Insights · Plastics Manufacturing HVAC

Plastics Manufacturing HVAC Duct Guide — Injection, Blow Moulding, Extrusion, Thermoforming and Rotomoulding

A working engineer's reference for HVAC ductwork in Australian plastics manufacturing plants — press hood capture for injection and blow moulding, extrusion line LEV, thermoforming oven extract, rotational moulding kiln exhaust at 250 to 350 C, regrind dust capture to NFPA 654, polyurethane isocyanate handling to a workplace exposure standard of 0.005 ppm, PVC compounding acid-vapour service, and the duct construction codes (AS 1668.2, AS 4254, AS 1530.4) that govern every project from the smallest Bayswater moulder to the largest Iplex pipe extrusion line.

By · Published · 38 min read · Reviewed by SBKJ QA & Engineering

Why plastics manufacturing HVAC is its own discipline

Walk into any reasonably sized injection moulding hall in Dandenong, Smithfield or Wacol on a still summer afternoon and you can read the HVAC design from the shop floor without consulting the drawings. If the canopies above the presses look like an afterthought and the operators have moved their fans to the same three positions year after year, the system was designed for the building, not the process. If the canopy is engineered for the specific press tonnage and the platen geometry, with branch ducts sized to maintain transport velocity right back to the header, and a dedicated cooling air supply terminating at low level near the operator station, the engineer who specified it understood that plastics manufacturing HVAC sits in a category of its own.

The discipline is its own because the process exposes the ductwork to a peculiar combination of conditions found nowhere else in light manufacturing. Melt temperatures from 180 C for low-density polyethylene through to 380 C for fluoropolymers and high-temperature engineering thermoplastics. Combustible dust from regrinding and granulating that can deflagrate at concentrations as low as 30 grams per cubic metre. Acidic vapour from polyvinyl chloride compounding. Isocyanate fume from polyurethane reaction injection moulding at workplace exposure standards orders of magnitude tighter than common workshop contaminants. Sensible heat loads ranging from 30 to 150 kilowatts per press depending on tonnage, throughput and resin. Cleanroom-grade hygiene demands on medical and food-contact mould cells. And alongside all of this, the dull but financially critical reality that plastics manufacturing margins are thin, energy is the second largest controllable cost after resin, and the HVAC system either pays its way or it loses the operator money every shift.

This guide is the working reference SBKJ engineers use when scoping ductwork machinery for plastics plant projects across Australia and the broader Asia-Pacific region. It is written for the consulting mechanical engineer specifying a new injection moulding facility, the project manager planning an extrusion line relocation, the works engineer at an existing plant trying to fix capture problems on a 20-year-old hood arrangement, and the operator commissioning a new rotational moulding cell. Where SBKJ machinery is the right tool we say so, with the actual specifications and the duct quantities the project will need. Where the project needs something off-machine, like glass-reinforced polyester for a PVC compounding line, we say so as well.

The structure of this guide follows the process. We start with the press hall — injection, blow, extrusion, thermoforming, rotational moulding — because that is where the heat and fume capture problem dominates. We then work outward into material handling, regrind, decorating and finishing, ending with cleanroom medical and food-contact moulding which are growing fast on the back of contract manufacturing for medical device and packaging clients. The Australian operator landscape is covered explicitly, because every project has to reference the way the resident Australian plastics processors run their plants. SBKJ machine recommendations are integrated through the text and consolidated at the end.

Injection moulding press halls — the hood capture problem

The injection moulding press is the workhorse of Australian plastics manufacturing. From the small 50 tonne presses at a custom moulder in Reservoir to the 4,000 tonne presses at Pact Group's structural moulding operations, the basic HVAC problem is the same: capture heat and fume rising off the barrel, the nozzle, the mould face and the freshly demoulded part, before either reaches the operator or accumulates under the building roof.

The fume composition depends on the resin. Polyethylene and polypropylene running at 180 to 240 C produce light hydrocarbon vapour, organic acids from antioxidant breakdown and trace aldehydes. Polystyrene and ABS at 200 to 260 C add styrene monomer and butadiene at trace levels, with styrene being the most consequential because the Safe Work Australia workplace exposure standard is 50 parts per million TWA. Polycarbonate at 280 to 320 C and nylon (PA6 and PA66) at 260 to 320 C add bisphenol A and caprolactam respectively. Polyvinyl chloride at 180 to 210 C generates hydrogen chloride if the melt is overheated, which is why PVC injection is run with tight temperature discipline and dedicated acid-resistant LEV. Engineering thermoplastics like polybutylene terephthalate (PBT), polyetheretherketone (PEEK) and polyphenylene sulfide (PPS) running above 300 C produce more complex fume mixtures requiring case-by-case capture assessment.

Capture velocity at the hood face for a standard thermoplastic press follows the ASHRAE Applications Chapter 33 industrial ventilation guidance, with the AS 1668.2 building-level dilution overlay:

  • Standard commodity thermoplastics (PE, PP, PS, ABS): 0.5 to 1.0 m/s capture velocity at hood face. Lower end for small presses and quiet workshops, upper end for high-throughput halls with significant operator presence.
  • Engineering thermoplastics (PC, PA, PBT): 1.0 to 1.5 m/s. The higher melt temperatures drive more vigorous fume rise and the more complex fume chemistry justifies higher capture margin.
  • High-temperature thermoplastics (PEEK, PPS, fluoropolymers): 1.5 to 2.0 m/s, with hood enclosure preferred over canopy capture.
  • PVC injection: 1.0 to 1.5 m/s with acid-resistant duct construction. Enclosed hood preferred to prevent HCl release at any point.
  • Polyurethane RIM: 1.5 to 2.5 m/s at the access opening of a fully enclosed cell. Capture is at the enclosure boundary, not at the press itself.

The exhaust volume per press is then calculated by multiplying the capture velocity by the effective hood face area, with adjustment for the cross-draught factor at the hood elevation. For a typical 200 tonne press with a 1.2 m by 2.0 m hood positioned 1.5 m above the platens, design capture velocity 0.8 m/s, the exhaust volume is approximately 6,900 m3/h per press, or roughly 1.9 m3/s. Scale this across 30 to 50 presses in a medium-sized hall and the combined exhaust runs 60,000 to 100,000 m3/h, which is the design basis for the AHU and the heat recovery scope.

Branch duct sizing applies the transport velocity discipline. For thermoplastic fume without significant particulate, transport velocity 8 to 12 m/s in horizontal branches is adequate. Where fines from mould flash or runner regrind have a chance of entering the duct, transport velocity is uplifted to 12 to 15 m/s to prevent settling. The header velocity is typically 10 m/s, balancing fan pressure rise against material cost. Galvanised steel to AS 1397 G275 coating, 0.8 mm gauge for branches up to 400 mm equivalent diameter, 1.0 mm gauge for 400 to 800 mm, 1.2 mm above 800 mm is the standard build for a Class B sealed duct system to AS 4254.

The press cooling air supply is the other half of the equation. Operators standing in front of a 280 C barrel for an 8-hour shift cannot work without local cooling air, and the difference between a well-designed cooling supply and a poorly-designed one is roughly 5 to 8 percent of plant productivity. Cooling air supply is typically a low-level supply terminal at operator chest height, delivering 22 to 24 C conditioned air at face velocity 0.3 to 0.5 m/s, sized for the operator's working position rather than the press itself. This is the air that the operator feels, and it is the air that determines whether the hood capture is sufficient or whether the press hall ventilation is fighting the operator's local environment.

Blow moulding — parison cooling air supply and heat extract

Extrusion blow moulding produces hollow plastic parts — bottles, jerry cans, water tanks, technical containers — by extruding a tubular parison of molten plastic and inflating it inside a closed mould. Injection blow moulding is the variant for smaller, higher-precision parts like pharmaceutical bottles. Stretch blow moulding is the dominant route for PET bottles and is the process behind every PET preform-to-bottle conversion line at Visy, Pact Reuse and the rest of the Australian beverage packaging supply chain.

The HVAC challenge in blow moulding is twofold. First, the parison cooling air supply: as the parison emerges from the die head it must cool partially before the mould closes, and a controlled supply of conditioned air to the parison zone is part of the process control. Cooling air is typically conditioned plant air at 18 to 22 C dry-bulb, delivered at 1 to 3 m/s velocity across the parison length, with relative humidity controlled to below 60 percent to prevent condensation on the cold mould surfaces. Second, the heat extract from the mould region: the mould itself rejects heat from each cycle to either cooling water or air-cooled circuits, and ambient air around the mould heats up rapidly without adequate extract.

Typical specifications for a medium-sized blow moulding hall running 6 to 15 machines on PET bottle production:

  • Hall dilution: 8 to 15 ACH, biased toward the higher end where stretch blow with PET preform reheat is the dominant process because the preform infrared heater banks add significant sensible heat to the room.
  • Parison cooling air supply: dedicated conditioned air at 18 to 22 C, delivered through ducted terminals at each die head, total volume 500 to 1,200 m3/h per blow moulding head depending on parison length and resin.
  • Mould region extract: capture hood at the mould platen elevation, capture velocity 0.5 to 0.8 m/s at hood face, total extract 1,500 to 3,500 m3/h per machine.
  • Trimming station extract: waste plastic flash falls into chutes and is conveyed pneumatically to granulators. The conveying path is dust LEV per NFPA 654 (see regrind section below).
  • Pre-form heater bank extract: for stretch blow lines, the infrared preform heater bank generates 50 to 150 kW of radiant heat plus convective rise from the preform itself. Capture hood above the heater bank, transport ducting in galvanised, terminating at the hall return system or dedicated exhaust depending on heat recovery scheme.

Visy Industries operates extensive PET preform and bottle production at facilities including their Coolaroo facility in north Melbourne and the larger preform operations supplying their beverage customer base. The HVAC architecture at these facilities reflects a mature understanding of stretch blow moulding ventilation: dedicated cooling air supply to the preform reheat zone, mould region extract sized to the cycle rate, and heat recovery from combined exhaust feeding plant pre-heat duty. Pact Reuse, with its returnable plastic container production, runs a similar HVAC architecture across its Mulgrave-headquartered network. Aeropak's aerosol container production at Hallam in southeast Melbourne uses injection blow moulding for the aluminium-replacement plastic aerosol bodies, with HVAC tailored to the smaller machine population and tighter cleanliness requirement.

