dilution.

Polypropylene (PP)

The second largest volume thermoplastic. Processed by extrusion, injection moulding, blow moulding and biaxially oriented film. Not hygroscopic. PP dust is combustible per NFPA 660 with Kst similar to PE. Processing emissions minor. HVAC profile similar to PE.

Polyvinyl chloride (PVC) — rigid and flexible

The largest volume polymer used in pipe and profile applications. Processed by extrusion (pipe, profile, sheet), injection moulding (fittings), calendering (sheet, leather cloth) and blow moulding (lower volume). PVC processing is the most chemically demanding common thermoplastic — HCl release at the die face at high operating temperatures (5 ppm STEL), plasticiser vapour release in flexible PVC compounding and calendering (DOP, DEHP), and historical VCM exposure on legacy plant (1 ppm STEL). The HVAC profile requires dedicated PVC processing zone extract with caustic mist scrubber, 304L stainless ductwork, continuous HCl monitoring and a negative pressure cascade.

Polyethylene terephthalate (PET)

The largest volume packaging polymer for beverage bottles. Processed by injection moulding (preform), stretch blow moulding (bottle), film extrusion (sheet) and fibre. PET is hygroscopic and requires dehumidifier dryer at 150-180°C to dewpoint below minus 40°C before processing. PET recycling — mechanical wash and repelletise plus solid-state polymerisation for food-grade rPET — is the largest single segment of the Australian plastic recycling base. PET dust is combustible but at lower Kst than PE/PP.

Polystyrene (PS) and high-impact polystyrene (HIPS)

Used for packaging (PS food contact, HIPS appliance housings), insulation (expanded PS foam, extruded PS foam) and broader industrial moulding. Processing PS releases styrene up to 50 ppm WES zone. PS expanded foam (EPS) and extruded foam (XPS) production has additional pentane blowing agent VOC release. The HVAC profile is dominated by styrene capture in PS moulding and pentane control in foam production.

Acrylonitrile-butadiene-styrene (ABS)

Used for automotive interior trim, appliance housings, electronics housings and the recycled E-waste plastic stream. Processed by injection moulding and extrusion. ABS is hygroscopic and requires drying at 80°C. Processing releases trace styrene and acrylonitrile (low ppm range, well below WES). ABS dust is combustible per NFPA 660.

Polyamide (PA) — nylon

Engineering thermoplastic used for automotive structural and under-bonnet, electrical and mechanical applications. Processed by injection moulding and extrusion. Highly hygroscopic — drying at 80-100°C mandatory. Processing releases caprolactam at trace level.

Polycarbonate (PC)

Engineering thermoplastic used for optical media, automotive lighting and electronics housings. Processed by injection moulding. Hygroscopic — drying at 120°C mandatory. Processing emissions minor.

Polyoxymethylene (POM) — acetal

Engineering thermoplastic used for precision gears and mechanical components. Processed by injection moulding. POM processing releases formaldehyde at trace level on overheating — dedicated extract at the moulder is good practice on high-throughput POM.

Polymethylmethacrylate (PMMA) — acrylic

Engineering thermoplastic used for transparent applications. Processed by injection moulding, extrusion and cast sheet production. Cast sheet production with MMA monomer adds a flammable liquid duty (AS 1940). PMMA dust from machining cast sheet is combustible.

Polyurethane (PU)

Thermoset and thermoplastic. PU rigid foam used for insulation panels (PIR, PUR), PU flexible foam used for furniture and mattress, PU integral skin used for steering wheels and automotive components, PU elastomers used for specialty applications. PU casting involves isocyanate (TDI, MDI) at 0.005 ppm STEL — the most chemically demanding duty in any plastic plant. The HVAC specification requires dedicated isocyanate scrubber, 304L stainless ductwork, continuous monitoring and a negative pressure cascade.

Phenolic and urea-formaldehyde — Bakelite and related

Thermoset moulding compounds used for electrical fittings, automotive ignition components and some specialty industrial applications. Phenolic releases phenol vapour and formaldehyde at 1 ppm STEL. Urea-formaldehyde similarly. The HVAC specification requires dedicated formaldehyde scrubber and 304L stainless ductwork.

Resin storage silo and pneumatic conveyor HVAC

Bulk resin arrives at a plastic plant by tanker (for larger sites) or by supersack (for smaller sites). The resin is pneumatically conveyed from the tanker discharge or supersack station to an overhead storage silo, then from the silo to the moulding or extrusion line through a vacuum or pressure conveyor. The HVAC engineer is dealing with two interconnected challenges in this zone.

Polymer dust release at the silo vent. Each tonne of resin pneumatically conveyed sheds 0.1-1 kg of fine polymer dust depending on the polymer family and the conveying velocity. The dust accumulates in the silo headspace and has to be vented to atmosphere through a filter rather than back-pressurising the conveyor. The silo vent filter is typically a pulse-jet bag filter sized for the conveying air rate, with the dust returned to the silo bottom by reverse flow or by gravity. On PE, PP and ABS, the silo vent filter is NFPA 660 dust hazard rated, with deflagration venting per NFPA 68 and bonded electrical grounding throughout.

Static charge accumulation in the conveyor. Polymer pellets accumulate electrostatic charge as they travel through the conveyor — values up to 50 kV measured on the conveyor wall. Static discharge in a dust-laden enclosed space is the worst case ignition scenario in a combustible dust line. Bonded electrical grounding across the entire conveyor and silo system, with documented continuity testing at commissioning and annual interval, is the standard control. Conductive antistatic-treated galvanised duct or 304L stainless is the wetted-side specification.

The cyclone separator upstream of the bag filter handles the bulk of the entrained dust at the silo vent. Cyclone selection is sized for the particle size distribution of the polymer dust — typically 50-500 micron at the inlet, dropping to less than 10 micron after the cyclone. The bag filter polishes the remaining fines. On a plant handling more than 5 polymer families across multiple silos, segregated filtration is good practice — combining the dust streams from different polymers in a single filter creates a mixed-dust analysis complication.

Cooling and conditioning of the silo headspace is rarely required for thermoplastic resin in Australian climate conditions. Hygroscopic resins (PET, PA, PC, ABS, PMMA) need to be kept dry from the silo onward, and the silo is typically blanketed with dehumidified air from the dryer regeneration loop or with dry compressed air at -40°C dewpoint. Direct outside air to the silo is acceptable for non-hygroscopic resin only.

Dehumidifier dryer HVAC

Hygroscopic resin drying is a process duty that the HVAC system has to support but is typically delivered by a packaged adsorption desiccant wheel dryer rather than by central HVAC equipment. The HVAC engineer is dealing with the inlet supply to the dryer (typically a dedicated dehumidified air supply on the regeneration loop) and the exhaust from the dryer (which carries water vapour, dust shedding from the resin and trace VOC).

Typical drying parameters by resin are PET at 150-180°C with dewpoint below minus 40°C and residence 4-6 hours, PA at 80°C with dewpoint below minus 40°C and residence 4 hours, PC at 120°C with dewpoint below minus 40°C and residence 3-4 hours, ABS at 80°C with dewpoint below minus 30°C and residence 2-3 hours, and PMMA at 80°C with dewpoint below minus 30°C and residence 2-3 hours. The drying tower is sized for the moulder or extruder throughput rate plus a safety factor.

The desiccant wheel regenerates by exposure to hot air at 180-250°C for the appropriate residence — the moisture absorbed in the process leg desorbs in the regeneration leg and is discharged to atmosphere through the exhaust stack. The exhaust temperature peaks at 180°C immediately downstream of the regeneration heater and drops to ambient further downstream. The exhaust ductwork is aluminised steel or 304L stainless for the hot section, transitioning to galvanised on the cooler runs. Insulation is required to prevent condensation on the duct wall and to keep the duct surface temperature below the operator burn threshold per AS 1657.

