What temperature and humidity does chocolate tempering require?

Chocolate tempering is the controlled crystallisation of cocoa butter into the stable Form V (Beta) crystal structure. The tempering cycle moves the chocolate through three distinct temperatures — heating to 45 to 50 degrees Celsius to melt all crystal forms, cooling to 26 to 28 degrees Celsius for milk chocolate (28 to 30 for dark chocolate) to initiate Form IV and Form V crystal nucleation, and gentle reheating to 29 to 30 degrees Celsius for milk chocolate (31 to 32 for dark chocolate) to melt out the unstable lower forms while preserving the stable Form V. The tempering room ambient runs at 18 to 22 degrees Celsius with relative humidity controlled below 50 percent — higher humidity drives sugar bloom on the finished chocolate, lower humidity is acceptable but unnecessary. The enrobing tunnel cooling section runs at 10 to 15 degrees Celsius with controlled airflow at 0.3 to 0.5 metres per second over the chocolate to support the Form V crystallisation without thermal shock. Bahen and Co Margaret River WA, Koko Black Melbourne, Loving Earth and Pana Chocolate all run dedicated tempering rooms at this specification. The HVAC duct construction is 316L stainless throughout with sealed-seam AS 4254 Class B construction to hold the humidity and pressurisation differential against the adjacent enrobing and cooling tunnel envelopes. Dehumidification at the supply air handler is the engineering control of choice — chemical desiccant wheel or condensing coil refrigerant dehumidifier.

What workplace exposure standard applies to cocoa dust and coffee chaff in an Australian roastery or chocolate factory?

Safe Work Australia sets respirable dust at 5 milligrams per cubic metre 8-hour time-weighted average and inhalable dust at 10 milligrams per cubic metre 8-hour TWA for general particulates not otherwise classified, which covers cocoa dust, cocoa shell dust, sugar dust, coffee bean dust and roasted coffee chaff. Chocolatier's asthma (the chocolate industry equivalent of baker's asthma) is documented occupational respiratory disease arising from chronic cocoa dust exposure, particularly cocoa shell dust from the winnowing operation and from cocoa powder handling. Coffee processing introduces additional exposure to caffeine dust (sublimation from the roaster drum produces a fine caffeine aerosol that condenses on cooler downstream ducting), green coffee bean dust (handling of unroasted green bean in the storage and feed hopper), and the green bean moisture (GBM) release during the early stages of roasting. Carbon monoxide exposure from LPG and natural gas roaster combustion is controlled at 30 ppm 8-hour TWA, carbon dioxide at 5000 ppm 8-hour TWA and 30000 ppm STEL. The HVAC duct response is local exhaust ventilation at every dust generation point at 0.5 metres per second minimum capture velocity per the ACGIH Industrial Ventilation Manual, dedicated dust collector ductwork separate from the building general exhaust, and clean dilution supply air at 20 to 30 air changes per hour over the working zones.

How does NFPA 86 industrial roaster exhaust differ from NFPA 96 commercial kitchen exhaust in a coffee or chocolate operation?

NFPA 86 (Standard for Ovens and Furnaces) governs the industrial coffee roaster, cocoa roaster, nut roaster and similar elevated-temperature batch and continuous processing equipment. NFPA 96 (Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations) governs grease-laden exhaust from commercial cooking — in a coffee, tea or chocolate operation this typically applies to any in-house cafe or food service exhaust, plus the chocolate enrober cocoa butter mist exhaust where the cocoa butter aerosol behaves similarly to cooking oil mist. The two standards apply different fire integrity and cleanout requirements. NFPA 86 demands high-temperature stainless or refractory-lined duct rated for the 650 to 800 degree Celsius afterburner discharge, combustion air supply interlocked with roaster burner operation, flue gas extraction sized for the burner heat release, and NFPA 86 Annex B compliance for explosion relief on the combustion chamber and gas train. NFPA 96 demands grease-tight welded duct, integrated wet chemical or water mist suppression per AS 1851, cleanout access at every 6 metres, slope to drain, and discharge stack 3 metres minimum clear of any outdoor air intake. Vittoria Coffee, Lavazza Australia, Industry Beans, Allpress, Five Senses, Mecca, Single O, Campos, Coffex and DiBella all run NFPA 86 industrial roaster exhaust scope. The Cadbury Mondelez Hobart, Lindt Marsfield, Nestle Campbellfield, Haigh's Adelaide, Koko Black, Loving Earth and Bahen and Co bean-to-bar operations all run NFPA 86 on the cocoa roaster plus parallel NFPA 96 on the enrober cocoa butter mist extract.

What pressurisation cascade does FSANZ 4.2.1 require across a chocolate factory or coffee roastery process flow?

FSANZ Food Standards Code 4.2.1 (general food safety requirements), 4.2.2 (food safety practices and general requirements), 4.2.3 (food safety programs) and 4.2.4 (primary production and processing standards) plus AS 4696 hygiene principles require air to flow from clean to dirty zones at all times in any food manufacturing facility. Australian export-licensed chocolate and confectionery operations — Cadbury Mondelez exporting to ASEAN, the Middle East, the Pacific Islands and the United States under AQIS export licence; Haigh's exporting Easter egg and gift assortment to ASEAN; Bahen and Co exporting single-origin bean-to-bar bar to specialty markets; Ferrero exporting Nutella, Tic Tac and Kinder product through the Lithgow plant; coffee roasters exporting roasted coffee to Pacific, ASEAN and specialty markets — build a multi-step cascade: final packaging and case-erect at plus 25 Pascals, primary wrapping and labelling at plus 15 Pascals, enrobing and tempering at plus 10 Pascals, cocoa mass and conching at plus 5 Pascals, cocoa winnower extract room at neutral to minus 5 Pascals, bulk cocoa and sugar handling at minus 15 Pascals, coffee roasting and afterburner room at minus 10 to minus 20 Pascals. AQIS auditors and Allergen Bureau VITAL auditors verify the cascade with calibrated micromanometers at routine audit. Sealed-seam AS 4254 Class B or SMACNA Class A duct construction is the minimum to hold the cascade.

What duct construction does the tempering and enrobing line on a chocolate factory require?

The tempering room operates at 18 to 22 degrees Celsius ambient with relative humidity controlled below 50 percent and tempering chocolate temperatures cycling through 45 to 50 degrees Celsius (full melt), 26 to 30 degrees Celsius (Form V crystallisation), and 29 to 32 degrees Celsius (final temper). The enrobing tunnel cooling section runs at 10 to 15 degrees Celsius with chocolate cooling to set the Form V crystal structure. Duct construction is 316L stainless throughout with sealed-seam AS 4254 Class B because the warm-cool transitions and the controlled humidity envelope generate aggressive corrosion on any galvanised duct, plus the cocoa butter mist deposit on extract ductwork requires the cleanable 316L surface finish. The enrobing cocoa butter mist extract is treated under NFPA 96 commercial kitchen scope — integrated wet chemical or water mist suppression, 30 degrees minimum slope on horizontal runs, removable cleaning panels at 3 metre intervals, dedicated discharge fan with cleanout access. The tempering and enrobing refrigeration plant typically runs R454B or R32 lower-GWP refrigerant under AS/NZS 1677 and AS/NZS 5149, with R744 (CO2) increasingly specified on new installations for the premium bean-to-bar operators including Bahen and Co Margaret River and Koko Black Melbourne.

What are the SBKJ machine specs for a coffee roastery or chocolate factory HVAC duct fabrication scope?