Extrusion lines — PE, PP, PVC, PET pipe and profile

Extrusion is the dominant plastics process for continuous products — pipe, profile, sheet, film, monofilament. The extruder takes resin pellets, melts and pressurises them through a screw barrel, and forces the melt through a die at the end. Extrusion melt temperatures span 180 C for LDPE film through 280 C for PET monofilament and approaching 300 C for some engineering polymer profiles. The Australian plastics pipe industry — Iplex Pipelines (part of Fletcher Building) at facilities in Sydney, Melbourne, Brisbane and Perth, Vinidex (part of Aliaxis), Polypipe Australia and several smaller pipe extruders — runs continuous extrusion lines for HDPE, PP, PVC and multilayer composite pipe at scales from small instrument tubing through to 1200 mm and above water and gas main pipe.

The HVAC challenge on an extrusion line is concentrated at three points along the line. First, the die head where the melt exits the extruder and enters the cooling tank or air cooling section. Heat and fume rise vigorously from the die. Second, the cooling tank or air ring, where evaporative cooling water adds humidity to the room air and where any solvent or surfactant from the cooling fluid joins the air. Third, the take-off and cutting station, where dust from any sawing, punching or kerfing operations is generated.

Capture and dilution specifications for a typical Australian PE or PP pipe extrusion line running 200 to 800 kg/h throughput:

  • Die head capture: canopy hood above the die exit, capture velocity 1.0 to 1.2 m/s at hood face, hood face area sized for the die diameter plus 200 mm margin on each side. Total capture volume 1,500 to 3,500 m3/h depending on die size.
  • Cooling tank ventilation: low-level supply along the tank length to introduce make-up air, high-level extract above the tank to remove humidity. Volume sized for tank length and water surface area, typically 800 to 2,000 m3/h per linear metre of tank.
  • Cutting station extract: dust LEV at the saw or rotary cutter, capture velocity 0.7 to 1.0 m/s at hood face, transport velocity 18 m/s minimum to NFPA 654 because the pipe sawdust is combustible. Terminating at a cyclone plus filter combination with explosion isolation.
  • Hall dilution: 6 to 10 ACH, biased lower because the line itself is a closed system that limits release to the hall.
  • Stockpile and yard extract: for indoor finished pipe storage prior to despatch, minimal extract beyond standard warehouse ventilation at 4 to 6 ACH.

PVC pipe extrusion adds the acid-vapour service requirement. The PVC compound itself releases small amounts of HCl during normal melt processing, and the release rises rapidly if the melt is overheated. The die head extract on a PVC extrusion line must therefore be acid-resistant from the hood inward — either glass-reinforced polyester (GRP), HDPE-lined carbon steel, or 316L stainless. Galvanised duct on a PVC die head extract fails within 12 to 24 months as the zinc coating corrodes under HCl condensate. The capture velocity is uplifted to 1.5 m/s at the hood face for PVC versus 1.0 m/s for polyolefin extrusion, recognising the lower workplace exposure tolerance for HCl.

Multilayer composite pipe extrusion — common at Iplex and Vinidex for water and gas service pipe combining HDPE structural layers with EVOH gas barrier or aluminium foil composite — uses tandem extruders feeding a common die. The HVAC architecture must handle the combined heat load from multiple extruders and the more complex fume mixture, with capture at each extruder die discharge plus the main composite die exit.

Thermoforming — sheet oven extract at 180 to 220 C

Thermoforming is the process behind disposable plastic packaging, automotive interior panels, refrigerator liners, point-of-sale displays and a thousand other formed plastic parts. Vacuum forming and pressure forming are the dominant variants, with twin-sheet forming used for hollow structural parts. The process takes a flat plastic sheet (typically PS, PP, PVC, PET-G, PET, HIPS, ABS or polycarbonate), heats it in an oven until soft, and forms it over a mould by vacuum, pressure or both.

The HVAC challenge is concentrated in the sheet oven. The oven heats the sheet by radiant infrared or quartz lamp heaters to 180 to 220 C depending on the resin, and the room above and around the oven sees significant sensible heat plus the convective rise from the heated sheet. Operator access to the oven for sheet loading and product unloading creates a thermal exposure problem that good HVAC must mitigate.

Typical specifications for a thermoforming hall:

  • Sheet oven extract: capture hood above the oven exit zone, capture velocity 0.7 to 1.2 m/s at hood face, hood face sized for the sheet width plus 300 mm margin. Total volume 4,000 to 12,000 m3/h per oven depending on sheet size.
  • Mould region extract: capture hood at the forming platen, lower than the oven extract because the heat load drops sharply after the sheet is formed. Capture velocity 0.5 to 0.8 m/s.
  • Trim and finishing extract: dust LEV at trimming presses and edge sanders, NFPA 654 transport velocity 18 m/s in horizontal duct.
  • Hall dilution: 10 to 18 ACH, biased high because the sheet oven heat load is significant relative to the building volume in a typical mid-sized thermoforming hall.
  • Pre-heat sheet storage: for facilities with sheet pre-conditioning prior to forming, a separate climate-controlled storage zone at 18 to 24 C, 40 to 55 percent RH, ensures consistent sheet behaviour in the oven.

Detmold Group's facilities at Brendale in Queensland and elsewhere combine thermoformed plastic film with paperboard for food packaging, with HVAC designed for both the plastics process and the food-contact hygiene requirement. Cospak in Sydney and Tooltech Plastics each run thermoforming lines for industrial packaging and component production with HVAC sized to the specific machine population. Plastamasta and similar truck and automotive trim moulders use thermoforming for large interior parts with HVAC integrated into a broader automotive assembly hall environment.

Rotational moulding — kiln exhaust at 250 to 350 C

Rotational moulding (rotomoulding) is the process behind plastic water tanks, agricultural containers, kayaks, road barriers, plastic pallets and a wide range of large hollow plastic parts. The process takes resin powder (typically LLDPE, HDPE, polypropylene, or nylon for specialty parts), loads it into a hollow mould, and rotates the mould inside a heated kiln at 250 to 350 C until the resin melts and coats the mould interior. The mould then moves to a cooling station where it is cooled by air or water spray before demoulding.

The Australian rotational moulding industry is concentrated around the water tank and agricultural container market, with operators including Polymaster (Melbourne), Bushman Tanks (Bundaberg in Queensland), Tankworks Australia, Coopers Plastics, Crystal Pools for rotomoulded swimming pool components, Pioneer Plastics, and a long tail of regional moulders serving local rural and industrial markets. The HVAC architecture across these facilities is broadly similar, with variations driven by the kiln type (oil-fired, gas-fired or electric), the mould carousel size, and the building footprint.

HVAC specifications for a typical rotational moulding cell with one or two kilns:

  • Kiln exterior temperature 250 to 350 C: the kiln chassis and exterior radiate significant heat. The space above the kiln must be ventilated by canopy hood at the kiln top, capture velocity 0.5 to 0.8 m/s at hood face, total volume 8,000 to 15,000 m3/h per kiln depending on size.
  • Kiln door open extract: when the kiln door opens for mould removal, a brief but intense pulse of hot air at 250 to 350 C exits the kiln. The canopy hood must be sized for this peak event, not just the steady-state radiation load.
  • Mould cooling station extract: capture hood at the cooling station, capture velocity 1.0 m/s at hood face. The cooling station produces water vapour if water spray cooling is used, plus significant sensible heat as the mould cools from 200 C down to demoulding temperature.
  • Powder loading station extract: dust LEV at the powder loading station, NFPA 654 transport velocity 18 m/s, terminating at a cyclone plus filter with explosion isolation.
  • Hall dilution: 8 to 15 ACH plus the dedicated kiln and cooling station capture. The dilution ACH is biased high in facilities with multiple kilns because the combined radiated heat load is substantial.

The kiln exhaust duct material specification is unusual relative to other plastics process duct. The combination of 250 to 350 C continuous temperature plus the possibility of brief excursions to 400 C during upset events demands either:

  • Mild steel at 2.0 mm minimum gauge, insulated externally with mineral wool or calcium silicate sheath rated to 600 C, with a vapour-tight outer jacket. Most cost-effective for the main capture and transport runs.
  • 304L stainless to ASTM A240, for the section nearest the kiln where surface temperature is highest. Stainless does not require external insulation for thermal protection but is often insulated for personnel safety.
  • High-temperature ducting with refractory liner in the rare case of an oil-fired kiln with significant unburned hydrocarbon in the exhaust stream.

Polymaster's Melbourne facilities operate large carousel rotomoulding machines with kiln populations of 4 to 8 stations per machine. Bushman Tanks' Bundaberg site is one of the largest single rotomoulding operations in Australia, producing rural and industrial water tanks at scale. Both operate HVAC architectures built around the kiln capture hood as the primary load, with hall dilution as a secondary system.

Material handling and silo extraction

Every plastics manufacturing plant runs a material handling system that brings resin pellets and powder from delivery (bulk tanker, octabin, FIBC bag or sack) into the press hopper or extruder feed throat. The system involves bulk silos, day silos, intermediate hoppers, pneumatic conveying lines and gravity feed drops. Every transfer point is a potential dust release point, and the cumulative dust load in a busy materials yard can be significant.

The HVAC and LEV at material handling points must address two issues. First, the dust release to the working environment, which is a workplace exposure problem governed by AS 1668.2 dilution and local capture, plus the resin-specific WES values (where applicable). Second, the combustible dust risk under NFPA 654, which requires explosion protection on dust collectors, hazardous area classification of dust-generating zones under AS/NZS 60079, and bonding and earthing of all duct sections per AS 1020.