Discharge to atmosphere is through a roof stack. The stack height and termination is sized per AS 1668.2 and the local Environment Protection Authority requirements — typically 2-3 metres above the building roof line, with appropriate weather protection. Some plants recirculate the dryer regeneration exhaust back to the desiccant wheel on a closed-cycle system to recover regeneration heat, but this is not appropriate for plastic plant process zone exhaust where contamination would compound across multiple cycles.

Injection moulding bay HVAC

The injection moulding bay is the largest single zone in most plastic plants and the HVAC profile is dominated by process heat extract and general dilution. A typical 200-tonne injection moulder (Engel, Arburg, Sumitomo Demag, Krauss-Maffei, Husky, Negri Bossi or equivalent) rejects 25-35 kW of cooling water heat continuously to the chiller circuit, plus 5-10 kW of radiated heat from the barrel and nozzle, plus 2-3 kW of hydraulic system heat to the surrounding air. Across a bay of 20 moulders, the combined sensible heat load is 600-900 kW continuous — comparable to a small office building.

General dilution ventilation is sized at 6-10 air changes per hour with outside air component per AS 1668.2 for the working population. Galvanised G90 supply and return ductwork is the standard specification, with TDF flange connections per AS/NZS 4254. Pressure class 500 Pa positive on the supply, with sealing class C.

Localised extract at the hot runner manifold and at the mould tip is good practice on engineering polymer processing — POM (formaldehyde release), PA (caprolactam release), ABS (styrene and acrylonitrile release), PC (minor VOC). The localised extract is typically a small canopy hood above the manifold with 0.3-0.5 m/s capture velocity at the hood face, plumbed to a common process exhaust riser. The process exhaust ductwork is galvanised, sized at 8-12 m/s.

Hot runner tip extract — a narrow extract slot directly adjacent to the mould opening to capture the brief steam release at part ejection — is sometimes used on high-precision engineering polymer applications. The hood face capture velocity is 0.5-1 m/s. Steam release at part ejection is brief but releases trace VOC from the resin into the operator breathing zone if not captured.

Process water cooling tower exhaust serves the chiller circuit and is a separate consideration — the cooling tower discharge is moist air at ambient temperature, typically routed to an external cooling tower or roof-mounted dry cooler. The cooling tower itself is not normally an HVAC duct system but the make-up and overflow lines pass through the building envelope.

Compressed air for the moulder mould opening and clamping is a separate system with its own dryer. The compressed air dryer exhaust on adsorption-type dryers can carry trace oil and water mist and is plumbed to the general roof discharge.

Floor-mounted radiant heat from the moulder pumps and clamp units accumulates at the working positions adjacent to the moulder. Spot cooling at operator positions — fan-coil units or local supply diffusers — is good practice on busy bays. Air conditioning of the entire bay to office comfort temperatures is rarely economical given the process heat load, but maintaining 26-28°C dry bulb in summer with appropriate radiant heat management is achievable and standard practice on premium plastic plants.

Blow moulding line HVAC

Blow moulding lines come in three families with different HVAC profiles. Extrusion blow moulding (HDPE bottles, jerry cans, drums) extrudes a parison from the extruder head and clamps it in the mould before inflating with compressed air. Injection blow moulding (cosmetics bottles, pharmaceutical containers) injects a preform first and then transfers to the blow station. PET stretch blow moulding (beverage bottles) injects a preform on a dedicated injection moulder, then transfers to the stretch blow station typically running 24,000-40,000 bottles per hour.

The HVAC profile is similar to injection moulding with two additional duties. First, the extruder head on extrusion blow moulding releases minor smoke and condensate at the die face — dedicated extract over the head with 0.3-0.5 m/s capture velocity is standard. Second, the PET preform conditioning oven on stretch blow moulding operates at 100-130°C and rejects 30-60 kW thermal load per blow line — dedicated extract over the conditioning oven, with localised supply for operator working position cooling.

Galvanised G90 ductwork throughout. General dilution at 6-10 ACH. The PET preform conditioning oven extract transitions through aluminised steel for the section closest to the oven.

PET stretch blow lines handle high product throughput and the moulds are changed frequently — the mould fitting room adjacent to the production hall is typically a separately conditioned space at 20-22°C for mould try-out work. The mould fitting room HVAC is similar to the injection moulding mould storage and try-out room treated in a later section.

Extrusion line HVAC

Extrusion lines come in many configurations — pipe extrusion, profile extrusion, sheet extrusion (often coupled with thermoforming), film extrusion (blown or cast), and co-extrusion multi-layer (food packaging, automotive sealing systems). The HVAC profile is dominated by extruder barrel heat rejection, die face extract and water bath cooling vapour.

A typical 90 mm extruder running at 500 kg/hour PVC pipe duty consumes 60-80 kW of motor power, of which approximately 40-50 kW is rejected as barrel heat to the surrounding air. A 150 mm extruder running 2 tonne/hour PE pipe duty rejects 120-150 kW. Across a multi-line extrusion shop the combined heat rejection can exceed 1 MW continuous. General dilution at 6-8 ACH plus localised extract at each extruder head.

The die face extract captures minor smoke, water vapour from the calibration water bath and trace VOC from the die. PVC extrusion adds HCl risk on overheating — the PVC processing extract treatment in the dedicated section below applies. PE/PP/HDPE pipe extrusion releases minor aldehyde and hydrocarbon at trace level. PET sheet extrusion releases minor PET dust and oligomer.

Sheet extrusion line coupled with thermoforming adds a vacuum forming station downstream. The thermoforming oven heats the sheet to forming temperature (typically 160-180°C for PS, 130-150°C for PVC, 220-260°C for PET) then transfers to the forming station. Localised extract over the thermoforming oven captures release vapours from the sheet surface. Thermoformed parts handed off to trim station — minor PE/PP/PS plastic dust capture at the trim station.

Film extrusion (blown or cast) adds an air ring or water bath cooling stage downstream of the die. Blown film extrusion typically has minor extract at the die face only. Cast film extrusion with chill roll cooling may have a wider extract zone over the chill roll bank.

Co-extrusion multi-layer lines combine 2-7 extruders feeding a common die. The HVAC implication is that the combined heat rejection from the multiple extruders is concentrated at the die station — localised cooling at operator working positions and dedicated extract over the die station are standard.

Calendering line HVAC

Calendering is used for PVC sheet, PVC leather cloth, PVC film and some rubber products. The line consists of a banbury or kneader mixer feeding a stack mill of typically 4-5 heated rolls that progressively reduce the material to the final sheet thickness. The roll temperatures run 150-200°C and the line generates substantial process heat plus plasticiser vapour release.

Plasticiser vapour (DOP, DEHP, DINP) is the dominant HVAC concern on PVC calendering. The plasticiser evaporates from the surface of the heated rolls and condenses on cooler surfaces downstream. A dedicated extract canopy over the stack mill captures the plasticiser vapour before it reaches the operator breathing zone. The extract air is treated through a plasticiser condenser (heat exchanger with chilled water) or a wet scrubber sized for plasticiser aerosol. 304L stainless ductwork on the section closest to the stack mill, galvanised downstream.

HCl release on temperature excursions is a secondary concern. Continuous HCl monitoring at the operator breathing zone with alarm trip to the calender line control is good practice on PVC calendering. The HCl scrubber treatment in the dedicated PVC section below applies on excursion.

General dilution at 8-10 ACH because of the plasticiser vapour load. The calendering hall is typically a separate building or fire-rated compartment because of the fire load on the calender rolls.

Polymer compounding HVAC — twin-screw extruder and additive dosing

Polymer compounding is the most additive-intensive process in any plastic plant. A twin-screw compounder receives base polymer plus additives — masterbatch (concentrated colour), filler (calcium carbonate, talc, glass fibre), flame retardant (antimony trioxide, brominated, phosphorus-based), antimicrobial, UV stabiliser, antioxidant, lubricant, impact modifier — at the dosing station, melts and disperses through the twin-screw, then pelletises the compound for shipment or in-house consumption.