The combined SBKJ machinery footprint for a major Australian coffee roastery, chocolate factory or confectionery plant duct fabrication scope is: one SBAL-V auto duct line at 316L stainless variant (SBAL-V-1250J or SBAL-V-1500J, handling 0.5 to 1.5 millimetre material, 1250 or 1500 millimetre maximum width, 16 metres per minute forming speed, 87 kilowatts, 380V 50Hz 3-phase) for the production-zone rectangular duct; one SBAL-III auto duct line at galvanised for the dry-zone and dry-plant-room scope; one SBTF-1602 spiral tubeformer with multi-material capability (galvanised, 316L stainless, 304L stainless) for round duct to 1600 millimetre diameter; one SBFB-1500 spiral fitting forming line for the round-duct fittings 80 to 1500 millimetre; one SBSF-1525 round-duct flanger for 75 to 152 millimetre flange width on round duct ends, handling 0.5 to 2.5 millimetre stainless or 0.5 to 2 millimetre black steel; one SB-ZF1500 stitchwelder for continuous TIG seam on 0.8 to 3 millimetre material with 100 to 1500 millimetre working length and Phi-150 to Phi-1500 diameter range; one SBPC1500 plasma cutter in spark-resistant configuration for Zone 21 plate prep; one SBLR-600 longitudinal seam welder for in-shop seam welding on rolled-and-formed duct sections up to 6 metres long. Combined output supports 5,000 to 15,000 square metres per month duct fabrication, sufficient for the largest greenfield Australian chocolate factory build, a major coffee roastery expansion or a confectionery plant refit.

Insights · Coffee, Tea, Cocoa & Chocolate HVAC

Coffee Roastery, Tea, Cocoa, Chocolate, Bean-to-Bar and Confectionery Manufacturing HVAC Duct Guide

A specification reference for HVAC ductwork across the full Australian coffee, tea, cocoa and chocolate manufacturing chain — from the green-bean storage and pneumatic conveying at the Mareeba and Atherton Tablelands coffee growers Skybury, Jaques Coffee Plantation and Mountain Top Coffee, through the commercial drum roaster and afterburner at Vittoria Coffee Sydney NSW, Lavazza Australia Sydney and Melbourne, Industry Beans Fitzroy VIC, Toby's Estate Sydney, Coffee Supreme Carlton VIC, Veneziano Coffee Roasters Melbourne, Padre Coffee, Allpress Espresso Australia Annandale NSW, Five Senses Coffee Perth and Manjimup WA, Mecca Coffee Sydney and Brisbane, Single O Sydney and Melbourne, Coffex Coffee Brisbane, Pablo and Rusty's, Campos Coffee, DiBella Coffee Brisbane, Hudson's Coffee and Inglewood Coffee Roasters, through the tea blending and packaging line at T2 Tea Unilever Melbourne, Madame Flavour Tea, Tielka Tea Mooloolaba QLD, Higher Living Tea Mornington Peninsula VIC, Twinings Australia, Tetley Australia, Bushells Tea and Dilmah Australia, into the cocoa winnower and conching line at Cadbury Mondelez Hobart TAS (Australia's biggest chocolate factory founded 1922) and Claremont VIC, Lindt and Spruengli Marsfield NSW, Nestle Campbellfield VIC, Allen's Confectionery Botany NSW, Haigh's Chocolates Adelaide SA (founded 1915), Koko Black Melbourne, Loving Earth Melbourne (vegan bean-to-bar), Pana Chocolate Melbourne, Bahen and Co Margaret River WA, Daintree Estates FNQ, Hadleigh Park Chocolatier, APQB Plumtree and Sweet William, Whittaker's, Darrell Lea Burwood NSW, San Churro and Ferrero Australia Lithgow NSW (Nutella, Kinder, Ferrero Rocher, Tic Tac), and finally through the enrobing, cooling tunnel, packaging and case-erect lines under the full FSANZ 4.2.1 to 4.2.4, AS 4696, Allergen Bureau VITAL, AQIS export, Halal, Kosher and Organic certification envelope. Built around the operator workflows used across the Australian Coffee Industry (ACAA), the T2 Tea standards, the Glee Tea Brisbane regional operator and the broader specialty and mass-market sectors — and aligned to AS/NZS 60079.10.2 dust atmospheres, AS 3957 dust hazard, NFPA 660 (2025 combustible dust consolidation), NFPA 86 industrial oven and roaster, NFPA 96 commercial kitchen, NFPA 68 deflagration venting, NFPA 69 explosion protection, NFPA 654 combustible particulate, AS 1668.1 fire and smoke control, AS 1668.2 mechanical ventilation, AS 4254 ductwork construction class, AS 1530.4 fire integrity, AS 1851 routine service, AS/NZS 1677 refrigeration, AS/NZS 5149 refrigeration safety, AS 4326 cold chain, AS/NZS 4674 food premises construction, AS 4696 hygienic production, FSANZ 4.2.1, 4.2.2, 4.2.3, 4.2.4 and 3.2.2, ISO 22000 food safety management, HACCP and the AQIS, Allergen Bureau VITAL, Halal, Kosher and Organic certification programmes.

By SBKJ Engineering Team · Published May 20, 2026 · 46 min read · Reviewed by SBKJ QA & Engineering

Why coffee, tea, cocoa and chocolate HVAC is its own engineering category

Coffee roasting, tea processing and chocolate manufacturing share an engineering footprint that no other Australian food manufacturing sector duplicates. The plants combine the high-temperature batch-and-continuous roaster exhaust scope of a specialty oven manufacturer with the combustible dust hazardous-area scope of a flour milling operation, layered on top of a controlled-temperature, controlled-humidity tempering and cooling envelope that has no parallel in dairy, meat or general bakery production. A modern Australian coffee roastery or chocolate factory runs perhaps a dozen distinct climatic envelopes inside one building footprint — the green-bean storage at 18 to 22 degrees Celsius and 50 to 60 percent relative humidity, the roaster drum at 180 to 230 degrees Celsius, the afterburner combustion chamber at 650 to 800 degrees Celsius, the cocoa winnower with airborne shell and nib dust at Zone 21 hazardous-area classification, the conching at 50 to 70 degrees Celsius, the tempering at 26 to 32 degrees Celsius, the enrobing tunnel at 10 to 15 degrees Celsius, the chocolate cold storage at 12 to 18 degrees Celsius, the tea blending and packaging at 18 to 22 degrees Celsius, the confectionery sugar cook at 120 to 150 degrees Celsius and the dispatch chiller at 4 to 8 degrees Celsius — with each envelope demanding its own duct material, construction class, pressurisation differential and regulatory compliance scope.

The engineering brief is dominated by three distinct hazards that operate in parallel. The first is the coffee roaster volatile organic compound (VOC) emission profile, dominated by acetic acid, acetaldehyde, furfural, methylfuran, pyrazines and pyridines from the Maillard reaction and the Strecker degradation that develop the roast flavour, plus sulfur compounds and caffeine sublimation. Every Australian local council EPA enforces an emission limit on the roaster discharge, which drives the requirement for a thermal oxidiser (afterburner) running at 650 to 800 degrees Celsius with 0.3 to 0.5 second residence time on any commercial roaster above 12 kilograms per batch capacity. The second is the cocoa, sugar and coffee chaff combustible dust hazard, all classified under AS 3957 and the 2025 consolidated NFPA 660 (which now subsumes NFPA 61 agricultural dust, NFPA 484 metal dust, NFPA 654 combustible particulate and NFPA 664 wood dust into a single standard). Cocoa dust Kst is 100 to 130 St1, sugar dust Kst is 130 to 160 St1, coffee chaff Kst is 80 to 110 St1 — all explosible at minimum airborne concentrations of 60 to 70 grams per cubic metre. The third is the FSANZ 4.2.1 to 4.2.4 hygiene and allergen management scope, which is amplified in the chocolate sector because every facility runs multiple parallel lines combining the five major Australian allergens (peanut, tree nut, dairy, soy, wheat) with the principal dairy-free vegan and lactose-free consumer market segment.