Material handling LEV specifications for a typical Australian plastics plant:

  • Silo loading vent filtration: bulk tanker delivery to silo displaces air at high velocity through a silo top vent. The vent must terminate at a filter unit sized for the delivery rate, typically 2,000 to 6,000 m3/h depending on tanker capacity and pumping rate. Vent material is round galvanised duct, with bonding and earthing.
  • Pneumatic conveying terminal filter: at the end of the conveying line, the conveying air separates from the material in a cyclone plus filter combination. The conveying air filter handles 500 to 2,000 m3/h depending on conveying capacity. Cyclone discharge must be sealed against air ingress to prevent backflow of fine dust into the working area.
  • Hopper loading station LEV: at the operator-attended hopper loading point (octabin tip station, sack tip station), an LEV hood with capture velocity 0.7 to 1.0 m/s, terminating at a dedicated dust collector. NFPA 654 transport velocity 18 m/s in horizontal branch.
  • Day silo room ventilation: for silo rooms housing multiple day silos, hall dilution 8 to 12 ACH plus point LEV at every transfer. Hazardous area classification Zone 22 if combustible dust is occasionally present, Zone 21 if persistent.
  • Drying hopper extract: for resins requiring pre-drying (PA, PC, PBT, PET), the drying hopper exhaust is at 80 to 160 C with significant water vapour load. Galvanised duct rated for the temperature, with insulation to prevent condensation in the duct.

The dust collector for a combustible plastic dust LEV system is the critical safety element. Specifications:

  • Located outside the building envelope wherever possible, with weather protection and access for filter maintenance.
  • Deflagration vented to AS/NZS 60079 and the relevant NFPA 68 venting calculation. The vent area is sized to the dust Kst value (typically 100 to 300 bar.m/s for plastic dust) and the collector vessel volume.
  • Explosion isolation at the building entry point on the dust duct. Options include passive isolation valves (flap valves), active isolation valves (rotary valves with timing), or chemical suppression systems with explosion suppression cartridges.
  • Continuous level monitoring on the collector hopper to prevent overfilling, which can trigger dust accumulation in the duct upstream.
  • Bonding and earthing to AS 1020 across every section of duct. The earthing system is verified at commissioning by resistance measurement and re-verified annually.

Granulator and shredder regrind LEV — NFPA 654 in detail

Regrind operations — granulating reject parts, sprue and runner, edge trim, and recycle feed — are the highest-risk operations in a plastics plant from a combustible dust perspective. The granulator blade reduces the parts to a target particle size (typically 4 to 12 mm for in-process reuse) and the action of the blade generates a population of fine particles in the airborne fraction. The fine fraction is what creates the dust hazard. NFPA 654 governs the assessment and the control.

The combustible dust assessment proceeds by sampling the airborne dust from the granulator vicinity and analysing it for particle size distribution and explosion characteristics. The key parameters:

  • Particle size distribution: the airborne fraction below 500 micron is the dust hazard fraction. Below 75 micron the hazard is highest.
  • Kst value (deflagration index): ranges 50 to 300 bar.m/s for typical plastic dust, with finer particles giving higher Kst. PE and PP regrind typically run 100 to 200 bar.m/s. PS and ABS regrind can exceed 250.
  • Minimum ignition energy (MIE): 10 to 100 mJ depending on resin and particle size. Below 30 mJ the dust can be ignited by static electricity discharge, which is why bonding and earthing of all duct is mandatory.
  • Minimum explosible concentration (MEC): typically 30 to 100 grams per cubic metre. Below the MEC the dust cannot deflagrate; above it, deflagration is possible if an ignition source is present.
  • Layer ignition temperature: the temperature at which a 5 mm dust layer self-ignites. Typically 350 to 450 C for plastic dust.

Granulator LEV design follows from the assessment. Standard specifications:

  • Capture hood at granulator infeed and discharge, capture velocity 0.7 to 1.0 m/s at hood face. The infeed hood prevents dust release to the operator; the discharge hood prevents dust release from the regrind container.
  • Round duct construction, 1.6 mm mild steel or 1.0 mm stainless, with welded longitudinal seams or high-quality spiral lockseam. Rectangular duct is avoided because a deflagration overpressure event distorts and ruptures rectangular duct, where round duct survives.
  • Transport velocity above 18 m/s horizontal, 15 m/s vertical. Below these velocities, dust settles in the duct, accumulates over time, and creates a secondary deflagration risk during normal cleaning operations.
  • No dead legs or capped tees. Dust accumulates in dead legs and creates a primary explosion source.
  • Cleanout doors at every elbow, for inspection and dust removal. Cleanout doors must be flanged with bolted closure rated to the deflagration overpressure.
  • Spark detection and extinguishing in the duct, typically infrared detector with water mist or chemical extinguisher. Sparks from the granulator blade hitting a foreign object can ignite the dust cloud in the duct.
  • Bonding and earthing to AS 1020 across every duct section, every elbow and every joint. Static accumulation on an isolated duct length is the most common ignition source in plastic dust deflagration incidents.
  • Deflagration-vented dust collector outside the building, sized to NFPA 68 venting calculation. Vent discharge area kept clear of personnel access routes.
  • Explosion isolation at the building entry point, by passive flap valve, active rotary valve or chemical suppression.
  • Hazardous area classification Zone 21 inside the duct, Zone 22 in the room around the granulator. Electrical equipment in the classified zones must be EEx-certified to AS/NZS 60079.

AS 3957 dust hazard assessment is the Australian standard providing complementary guidance to NFPA 654 for dust risk evaluation. The two are typically applied together, with NFPA 654 providing the technical detail on equipment specification and AS 3957 providing the assessment framework for the workplace risk.

NFPA 484 historically covered combustible particulate solids in a broader sense, and is still referenced in some plant specifications, though the bulk of contemporary plastics plant assessment work in Australia follows NFPA 654 supplemented by AS 3957 and AS/NZS 60079. Project specifications should reference both NFPA standards by their current edition.

Compounding twin-screw extruder — fume capture at the die

Compounding is the process of melt-blending resin with additives, fillers, masterbatch, regrind and reinforcement to produce a finished pellet ready for downstream moulding. The twin-screw extruder is the dominant compounding machine, with capacities ranging from small lab-scale 18 mm screw diameters through to 200 mm production lines processing tonnes per hour. The Australian compounding industry serves the broader plastics value chain, with operators like Coopers Plastics, several specialist masterbatch producers, and the compounding arms of the major resin importers.

Compounding HVAC is challenging for two reasons. First, the die head fume is more complex than simple injection moulding fume because the compounding process by definition involves additives — antioxidants, UV stabilisers, slip agents, flame retardants, plasticisers, processing aids — that each have their own vapour pressure and decomposition profile. Second, the throughput is typically higher than injection moulding (a 100 mm twin-screw extruder running 800 kg/h is much higher fume mass flow than a single 200 tonne injection press), so the capture volume scales accordingly.

Capture specifications:

  • Die head capture hood, canopy at the strand die exit, capture velocity 1.0 to 1.5 m/s at hood face. Hood face sized for the die plate width plus 200 mm margin.
  • Pellet cooling water bath ventilation, for underwater pelletising lines, modest extract to remove water vapour and any volatile organic compounds from the bath.
  • Cooling and conveying air capture, at the pellet collection cyclone, with filter on the conveying air discharge.
  • Hopper and side-feed extract, at the additive feed points where powder additives are introduced to the extruder. Capture velocity 0.7 to 1.0 m/s at the hood face.

For halogenated flame retardant compounding (still significant in cable insulation and engineering applications), the die head fume can include hydrogen halide vapour during normal operation and higher levels during process upset. Acid-resistant duct construction (GRP, HDPE-lined or 316L) is required on the die head extract. Workplace exposure standards for the specific halogen compounds and the associated regulatory regime apply.

PVC compounding — HCl and legacy concerns

PVC compounding is its own discipline within plastics manufacturing because of the inherent chemistry of polyvinyl chloride. The polymer is stable in normal use but the melt processing window is narrower than for polyolefins, and any overheating during processing releases hydrogen chloride. The compounding step adds plasticisers (DEHP and its replacements), heat stabilisers, lubricants and pigments to the PVC, and each of these has its own vapour signature.

The Safe Work Australia workplace exposure standard for vinyl chloride monomer is 1 ppm TWA, which is the regulatory baseline. Modern PVC resin is delivered with VCM content below 1 ppm, so the monomer is not generally a workplace problem — but the HCl from melt processing, plus the plasticiser vapour, plus historically lead stabiliser fume (now largely phased out in Australian compounding) drive the HVAC specification.

Key requirements:

  • Acid-resistant duct construction on the kneader, pelletiser and die head extract. Glass-reinforced polyester (GRP) is the lowest-cost option, HDPE-lined carbon steel is mid-range, 316L stainless is the longest service life. Galvanised is unsuitable and fails within 12 to 24 months.
  • Plasticiser vapour capture at the heated mixer and the storage tanks. DEHP and its substitutes have workplace exposure standards in the order of 5 mg/m3, and the higher-temperature mixers can generate measurable vapour.
  • Acid scrubber on the combined extract stream, terminating in a caustic scrubber (sodium hydroxide solution) before atmospheric discharge. The scrubber neutralises HCl and any plasticiser vapour traces.
  • Hall dilution 12 to 18 ACH with dedicated point capture at every release source. Higher dilution than standard polyolefin compounding because the consequence of HCl release is higher.
  • Lead stabiliser legacy: facilities that historically used lead stabilisers must address any residual lead-containing dust during decommissioning or refurbishment, with classified work practices and dedicated HEPA filtration. Modern compounding has largely transitioned to calcium-zinc stabilisers, but the legacy lead deposits in older buildings remain a hazard during M&E refurbishment work.

Polyurethane reaction injection moulding — isocyanate at 0.005 ppm

Polyurethane reaction injection moulding (RIM) produces large parts — vehicle body panels, refrigerator linings, structural foam parts, soft-touch interior trims — by mixing two reactive liquid streams (polyol and isocyanate) and injecting the mixture into a mould where it expands and cures into a rigid or flexible polyurethane structure. The chemistry is the dominant HVAC concern because isocyanates (toluene diisocyanate TDI and methylene diphenyl diisocyanate MDI) are sensitisers and respiratory irritants with a Safe Work Australia workplace exposure standard of 0.005 parts per million TWA — among the lowest WES values in industrial ventilation.