The HVAC profile is dominated by additive dust capture at the dosing station and additive fume capture at the die head. Additive dust release from the dosing station is significant — fine powders fed by gravimetric feeder generate dust clouds at every transfer. Source capture at every dosing port with 0.5-1 m/s capture velocity at the hood face is the standard. The dust collector is sized for the polymer family and the additive mix — flame retardant antimony trioxide at 0.5 mg/m³ WES drives the strictest specification, with HEPA H13 final filter and 304L stainless ductwork.

Where the polymer base is PE, PP or ABS, the dust is combustible per NFPA 660 and the dust collector is explosion vented per NFPA 68 with spark-resistant fans on the extract. Bonded electrical grounding throughout the dust extraction system. The dust hazard analysis is a project-specific exercise — the additive mix can shift the Kst classification by an order of magnitude depending on the filler and additive ratios.

FR additive fume release at the die head is the secondary HVAC duty. Brominated FR generates HBr trace release on the die face. Antimony trioxide vaporises at temperatures above 200°C and recondenses on cooler surfaces. The localised extract over the die head with 304L stainless ductwork captures the fume at source.

Colour change on a compounder generates a high-volume purge with mixed polymer and colour residue. The purge stream is diverted to a dedicated purge collection rather than the main pelletiser, and the surrounding bay HVAC handles the brief release.

General dilution at 8-12 ACH because of the additive dust and fume load. The compounding hall is typically a separate building or fire-rated compartment because of the polymer and FR additive fire load. Pressure cascade negative relative to surrounding spaces to contain dust and fume migration.

Pelletising line HVAC

Pelletising is the final stage of compounding and the final pre-shipment stage on a new polymer production line. The molten extruder discharge is forced through a die plate, cooled, and cut into pellets. The two dominant technologies are underwater pelletiser (UWP) and strand pelletiser.

Underwater pelletiser cuts the polymer in water — the die plate is submerged in a circulating water tank, and the cutter blades rotate against the die face. UWP discharges water mist and minor pellet dust at the die face. Localised extract with 0.3-0.5 m/s capture velocity at the hood face. The extract air carries water mist that is condensed in a downstream cooler-condenser. Galvanised ductwork with insulated section for the cooler-condenser.

Strand pelletiser extrudes the polymer as a continuous strand, cools the strand in a water bath, and cuts the strand at the pellet length. Strand pelletiser discharges water vapour at the bath, minor pellet dust at the cutter, and trace VOC from the molten polymer surface. Localised extract over the water bath and cutter. Galvanised ductwork.

The pelletising hall is typically integrated with the compounding hall on a compounding plant, or located adjacent to the extruder discharge on a virgin polymer production line. General dilution at the surrounding compounder rate (8-12 ACH).

PVC processing HVAC — HCl scrubber and plasticiser control

PVC is the most chemically demanding common thermoplastic on any plastic plant. The HVAC specification has to handle three concurrent duties — HCl release at the die face on operating temperature excursions, plasticiser vapour release in flexible PVC compounding and calendering, and the legacy VCM exposure route on plant processing virgin PVC.

HCl scrubber on PVC processing zones. Every PVC extrusion, injection moulding, calendering or coating line has a finite probability of operating temperature excursion above 200°C — the temperature at which PVC begins to thermally degrade and release HCl. The Safe Work Australia WES for HCl is 5 ppm STEL, with chlorine at 0.5 ppm. Mandatory dedicated extract over PVC processing zones, sized for the worst-case excursion. The extract is treated through a wet caustic mist scrubber (sodium hydroxide solution) sized for HCl absorption, with 304L stainless ductwork, PTFE gaskets at every flange, and continuous HCl monitoring with alarm trip to the line control. The scrubber discharge is sampled at quarterly or annual interval and the scrubber recirculation pH is logged continuously.

Plasticiser vapour control on flexible PVC. Flexible PVC (DOP, DEHP plasticised) calendering and compounding releases plasticiser vapour from heated rolls and from the compounder die head. Localised extract with plasticiser condenser (chilled water heat exchanger) or wet scrubber. 304L stainless ductwork on the hot section adjacent to the process equipment, galvanised downstream. The plasticiser condensate is recovered as a waste stream to AS 1940 flammable liquid handling.

VCM exposure on legacy plant. Plant processing virgin PVC produced from VCM (vinyl chloride monomer) retains a residual VCM content in the resin. The VCM STEL is 1 ppm — well below typical residual content in modern PVC resin. Legacy plants processing PVC from a recent VCM source may carry detectable VCM in the bay atmosphere at the resin handling stage. Continuous VCM monitoring at the resin handling area is good practice on legacy plants and is no longer required on plants processing PVC from longer storage where VCM has volatilised away.

Lead and tin stabiliser legacy exposure. Older PVC formulations used lead and tin organotin stabilisers. The WES for lead is 0.05 mg/m³ and for tin organotin is 2 mg/m³. Modern PVC formulations have shifted to calcium-zinc stabilisers, but older plants and certain rigid PVC pipe formulations may retain lead or tin. The HVAC specification on a plant processing lead-stabilised PVC includes dedicated dust capture at the dosing station, HEPA H13 final filter, and continuous lead-in-air monitoring per Safe Work Australia.

The PVC processing zone is a separately conditioned and ventilated compartment with negative pressure cascade relative to surrounding spaces. The combined extract from HCl scrubber, plasticiser scrubber and dust collection runs to a dedicated roof stack with continuous monitoring and emergency shutdown trip.

Polyurethane PU foam casting HVAC — isocyanate scrubber

Polyurethane PU foam casting is the most chemically demanding HVAC duty in any plastic plant. The TDI (toluene diisocyanate) and MDI (methylene diphenyl diisocyanate) used as the cross-linking component of PU formulations have a Safe Work Australia WES of 0.005 ppm STEL — five thousand times stricter than the styrene STEL and roughly comparable to the strictest WES on the entire table. A single failure of source capture or a single ductwork leak in an isocyanate exhaust system can cause an exposure event at the worker breathing zone within minutes.

The PU foam casting line for insulation panel manufacturing typically consists of a metering and mixing head that dispenses the isocyanate and polyol components onto a continuously advancing conveyor between the panel facings. The reaction is exothermic and the foam rises and cures within seconds. The PU flexible foam casting line for furniture and mattress is similar but with different formulation.

The HVAC specification for PU casting includes the following.

Source capture at every casting station. Capture hood above and downwind of the mixing head with 1-2 m/s capture velocity at the hood face. The hood is sized for the casting throughput plus a safety factor.

Wet caustic scrubber on the exhaust. Isocyanate aerosol is absorbed by reaction with caustic solution. The scrubber is sized for the worst-case casting release, with 304L stainless construction and PTFE gaskets. Recirculation pH monitored continuously.

HEPA H13 final filter as polishing stage. Downstream of the scrubber, a HEPA H13 final filter polishes the discharge to remove any remaining aerosol carryover. The filter is housed in a 304L stainless plenum to AS/NZS 4254 leakage class A.

304L stainless ductwork throughout the isocyanate path. PTFE gaskets at every flange. No EPDM, no butyl, no silicone in the isocyanate path. Welded seams preferred over riveted on the high-stress runs.

Dedicated exhaust stack with continuous monitoring. The PU exhaust discharges through a dedicated roof stack with continuous TDI/MDI monitoring and alarm trip to the casting line control. The monitoring sample location is downstream of the HEPA H13 final filter.

Negative pressure cascade across the entire PU zone. The PU casting hall is held negative relative to surrounding spaces by 25-50 Pa. Operator entry is through an air lock vestibule. PPE handling room with separate ventilation and decontamination capability.