SBKJ Group has supplied auto duct production lines, spiral tubeformers, stitchwelders, plasma cutters and longitudinal seam welders into the Australian coffee, tea, cocoa and chocolate sector for more than a decade. Our engineers from the Box Hill North VIC office have walked the Vittoria Coffee Sydney roastery, the Lavazza Australia commercial roast plant, the Industry Beans Fitzroy specialty roasting operation, the Cadbury Mondelez Hobart chocolate factory (Australia's biggest), the Lindt and Spruengli Marsfield NSW premium chocolate operation, the Haigh's Adelaide gift assortment line and the Bahen and Co Margaret River bean-to-bar operation. We have seen what fails, what stands up to a fifteen-year roaster-afterburner thermal cycling environment, and what the AQIS auditor and the WorkSafe inspector flag first when a chocolate factory is at risk of dust deflagration non-conformance. This guide is written against that field experience. Pricing is held back here because pricing is meaningful only in the context of a specific plant brief; talk to an SBKJ engineer for an itemised landed-cost worksheet that ties scope to scope.

The Australian coffee, tea, cocoa and chocolate sector — operators, plants and product categories

Before specifying HVAC ductwork for any coffee roastery, tea blender, cocoa processor or chocolate factory the engineering team has to know the product category, the operator, the plant scale, the export licence portfolio and the regulatory envelope. Australia operates one of the most distinctive coffee, tea and chocolate sectors in the OECD — a thriving specialty coffee roaster population concentrated in Melbourne, Sydney, Brisbane and Perth that exports to ASEAN and the United States; a tea sector dominated by global brands with significant local operations; a chocolate sector spanning the largest southern-hemisphere chocolate factory (Cadbury Mondelez Hobart) through European-owned premium operations (Lindt, Lindt and Spruengli, Ferrero) to a fast-growing bean-to-bar premium and vegan segment (Bahen and Co, Loving Earth, Pana, Koko Black).

Commercial and specialty coffee roasting — the Australian specialty roaster footprint

Vittoria Coffee is the largest Italian-Australian commercial coffee roaster in Australia, with the principal roasting operation in Sydney NSW under the broader Vittoria Group umbrella. Vittoria runs traditional Italian-style espresso roast profile through high-capacity drum roasters supplying the broader food-service and retail market. The Vittoria roasting plant exhausts under full NFPA 86 industrial roaster scope with afterburner thermal oxidiser, dedicated chaff cyclone and 316L stainless stack ductwork.

Lavazza Australia operates the Italian Lavazza brand under licensed roasting in Australia, with plants at Sydney and Melbourne. Lavazza Australia roasts both commercial blend and premium single-origin coffee for the Australian retail and food-service market, and exports to neighbouring Pacific and ASEAN markets. The Hudson's Coffee chain, which was previously owned by the Lavazza group, operates retail cafe networks across Australia with roasting integrated into the broader Lavazza Australia operation.

Industry Beans at Fitzroy VIC is Australia's biggest specialty coffee roaster by retail recognition in the specialty segment, supplying single-origin and signature blend product through the Industry Beans cafe network and through wholesale distribution to specialty cafes across Melbourne and beyond. Industry Beans runs continuous batch roasting at multiple drum roasters with full afterburner and dust collection scope.

Toby's Estate Coffee Roasters at Chippendale Sydney NSW operates the original Toby's Estate roasting operation, founded by Toby Smith and now part of the broader Veneziano Coffee Roasters / Spinelli's Group portfolio. Toby's Estate runs single-origin specialty roasting with substantial export to the Asian specialty market.

Veneziano Coffee Roasters at Melbourne VIC under the Spinelli's Group umbrella is one of Australia's largest specialty coffee groups, operating Veneziano, Toby's Estate and related brands across multiple Australian states. The Veneziano Melbourne roastery runs continuous specialty roasting with full HVAC compliance scope.

Coffee Supreme at Carlton VIC, originally a New Zealand specialty roaster expanded into Australia, operates a roasting and distribution operation supplying the specialty cafe market across Melbourne and Sydney.

Padre Coffee at Brunswick East and Black Rock VIC operates specialty roasting across multiple Melbourne sites, supplying the specialty cafe market and wholesale distribution through the Padre Group brand portfolio.

Allpress Espresso Australia at Annandale NSW operates the New Zealand-founded Allpress brand under Australian roasting capability, supplying the specialty espresso market across Sydney and beyond with a particular focus on the food-service quality espresso segment.

Five Senses Coffee at Perth WA with secondary operations at Manjimup WA is Western Australia's largest specialty coffee roaster, supplying the Perth, Adelaide and broader Western Australian specialty cafe market with single-origin and signature blend coffee.

Mecca Coffee at Sydney NSW and Brisbane QLD operates one of Australia's most recognised specialty coffee brands, supplying the premium specialty cafe market through wholesale distribution and direct retail cafe operations.

Single O at Surry Hills Sydney NSW and Collingwood Melbourne VIC operates one of Australia's earliest direct-trade specialty roasters, supplying both the Single O cafe network and broader wholesale specialty distribution.

Coffex Coffee at Brisbane QLD operates the Coffex brand under licensed Australian roasting, supplying the Queensland and broader east-coast market with commercial and specialty coffee.

Pablo and Rusty's at Sydney NSW and broader east-coast distribution operates one of Australia's most distinctive specialty roaster brands, with substantial international export to the Asian specialty market.

Campos Coffee at Sydney NSW, Brisbane QLD, Adelaide SA and Perth WA operates one of Australia's most recognisable specialty coffee brands with national retail cafe network and substantial wholesale distribution. Campos runs centralised specialty roasting feeding into the national distribution network.

DiBella Coffee at Brisbane QLD operates one of Queensland's largest specialty roasters, with substantial wholesale distribution across the east coast and into the broader Australian food-service market.

Inglewood Coffee Roasters at South-East Queensland operates a substantial specialty roastery feeding the broader east-coast specialty market, with full afterburner and dust collection scope on the roaster stack.

Outside the named major specialty roasters, Australia hosts more than 500 active specialty coffee roasters of various scales, predominantly concentrated in the Melbourne, Sydney, Brisbane and Perth metropolitan markets. The Australian Coffee Industry Association (ACAA, formerly the Australian Specialty Coffee Association) represents the sector and maintains roasting and food-safety standards across the membership.

Australian coffee growing — the Mareeba and Atherton Tablelands origin

Australia operates one of the smaller but distinctive coffee-growing origins in the global market, with the principal growing region in the Mareeba and Atherton Tablelands region of Far North Queensland, plus smaller plantations at Coffs Harbour NSW and the Northern Rivers region of northern NSW. The Australian coffee plantation sector covers wet processing (washed coffee), dry processing (natural coffee) and hulling, grading and sorting operations, with the principal operators including Skybury Coffee (the largest Australian coffee plantation at Mareeba QLD), Jaques Coffee Plantation (Mareeba QLD), Mountain Top Coffee (Atherton Tablelands QLD) and several smaller plantations across the broader region.

The HVAC engineering scope at the Australian coffee growing tier is materially distinct from the urban roastery scope — the plantation operations focus on green-bean drying, hulling, grading, sorting and bulk storage rather than roaster combustion exhaust. Green-bean drying runs at 40 to 50 degrees Celsius for 24 to 72 hours on a parchment-on coffee bean, with controlled airflow at 0.5 to 1.0 metres per second over the drying beds. Pre-hulling moisture content is 10 to 12 percent in the green bean. The hulling, grading and sorting operations generate substantial coffee dust and chaff that requires dedicated capture and collection. Bulk green-bean storage at 18 to 22 degrees Celsius and 50 to 60 percent relative humidity preserves the bean quality for shipment to the urban roastery customers.