The HVAC strategy for PU RIM is enclosure first, dilution second. Standard practice:

  • Fully enclosed press cell, with rigid panel walls and a controlled access door. The cell encloses the press, the mould region, the immediate demould area, and the cure conveyor if applicable.
  • Negative pressure inside the cell at 12.5 to 25 Pa relative to the surrounding workshop, maintained by the cell exhaust fan.
  • Exhaust at the access door opening at 0.5 m/s minimum face velocity. The face velocity is verified at every operational scenario, including door fully open during mould unloading.
  • Activated carbon scrubber on the cell exhaust before atmospheric discharge. Carbon bed sized for the isocyanate vapour load with breakthrough monitoring.
  • Polishing stage on the scrubber discharge, typically a second smaller carbon bed or wet scrubber, before atmospheric stack release.
  • Ductwork material: 316L stainless or HDPE to resist isocyanate condensate and amine catalyst vapour. Galvanised and 304L are not adequate for long service.
  • AS 4254 Class A seal on the exhaust duct because outward leakage of isocyanate into the workshop is a regulatory event.
  • Personal exposure monitoring with passive samplers worn by operators in the cell area, verifying that the WES is not exceeded.
  • Emergency response equipment: isocyanate spill containment, emergency shower at the cell exit, respiratory protection rated for isocyanate, breakthrough monitoring on carbon scrubber tied to emergency shutdown.

The PU RIM cell is treated by Australian regulators as a controlled chemical exposure environment, and the WES compliance burden is significant. Operators including some component suppliers to the automotive industry, refrigerator manufacturers and a small number of specialist plastics processors maintain certified PU RIM operations with the supporting HVAC architecture.

Plastic welding and heat staking — fume extract at assembly stations

Many plastic moulded parts are assembled by welding — ultrasonic welding, vibration welding, hot plate welding, infrared welding, laser transmission welding — or by heat staking (deforming a plastic boss to retain a component). Each of these processes generates fume from the localised melting of the plastic at the weld interface. The fume is small in volume but is released directly at the operator workstation.

Specifications for plastic welding LEV:

  • Capture arm at each welding station, articulated to position close to the weld point. Capture velocity 0.7 to 1.0 m/s at the arm intake.
  • Manifold to filter unit, typically a HEPA plus carbon filter combination. The carbon is for any volatile organic component of the fume; the HEPA captures particulate.
  • Dedicated extract at each ultrasonic or vibration welding head, integrated with the machine if a packaged solution is purchased.
  • Hall dilution 6 to 10 ACH at the assembly station bank, sufficient to capture any fume not collected at source.

The fume from welding fluoropolymers (PTFE, PFA, FEP) is significantly more hazardous than from polyolefins, requiring dedicated capture and disposal under controlled conditions. Operators welding fluoropolymers must apply the relevant Safe Work Australia guidance for polymer fume fever risk.

Decorating and printing — solvent-based versus UV ink

Many plastic products are decorated by printing — offset, screen, pad, digital — or by coating, lamination or labelling. The decorating process is its own HVAC challenge because of the solvents and inks involved.

Solvent-based inks remain in use for some specialist applications, despite a long industry trend toward UV-curable and water-based alternatives. The solvents are typically ethyl acetate, isopropyl alcohol, methyl ethyl ketone, toluene and various proprietary blends, with each having a workplace exposure standard and a flash point. AS 1940 governs the storage and handling of these flammable liquids in the plant. AS/NZS 60079 governs the hazardous area classification around the printing press if the solvent inventory is significant.

Solvent-based printing extract specifications:

  • Capture hood at the press exit and at the drying tunnel exit, capture velocity 0.7 to 1.0 m/s.
  • Drying tunnel exhaust sized for the solvent evaporation rate, with the exhaust volume calculated to keep the solvent concentration below 25 percent of the lower flammable limit.
  • Solvent recovery by condensation, absorption or thermal oxidation depending on solvent type and economics. Activated carbon adsorption with steam regeneration is a common route.
  • Acid-resistant or solvent-resistant duct construction. Stainless 304L or 316L is the typical choice. Galvanised is unsuitable for long-term solvent service.
  • Ex-rated electrical equipment in the classified zones, to AS/NZS 60079 Zone 1 or 2 depending on operational classification.
  • Static control on the press and ductwork to prevent ignition from electrostatic discharge.

UV-curable inks are the dominant choice for modern decorating, with significantly lower workplace exposure burden. The UV ink fume is minor and is typically captured by a small hood at the UV cure lamp bank with a HEPA plus carbon filter. The hall dilution at 8 to 12 ACH covers the residual.

Water-based inks are increasingly used for flexographic and digital printing on plastic packaging. The water-based extract is essentially a humidity management problem rather than a solvent capture problem. Drying tunnel exhaust handles the water vapour, with heat recovery to plant pre-heat duty where economic.

Mould release spray booth extract

Mould release agents are applied to mould surfaces to facilitate part release after moulding. The agents range from simple silicone sprays to water-based release emulsions to wax-based formulations. Spray application is typical, with operator-controlled spray guns at the mould face during mould preparation or at scheduled intervals.

The spray booth extract for mould release agent application is sized for the spray rate plus the booth ventilation requirement. Typical specifications:

  • Booth face velocity 0.5 m/s minimum at the booth opening, with the operator working from outside the booth into the booth space.
  • Filter section in the booth exhaust, with paint-arrestor pads for the bulk overspray and a polishing filter for fine droplets.
  • Solvent capture if solvent-based release agents are used, with carbon adsorption or thermal oxidation.
  • Heat recovery on the booth exhaust where the booth is conditioned (a spray booth in a moulding hall typically has conditioned supply to maintain operator comfort).

Cleanroom medical and pharmaceutical plastic moulding

Medical device contract moulding is one of the fastest growing segments of Australian plastics manufacturing, with operators serving both domestic medical device manufacturers and export markets. The HVAC architecture for medical moulding is a cleanroom specification, typically ISO 7 or ISO 8 under ISO 14644-1, with the Australian standard AS 1807 providing complementary guidance.

Operators with significant medical moulding presence include contract manufacturing organisations like Patheon/Catalent Australia for pharmaceutical primary packaging and device components, Berry Global Australia in the medical packaging segment, and several specialist plastics processors serving the diagnostic, surgical and drug delivery device markets. The growth in onshore medical manufacturing under the federal government's manufacturing priority programmes has driven capacity expansion across the sector.

Specifications for ISO 7 medical plastics moulding cells:

  • ACH 30 to 60 in the mould cell, with H13 HEPA terminal filtration at ceiling diffusers.
  • F9 prefilter at the AHU, with magnehelic gauges for differential pressure monitoring.
  • Positive pressure cascade 12.5 to 25 Pa relative to adjacent corridors, with airlocks at every personnel and material entry point.
  • 304L stainless supply ductwork, sealed to AS 4254 Class A with welded longitudinal seams on runs above DN 250.
  • Smooth-bore duct construction — no internal liner, no exposed insulation, no fibre release pathway into the airstream.
  • Cleanable surfaces on every duct, terminal and access door. Cleanroom-grade brushed or 2B mill finish on stainless.
  • Laminar flow protection at 0.5 m/s downflow velocity over critical operations (e.g. pharmaceutical primary packaging where the moulded part contacts product).
  • Particle counting validation per ISO 14644-3 at minimum quarterly intervals, with annual recertification.
  • Sterilisation compatibility on the duct surfaces where the process includes vapour-phase hydrogen peroxide or ethylene oxide sterilisation of the cell.

The injection press itself within the cleanroom is selected for cleanroom service — servo-electric drives in preference to hydraulic, sealed bearings, low particulate construction. The HVAC architecture supports this by maintaining the cleanliness class, but the press selection is part of the overall cleanroom strategy.

Food contact plastic moulding hygiene HVAC

Plastic moulding for food contact materials (FCM) operates under HACCP-aligned hygiene principles, with HVAC providing both the cleanliness control and the contamination prevention. The Australian operators include Visy in PET preform and bottle production, Pact Group in rigid plastic packaging, Sealed Air Australia (Cryovac) at Tullamarine and Smithfield in flexible packaging, Plasdene Glass-Pak in associated packaging applications, and many smaller moulders supplying the food and beverage industry.

Specifications for food contact moulding HVAC:

  • EN 1822 EPA or HEPA filtration at the AHU terminal. EPA H10 or HEPA H13 depending on the specific FCM application. The filter classification is documented in the food safety plan.
  • ACH 12 to 20 in the moulding cell, biased to the higher end where direct food contact is the application.
  • Positive pressure in the moulding cell relative to adjacent areas to prevent ingress of contaminating air from material handling, warehouse or operator areas.
  • 304L stainless supply ductwork, no internal liner, no exposed insulation. The duct interior surfaces must be cleanable to FCM hygiene standard.
  • HACCP zoning at the moulding cell level — high-risk zones with positive pressure and HEPA-filtered air, low-risk zones with controlled ventilation but lower filtration class.
  • Cleaning regime compatible with the duct construction. Most food-contact moulders use a wet cleanable HVAC system with sealed surfaces.