No recirculation back into the workplace. PU exhaust discharges to atmosphere only. Heat recovery from the exhaust is permissible only through a sealed heat exchanger that does not allow cross-contamination.

PU foam casting HVAC specification should always be developed with input from an industrial hygienist with PU-specific experience. The downstream consequences of an isocyanate exposure event include sensitisation of the affected worker (a lifetime occupational health condition that ends the worker's eligibility for PU industry work), regulatory action by the state work health and safety regulator, and significant cost to the operator.

Phenolic and urea moulding HVAC — formaldehyde scrubber

Phenolic (Bakelite) and urea-formaldehyde moulding compounds are used for electrical fittings, automotive ignition components and some specialty industrial applications. Both release formaldehyde during cure — the Safe Work Australia WES for formaldehyde is 1 ppm STEL.

The HVAC specification follows a similar pattern to PU casting but at less extreme stringency. Source capture at every press with 0.5-1 m/s capture velocity. Wet scrubber on the discharge sized for formaldehyde absorption (typically sodium bisulfite or caustic solution). 304L stainless ductwork on the hot section. Continuous formaldehyde monitoring at the operator breathing zone with alarm trip to the press control. Negative pressure cascade across the phenolic moulding zone.

Phenol vapour release from the cure additionally — the cure releases trace phenol that is captured in the same scrubber path. The scrubber is sized for combined formaldehyde and phenol load.

The phenolic moulding hall is typically a smaller zone within a broader plastic plant or a dedicated specialty plant. General dilution at 8-10 ACH plus the dedicated source capture.

Plastic decoration line HVAC — print and hot stamp

Plastic decoration applies print, hot stamp, paint or coating to moulded or extruded plastic parts. The major technologies are pad printing (small moulded parts), screen printing (flat or curved surfaces), hot stamping (foil transfer), in-mould decoration (label inserted during moulding), and broader spray paint and coating.

The HVAC duty is solvent VOC capture at the print head plus minor heat extract. Pad printing and screen printing use solvent-based inks with high VOC content (typically 50-90% organic solvent on a non-VOC-reduced ink). Hot stamping releases minor VOC from the foil adhesive at the stamp temperature. Spray paint and coating are treated under the broader automotive paint booth framework that we cover in the dedicated automotive paint booth guide.

Source capture at the print head with 0.5-1 m/s capture velocity at the hood face. VOC abatement on the discharge — carbon filter for lower-tonnage installations, regenerative thermal oxidiser (RTO) for higher-tonnage installations. Galvanised ductwork on the cooler runs, 304L stainless on the RTO inlet plenum where the temperature can spike to 800-1000°C during normal operation.

RTO inlet plenum specification is critical. The plenum is welded 304L stainless steel to AS/NZS 4254 leakage class A. The plenum is sized for the worst-case process release plus the RTO purge cycle. Insulation rated for the operating temperature. The SBKJ SB-ZF1500 stitchwelder is the recommended machine for fabricating welded stainless plenums to this duty.

The decoration line is typically a separate zone within the broader plastic plant or a separate building. General dilution at 8-10 ACH plus the dedicated solvent capture. Hazardous area zoning per AS/NZS 60079 in the immediate spray paint or solvent-handling zone.

Mould storage and maintenance HVAC

Plastic plants typically have a substantial mould inventory — moulds are expensive precision tooling and are stored on racking when not in production. The mould storage area is a conditioned space at 18-22°C and 40-60% RH to prevent corrosion on the precision mould surfaces. The HVAC profile is similar to a general industrial storage area with the addition of humidity control.

The mould maintenance and repair workshop is a sub-zone of the mould storage area. The workshop includes mould polishing, machining for tool repair, welding for component replacement, and the broader precision tool work. Localised extract at every welding station, polishing station and machining station. The welding fume capture follows the broader steel fabrication framework — galvanised ductwork with HEPA H13 final filter on the welding fume extraction.

The mould fitting room is a separate zone where new moulds are tested before commissioning into production. The mould fitting room is typically equipped with a smaller injection moulder or blow moulder for try-out, plus measurement and inspection equipment. HVAC is similar to the broader mould storage area — 18-22°C, 40-60% RH, with localised process heat extract over the try-out moulder.

Some specialty plant — particularly aerospace and medical device moulders — operate the mould storage and fitting room to ISO 14644 Class 8 cleanliness for product quality reasons. The HVAC specification in that case follows the lay-up clean room treatment described in our composite manufacturing guide.

Plastic recycling — shred and granulate line HVAC

Plastic recycling is the fastest growing manufacturing segment in Australia under the National Plastics Plan and the state-level container deposit programmes. The shredding and granulating line is the front end of every plastic recycling plant — bales of post-consumer or post-industrial plastic are broken down, contaminants are removed, and the plastic is reduced to a flake or pellet size suitable for downstream wash, melt and repelletise.

The HVAC profile is dominated by dust extraction at the shredder discharge and at every conveyor transfer. Plastic recycling dust is higher tonnage than virgin polymer dust because the input is dirty — food residue, label, paper, dust and grit. The dust hazard analysis follows NFPA 660 and the dust is typically classified St-1 or St-2 depending on the polymer mix.

Cyclone separator at the shredder discharge handles the bulk of the entrained dust. The cyclone is sized for the shredder throughput with 1-2 m/s tangential velocity at the inlet. The cyclone underflow is returned to the conveyor or to a separate fines collection.

Bag filter downstream of the cyclone polishes the fines. The bag filter is sized for the polymer dust profile, with NFPA 660 explosion venting per NFPA 68 deflagration venting (the bag filter is positioned outside the building or with the deflagration vent ducted to a safe discharge location), spark-resistant fans on the inlet, and bonded electrical grounding throughout.

The shred-granulate line is typically a separate building or fire-rated compartment because of the dust hazard and the polymer fire load. General dilution at 10-15 ACH because of the dust and the odour. Pressure cascade negative relative to surrounding spaces.

Antistatic-treated galvanised ductwork on the dust extraction. The dust velocity in the duct is 18-22 m/s — high enough to transport dust without settling, low enough to limit abrasive wear. Long radius elbows mandatory. Cleanout doors at every change of direction and at every 6 metres of straight run per NFPA 91 framework.

Plastic recycling — wash plant HVAC

The wash plant for PET bottle recycling and similar post-consumer plastic streams uses sodium hydroxide and hot water with detergent to remove label, food residue and surface contamination. The wash temperature is typically 80-95°C and the caustic concentration is 1-3% sodium hydroxide. The wash tank exhaust carries water vapour, caustic mist, detergent aerosol and trace VOC from the dissolved contaminants.

The HVAC specification includes the following.

Localised extract at every wash tank and rinse stage. Capture hood over the tank with 0.3-0.5 m/s capture velocity at the hood face. The extract velocity in the duct is 8-12 m/s because the air carries water mist that has to remain entrained.

Caustic mist scrubber on the discharge. Wet scrubber sized for caustic mist absorption, with neutralising water recirculation. The scrubber discharge pH is monitored continuously. 304L stainless construction with PTFE gaskets.

304L stainless ductwork on the wet section. The wet section is the duct run from the wash tank hood to the scrubber inlet. The duct material is 304L stainless with PTFE gaskets. Galvanised duct will corrode rapidly in caustic mist service.

Insulated duct with weep drainage. The water vapour condenses on the duct wall during cooler periods and the condensate drains to a low-point drain. The duct is insulated to prevent condensation on the outside and to maintain the wall temperature above the dewpoint.

Ventilation of the wash hall. General dilution at 10-15 ACH because of the humidity and heat. The wash hall is typically a separate building or fire-rated compartment.

Plastic recycling — density separation and air classifier HVAC

Float-sink density separation and air classifier separation are intermediate stages between the wash plant and the repelletiser. Float-sink uses the density difference between PET (1.38 g/cm³, sinks) and HDPE/PP (less than 1 g/cm³, floats) to separate mixed plastic streams. Air classifier uses an air stream to separate by terminal velocity rather than density.