Tea blending and packaging — the Australian tea sector

Australia consumes substantial volumes of tea across multiple format categories — teabag, loose leaf, ready-to-drink iced tea and specialty herbal infusion. T2 Tea, founded in 1996 in Melbourne and acquired by Unilever in 2013, is Australia's most recognisable specialty tea brand with retail stores across Australia and overseas. T2 operates blending, packaging and distribution from its Melbourne base, with substantial loose-leaf, teabag and pyramid bag product across the premium retail segment.

Madame Flavour Tea at Melbourne VIC operates the premium loose-leaf tea brand founded by Corinne Smith, supplying the premium retail and food-service market with single-origin and signature blend tea.

Tielka Tea at Mooloolaba QLD operates one of Australia's leading organic and ethical tea brands, supplying certified organic loose-leaf tea to the premium retail and food-service market.

Higher Living Tea at the Mornington Peninsula VIC operates a premium loose-leaf and pyramid bag tea brand with substantial wellness and herbal infusion product across the Australian retail market.

Twinings Australia operates the global Twinings tea brand under licensed Australian distribution and packaging, supplying the mass-market and premium retail tea segments.

Tetley Australia operates the global Tetley tea brand under licensed Australian distribution, supplying the mass-market retail tea segment.

Bushells Tea, owned by Unilever, is Australia's biggest tea brand by volume and operates the mass-market black tea segment across Australian retail. Bushells runs blending, packaging and distribution from Unilever Australian facilities.

Dilmah Australia distributes the Sri Lankan-origin Dilmah brand across Australia, with packaging operations at Australian sites for the local retail and food-service market.

The HVAC engineering scope at the tea blender and packager tier is materially less demanding than coffee or chocolate — tea blending is a cool, dry operation at 18 to 22 degrees Celsius and 40 to 55 percent relative humidity, with the principal hazards being dust capture (loose-leaf tea blending generates substantial fine tea dust requiring dedicated collection) and pyramid bag and teabag heat seal smoke from the packaging line. Tea drying upstream of blending runs at 80 to 110 degrees Celsius for black tea oxidation, 100 to 110 degrees Celsius for green tea steam fixation or pan-fire, with intermediate temperatures for oolong and white tea processing, all of which generate substantial water vapour and aromatic VOC release.

Chocolate manufacturing — the mass-market and premium sector

Cadbury Mondelez operates Australia's largest chocolate factory at Hobart TAS, founded in 1922 and continuously expanded, producing the iconic Cadbury Dairy Milk, Caramello, Cherry Ripe, Picnic, Crunchie, Flake, Twirl, Time Out and Bournville product range. The Cadbury Mondelez Hobart operation is one of the largest chocolate manufacturing operations in the southern hemisphere and combines milk chocolate conching, cocoa winnowing, chocolate enrobing, mould casting and full packaging into a single integrated facility. The Australian dairy crumb (milk powder, milk fat and sugar pre-cooked into a stable crumb) is the distinctive ingredient that defines the Cadbury Dairy Milk flavour profile and is produced in parallel at the Hobart plant. The Cadbury Mondelez Claremont VIC operation supports the broader Australian chocolate confectionery production scope.

Lindt and Spruengli Australia at Marsfield NSW operates the Swiss premium chocolate brand under Australian distribution and limited Australian production, with the Lindor truffle and Excellence dark chocolate product portfolio as the flagship lines. Lindt operates the most premium milk and dark chocolate segment in Australia.

Nestle Australia at Campbellfield VIC operates the chocolate confectionery production for KitKat, Smarties, Aero and Crunch product, supplying the Australian retail and food-service market across the Nestle confectionery portfolio. The Nestle Campbellfield operation is one of Australia's largest confectionery production facilities and runs full conching, tempering, enrobing and packaging scope.

Allen's Confectionery at Botany NSW, now part of Nestle Australia, operates Australia's most recognisable confectionery brand portfolio including Snakes Alive, Party Mix, Frogs, Strawberries and Cream, Jelly Babies and dozens more under the broader Allen's umbrella. The Allen's Botany operation runs the sugar confectionery line with substantial sugar cook, syrup deposit, jelly setting and dusting operations.

Whittaker's Chocolate at Porirua New Zealand operates the New Zealand premium chocolate brand under New Zealand production, with substantial distribution into the Australian premium chocolate retail market.

Australian Premium Quality Brands (APQB) operates the Plumtree (allergen-free) and Sweet William (vegan dairy-free) chocolate brands under dedicated Australian production focused on the allergen-free and vegan chocolate segment. APQB operates one of the few fully nut-free, dairy-free chocolate facilities in Australia.

Hadleigh Park Chocolatier at Melbourne VIC operates one of Australia's premium chocolate manufacturers with substantial gift and assortment product across the Australian retail premium segment.

Daintree Estates at Far North Queensland operates Australia's only commercial tropical cocoa plantation, supplying single-origin Australian cocoa to bean-to-bar manufacturers and premium chocolate brands.

Bahen and Co at Margaret River WA operates Australia's most recognisable premium bean-to-bar chocolate manufacturer, with single-origin chocolate bar production from raw cocoa bean through roasting, winnowing, grinding, conching, tempering and bar moulding on a vintage stone grinder and traditional artisan process. Bahen and Co exports premium single-origin bar to the European and Asian specialty market.

Loving Earth at Melbourne VIC operates Australia's leading vegan and dairy-free bean-to-bar chocolate brand, with raw cocoa, organic and biodynamic certification across the product portfolio.

Pana Chocolate at Melbourne VIC operates a leading raw, vegan and organic chocolate brand with substantial export to the Asian and Middle Eastern specialty markets.

Koko Black at Melbourne VIC operates Australia's premium chocolate retail brand, with single-origin chocolate bar, truffle, praline and assortment production from a dedicated Melbourne production facility. Koko Black exports premium gift product to ASEAN and the Middle East.

Haigh's Chocolates at Adelaide SA, founded in 1915, is Australia's oldest family-owned chocolatier and operates premium chocolate gift, Easter egg, frog and assortment production from the Adelaide facility. Haigh's exports gift and assortment to ASEAN and the United Kingdom premium gift market.

San Churro at Sydney NSW and Melbourne VIC operates the chocolate cafe and dessert retail brand with substantial chocolate sauce and topping production from Australian facilities.

Darrell Lea at Burwood NSW operates one of Australia's most distinctive confectionery brands, particularly recognised for the liquorice product portfolio plus the broader chocolate and sugar confectionery range.

Ferrero Australia at Lithgow NSW operates the Italian Ferrero Group Australian production, producing Nutella spread, Kinder confectionery, Ferrero Rocher pralines and Tic Tac mints under licensed Australian production. The Ferrero Lithgow operation is one of the largest confectionery operations in regional NSW and runs full chocolate, sugar confectionery and spread production.

What makes coffee, tea, cocoa and chocolate HVAC mechanically distinctive

Coffee roaster exhaust at 180 to 230 degrees Celsius and the afterburner thermal oxidiser

The commercial drum coffee roaster is the most distinctive HVAC fixture in any Australian roastery operation. Drum temperatures run 180 degrees Celsius at green-bean charge through to 230 degrees Celsius at the dark roast first crack to second crack development phase, with the exhaust stack at the drum outlet running 30 to 50 degrees Celsius below the drum temperature due to airflow dilution. The roast development cycle moves through several characteristic temperature stages — green-bean moisture drive-off at 100 to 150 degrees Celsius (steam release and the distinctive grassy aroma of green-bean moisture release), yellow phase at 150 to 180 degrees Celsius (Maillard reaction begins, aldehyde and Strecker degradation aroma develops), first crack at 196 to 205 degrees Celsius (the audible cracking as the bean cell structure expands and water vapour escapes, marking the transition from light to medium roast development), development at 210 to 219 degrees Celsius (medium roast flavour development, characteristic caramel and acetic acid aroma) and second crack at 225 to 230 degrees Celsius (dark roast oils migrate to the bean surface, characteristic dark chocolate and pyrazine aroma).