Material selection by zone and resin chemistry

The duct material selection in a plastics plant follows from the chemistry, the temperature and the regulatory regime in each zone. The summary table:

  • General injection moulding hall (PE, PP, PS, ABS): Galvanised steel to AS 1397 G275, 0.8 to 1.2 mm gauge, sealed to AS 4254 Class B. Standard SMACNA-equivalent construction.
  • Engineering thermoplastic hall (PC, PA, PBT): Galvanised G275 for most runs, with stainless 304L at the press hood where condensate from heated barrel fume could attack zinc. Class B seal acceptable on most runs.
  • PVC compounding and extrusion: GRP (glass-reinforced polyester) for cost-effective acid resistance; HDPE-lined carbon steel for mid-range cost; 316L stainless to ASTM A240 for the longest service life. Class A seal on the extract side.
  • Rotational moulding kiln exhaust: Insulated mild steel 2.0 mm gauge at the kiln, or 304L stainless at higher temperature exposure. Mineral wool or calcium silicate external insulation rated to 600 C.
  • Thermoforming oven exhaust: Galvanised G275 for typical 180 to 220 C duty; 304L for fluoropolymer thermoforming where temperature exceeds 280 C.
  • Polyurethane RIM cell exhaust: 316L stainless or HDPE for isocyanate and amine resistance. Class A seal mandatory.
  • Combustible dust LEV (regrind, granulator, material handling): Round duct, 1.6 mm mild steel or 1.0 mm stainless 304, welded longitudinal seam or precision spiral lockseam. Bonding and earthing per AS 1020 on every section.
  • Solvent printing extract: 304L or 316L stainless to resist solvent and ink condensate.
  • Cleanroom medical moulding supply: 304L stainless, smooth-bore, no internal liner, AS 4254 Class A seal, welded longitudinal seams on DN 250 and above.
  • Food contact moulding supply: 304L stainless, cleanable surfaces, EN 1822 filtration, AS 4254 Class A.
  • Outdoor air intake plenums: Aluminium or galvanised G275 with corrosion-resistant coating. Coastal sites (Brisbane, Sydney coastal, Perth coastal, Newcastle, Wollongong) require 316L on intake louvre frames and bird screens.

The material cost differential is significant. Galvanised AS 1397 G275 coil at 2026 Melbourne pricing is the baseline. 304L stainless to ASTM A240 runs roughly 3.5 to 4.5 times the galvanised price per tonne. 316L is roughly 1.4 to 1.6 times 304L. GRP fabricated duct is mid-range, depending on resin system and reinforcement. HDPE-lined carbon steel is competitive with stainless on cost when the lining application is mature. The fabricated cost differential narrows because tooling, freight and installation labour are similar across materials. For a typical mid-sized Australian plastics plant ductwork programme, we typically see 70 to 85 percent of total ductwork tonnage in galvanised and 15 to 30 percent in stainless or alternative material, with the proportions weighted toward the higher-value materials for medical, food-contact, isocyanate and acid-vapour service.

For a deeper comparison of the steel grade trade-offs, see our reference on galvanised vs stainless steel duct selection.

Seal class to AS 4254 — when each is appropriate

AS 4254 ductwork construction defines seal classes broadly equivalent to SMACNA Class A, B and C. The selection by application:

  • Class A (tightest): Cleanroom medical moulding supply, food contact moulding supply, isocyanate exhaust, acid-vapour exhaust on PVC compounding, combustible dust LEV at the building envelope crossing point. Every cubic metre of leakage is a regulatory or economic event.
  • Class B (standard): General moulding hall dilution supply and return, press hood extract, oven exhaust, kiln exhaust, blow moulding parison supply.
  • Class C (least tight): Acceptable on outdoor air intake plenums and short transition ducts between AHU and main duct. Not acceptable for any internal distribution.

Achieving Class A on stainless construction requires welded longitudinal and transverse seams on diameters above DN 250, TDF or TDC flanges with continuous EPDM or silicone gasket at access points, intumescent caulk sealing at all wall and floor penetrations, and pressure decay testing at 1.5 times design static pressure for 15 minutes minimum. The SBKJ auto duct line with welding station integration is configured for Class A production on stainless.

Class B on galvanised is the workhorse for the general moulding hall and is achievable on a standard SBAL-V production run with TDF flange and intumescent caulk sealing at penetrations. Class B leakage on a typical Australian plastics plant ductwork programme is verified by pressure decay test on representative sections during commissioning.

AS code compliance summary — what every project must demonstrate

The Australian regulatory environment for plastics manufacturing HVAC is mature and well-defined. The key standards and their roles:

  • AS 1668.2 Mechanical ventilation in buildings — ventilation design for indoor air contaminants: sets the dilution ACH and minimum supply air requirements for the building as a whole. Provides the framework for the workplace air quality compliance.
  • AS 4254 Ductwork for air-handling systems in buildings: covers duct construction including gauge, support spacing, joint types, seal class, pressure rating and material specification. Every duct in the plant references AS 4254 for the fabrication standard.
  • AS 1530.4 Fire-resistance tests for elements of construction — methods for fire tests on building materials, components and structures: applies to every duct penetration through a fire-rated wall or floor. The fire-rated penetration system must be tested to AS 1530.4 and documented in the building fire safety case.
  • AS 1530.3 Simultaneous determination of ignitability, flame propagation, heat release and smoke release: applies to non-metallic duct materials (GRP, HDPE) where used in occupied spaces. The material must demonstrate ignitability and flame propagation indices within the acceptable range.
  • AS 1397 Continuous hot-dip metallic coated steel sheet and strip: specifies the galvanised steel grade for general ductwork. G275 coating weight (275 grams per square metre of zinc per side) is the standard for plastics manufacturing HVAC.
  • AS/NZS 60079 Explosive atmospheres — equipment classification: applies to all hazardous areas in the plant where combustible plastic dust or flammable solvent generates an explosive atmosphere. Sets the equipment classification (EEx ratings) and the zone classification (Zone 1, 2, 21, 22) requirements.
  • AS 1940 Storage and handling of flammable and combustible liquids: governs the storage and handling of solvent-based inks, mould release solvents, adhesives and other flammable liquids in the plant. Sets the bunding, ventilation and ignition source control requirements for solvent storage areas.
  • AS 3957 Dust hazard assessment: provides the Australian framework for combustible dust risk evaluation. Applied alongside NFPA 654 (and historically NFPA 484) for plastics regrind and material handling dust assessment.
  • AS 1807 Cleanroom and clean air device testing: Australian standard for cleanroom validation, applied alongside ISO 14644-1 and ISO 14644-3 for medical and pharmaceutical plastics moulding.
  • AS 1020 Control of undesirable static electricity: governs bonding and earthing of duct sections in combustible dust LEV systems.
  • AS 3958.1 Ceramic tile installation: referenced where thermoplastic polyurethane (TPU) is used in tile bonding contexts, with related vapour management requirements.

International references that are commonly cited in Australian plastics plant specifications:

  • NFPA 654 Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing and Handling of Combustible Particulate Solids: the technical reference for combustible plastic dust LEV design.
  • NFPA 484 Standard for Combustible Metals: historically referenced for broader combustible particulate solids guidance, though most plastic dust assessment now follows NFPA 654.
  • ASHRAE Handbook — HVAC Applications, Chapter 33 Industrial Ventilation: the comprehensive reference for industrial ventilation design including hood capture velocity, transport velocity and air-cleaning system selection.
  • EN 1822 High-efficiency air filters (EPA, HEPA and ULPA): the European filter classification used in food-contact and medical applications.
  • ISO 14644-1 Cleanrooms and associated controlled environments — classification of air cleanliness: the international cleanroom classification standard.
  • ISO 472 Plastics — Vocabulary: standardised terminology for plastics processing, referenced in plant specifications.
  • ISO 1133 Plastics — Determination of the melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of thermoplastics: melt flow index reference for resin characterisation.

Safe Work Australia workplace exposure standards (WES) drive the workplace air quality compliance:

  • Styrene: 50 ppm TWA. Relevant to polystyrene injection moulding and polyester compounding.
  • Vinyl chloride monomer: 1 ppm TWA. Relevant to PVC processing, though modern resin VCM content is below 1 ppm.
  • Formaldehyde: 1 ppm STEL. Relevant to phenolic resin compounding and amine-cured polymers.
  • Toluene diisocyanate (TDI) and methylene diphenyl diisocyanate (MDI): 0.005 ppm TWA. Relevant to polyurethane RIM and reactive polyurethane processing.
  • Plasticiser DEHP (di-2-ethylhexyl phthalate): 5 mg/m3 TWA. Relevant to PVC compounding.
  • Caprolactam: 5 mg/m3 TWA. Relevant to nylon 6 polymerisation and processing.
  • Acrylonitrile: 2 ppm TWA. Relevant to ABS and SAN processing.
  • 1,3-butadiene: 2 ppm TWA. Relevant to SBR and high-impact polystyrene processing.

Australian plastics operators — who runs what, and where

The Australian plastics manufacturing landscape is dominated by a small number of large operators alongside a long tail of specialist moulders, compounders and converters. Understanding the operator landscape helps the consulting engineer or works engineer pitch the HVAC specification appropriately.

Major rigid plastics packaging operators

Pact Group Holdings (ASX:PGH) — headquartered at Mulgrave, Victoria, Pact operates the largest rigid plastics packaging footprint in Australia and New Zealand with over 80 manufacturing sites across the region. The portfolio spans injection moulding (pails, containers, closures), blow moulding (bottles, jerry cans), thermoforming (trays, lids) and a growing recycled plastics business through Pact Reuse. HVAC at Pact facilities ranges from standard injection moulding hall ventilation through to food-contact specification on dairy and beverage packaging lines. The group's recycling business adds the regrind and pelletising HVAC challenge at material recovery facilities.

Visy Industries — private, founded by Anthony Pratt's father and now under family ownership, Visy is the largest paper and packaging group in Australia. The plastics segment includes PET preform and bottle production, food and beverage packaging containers, and specialist plastic sheet for industrial use. The Coolaroo facility in north Melbourne is one of the larger plastics operations in Australia. HVAC at Visy plastics facilities is mature, with cleanroom-grade specification on the food-contact lines.

Amcor PLC (ASX:AMC, NYSE:AMCR) — Amcor is the global packaging company with significant Australian operations including flexibles and rigids manufacturing. The Australian footprint includes injection moulding, thermoforming and extrusion lines for pharmaceutical and food-contact packaging.

Sealed Air Australia (Cryovac) — with facilities at Tullamarine, Victoria and Smithfield, New South Wales, Sealed Air manufactures flexible packaging including shrink film, vacuum packaging and protective packaging. HVAC includes extrusion line ventilation, food-contact zoning and significant heat recovery from the film extrusion process.