The HVAC profile is dominated by dust extraction. Air classifier inherently uses an air stream and the discharge stream carries dust that is captured downstream of the classifier. Float-sink generates dust at the dry handling stage before and after the wet separation.

Bag filter on the air classifier discharge sized for the polymer dust profile. NFPA 660 explosion venting where the polymer mix triggers combustible dust classification. Spark-resistant fans. Bonded electrical grounding.

Antistatic-treated galvanised ductwork. General dilution at 10-12 ACH at the broader sorting hall.

Plastic recycling — crystallisation and SSP HVAC

Food-grade PET recycling (rPET) requires a solid-state polymerisation (SSP) reactor downstream of the wash and repelletise stages. The SSP process re-builds the molecular weight of the recycled PET pellet by heating at 180-220°C under vacuum or nitrogen purge for 8-12 hours. The recycled pellet is upgraded from a mechanical recycle stream to a food-contact grade pellet.

The crystalliser upstream of the SSP reactor pre-crystallises the wet pellet at 160-180°C to prevent agglomeration during the SSP cycle. The crystalliser exhaust carries water vapour and minor PET dust. Galvanised ductwork with insulated section.

The SSP reactor operates under vacuum or under nitrogen blanket. The vacuum pump discharge or the nitrogen vent discharges to atmosphere through a roof stack. The exhaust is hot (180-220°C) and is treated through aluminised steel or 304L stainless ductwork.

The crystallisation and SSP hall is typically a separately conditioned compartment because of the heat load and the nitrogen blanket. Oxygen monitoring at the operator working positions with alarm trip — the nitrogen vent in confined space is a confined-space asphyxiation hazard.

Plastic recycling — pyrolysis chemical recycling HVAC

Pyrolysis chemical recycling is the most recent addition to the Australian plastic recycling chain. Pyrolysis converts mixed end-of-life plastic — typically the residual stream after mechanical recycling has separated the high-value PET and HDPE — into pyrolysis oil, gas and char. The pyrolysis oil is upgraded by hydrotreatment or by direct cracking to produce naphtha, diesel and other refinery feedstocks. The major Australian operators in this segment include APR Plastics, Plastic Energy, Licella Hot Bottle and a number of newer pilot-to-commercial plants now in construction.

The pyrolysis reactor operates at 350-450°C in an inert atmosphere (nitrogen or recycled pyrolysis gas). The pyrolysis gas is a complex mixture of light olefin, aromatic, oxygenate and water vapour. The HVAC and process exhaust system is the most demanding duty on any plastic recycling plant.

The HVAC specification includes the following.

Zone 1 hazardous area classification per AS/NZS 60079. The reactor zone and the condensation train are classified Zone 1 for the inflammable pyrolysis gas. Electrical equipment selection per the zoning. Hazardous area duct construction with conductive bonded grounding.

304L stainless ductwork throughout the pyrolysis gas extract path. The temperature (350-450°C at the reactor outlet) and the chemical reactivity rule out galvanised. 304L stainless is the standard, with PTFE gaskets at every flange and welded seams on the high-stress runs.

Dedicated flare or RTO for off-gas. The pyrolysis off-gas (the lighter fraction not captured in the condensation train) is combusted in a flare or in a regenerative thermal oxidiser. The flare or RTO inlet plenum is welded 304L stainless to AS/NZS 4254 leakage class A. The SBKJ SB-ZF1500 stitchwelder is the recommended machine for the welded stainless plenum.

Continuous gas monitoring with alarm trip to reactor shutdown. The reactor zone is continuously monitored for combustible gas, oxygen and the specific pyrolysis gas components. Alarm trip to reactor shutdown is hard-wired to the safety instrumented system per AS 61511.

AS 1940 flammable liquid handling on condensate. The pyrolysis oil condensate is a flammable liquid by AS 1940 classification. Storage, transfer and bay HVAC follow AS 1940. The condensate handling area is typically Zone 1 or Zone 2 depending on the design pressure and the leak rate.

General dilution at the pyrolysis hall. 10-15 ACH at the broader hall, with the high-rate extract concentrated at the source-capture zones. Operator entry through air lock vestibule. PPE handling room with separate ventilation.

Pyrolysis chemical recycling HVAC specification should always be developed with input from a process safety engineer with pyrolysis-specific experience. The downstream consequences of a pyrolysis gas release include fire and explosion risk, regulator action and significant cost.

E-waste plastic recovery HVAC

E-waste plastic recovery — recovering ABS and HIPS housings from PCs, TVs, white goods and other waste electrical and electronic equipment — overlaps with the broader WEEE recovery chain. The plastic separation stage follows the metal and component recovery stage. The HVAC duty on the plastic recovery is similar to general plastic recycling shred and granulate, with additional consideration for brominated flame retardant (BFR) content in older WEEE plastic streams.

BFR content in older WEEE plastic releases HBr trace fume during high-temperature processing. The HVAC specification includes localised extract over any heated processing stage, 304L stainless ductwork on the hot runs, and scrubber treatment on the discharge.

Antimony trioxide synergist content (commonly used with BFR) drives the 0.5 mg/m³ WES — the source capture at the dust handling stage is sized for the worst-case antimony loading.

Regenerative thermal oxidiser RTO and abatement HVAC

The regenerative thermal oxidiser (RTO) is the standard abatement technology for plastic plant VOC at moderate to high tonnage. The RTO combusts the VOC at 800-1000°C in a thermal oxidation chamber, with ceramic regenerative beds recovering the combustion heat to pre-heat the inlet stream. RTO is used on decoration line VOC, on pyrolysis off-gas, on PVC processing where the combined extract justifies thermal treatment, and on some PU casting installations.

The HVAC specification for the RTO includes the following.

RTO inlet plenum to AS/NZS 4254 leakage class A. The inlet plenum is welded 304L stainless steel, with insulation rated for the operating temperature, sized for the worst-case process release plus the RTO purge cycle. The plenum is fabricated to leakage class A with a leakage test at commissioning. The SBKJ SB-ZF1500 stitchwelder is the standard machine for plenum fabrication.

Combustible gas detection on the inlet stream. The inlet stream concentration is monitored to prevent operation at concentrations above 25% of the lower explosive limit (LEL). Alarm trip to dilution air injection or to system shutdown.

Insulated stack on the outlet. The RTO outlet temperature is typically 300-500°C after heat recovery. The outlet stack is aluminised steel or 304L stainless with insulation, terminated to AS 1668.2 stack discharge requirements.

The RTO is typically located outside the building or in a separate building because of the size and the noise. The RTO inlet plenum and the outlet stack are the only HVAC duct elements that connect through the main process building envelope.

Office, amenity and workshop HVAC

The office and amenity blocks attached to a plastic plant follow standard commercial HVAC practice — galvanised G90 ductwork, general dilution at 6 L/s per person per AS 1668.2, fan-coil or variable air volume terminal units, comfort cooling and heating to 22°C ±2°C. The interface with the production hall HVAC is the dominant HVAC consideration — the office and amenity block are positively pressurised relative to the production hall to prevent process odour and dust migration into the office. AS 1530.4 fire-rated ductwork at the boundary between office and production hall.

The workshop and tool fab attached to the plant for in-house mould steel work follows the broader steel fabrication HVAC framework — refer to our dedicated steel fabrication guide. The dominant HVAC duties are welding fume extraction at every welding station, machining coolant mist extraction at every machine tool, and general bay ventilation.

Pressure cascade and fire compartment design

A modern plastic plant operates a pressure cascade across multiple zones with different cleanliness, contamination and fire load requirements. The pressure cascade is a fundamental design element — done correctly it directs airflow from clean to less clean and contains process emissions to the source zone; done incorrectly it allows process odour and contamination to migrate into the office and amenity blocks.