The exhaust gas profile across the roast cycle is dominated by the Maillard reaction products (pyrazines, pyridines, furans, furfural) and the Strecker degradation products (aldehydes, ketones, sulfur compounds). At dark roast, the exhaust additionally carries sublimated caffeine that condenses on cooler downstream ducting as a fine yellow film. Acetic acid, formic acid and the sulfurous acid from sulfur compound oxidation produce a mildly acidic condensate (pH 3 to 5) that aggressively corrodes any galvanised duct in the discharge stack.

The afterburner thermal oxidiser is mandatory on every commercial roaster above approximately 12 kilograms per batch under most Australian local council EPA emission limits. The afterburner runs at 650 to 800 degrees Celsius with 0.3 to 0.5 second residence time to oxidise the VOC and odour load to acceptable atmospheric discharge concentration. Afterburner sizing is calculated against the maximum batch throughput, the roast profile peak VOC concentration and the EPA emission limit. Heat recovery from the afterburner discharge pre-heats the roaster supply air on continuous operations and can reduce the total natural gas or LPG demand by 30 to 50 percent on the next batch cycle — the recovered heat is a substantial OPEX saving on any larger roastery operation.

The HVAC duct response across the full roaster exhaust circuit is 316L stainless steel throughout the hot section, with continuous TIG-welded longitudinal seams from the SBKJ SB-ZF1500 stitchwelder, uninsulated to prevent insulation degradation, 30 degree minimum slope on horizontal runs to drain condensate, expansion joints at every thermal transition, and a dedicated cyclone for chaff collection upstream of the afterburner.

Coffee chaff collection cyclone — the silverskin handling envelope

Coffee chaff (the silverskin that separates from the green bean during roasting) is the principal solid particulate in the roaster exhaust. Chaff load on a commercial drum roaster is approximately 1 to 2 percent of green-bean mass, which on a 25 kilogram batch roaster produces 250 to 500 grams of chaff per batch. The chaff is highly combustible (Kst 80 to 110 St1 explosible under AS 3957 and NFPA 660) and ignites readily — chaff fires in the cyclone catch bin are the single most common roaster operational incident in Australian roasteries. The chaff cyclone is 316L stainless with 1.5 millimetre gauge body and fully welded longitudinal seams from the SB-ZF1500 stitchwelder. Discharge to a sealed metal catch bin with explosion isolation for any backflow protection. The catch bin is grounded to the same earth grid as the cyclone and the upstream ductwork.

Cocoa dust deflagration — the chocolate factory equivalent of flour dust

Cocoa dust carries a Kst dust deflagration index in the 100 to 130 bar metre per second range, classifying as St1 explosible dust under AS 3957 and the 2025 consolidated NFPA 660. Sugar dust runs higher at 130 to 160 bar metre per second, also St1. Both are explosible at minimum airborne concentrations of 60 to 70 grams per cubic metre, and minimum ignition energy is well under 100 millijoules. The Australian chocolate sector — Cadbury Mondelez Hobart, Lindt Marsfield, Nestle Campbellfield, Allen's Botany, Haigh's Adelaide, Koko Black Melbourne, Loving Earth, Pana, Bahen and Co Margaret River, Daintree Estates, Hadleigh Park, APQB, Whittaker's, Darrell Lea Burwood, San Churro and Ferrero Lithgow — handles cocoa powder, cocoa nib, cocoa butter, sugar and chocolate crumb at industrial scale.

The cocoa winnower is the highest airborne dust generation point in the entire chocolate manufacturing chain. The winnower separates the cocoa nib from the cocoa shell after the cocoa bean roasting stage, generating a cyclone-collected nib stream that proceeds to grinding and a shell stream that proceeds to disposal or cattle feed. The winnower extract handles continuous airborne cocoa shell dust at concentrations frequently in the Zone 21 hazardous-area range during full operation. The cocoa grinder downstream of the winnower additionally generates fine cocoa nib and butter aerosol on the extract duct.

The HVAC duct response is the combined NFPA 68 deflagration venting on every dust collector, NFPA 69 explosion isolation valves on inlet and outlet ductwork, full bonding and grounding to a common earth grid (under 1 ohm joint resistance, under 10 ohms earth grid resistance to facility earth electrode per AS/NZS 60079.14), conductive duct construction with verified earth continuity at every joint, no internal duct insulation, no horizontal dust traps, and routine clean-down to keep settled dust load below the secondary deflagration threshold.

Chocolatier's asthma and cocoa shell respiratory exposure

Beyond the deflagration hazard, cocoa dust carries a substantial occupational respiratory exposure hazard. Chocolatier's asthma (the chocolate industry equivalent of baker's asthma) is documented occupational respiratory disease arising from chronic cocoa dust exposure, particularly cocoa shell dust from the winnowing operation and from cocoa powder handling. Safe Work Australia sets respirable dust at 5 milligrams per cubic metre 8-hour TWA and inhalable dust at 10 milligrams per cubic metre 8-hour TWA for general particulates not otherwise classified, which covers cocoa dust, cocoa shell dust, sugar dust, coffee bean dust and roasted coffee chaff.

The HVAC duct response is local exhaust ventilation at every dust generation point at 0.5 metres per second minimum capture velocity per the ACGIH Industrial Ventilation Manual, dedicated dust collector ductwork separate from the building general exhaust to prevent dust recirculation, and clean dilution supply air at 20 to 30 air changes per hour over the working zones. Cadbury Mondelez Hobart, Lindt Marsfield, Nestle Campbellfield and the major bean-to-bar operators all run engineered local exhaust ventilation as standard.

Conching at 50 to 70 degrees Celsius — the chocolate flavour development envelope

Conching is the chocolate flavour development process where the freshly ground chocolate liquor is mixed and aerated at 50 to 70 degrees Celsius for periods ranging from 12 hours (premium milk chocolate at high-intensity conching) to 72 hours (premium dark chocolate at extended conching). The conching process drives off volatile undesired flavour compounds (acetic acid, residual moisture, sulfur compounds), develops the desired flavour profile (additional Maillard reaction products at lower temperature, chocolate aroma maturation) and refines the chocolate particle size and viscosity.

The conching environment generates substantial volatile flavour compound off-gassing — the acetic acid, methylbutanal, dimethyl sulfide and other volatile compounds that conching removes have to be captured at the conche extract and either thermally oxidised or activated-carbon filtered before atmospheric discharge. The conche extract runs at 0.3 to 0.5 metres per second capture velocity over each conche opening, and discharges through a dedicated extract duct in 316L stainless to either a small thermal oxidiser (similar specification to the coffee roaster afterburner but at smaller scale) or an activated carbon filter bank.

Tempering at 26 to 32 degrees Celsius — the cocoa butter crystallisation envelope

Chocolate tempering is the controlled crystallisation of cocoa butter into the stable Form V (Beta) crystal structure. The cocoa butter polymorphism produces six distinct crystal forms (Form I through Form VI), of which only Form V provides the desired chocolate properties — glossy surface, crisp snap, smooth mouthfeel, resistance to fat bloom. The tempering cycle moves the chocolate through three distinct temperatures — heating to 45 to 50 degrees Celsius to melt all crystal forms (full melt phase), cooling to 26 to 28 degrees Celsius for milk chocolate (28 to 30 for dark chocolate) to initiate Form IV and Form V crystal nucleation (crystallisation phase), and gentle reheating to 29 to 30 degrees Celsius for milk chocolate (31 to 32 for dark chocolate) to melt out the unstable Form IV while preserving the stable Form V (final temper phase).