Pro-Pac Packaging (ASX:PPG) — a packaging manufacturer with plastics operations serving industrial and consumer markets across Australia and New Zealand.

Aeropak — at Hallam in southeast Melbourne, Aeropak produces aerosol containers and propellant packaging with injection blow moulding and related plastics processing.

Detmold Group — at Brendale, Queensland, and additional sites, Detmold produces paper and board packaging with plastic film coating and lamination. The HVAC architecture combines paper handling ventilation with plastic film extrusion and coating lines.

Cospak Plastic — a Sydney-based plastic packaging manufacturer with injection moulding and thermoforming capability across industrial and consumer markets.

Plasdene Glass-Pak — while primarily a glass packaging operation, Plasdene runs related plastics operations supporting their packaging portfolio.

Bonson Industrial — a Melbourne plastics packaging manufacturer.

Pipe and profile extrusion

Iplex Pipelines — part of the Fletcher Building group, Iplex is one of the largest plastics pipe manufacturers in Australia and New Zealand with sites in Sydney, Melbourne, Brisbane and Perth. The Iplex product range includes HDPE, polypropylene and PVC pipe across water, gas, mining, agricultural and industrial applications. HVAC at Iplex facilities focuses on extrusion line capture, regrind dust LEV (significant at scale), and finished pipe storage ventilation.

Vinidex — part of the Aliaxis group, Vinidex manufactures PVC, HDPE and related plastic pipe systems across Australia. Operations include both extrusion and injection moulding for fittings, with HVAC architecture similar to Iplex but with the operator-specific configuration variations typical of the segment.

Polypipe Australia — specialist plastic pipe extrusion serving water, drainage and infrastructure markets.

Rotomoulded water tanks and industrial containers

Polymaster — Melbourne-based, one of the larger rotomoulded water tank manufacturers serving the Victorian and broader Australian rural and industrial markets.

Bushman Tanks — at Bundaberg, Queensland, Bushman is one of the largest rotomoulded plastic water tank producers in Australia, serving rural and residential water storage markets nationally. The HVAC at Bundaberg covers multiple kiln stations on large carousel rotomoulding machines.

Tankworks Australia — an established rotomoulded plastic tank producer with regional manufacturing.

Coopers Plastics — rotomoulding and related plastic container manufacturing.

Crystal Pools — rotomoulded swimming pool components and related water containment products.

Pioneer Plastics — rotomoulded industrial and agricultural containers.

Automotive and industrial moulding

Plastamasta — truck and automotive plastics moulding, including large interior parts and exterior trim.

Hella Australia — automotive lighting injection moulding, with the precision moulding and optical surface quality requirements that come with automotive lighting production.

Hellermann Tyton — electrical and cable management plastic component manufacturing.

Schlemmer Group — automotive plastics with Australian distribution and some local manufacturing.

Romteck — industrial moulding with multi-segment market presence.

Tooltech Plastics — industrial and consumer plastics manufacturing.

Insulpak — insulated plastic packaging and related thermal containers.

Medical device contract moulding

Patheon / Catalent Australia — pharmaceutical primary packaging and medical device contract moulding, with cleanroom-grade facilities serving both domestic and export markets.

Berry Global Australia — medical and pharmaceutical packaging, with cleanroom moulding operations.

Tegrant and Sterifolio — specialist sterile packaging and medical device packaging operations.

Project sizing and machine quantification — what fabrication capacity does the project need

For the project manager or works engineer scoping the fabrication capacity required, the ductwork quantity estimate by zone provides the basis for machinery selection. Indicative figures for typical Australian plastics plants:

  • Small plastics plant (500 to 2,000 m2 floor area, 5 to 15 presses): Rectangular galvanised duct 1,500 to 5,000 m, round galvanised duct 500 to 1,500 m, stainless duct 50 to 200 m. Fabrication time on one SBAL-V line running single shift: 4 to 8 weeks.
  • Medium plastics plant (2,000 to 10,000 m2, 15 to 50 presses or equivalent extrusion lines): Rectangular galvanised 5,000 to 15,000 m, round galvanised 1,500 to 4,000 m, stainless 200 to 1,000 m. Fabrication time on one SBAL-V running double shift plus SBTF tubeformer: 8 to 16 weeks.
  • Large plastics plant (over 10,000 m2, 50+ presses or major extrusion installation): Rectangular galvanised 15,000 to 40,000 m, round galvanised 4,000 to 10,000 m, stainless 1,000 to 3,000 m. Two SBAL-V lines plus dedicated SBTF tubeformer, plus elbow former and stiffener line.
  • Cleanroom medical moulding facility (1,000 to 3,000 m2 cleanroom area): Stainless 304L duct 500 to 2,000 m, sealed to AS 4254 Class A with welding station integration. SBAL-V configured for stainless, plus SBTF for round stainless spiral duct.
  • Major rotomoulding facility (Polymaster, Bushman scale): High-temperature insulated mild steel for kiln exhaust 200 to 800 m, galvanised general 2,000 to 8,000 m, stainless 100 to 400 m. SBAL-V plus SBHF hydraulic flange former for heavy-gauge plenum work at kiln capture.

The machinery quantity is then a function of fabrication time available and project schedule. For a project with 12 to 18 month fitout window, one SBAL-V running double shift covers most small and medium plants. For projects with 6 to 9 month fitout windows (typical for retrofit or expansion projects), two SBAL-V lines plus dedicated round duct fabrication are required.

SBKJ machine selection for plastics manufacturing duct fabrication

The SBKJ machine range covers every fabrication operation needed for plastics plant ductwork, from the largest galvanised plenum to the smallest stainless cleanroom branch. The recommended machine selection by application:

SBAL-V auto duct production line — the workhorse

The SBAL-V is the senior model in the SBKJ auto duct line range, designed for high-throughput production of rectangular TDF-flanged duct in one pass. Specifications:

  • Line speed: 16 metres per minute peak, with typical production rate 8 to 12 m/min on standard galvanised duty.
  • Total drive power: 87 kW across decoiler, leveller, notcher, lockformer, slitter, beader, TDF flange former and cut-off station.
  • Coil capacity: 0.5 to 1.5 mm gauge, up to 1500 mm coil width. Covers the full range of plastics plant duct gauges in single-pass production.
  • Materials: Galvanised AS 1397 G275 as standard; 304L and 316L stainless as configured option with stainless-compatible roller tooling and dedicated cutting station.
  • Output: 25 to 45 metres of finished duct per shift on galvanised, 20 to 35 metres on stainless, depending on the proportion of TDF flange operations and the section size mix.
  • Best fit: Medium to large plastics plant general HVAC programme. Cleanroom medical and food-contact stainless work with optional welding station integration. See the SBAL-V product page for full technical specification.

SBAL-III auto duct line — mid-tier production

The SBAL-III sits below the SBAL-V in the auto duct line range, with lower total drive power and a more compact footprint. Specifications:

  • Line speed: 14 metres per minute peak.
  • Total drive power: 15.7 kW — significantly lower than SBAL-V because the SBAL-III uses different forming geometry and a more compact drive arrangement.
  • Coil capacity: 0.5 to 1.2 mm gauge, up to 1300 mm coil width.
  • Best fit: Small to medium plastics plant general HVAC programme. Cost-effective choice for plants where the full SBAL-V capacity is not justified by project quantity.

SBAL-II compact auto duct line

The SBAL-II is the compact entry-level auto duct line, designed for smaller fabrication shops and lower-volume duty. Specifications:

  • Line speed: 18 metres per minute peak.
  • Total drive power: 5.5 kW.
  • Coil capacity: 0.5 to 1.2 mm gauge.
  • Best fit: Small plastics plant general HVAC programme. Suitable for fabrication shops with episodic plastics plant work as part of a broader mixed HVAC fabrication portfolio.

SBTF spiral tubeformer range — round duct fabrication

The SBTF range covers round spiral duct fabrication for kiln exhaust, oven extract, granulator dust LEV, blow moulding cooling supply, and any other round duct application across the plant. The models:

  • SBTF-1500C: compact mid-range spiral tubeformer, diameter range 80 to 1500 mm in standard configuration, suitable for most plastics plant round duct duty.
  • SBTF-1602: mid-large spiral tubeformer with extended diameter range up to 1600 mm, supporting larger kiln exhaust and high-volume LEV ductwork.
  • SBTF-2020: large-diameter spiral tubeformer for the largest exhaust ducts in major rotomoulding facilities and large extrusion installations, diameter range extending to 2000 mm.

SBTF tubeformers produce high-quality spiral lockseam round duct that achieves AS 4254 Class B seal on standard configuration and Class A on profiled lockseam with appropriate sealant. The spiral lockseam profile is particularly well suited to combustible dust LEV because it provides the structural integrity to survive a deflagration overpressure event better than rectangular duct.

SBEM-1250 elbow former — standard fittings production

The SBEM-1250 elbow former produces gored and pressed elbows for both galvanised and stainless duct programmes. The machine handles standard elbow geometries including 90 degree, 45 degree and custom angle elbows up to 1250 mm diameter. The elbow former is a key part of the SBKJ machine set because elbow fabrication on traditional hand methods is labour-intensive and inconsistent — mechanised elbow forming on the SBEM-1250 ensures uniform geometry and quality across the project.

SBSF-1525 stiffener former — large-section reinforcement

The SBSF-1525 stiffener former produces reinforcement stiffeners for large-section duct and plenum work, with 2.5 kW drive power for handling heavy-gauge sections up to 1525 mm. Stiffeners are required on every rectangular duct above approximately 600 mm equivalent diameter to meet AS 4254 deflection limits under design pressure. The mechanised stiffener former produces consistent stiffener geometry that integrates cleanly with the TDF flange and the duct body.

SBFB-1500 floating beam / box folder — large plenum fabrication

The SBFB-1500 handles large-section box folding for plenum and equipment housing fabrication, with 7.5 kW drive and a working speed of 1.20 m/min. Working width up to 1500 mm covers the typical AHU plenum and equipment penetration housing requirements. This machine is used for the major plenums at AHU connections, large transition pieces and equipment housings that fall outside the standard rectangular duct production envelope.