A typical pressure cascade for an Australian plastic plant is as follows.

Most positive — office and amenity blocks. Positively pressurised relative to corridors and the production hall by 10-25 Pa. Outside air supply sized per AS 1668.2 occupancy plus a balance flow to maintain the differential.

Slightly positive — production hall general. Slightly positive relative to corridors and external by 5-10 Pa, to prevent dust ingress.

Slightly negative — dedicated process zones. The compounding hall, the calendering hall, the PVC processing zone, the decoration line and the PU casting zone are slightly negative relative to surrounding spaces by 5-25 Pa to contain process emissions to the zone.

More negative — strict containment. The PU casting zone (PU isocyanate STEL 0.005 ppm) is held 25-50 Pa negative. The pyrolysis reactor zone is held at process pressure with confined-space monitoring at the operator working positions.

Most negative — exhaust collection. The dust collector, the scrubber and the RTO are at the most negative point in the cascade — the suction side of the extract fan.

Fire compartment design follows the National Construction Code Volume One (Building Code of Australia) and AS 1530.4. Plastic plants typically have multiple fire compartments — the production hall, the office and amenity, the warehouse, the compounding hall, the PVC processing zone, the PU casting zone, the pyrolysis hall and the broader chemical zones. Each compartment boundary is fire-rated. Ductwork penetrating a fire compartment boundary is fire-rated to AS 1530.4 with fire dampers per AS 1851 routine service.

Energy efficiency and the operating cost picture

Plastic plant HVAC is typically the third or fourth largest energy consumer on the site after the moulder or extruder motors, the chiller and the compressor. A 5,000 m² plastic plant in Melbourne climate typically consumes 200-400 kW of HVAC fan, chiller and air handling power at peak summer, with annual energy consumption in the order of 600-1,200 MWh on HVAC alone. The opportunities for reduction are well-documented.

Heat recovery from process exhaust. The dehumidifier dryer exhaust, the injection moulder cooling tower discharge and the extruder die face extract are all warm air streams that can pre-heat winter make-up air through a sealed plate-and-frame heat exchanger. Typical heat recovery of 60-75% sensible.

Variable frequency drive on fan motors. The HVAC fan motors are typically continuously rated and are sized for peak duty. VFD control to match the actual duty cycle delivers 30-50% fan energy reduction over fixed-speed operation. AS 1668.2 dilution rates are reduced during low-occupancy hours.

Sealed dampers and tight ductwork. AS/NZS 4254 leakage class A or B on the supply and return ducts reduces fan energy and improves zone pressure stability. Sealing class C and below are increasingly considered substandard on new construction.

Outside air free cooling. Melbourne climate has approximately 2,500 hours per year of outside air below 18°C — sufficient for free cooling of the production hall during cooler periods. The AHU economiser cycle delivers 20-30% chiller energy reduction over a continuous mechanical cooling operation.

Demand-controlled ventilation. CO2 monitoring at the office and the production hall, with VAV control of the outside air component, delivers a further 10-20% reduction over fixed-rate ventilation.

The ISO 14001 environmental management system is the standard framework for tracking and reporting HVAC energy and emissions. The major Australian plastic plant operators (Amcor, Pact, Orora, Cleanaway) all operate ISO 14001 certified sites with annual energy and emission reporting against documented targets.

Materials specification matrix — duct by zone

The single most common rework item we see at plastic plant HVAC commissioning is a duct material specification that does not match the process duty. The matrix below covers the typical zone-by-zone specification.

General supply and return — galvanised G90 to AS/NZS 4254. Standard galvanised duct construction. Pressure class 500 Pa positive, 250 Pa negative. Sealing class C or B per AS/NZS 4254. Applicable to all production hall general HVAC, office and amenity blocks, mould storage and the broader non-process zones.

Injection, blow, extrusion process heat extract — galvanised G90 or aluminised steel for elevated temperature. Galvanised acceptable up to 150°C operating temperature. Aluminised steel for sustained operating temperature 150-300°C — relevant on dehumidifier dryer exhaust intermediate runs and on hot extruder bay exhaust.

PVC HCl scrubber and PVC processing exhaust — 304L stainless steel with PTFE or EPDM gaskets. Galvanised is not acceptable in HCl service — zinc coating dissolves rapidly. 304L stainless with PTFE gaskets is the standard. 316L stainless is the upgrade for harshest HCl service. Welded seams preferred on the high-stress runs.

Polyurethane isocyanate scrubber — 304L stainless steel with HEPA H13 final filter. Galvanised is not acceptable in PU isocyanate service. 304L stainless with PTFE gaskets, HEPA H13 final filter in a welded stainless plenum to AS/NZS 4254 leakage class A. The SBKJ SB-ZF1500 stitchwelder is the standard machine for the plenum fabrication.

Plastic recycling wash plant caustic scrubber — 304L stainless steel with PTFE gaskets. Galvanised is not acceptable in caustic mist service. 304L stainless with PTFE gaskets. Insulated duct with weep drainage on the wet section.

Pyrolysis pyrolysis-gas extract — 304L stainless steel, Zone 1 hazardous area to AS/NZS 60079. The temperature and chemical reactivity rule out galvanised. 304L stainless with welded seams on the high-stress runs. Conductive bonded grounding throughout for the Zone 1 classification.

Polymer dust extraction — antistatic-treated galvanised or 304L stainless with bonded grounding. Where NFPA 660 dust hazard analysis triggers combustible dust classification, the duct material is antistatic-treated or 304L stainless with continuous bonded grounding. Spark-resistant fans on the extract. Duct velocity 18-22 m/s.

Formaldehyde scrubber on phenolic moulding — 304L stainless steel. Galvanised not acceptable in formaldehyde service. 304L stainless with PTFE gaskets.

RTO inlet plenum and outlet stack — welded 304L stainless steel to AS/NZS 4254 leakage class A. The high operating temperature and the requirement for low leakage drive the welded stainless specification. The SBKJ SB-ZF1500 stitchwelder is the recommended machine.

SBKJ duct fabrication machinery for the Australian plastic plant

SBKJ Group manufactures three core machine families that cover the duct fabrication requirements of a typical Australian plastic or polymer manufacturing facility. Each machine is supplied in 380V/50Hz Australian configuration with English-language documentation, ISO 9001 manufacturing certification, CE certification on the electrical and safety systems, and after-sales support from the SBKJ Australian office at Box Hill North Victoria.

SBAL-V Auto Duct Production Line

The SBAL-V coil-fed auto duct production line is the workhorse for rectangular duct fabrication on every plastic plant in the SBKJ customer base. The line takes galvanised, aluminised or 304L stainless steel coil through a single-pass process that includes cut-to-length, corner notching, longitudinal Pittsburgh seaming and TDF flange forming. Throughput is typically 8-15 metres per minute on standard galvanised G90 at 0.8-1.2 mm gauge, with reduced throughput on 304L stainless and on heavier gauge applications.

For the Australian plastic plant, the SBAL-V handles the general supply and return ductwork (galvanised G90), the injection and blow moulding bay process heat extract (galvanised), the extrusion line heat extract (galvanised), the dehumidifier dryer intermediate runs (aluminised), and the 304L stainless duct serving PU isocyanate scrubber, PVC HCl scrubber, recycling wash plant caustic scrubber and formaldehyde scrubber paths. The SBAL-V swap from galvanised to stainless is a tooling change of approximately 30 minutes — a single line can handle the full material mix on a typical plastic plant. Read the SBAL-V technical specification.

SBTF Spiral Tubeformer

The SBTF spiral tubeformer produces round spiral duct from galvanised, aluminised or 304L stainless coil. Plastic plant applications include general process exhaust runs, dust extraction return air on the polymer compounding and recycling shred lines, dehumidifier dryer exhaust on the cooler downstream sections, and OOA cure oven exhaust on the broader composite-adjacent installations. The SBTF handles diameters from 80 mm to 1500 mm depending on configuration. Round spiral duct is the preferred geometry for high-velocity dust extraction service because the seam strength is higher than rectangular duct at equivalent gauge.