The tempering room ambient runs at 18 to 22 degrees Celsius with relative humidity controlled below 50 percent. Higher humidity drives sugar bloom on the finished chocolate (water absorbed onto the chocolate surface dissolves and recrystallises the sugar producing a whitish surface haze), lower humidity is acceptable but unnecessary. The HVAC duct construction is 316L stainless throughout with sealed-seam AS 4254 Class B construction to hold the humidity and pressurisation differential against the adjacent enrobing and cooling tunnel envelopes. Dehumidification at the supply air handler is the engineering control of choice — chemical desiccant wheel or condensing coil refrigerant dehumidifier. Bahen and Co Margaret River, Koko Black Melbourne, Loving Earth and Pana Chocolate all run dedicated tempering rooms at this specification.

Chocolate enrobing tunnel and cooling at 10 to 15 degrees Celsius

The chocolate enrober applies a tempered chocolate coating to the underlying centre (biscuit, wafer, fondant, caramel, nut cluster, fruit centre) by passing the centre through a continuous chocolate curtain — the enrobing shower. The freshly enrobed product passes immediately into the cooling tunnel where the chocolate coating sets through Form V crystallisation. The cooling tunnel runs at 10 to 15 degrees Celsius with controlled airflow at 0.3 to 0.5 metres per second over the chocolate to support the Form V crystallisation without thermal shock that would produce fat bloom or surface defects.

The enrobing operation generates substantial airborne cocoa butter mist and fine chocolate dust on the enrobing chamber extract. Cocoa butter mist behaves similarly to cooking oil mist and is treated under NFPA 96 commercial kitchen scope — grease-tight welded duct construction, integrated wet chemical or water mist suppression per AS 1851, 30 degrees minimum slope on horizontal runs, removable cleaning panels at 3 metre intervals, dedicated discharge fan with cleanout access. The Cadbury Mondelez Hobart enrobing line, the Cadbury Claremont line, the Lindt Marsfield Lindor enrobing, the Nestle Campbellfield KitKat enrobing line, the Allen's Botany sugar confectionery sanding line and the bean-to-bar operations at Bahen and Co, Loving Earth, Pana, Koko Black and Haigh's all run dedicated enrober extract under combined NFPA 96 and FSANZ 4.2.1 compliance scope.

Tea drying and oxidation at 80 to 110 degrees Celsius

Tea processing distinguishes between four principal tea categories by the oxidation and drying treatment applied to the freshly plucked leaf. Black tea is fully oxidised (the leaf is bruised and held at controlled humidity and temperature to allow enzymatic oxidation of the polyphenols, producing the distinctive dark brown colour and robust flavour) then dried at 80 to 110 degrees Celsius to lock in the oxidation state and reduce moisture to under 5 percent. Green tea is steam-fixed or pan-fired immediately after plucking at 100 to 110 degrees Celsius to denature the polyphenol oxidase enzymes before any oxidation can begin, then dried at 80 to 90 degrees Celsius. Oolong tea is partially oxidised (20 to 80 percent depending on the style) then fixed and dried. White tea is minimally processed with gentle drying at 50 to 70 degrees Celsius.

The Australian tea sector imports the majority of finished or semi-finished tea, with blending and packaging the principal Australian operation rather than full tea processing. T2 Tea Melbourne, Madame Flavour, Tielka, Higher Living, Twinings Australia, Tetley, Bushells and Dilmah Australia all run blending and packaging rather than full tea processing. The HVAC engineering scope at the tea blending and packaging tier is materially less demanding than coffee or chocolate, but the loose-leaf tea blending operations generate substantial fine tea dust requiring dedicated capture, and the pyramid bag and teabag heat seal jaws on the packaging line generate heat seal smoke containing low concentrations of formaldehyde (1 ppm STEL under Safe Work Australia) and other VOC.

Confectionery sugar cook at 120 to 150 degrees Celsius

Sugar confectionery production at Allen's Botany, Darrell Lea Burwood, Ferrero Lithgow (for Kinder and related sugar confectionery), San Churro and the broader confectionery sector runs sugar boiling kettles and continuous sugar cookers at 120 to 150 degrees Celsius for hard candy, caramel, toffee, fudge and related product. The sugar cook generates substantial steam release, sugar inversion volatiles and the characteristic caramelisation aroma compounds (furanones, diacetyl, caramelisation Maillard products). The capture exhaust over the sugar cooker runs at 0.5 to 1.0 metres per second capture velocity with discharge through a wet scrubber to remove the steam and aerosolised sugar before atmospheric discharge.

Glucose syrup, invert sugar syrup and sugar dust handling on the upstream side of the sugar cooker presents Zone 22 hazardous-area dust hazard equivalent to flour dust. The sugar dust extraction runs the same NFPA 68 deflagration venting, NFPA 69 explosion isolation, bonding and grounding and conductive duct construction as cocoa dust handling.

Refrigeration plant on the chocolate enrobing cooling tunnel and bulk chocolate cold storage

The chocolate enrobing cooling tunnel, the bulk chocolate cold storage (12 to 18 degrees Celsius for finished bar and assortment product) and the dispatch chiller (4 to 8 degrees Celsius) all run refrigeration plant under AS/NZS 1677 and AS/NZS 5149. Modern Australian chocolate factory installations are migrating from the legacy R410A and R134a refrigerants to lower-GWP alternatives — R32, R454B, and increasingly R744 (CO2) on the premium bean-to-bar operators including Bahen and Co Margaret River and Koko Black Melbourne. R32 is rated A2L mildly flammable under AS/NZS 5149 with reduced charge limits and ventilation requirements in occupied space. R454B is the direct R410A replacement at lower GWP. R744 CO2 is rated A1 non-flammable with negligible global warming potential but requires substantially higher operating pressure (60 to 90 bar) than the legacy hydrofluorocarbon plant.

Allergen segregation across the chocolate and confectionery factory

The Australian chocolate and confectionery sector handles all five major Australian allergens — peanut, tree nut, dairy (milk), wheat (gluten) and soy — plus egg in some product categories. The Allen's Confectionery operation at Botany NSW under Nestle handles peanut and tree nut in the same facility as nut-free product. The Cadbury Mondelez Hobart operation handles dairy milk chocolate alongside dark chocolate (which must remain dairy-free for vegan and lactose-free consumer market). Loving Earth, Pana Chocolate and the bean-to-bar vegan operators run dedicated dairy-free facilities. Australian Premium Quality Brands APQB runs the Plumtree and Sweet William dedicated vegan and dairy-free chocolate facility.

The Allergen Bureau VITAL (Voluntary Incidental Trace Allergen Labelling) programme requires positive separation between allergen-containing and allergen-free parallel lines. The HVAC engineering response is dedicated supply and extract per allergen zone with no shared return air across boundaries, sealed-seam AS 4254 Class B duct construction to hold the pressurisation differential (plus 25 Pa on allergen-free packaging relative to allergen-containing parallel line), HEPA-filtered supply at MERV 14 minimum across the allergen-sensitive packaging zone, and routine air-sample testing for protein residue at every product changeover.

The green bean storage and pneumatic conveying envelope — the start of the roastery scope

The green-bean storage and pneumatic conveying envelope is the first HVAC zone in any coffee roastery and the equivalent zone in chocolate manufacturing is the cocoa bean storage upstream of the cocoa roaster. Green coffee bean bulk storage runs at 18 to 22 degrees Celsius and 50 to 60 percent relative humidity to maintain the green-bean moisture content at 10 to 12 percent for optimal roast development. Bulk green-bean storage at higher humidity drives the green bean to absorb moisture from atmosphere, producing inconsistent roast results; at lower humidity the bean dehydrates and produces a hollow, dry, papery roast profile. The storage envelope is typically a controlled bulk warehouse or jute-bag stack with dehumidification supply at the conditioned space target.