SBHF hydraulic flange former — heavy-gauge plenum work

The SBHF hydraulic flange former produces flanges on heavy-gauge plenum sections, AHU housings and large equipment penetrations. The hydraulic drive provides the force required for thicker gauge work that exceeds the capacity of the standard SBAL-V flange forming station. For kiln exhaust plenums on rotomoulding facilities and the large penetration housings on combustible dust collectors, the SBHF is the right tool.

SBPC1500 plasma cutter — stainless penetrations and branch fittings

The SBPC1500 plasma cutting table handles stainless penetrations, branch fittings, end caps and custom fabrications on stainless and heavier gauge mild steel. The plasma cut edge on stainless is significantly cleaner than mechanical shearing and is suitable for cleanroom and food-contact duct work where edge finish matters. The SBPC1500 is integrated with the SBAL-V on cleanroom medical and food-contact programmes.

SBLR-600 / SBLR-600A — lockformer and seam closure

The SBLR series handles longitudinal seam lockforming for round and rectangular duct, with 7.6 m/min line speed on the SBLR-600 and SBLR-600A. The lockformer produces the longitudinal seam profile required for snap-lock or Pittsburgh lockseam closure on smaller diameter duct sections, complementing the SBAL-V for sections below the auto duct line size envelope.

Machine selection by plant type — the SBKJ recommendation

Consolidating the machine selection by plant type:

  • General plastics moulding hall (galvanised dominant): SBAL-V or SBAL-III for rectangular duct programme, SBTF-1500C or SBTF-1602 for round duct, SBEM-1250 for elbows, SBSF-1525 for stiffeners. SBAL-V configured for galvanised duty, single shift covers small plant, double shift covers medium, two lines double shift covers large plant.
  • Cleanroom medical moulding facility (304L stainless): SBAL-V configured for 304L stainless with plasma cutter integration and welding station, SBTF-1602 configured for 304L round, SBPC1500 plasma cutter for penetrations. AS 4254 Class A seal achievable on standard production with welded seams on DN 250 and above.
  • Food contact moulding facility (304L stainless): Same machine set as cleanroom medical but with smooth-bore configuration and EN 1822 filter housing integration. Cleanable surfaces required throughout.
  • PVC compounding hall (FRP and HDPE): Off-machine fabrication for the GRP and HDPE-lined runs (these materials are not processed on a sheet-metal duct line), with SBAL-V for the general galvanised programme outside the PVC zone, and SBTF for the acid scrubber stack and discharge runs.
  • Rotomoulding facility with high-temperature kiln exhaust: SBAL-V for galvanised general programme, SBHF hydraulic flange former for the heavy-gauge insulated mild steel kiln exhaust plenums, SBTF-2020 for the large-diameter round duct on kiln capture, SBPC1500 for stainless penetrations where required.
  • Pipe extrusion facility (Iplex, Vinidex scale): SBAL-V running double shift for the general galvanised programme, SBTF-1602 or SBTF-2020 for the round duct on regrind LEV and die head capture, dedicated combustible dust ductwork to NFPA 654 with bonding and earthing per AS 1020.
  • Polyurethane RIM facility: SBAL-V configured for 316L stainless on the RIM cell exhaust ductwork, with welding station integration for Class A seal achievement. Off-machine HDPE fabrication for the wet acid scrubber sections.

Heat recovery economics — the largest single energy opportunity

Heat recovery on plastics plant HVAC exhaust is consistently the highest-return engineering investment in the facility energy programme. The economics are driven by the temperature of the exhaust streams and the climate of the plant location.

For a typical Australian plastics plant the combined exhaust temperature, weighted across press hood extract, oven exhaust, kiln exhaust and dilution return, averages 30 to 50 C above ambient on a daily basis. The exhaust volume is large (10,000 to 100,000 m3/h depending on plant size) and operates continuously across the production shift pattern. The recoverable heat is therefore substantial, and the application — outdoor air pre-heat for the next shift's supply, hot water generation for plant cleaning and personnel facilities, absorption chiller drive for plant cooling — is consistently aligned with the production schedule.

Heat recovery options for plastics plant HVAC:

  • Glycol run-around coil: simple, reliable, no cross-contamination risk. Coil in the exhaust stream and a separate coil in the outdoor air intake, with a closed glycol loop circulating between them. Recovery effectiveness 40 to 60 percent depending on coil sizing and exhaust temperature. Best fit for plants with separated exhaust and supply AHU locations.
  • Air-to-air heat wheel: higher recovery effectiveness (60 to 80 percent), but requires exhaust and supply ducts to be co-located. Best fit for plants with integrated AHU rooms.
  • Plate heat exchanger: moderate effectiveness, no cross-contamination, common in food-contact and medical plants where any risk of exhaust-to-supply leakage is unacceptable.
  • Hot water generation: coil in the exhaust stream feeding a domestic hot water loop or process water loop. Especially attractive for facilities with significant hot water demand for cleaning, sterilisation or personnel facilities.
  • Absorption chiller drive: for facilities with high cooling load, an absorption chiller driven by exhaust heat at 80 to 120 C can offset compressor cooling load entirely during the summer months. Best fit for very large facilities with combined heat and cooling demand.

Payback periods on heat recovery equipment in Australian plastics plants typically run 3 to 5 years at 2026 industrial gas and electricity prices, with the higher end of the range for capital-intensive systems like heat wheels and absorption chillers, and the shorter end for simple glycol run-around installations. The duct geometry must accommodate the heat recovery coils with adequate face area, low pressure drop and drain provision for any condensate that forms on the recovery coil surface.

Commissioning and validation — what the project owes the operator

HVAC commissioning on a plastics plant follows the AS 4254 and AS 1668.2 framework, supplemented by NFPA 654 verification for combustible dust LEV and AS 1530.4 verification for fire-rated penetrations. The validation suite typically includes:

  • Pressure decay testing on completed duct sections before insulation. AS 4254 Class A or B verification at 1.5 times design static pressure. Sections that fail are repaired and re-tested.
  • Capture velocity measurement at every hood with calibrated anemometer. Verified at minimum 9 points across the hood face plus 3 points at hood elevation for cross-draught.
  • ACH verification by tracer gas decay or anemometric supply measurement. Verified to plus or minus 10 percent of design.
  • Pressure cascade verification at every zone boundary with all doors closed and worst-case door-open scenarios.
  • Fire damper drop tests on every fire damper with command from BMS, verifying actuator response time within 2 seconds.
  • Combustible dust LEV verification: transport velocity measurement, deflagration vent opening test, explosion isolation valve function test, bonding and earthing resistance measurement on every duct section.
  • Personal exposure monitoring with passive samplers for isocyanate, styrene, formaldehyde and other listed contaminants. Verifies that the WES is not exceeded in normal operation.
  • HEPA challenge testing per IEST-RP-CC034 with DOP or PAO aerosol on cleanroom medical and food-contact installations.
  • Particle counting per ISO 14644-3 on cleanroom installations.
  • Scrubber performance verification: inlet and outlet concentration measurement on PVC compounding HCl scrubber, PU RIM isocyanate scrubber and solvent printing thermal oxidiser.
  • Heat recovery effectiveness measurement at design and part-load conditions.

The commissioning report becomes the operations and maintenance baseline document. Operators with mature plant management routines re-verify capture velocities, ACH and pressure cascade annually, with full re-commissioning every 5 to 7 years or following any significant equipment change.

Maintenance programme — what keeps the system performing

Plastics plant HVAC degrades faster than typical building HVAC because of the process exposure. The maintenance programme that keeps capture, dilution and exhaust performing through the plant life:

  • Weekly: Visual inspection of hood positions and capture arm articulation. Static pressure check at AHU. Filter differential pressure read.
  • Monthly: Filter replacement on prefilters. Belt tension check on fans. Vibration analysis on critical fan motors.
  • Quarterly: Capture velocity measurement at sample hoods. Combustible dust collector cleaning. Bonding and earthing resistance check on dust LEV duct sections.
  • Semi-annual: Full filter replacement on terminal HEPA in cleanroom and food-contact installations. Scrubber media replacement on PVC compounding and isocyanate service.
  • Annual: Full HVAC commissioning re-verification including ACH, pressure cascade, fire damper drop tests, deflagration vent inspection, explosion isolation valve function test, scrubber performance.
  • 5 to 7 year: Full re-commissioning equivalent to original commissioning. Duct condition assessment with internal inspection where access permits. Material condition assessment on stainless and acid-resistant duct.

The maintenance discipline is what distinguishes a 25-year plastics plant HVAC system from a 10-year one. Operators with mature maintenance practices typically extend duct service life to 25+ years on galvanised and 35+ years on stainless, with the only major replacement events driven by plant reconfiguration rather than duct material failure.

The Australian context — why local fabrication matters

Australian plastics manufacturing operates in a market where imported fabricated duct from offshore suppliers is generally not economic. Duct is volumetric (the shipping cost dominates the imported price), the lead time discipline of an Australian project schedule does not tolerate 12 to 16 week ocean freight on a critical-path item, and the technical configuration of the duct to AS code rather than international code makes local fabrication the dominant model.

The SBKJ Group machinery offer is built around this reality. Machines are designed for Australian production conditions, supported by the Box Hill North, Victoria headquarters with English-language engineering and project support, and configured to AS 4254 and AS 1668.2 duct standards as the default rather than as an export adaptation. The SBAL-V auto duct production line, the SBTF spiral tubeformer range, the SBEM-1250 elbow former, the SBSF-1525 stiffener former and the rest of the SBKJ machine catalogue have been deployed across Australian HVAC fabrication shops serving plastics plants, food and beverage, pharmaceutical, automotive and broader industrial manufacturing.

For projects at the scale of Pact Group's network, Visy's PET preform operations, Iplex Pipelines' pipe extrusion programme or the rotomoulding operators serving the water tank market, the SBKJ machine offer covers the fabrication capacity required with single-source machinery support, parts continuity, and after-sales engineering. For smaller projects the same machinery covers the duct programme at scaled-down throughput, with the option to share machinery capacity across multiple project clients through a fabrication shop model.