SB-ZF1500 Stitchwelder

The SB-ZF1500 stitchwelder produces welded stainless plenums and welded stainless duct for the highest-leakage-class duct fabrication. Plastic plant applications include the RTO inlet plenum (the most common application), the PU isocyanate scrubber plenum, the PVC HCl scrubber plenum, the recycling wash plant caustic scrubber plenum, and the pyrolysis pyrolysis-gas extract plenum. The SB-ZF1500 produces seams to AS/NZS 4254 leakage class A on 304L stainless at 1.2-3.0 mm gauge. The welded plenum is the standard specification on every high-toxicity or high-temperature duty in a plastic plant.

SBPC1500 Plasma Cutter

The SBPC1500 plasma cutter handles the cut-to-shape and the access door fabrication on every fabrication run. Plastic plant applications include access door cutting on every duct run per NFPA 91 framework, cut-out for fire damper installation, and the broader plate-cut work for plenum fabrication.

SBLR-600 Welder

The SBLR-600 welder is the standard machine for site welding and shop welding of stainless duct sections. Plastic plant applications include the final assembly weld at every flange and at every transition piece on the stainless duct runs serving scrubber and pyrolysis duties.

Spark-resistant fans for NFPA 660 service

Where NFPA 660 dust hazard analysis triggers combustible polymer dust classification (PE, PP, ABS dust in compounding and recycling shred lines), the SBKJ ductwork is paired with spark-resistant fans, bonded electrical grounding throughout the dust extraction system, and explosion-rated dust collectors per NFPA 68 deflagration venting. The spark-resistant fan specification is mandatory and is not a customer-optional upgrade in combustible dust service.

For a typical Australian plastic plant or recycling plant the standard SBKJ machinery configuration is the SBAL-V auto duct production line plus the SBTF spiral tubeformer plus the SB-ZF1500 stitchwelder, with the SBPC1500 plasma cutter and SBLR-600 welder as ancillary machines. Lead time from purchase order to Factory Acceptance Test is 90-120 days, plus 35-45 days ocean freight to Melbourne, Sydney, Brisbane, Adelaide or Fremantle, plus 2-3 weeks for installation and commissioning by SBKJ engineers at the customer's Australian facility. Total project timeline from purchase order to first production duct is 6-8 months.

SBKJ Group will be exhibiting at ARBS 2026 in Sydney under the Australia Ducting Pty Ltd entity, exhibitor identifier 236. Our engineering team will be available to discuss plastic plant HVAC specifications, machinery configuration and any specific commissioning challenges across the full SBKJ product range. See the full SBKJ machinery range.

Commissioning and handover programme

Plastic plant HVAC commissioning is more demanding than standard commercial HVAC commissioning because the compliance burden is higher and the process tolerance bands are tighter. A complete commissioning programme for a plastic plant covers nine domains.

Capture velocity verification at every source-capture hood. Hot-wire anemometer measurement at the hood face under actual operating conditions, compared against the design capture velocity from ASHRAE Applications Chapter 33 or the bespoke design calculations. Failure to meet design capture velocity requires hood rework, fan resizing or duct rebalancing.

Dust load testing under simulated throughput. Dust collector duty cycle confirmation at the design throughput of polymer dust at the compounding additive dosing station and at the recycling shred line. HEPA filter integrity testing per ISO 14644 framework or the equivalent.

Isocyanate breakthrough testing on PU scrubber. Continuous TDI/MDI monitoring at the PU scrubber discharge, confirming the discharge concentration is below 0.005 ppm STEL under representative casting throughput. Breakthrough testing extended over a 24-hour cycle at the worst-case casting rate.

HCl breakthrough testing on PVC scrubber. Continuous HCl monitoring at the PVC scrubber discharge, confirming the discharge concentration is below 5 ppm STEL under representative PVC processing temperature excursion simulation. The scrubber recirculation pH is logged for the test period.

Pyrolysis gas alarm trip test. Combustible gas detector challenge test at every monitor station on the pyrolysis reactor zone, confirming alarm trip to reactor shutdown within the specified time. Hard-wired safety instrumented system trip test per AS 61511.

Polymer dust explosion vent inspection. Visual inspection of every deflagration vent on the dust collectors and silos, confirming the vent area, the vent latch and the discharge direction. The deflagration vent is sized per NFPA 68 calculation for the worst-case dust deflagration.

Pressure cascade verification. Differential pressure measurement at every doorway and pass-through between zones, confirming the design pressure cascade — office positive, production hall slightly positive, dedicated process zones slightly negative, PU and pyrolysis containment zones more negative.

24-hour stability run. Continuous data logging of temperature, humidity, pressure cascade and capture velocity over a 24-hour period under representative production load. Out-of-band events trigger HVAC rework before handover.

As-built drawing pack with material certificates. Complete as-built drawings to AS/NZS 4254 with material certificates for every duct material specification, gasket material specification, scrubber liner material specification and HEPA filter rating certificate. Ten-year retention on the documentation pack.

Construction lead time and project planning

A new plastic plant or plastic recycling plant HVAC build-out is a 12-24 month programme from concept to commissioning. The major milestones and typical durations are summarised below.

Concept and feasibility (months 1-3). Process flow definition, building envelope sizing, HVAC concept sizing, statutory authority pre-application, cost plan. The HVAC concept sizing is the foundation for every downstream design decision and a poor concept causes rework at every later stage.

Detailed design (months 4-9). Duct routing, AHU and chiller plant sizing, dust collector and scrubber sizing, controls and safety instrumented system design, statutory authority development application, building permit issue. The HVAC designer is typically a specialist consultant with plastic plant experience working with the plant operator and the prime building contractor.

Machinery procurement (months 6-12). Long-lead machinery including the SBAL-V auto duct production line, the SBTF spiral tubeformer, the SB-ZF1500 stitchwelder, the dust collector, the scrubber and the HEPA filter modules. SBKJ machinery lead time is 90-120 days plus 35-45 days ocean freight from Box Hill North dispatch. Procurement of the major plant items is typically run in parallel with detailed design.

Construction (months 10-18). Civil and structural construction, mechanical installation including duct, AHU, fan and process equipment, electrical installation, controls installation. The HVAC duct fabrication is typically run on-site at a fabrication shop adjacent to the production hall, with the SBAL-V auto duct production line operating during the construction phase. On-site fabrication is significantly faster than off-site fabrication and avoids transport damage on the duct sections.

Commissioning (months 18-22). Mechanical commissioning, electrical commissioning, controls commissioning, process commissioning under representative load. The commissioning programme described in the previous section runs through this phase.

Handover (months 22-24). Statutory authority sign-off, occupational hygiene baseline survey, operational training, documentation handover. First production run.

How SBKJ supports plastic and polymer manufacturing customers

SBKJ Group has supplied HVAC duct fabrication machinery to plastic and polymer manufacturing facilities across the Australian and global customer base — packaging majors, polymer compounders, PVC pipe extruders, PU foam panel manufacturers, plastic recyclers and the emerging pyrolysis chemical recycling segment. Our plastic plant customers typically use a combination of the SBAL-V auto duct production line, the SBTF spiral tubeformer and the SB-ZF1500 stitchwelder, configured for the specific duct material mix at the customer's facility.