Pneumatic conveying of green bean from the bulk storage to the roaster hopper generates substantial airborne dust (broken bean, jute fibre, dust from the green bean surface) and the conveying line is Zone 22 hazardous area under AS/NZS 60079.10.2 if the conveying dust concentration exceeds the minimum explosible concentration. The conveying line is 316L stainless via the SBKJ SBFB-1500 spiral fitting forming line for the round conveying duct sections and the SBSF-1525 round flanger for the flanged terminations. Earth bonding and grounding integrity per AS/NZS 60079.14 is verified at commissioning. A dust collector with NFPA 68 deflagration venting handles the conveying dust extract.

The roaster floor and drum roaster envelope

The roaster floor is the principal production zone in any coffee roastery and houses the drum roasters, the chaff cyclones, the afterburner thermal oxidisers and the immediate process control envelope. Drum roasters range from 5 kilogram batch laboratory roasters at the smallest specialty operation through 25, 60 and 120 kilogram production batch roasters at the mid-size specialty roaster (Industry Beans, Allpress, Five Senses, Mecca, Single O, Padre, Veneziano), up to 200 to 500 kilogram batch and continuous drum roasters at the largest commercial roasters (Vittoria, Lavazza Australia, Campos, DiBella, Coffex, Pablo and Rusty's).

The drum roaster runs natural gas or LPG burner combustion under the drum, with the combustion products plus the green-bean moisture release, chaff release and developing roast VOC discharging through the drum outlet to the chaff cyclone. Roast cycle duration is 8 to 16 minutes from green-bean charge to bean drop, with the temperature ramping continuously through the roast profile. The roaster control system manages the burner heat release, the drum airflow rate and the bean temperature curve against the target roast profile.

The roaster floor ambient runs at 22 to 28 degrees Celsius during full production, with substantial radiant heat from the drum roaster bodies plus the combustion exhaust capture canopies. Supply air at 8 to 15 air changes per hour with dedicated extract at the drum loading face captures the residual roast smoke and steam release that escapes the primary drum exhaust capture. The roaster floor pressurisation runs neutral to slightly negative relative to the broader facility, with positive cascade outward to the green-bean storage (positive 5 Pa) and the bagging and dispatch (positive 15 Pa).

The cocoa bean roaster, winnower and grinder envelope — the chocolate factory upstream

The cocoa bean roaster at Cadbury Mondelez Hobart, Lindt Marsfield, Nestle Campbellfield, Bahen and Co Margaret River, Koko Black Melbourne, Daintree Estates, Loving Earth and Pana operates at materially higher temperature than the coffee roaster — cocoa bean roasting runs at 120 to 150 degrees Celsius for milk chocolate cocoa, 130 to 170 degrees Celsius for dark chocolate cocoa, with continuous batch or continuous drum roasting for 20 to 40 minutes. The cocoa bean roaster exhaust is materially similar to the coffee roaster exhaust in HVAC duct terms — 316L stainless throughout, continuous welded longitudinal seams, dedicated afterburner thermal oxidiser at 650 to 800 degrees Celsius (although typically smaller scale than the coffee roastery afterburner because the cocoa roaster VOC discharge is lower per unit production), and a dedicated chaff and shell cyclone.

Downstream of the cocoa bean roaster sits the cocoa winnower — the equipment that separates the cocoa nib from the cocoa shell. The winnower uses a combination of mechanical cracking and pneumatic separation to produce two output streams: the cocoa nib (which proceeds to grinding and the downstream chocolate manufacturing) and the cocoa shell (which proceeds to disposal, cattle feed or specialty product as cocoa shell mulch). The winnower extract is the highest-dust generation point in the chocolate factory — airborne cocoa shell dust at Zone 21 hazardous-area concentration during full operation. The winnower extract duct is 316L stainless via the SBKJ SBFB-1500 with full NFPA 68 deflagration venting, NFPA 69 isolation, bonding and grounding and conductive duct construction.

The cocoa grinder downstream of the winnower converts the cocoa nib to cocoa mass (the liquid chocolate at approximately 50 degrees Celsius). The grinder runs as a stone grinder (traditional artisan process at Bahen and Co, Loving Earth, Pana), a roller refiner (commercial scale at Cadbury Mondelez, Lindt, Nestle, Koko Black, Haigh's, Hadleigh Park) or a ball mill (some specialty operations). The grinder extract handles fine cocoa nib aerosol and cocoa butter mist, with extract duct in 316L stainless under combined NFPA 68 dust deflagration and NFPA 96 cocoa butter mist scope.

Conching room — the chocolate flavour development envelope

The conche is the chocolate flavour development equipment that mixes and aerates the freshly ground chocolate mass at 50 to 70 degrees Celsius for periods ranging from 12 hours to 72 hours depending on the product. The conche extract handles substantial volatile flavour compound off-gassing — acetic acid, methylbutanal, dimethyl sulfide, residual moisture and the other volatile compounds that conching removes have to be captured and treated before atmospheric discharge. The conche room ambient runs at 22 to 28 degrees Celsius with controlled humidity at 40 to 55 percent relative humidity.

The HVAC duct construction in the conche room is 316L stainless throughout with continuous welded longitudinal seams from the SB-ZF1500 stitchwelder. The conche extract discharges through either a small thermal oxidiser (similar specification to the coffee roaster afterburner but smaller scale) or an activated carbon filter bank to remove the VOC load before atmospheric discharge. Heat recovery from the thermal oxidiser discharge pre-heats the conche room supply air or the facility hot water supply.

Tempering room — the cocoa butter crystallisation envelope

The tempering room is the most controlled-environment zone in the chocolate factory. Ambient temperature at 18 to 22 degrees Celsius, relative humidity below 50 percent, controlled airflow at 0.3 to 0.5 metres per second over the working surfaces. The tempering chocolate temperature cycles through 45 to 50 degrees Celsius (full melt), 26 to 30 degrees Celsius (Form V crystallisation initiation) and 29 to 32 degrees Celsius (final temper) on the production tempering machines. Manual hand-tempering at the bean-to-bar artisan operators (Bahen and Co, Loving Earth, Pana, Koko Black, Hadleigh Park) follows the same temperature cycle.

The HVAC duct construction is 316L stainless throughout with sealed-seam AS 4254 Class B construction to hold the humidity and pressurisation differential. Dehumidification at the supply air handler is the engineering control of choice — chemical desiccant wheel for the most demanding low-humidity applications, condensing coil refrigerant dehumidifier for the standard 40 to 50 percent RH applications. The tempering room runs at plus 10 to plus 15 Pa relative to the adjacent enrobing and cooling tunnel envelope and at plus 5 Pa relative to the broader facility, ensuring that any air flow is outward from the tempering room into the surrounding zones.

Enrobing line and cooling tunnel

The chocolate enrober applies a tempered chocolate coating to the underlying centre by passing the centre through a continuous chocolate curtain. The enrobing chamber generates substantial airborne cocoa butter mist and fine chocolate dust that requires dedicated capture. The freshly enrobed product passes immediately into the cooling tunnel where the chocolate coating sets through Form V crystallisation. The cooling tunnel runs at 10 to 15 degrees Celsius with controlled airflow at 0.3 to 0.5 metres per second over the chocolate.

The enrobing chamber extract is treated under NFPA 96 commercial kitchen scope — 316L stainless grease-tight welded duct construction, integrated wet chemical or water mist suppression per AS 1851, 30 degrees minimum slope on horizontal runs, removable cleaning panels at 3 metre intervals, dedicated discharge fan with cleanout access. The cooling tunnel envelope is 316L stainless with external insulation and sealed vapour-barrier joints to prevent condensate accumulation on the cold surfaces.