For more on the broader Australian HVAC fabrication setup and machinery economics, see our Australia HVAC duct fabrication setup 2026 reference. For the underlying AS code reference, see our AS 1668.2 mechanical ventilation code reference and AS 4254 ductwork construction reference.

Putting it together — from process map to ductwork programme

The complete project flow from initial process map to finished ductwork installation, for a representative medium-sized Australian plastics plant:

  1. Process inventory: List every press, extruder, oven, kiln, granulator and material handling station with resin, throughput, melt temperature and operating pattern.
  2. Combustible dust assessment: Apply NFPA 654 framework supplemented by AS 3957 to identify dust-generating zones and quantify the explosion risk.
  3. Hazardous area classification: Apply AS/NZS 60079 to classify Zone 21 and 22 areas around dust generators and Zone 1 and 2 areas around solvent handling.
  4. Capture and dilution design: Size hoods, capture velocities, transport velocities and dilution ACH per ASHRAE Applications Chapter 33 with AS 1668.2 overlay.
  5. Material selection: Specify duct material by zone using the chemistry, temperature and regulatory framework summarised above.
  6. Seal class: Apply AS 4254 Class A to cleanroom, food-contact, isocyanate, acid-vapour and combustible dust LEV at building boundary. Class B to general HVAC. Class C only on outdoor air intake plenums.
  7. Fire-rated penetration design: Document the AS 1530.4 tested system for every duct penetration through a fire-rated wall or floor.
  8. Heat recovery integration: Identify exhaust streams suitable for heat recovery and size the recovery coils or wheels into the duct system.
  9. Scrubber and treatment integration: Specify acid scrubbers, carbon scrubbers and thermal oxidisers as required, with the duct system integrated into the treatment train.
  10. Machinery selection: Match the SBKJ machine set to the project ductwork programme and the fitout schedule.
  11. Fabrication: Set up the fabrication shop with the selected machinery, train operators, run pilot production on representative sections, verify pressure test capability.
  12. Installation: Install duct main runs first, then branches, then terminations. Coordinate with mechanical and electrical trades on penetrations and clearances.
  13. Pressure testing: Test completed duct sections to AS 4254 seal class before insulation and concealment.
  14. Insulation and protection: Apply insulation as specified for thermal and acoustic protection.
  15. Commissioning: Complete the validation suite described above.
  16. Handover: Issue the commissioning report, the as-built drawings, the maintenance manual and the operations training.

The total project window from process inventory to handover for a medium-sized plastics plant typically runs 4 to 9 months depending on whether the project is new build or retrofit, with the fabrication and installation phase occupying 2 to 5 months of that total. Procurement of the SBKJ machinery on the project's critical path needs to be placed 16 to 22 weeks before fabrication starts, plus 2 to 3 weeks for installation and commissioning of the machinery itself in the fabrication shop.

Final notes from the engineering bench

Plastics manufacturing HVAC is one of the more rewarding disciplines in industrial ventilation because the process exposes the engineer to the full range of capture, dilution, dust, fume and cleanliness problems in a single facility. The same plant that runs a polyolefin injection press with simple capture hood will also run a polyurethane RIM cell with isocyanate scrubber, a PVC compounding line with acid-vapour service, a rotomoulding kiln with high-temperature exhaust and a cleanroom medical mould cell with cascade pressure. Designing the HVAC for one of these zones is one problem; designing it for all of them in a shared building envelope is the integration problem that defines the discipline.

The Australian standards framework — AS 1668.2, AS 4254, AS 1530.4, AS/NZS 60079, AS 1940 — supplemented by NFPA 654 for combustible dust and the ASHRAE Applications Chapter 33 framework for industrial ventilation, provides the regulatory baseline. The Safe Work Australia workplace exposure standards provide the air quality target. The plant's own production schedule, energy budget and capital constraint provide the design boundary. Within that frame, the engineer's job is to deliver capture and dilution that protects the workforce, contains the regulated emissions, recovers the heat where economic, and does so with a duct system that performs through the operational life of the plant.

SBKJ Group's role in this is the duct-forming machinery. The SBAL-V, SBAL-III, SBAL-II auto duct production lines, the SBTF spiral tubeformer range, the SBEM-1250 elbow former, the SBSF-1525 stiffener former, the SBFB-1500 box folder, the SBHF hydraulic flange former, the SBPC1500 plasma cutter and the SBLR-600 / SBLR-600A lockformers are the tools that turn the engineer's specification into the installed duct system. The machinery is configured for Australian production conditions, supported from Box Hill North, Victoria, and proven across Australian plastics manufacturing fabrication shops.

If you are scoping a plastics plant ductwork programme — new build, expansion, retrofit or refurbishment — we can help with the machinery selection, the duct programme estimation, the fabrication shop setup and the operator training. Reach out through the contact page and you will get an engineer's reply, not a sales pitch.

Discuss your plastics plant ductwork project with SBKJ →

FAQ

What capture velocity is required at an injection moulding press hood?

For standard PE, PP, PS and ABS at 200 to 280 C, capture velocity 0.5 to 1.0 m/s at the hood face. Engineering thermoplastics (PC, PA, PBT) at 280 to 320 C uplifted to 1.0 to 1.5 m/s. Polyurethane RIM and PVC require enclosed hoods with 1.5 to 2.5 m/s face velocity at the access opening. Transport velocity in branch ducts 10 to 15 m/s. Hood capture rate times open face area gives the design exhaust volume per press, typically 1,800 to 6,000 m3/h depending on press tonnage.

How is plastic regrind dust handled to NFPA 654?

Round duct construction, transport velocity above 18 m/s horizontal and 15 m/s vertical, deflagration-vented dust collector outside the building, explosion isolation at the building entry by passive flap valve or active rotary valve, bonding and earthing of every duct section per AS 1020. Heavy-gauge mild steel (1.6 mm) or stainless 304 round duct, no dead legs, cleanout doors at every elbow, spark detection and extinguishing in the duct. Kst values for plastic dust typically 50 to 300 bar.m/s with MIE 10 to 100 mJ.

What duct material is right for PVC compounding?

Galvanised fails within 12 to 24 months under HCl condensate attack. Use glass-reinforced polyester (GRP) for cost-effective acid resistance, HDPE-lined carbon steel for mid-range cost, or 316L stainless to ASTM A240 for the longest service life. FRP and HDPE are flame-rated to AS 1530.3 and have been the dominant choice for new PVC compounding LEV in Australia for the past decade. 316L is preferred near the kneader and pelletiser where thermal shock and pellet abrasion damage GRP.

How is isocyanate fume captured at a polyurethane RIM press?

Enclosure first, dilution second. Fully enclosed press cell, controlled access door, exhaust at 0.5 m/s minimum face velocity across the opening, activated carbon scrubber for TDI/MDI capture, polishing stage before atmospheric discharge. Ductwork is 316L stainless or HDPE, sealed to AS 4254 Class A on the exhaust side. Personal exposure monitoring with passive samplers verifies the WES of 0.005 ppm is not exceeded.

What are typical air change rates for the rooms in a plastics plant?

Injection moulding hall 6 to 12 ACH plus point exhaust at presses, blow moulding 8 to 15 ACH plus parison cooling supply, extrusion 6 to 10 ACH, thermoforming 10 to 18 ACH due to sheet oven heat, rotational moulding 8 to 15 ACH plus kiln exhaust, granulator and regrind 12 to 20 ACH classified Zone 21 if combustible dust persists, compounding 10 to 15 ACH, PVC compounding 12 to 18 ACH with acid-resistant LEV, cleanroom medical ISO 7 or 8 at 30 to 60 ACH, food contact 12 to 20 ACH with EN 1822 filtration.

Which SBKJ machine is the right fit for plastics manufacturing duct fabrication?

SBAL-V auto duct production line (16 m/min, 87 kW, 0.5 to 1.5 mm coil, up to 1500 mm coil width) is the workhorse for general galvanised duct. SBAL-III (14 m/min, 15.7 kW) and SBAL-II (18 m/min, 5.5 kW) cover smaller plants. SBTF-1500C, SBTF-1602 and SBTF-2020 spiral tubeformers handle round duct for kiln exhaust, oven extract and dust LEV. SBEM-1250 handles elbows. SBSF-1525 (2.5 kW) handles stiffeners. SBFB-1500 (7.5 kW, 1.20 m/min) handles large plenum work. SBHF hydraulic flange former for heavy-gauge plenums. SBPC1500 plasma cutter for stainless penetrations. SBLR-600 / SBLR-600A (7.6 m/min) for lockformed seams.

What AS standards apply to ductwork in an Australian plastics plant?

AS 1668.2 mechanical ventilation, AS 4254 ductwork construction, AS 1530.4 fire-rated penetrations, AS 1530.3 ignitability and flame propagation, AS 1397 galvanised steel, AS/NZS 60079 hazardous areas, AS 1940 flammable liquids, AS 3957 dust hazard assessment, AS 1807 cleanroom testing, AS 1020 static electricity control. NFPA 654 for combustible plastic dust, ASHRAE Applications Chapter 33 for industrial ventilation, EN 1822 EPA/HEPA filtration for food contact, ISO 14644 cleanroom classification, ISO 472 plastics vocabulary, ISO 1133 melt flow.

Why is heat recovery so attractive in plastics manufacturing HVAC?

Plastics processing exhaust averages 30 to 50 C above ambient across the operating shift, with kiln exhaust at 250 to 350 C and oven exhaust at 180 to 220 C providing high-grade recovery opportunities. A typical 10,000 m2 injection moulding facility rejects 800 to 1,500 kW of sensible heat through HVAC exhaust. Recovering 40 to 60 percent through glycol run-around or heat wheel offsets winter outdoor air pre-heat entirely in Melbourne, Sydney and Adelaide climates. Payback typically 3 to 5 years at 2026 industrial gas and electricity prices.

12-hour reply

Got a plastics plant ductwork specification question? An SBKJ mechanical engineer with plastics manufacturing experience replies within 12 hours — not a salesperson.

Ask an engineer