• Materials capability — galvanised G90, aluminised steel, 304L stainless and aluminium coil on the SBAL-V and SBTF, with appropriate forming tooling for each material. Welded stainless plenum production on the SB-ZF1500 to AS/NZS 4254 leakage class A. SBKJ machinery range.
• Australian sales and engineering — Box Hill North Victoria office covers all Australian customers from initial RFQ through installation, commissioning and after-sales. ARBS 2026 exhibition under Australia Ducting Pty Ltd entity, exhibitor identifier 236.
• Lead time — 90-120 days from purchase order to Factory Acceptance Test on a complete duct line, plus 35-45 days ocean freight to Melbourne, Sydney, Brisbane, Adelaide or Fremantle.
• Installation and commissioning — 1-2 SBKJ engineers on site for 5-10 days for installation, mechanical commissioning and electrical commissioning, with operator and maintenance training included.
• After-sales — one-year wear-parts kit shipped with the machine, 72-hour remote support response, 10-year+ parts continuity guarantee, English-language service from the Australian office.
• Compliance — full ISO 9001 manufacturing, CE certification on electrical and safety systems, AS/NZS 4254 duct construction compliance, AS 1668.2 ventilation framework familiarity, NFPA 660 combustible dust framework familiarity.

Get an SBKJ quote for plastic plant HVAC duct machinery →

FAQ

What workplace exposure limits apply to plastic and polymer manufacturing HVAC design in Australia?

Safe Work Australia publishes the Workplace Exposure Standards (WES) that bind any Australian plastic processing plant. The headline numbers on every plastic plant HVAC brief are styrene at 50 ppm 8-hour TWA and 100 ppm STEL, formaldehyde 1 ppm STEL (relevant to phenolic and urea moulding compounds), polyurethane isocyanate TDI and MDI at 0.005 ppm STEL, HCl 5 ppm STEL (relevant to PVC overheated or burning), chlorine 0.5 ppm (PVC processing emission), antimony 0.5 mg/m³ (flame retardant additive), and respirable and inhalable dust at 10 mg/m³ inhalable with a respirable fraction limit additionally applied. PVC plants on legacy lines retain the vinyl chloride monomer (VCM) STEL of 1 ppm. AS 1668.2 sets the general dilution ventilation framework but does not replace the source-capture velocities required to hit WES at the worker breathing zone.

Is polymer dust combustible and when does NFPA 660 apply?

Polyethylene (PE), polypropylene (PP), ABS and many other thermoplastic dusts are combustible by NFPA 660 (formerly NFPA 484 + 654) classification. Dust deflagration index Kst values for PE and PP typically sit in the St-1 to St-2 range. Any plastic plant that handles polymer dust above the 1/32 inch layer threshold across more than 5 percent of the building footprint triggers a dust hazard analysis. The downstream consequences are explosion-rated dust collectors with NFPA 68 deflagration venting or NFPA 69 explosion prevention, spark-resistant fans on the dust extraction system, bonded electrical grounding on all dust ductwork, and AS 3957 dust hazard area zoning. Polymer compounding plants and plastic recycling shredding lines are the two facility types where this analysis is non-negotiable.

What duct material should be specified for plastic plant zones?

Five zone categories cover most Australian plastic plants. (1) General supply and return — galvanised G90 to AS/NZS 4254. (2) Injection moulding and extrusion process heat extract — galvanised or aluminised steel for elevated temperature. (3) PVC HCl scrubber and PVC processing exhaust — 304L stainless steel with PTFE or EPDM gaskets, sized for HCl mist service. (4) Polyurethane isocyanate scrubber — 304L stainless steel with HEPA H13 final filter, mandatory for TDI/MDI at 0.005 ppm STEL. (5) Plastic recycling wash plant caustic scrubber and pyrolysis pyrolysis-gas extract — 304L stainless with hazardous area zoning per AS/NZS 60079. Polymer compounding additive dust extraction is antistatic-treated galvanised or stainless with bonded grounding and spark-resistant fans where the dust hazard analysis triggers NFPA 660.

How is hygroscopic resin dryer exhaust handled?

Hygroscopic resins — PET, polyamide nylon, polycarbonate, ABS, PMMA acrylic — are dried at 80-120°C with adsorption desiccant wheel dryers maintaining dewpoint below minus 40°C (typically below 50 ppm moisture). The dryer exhaust carries water vapour, dust shedding from the resin pellets and minor VOC release from any moisture-driven oligomer breakdown. The exhaust ductwork is galvanised for the cooler downstream sections and aluminised steel or 304L stainless for the section closest to the dryer where temperature peaks. The exhaust is typically discharged to atmosphere through a roof stack — recirculation back to the dryer regeneration loop is acceptable on closed-cycle desiccant systems but is not appropriate on process zone exhaust runs.

What is the HVAC treatment for polyurethane PU foam casting?

Polyurethane PU foam casting (rigid foam for insulation panels, flexible foam for furniture and mattresses) is the most chemically demanding HVAC duty in any plastic plant. The Safe Work Australia WES for TDI and MDI isocyanate is 0.005 ppm STEL — five thousand times stricter than the styrene STEL. The HVAC specification is mandatory source capture at every casting station, wet scrubber sized for isocyanate aerosol removal with caustic solution, HEPA H13 final filter as a polishing stage, 304L stainless ductwork with PTFE gaskets, dedicated exhaust stack with continuous monitoring, and dedicated PPE handling room with negative pressure cascade. Recirculation back into the workplace is prohibited. This duty cycle should always be specified by an industrial hygienist with PU-specific experience.

How does plastic recycling differ from virgin plastic plant HVAC?

Plastic recycling adds three duty cycles that virgin plant HVAC does not face. First, the shredding and granulating line handles dirty plastic with food, label, dust and grit contamination — dust extraction at the shredder discharge is much higher tonnage than virgin pellet handling, and the dust is combustible per NFPA 660. Second, the wash plant for PET bottle recycling uses sodium hydroxide and hot water with detergent — the wash tank exhaust requires caustic mist scrubber and 304L stainless ductwork. Third, pyrolysis chemical recycling (the APR Plastics, Plastic Energy and similar plants turning end-of-life plastic into fuel or feedstock) produces pyrolysis gas at the reactor and condensation zones — extract ductwork is 304L stainless with AS/NZS 60079 Zone 1 hazardous area classification, dedicated flare or RTO for off-gas, and continuous gas monitoring. The HVAC budget on a recycling plant is typically 30-50 percent higher than a comparable virgin plant of the same throughput.

What duct fabrication machinery does an Australian plastic plant operator typically need?

Three SBKJ machine families cover the duct fabrication requirements of a typical Australian plastic and polymer manufacturing facility. The SBAL-V auto duct production line forms galvanised supply and return ductwork plus the process heat extract from injection, blow moulding and extrusion bays at high throughput. The SBTF spiral tubeformer produces round duct for general process exhaust, dust extraction return air and dehumidifier exhaust. For 304L stainless ductwork serving PU isocyanate scrubber, PVC HCl scrubber, recycling wash plant caustic scrubber, and pyrolysis pyrolysis-gas extract, the SBAL-V handles stainless coil with adjusted forming tooling, and the SB-ZF1500 plenum stitchwelder produces the welded stainless plenums and RTO inlet plenums to AS/NZS 4254 leakage class A. Where polymer dust extraction triggers NFPA 660, the SBKJ duct is paired with spark-resistant fans and bonded electrical grounding.

What is the typical lead time for HVAC duct machinery for an Australian plastic plant?

For a typical Australian plastic plant or recycling plant — SBAL-V auto duct production line plus SBTF spiral tubeformer plus SB-ZF1500 stitchwelder for stainless plenums — plan 90-120 days from purchase order to Factory Acceptance Test, plus 35-45 days ocean freight to Melbourne, Sydney, Brisbane, Adelaide or Fremantle, plus 2-3 weeks for installation and commissioning by SBKJ engineers on site. Total project timeline from PO to first production duct is 6-8 months. SBKJ Group has Australian sales and engineering at the Box Hill North Victoria office, with the next ARBS 2026 trade show appearance under the Australia Ducting Pty Ltd entity, exhibitor identifier 236.