Bulk chocolate cold storage and dispatch chiller

Finished chocolate bar, assortment, truffle and gift product holds in bulk chocolate cold storage at 12 to 18 degrees Celsius with relative humidity below 60 percent. The cold storage envelope preserves the Form V crystal structure of the tempered chocolate against ambient warming that would melt the chocolate and against humidity excursion that would drive sugar bloom on the surface. The cold storage runs R32, R454B or R744 (CO2) refrigeration plant under AS/NZS 1677 and AS/NZS 5149, with pre-insulated 316L stainless panel duct inside the cold envelope, continuous vapour barrier on the warm side, butyl gasket seals at every penetration and thermal-break hangers to prevent heat bridging.

The dispatch chiller at 4 to 8 degrees Celsius supports the chilled distribution of premium gift product (Easter egg, advent calendar, gift assortment) that requires shorter shelf-life chilled distribution rather than ambient distribution. The cold chain from production through dispatch through retail is governed by AS 4326 (storage and transport of frozen meat and meat products, cross-applied to chocolate gift product) with the loading dock chilled airlock at 4 to 8 degrees Celsius and high-velocity air curtains at 1.5 to 2.5 metres per second maintaining the cold chain integrity during truck loading.

Tea blending and packaging envelope

The tea blending and packaging operation at T2 Tea Melbourne, Madame Flavour, Tielka, Higher Living, Twinings Australia, Tetley, Bushells and Dilmah Australia runs at 18 to 22 degrees Celsius ambient with 40 to 55 percent relative humidity. The principal hazards are dust capture (loose-leaf tea blending generates substantial fine tea dust requiring dedicated collection) and the heat seal smoke from the pyramid bag and teabag packaging line.

The tea blender extract runs at 0.3 to 0.5 metres per second capture velocity over each blending station with discharge to a dedicated dust collector under NFPA 68 deflagration venting (tea dust is rated St1 at the low end of the Kst range). The packaging line heat seal jaws generate heat seal smoke containing low concentrations of formaldehyde (1 ppm STEL under Safe Work Australia) and other VOC, with discharge through an activated carbon filter or thermal oxidiser before atmospheric discharge.

Confectionery sugar cook and syrup deposit envelope

Sugar confectionery production at Allen's Botany (Snakes Alive, Party Mix, Frogs, Strawberries and Cream, Jelly Babies), Darrell Lea Burwood (liquorice, sugar confectionery, chocolate-coated sugar product), Ferrero Lithgow (Kinder sugar confectionery, Tic Tac mints), San Churro and the broader sector runs sugar boiling kettles, continuous sugar cookers and syrup deposit lines at 120 to 150 degrees Celsius.

The sugar cook capture exhaust runs at 0.5 to 1.0 metres per second capture velocity over each cooker with discharge through a wet scrubber to remove the steam and aerosolised sugar before atmospheric discharge. The syrup deposit and starch moulding line generates fine sugar dust and starch dust at the cooling and demoulding stations, with extract under NFPA 68 deflagration venting on the dust collector.

Materials specification — why 316L stainless is the coffee, tea, cocoa and chocolate default

316L versus 304L in coffee, tea and chocolate

316L is the industrial coffee, tea, cocoa and chocolate default. The molybdenum addition in 316L (2 to 3 percent) resists the acid condensate from coffee combustion products (acetic acid, formic acid, sulfurous acid from sulfur compound oxidation), the chloride attack from coastal Australian sites (Margaret River WA, Hobart TAS, Mooloolaba QLD, Mornington Peninsula VIC), the trace chloride load in any food sanitation chemistry and the cocoa butter mist deposit on enrober extract ductwork. 316L delivers a 20 to 25 year facility life on the coffee roaster afterburner discharge and the chocolate enrober extract versus 10 to 15 years for 304L under the same conditions.

316L versus galvanised

Galvanised G275 ductwork is acceptable in isolated dry plant rooms with no chloride exposure, no direct cocoa or coffee dust exposure and no acid condensate exposure. Typical permitted zones are administrative office areas, dry electrical switch rooms, mezzanine plant rooms with positive pressurisation, the boundary services ventilation around the building envelope and the dry side of the bagging and case-erect dispatch operation. Outside those zones, galvanised is a 24 to 36 month replacement programme under the combined exposure of cocoa and coffee dust, acid condensate from roaster exhaust, sanitation chemistry and refrigeration plant load.

Where 304L is acceptable

304L is acceptable on the dry side of the operation — the green-bean storage at lower humidity, the office and dry plant room scope, the loading dock scope and the tea blending and packaging line where the ambient is dry and the principal dust load is tea (which is less aggressive than cocoa or coffee). The premium for 316L over 304L is 15 to 25 percent on the duct fabric cost line, and the engineering decision is whether the long-term corrosion environment justifies the premium. For the wet side of the operation (cocoa winnower, conching, enrobing extract, cooling tunnel, sugar cook capture), 316L is the default. For the dry side, 304L is acceptable.

Carbon steel for silo and collector body

Carbon steel at 1.2 to 1.5 millimetre gauge is acceptable for the cocoa and coffee bean silo body and the dust collector body where the dust pressure rating drives the gauge specification. The clean-side post-collector ductwork is 316L. The silo body construction is heavier gauge (3 to 6 millimetres) to withstand the static head pressure of the bulk bean load and the design deflagration pressure on the collector.

Air change rates and ventilation calculation

Australian Standard 1668.2 sets the minimum outdoor air, exhaust rate and pressurisation differential per zone. The typical air change rate per zone in a coffee roastery or chocolate factory is:

Green-bean storage — 4 to 8 air changes per hour with humidity-controlled supply at 50 to 60 percent RH.
Pneumatic conveying dust extract — continuous dust collector extract at 600 to 1200 cubic metres per hour per tonne of conveying capacity.
Roaster floor — 8 to 15 air changes per hour with dedicated drum roaster exhaust capture and afterburner discharge.
Cocoa winnower extract room — 15 to 25 air changes per hour with dedicated winnower dust extract.
Cocoa grinder extract — 10 to 15 air changes per hour with extract through combined NFPA 68 deflagration venting and NFPA 96 cocoa butter mist scope.
Conching room — 8 to 12 air changes per hour with dedicated conche extract through thermal oxidiser or activated carbon.
Tempering room — 10 to 15 air changes per hour with dewpoint-conditioned supply at below 50 percent RH.
Enrobing chamber extract — dedicated NFPA 96 scope at 0.5 to 1.0 metres per second capture velocity over the enrobing chamber.
Cooling tunnel — 15 to 25 air changes per hour at 10 to 15 degrees Celsius.
Bulk chocolate cold storage — 4 to 8 air changes per hour at 12 to 18 degrees Celsius.
Tea blending and packaging — 15 to 20 air changes per hour with dedicated dust extract at every blender.
Sugar cook capture — dedicated scope at 0.5 to 1.0 metres per second capture velocity over each cooker through wet scrubber.
Syrup deposit and starch moulding — 15 to 20 air changes per hour with dust extract through deflagration vented collector.
Packaging and case-erect — 15 to 20 air changes per hour with HEPA-filtered supply at MERV 14 minimum and positive pressurisation at plus 25 Pa.
Refrigeration machinery room — 15 to 30 air changes per hour minimum under AS/NZS 1677, increasing for any A2L refrigerant (R32, R454B) or A1 high-pressure plant (R744 CO2).
Loading dock — 8 to 12 air changes per hour with dock door air curtain integration.

The total facility outdoor air rate on a Cadbury Mondelez Hobart scale chocolate factory typically sits at 30 to 50 cubic metres per second of conditioned outdoor air, with the cocoa winnower dust extract and the cocoa roaster afterburner combustion air supply dominating the load. For a major commercial coffee roastery at Vittoria, Lavazza Australia or Campos scale the total outdoor air is 5 to 15 cubic metres per second depending on the production volume.

Standards and regulatory references

Australian coffee, tea, cocoa and chocolate HVAC ductwork is governed by an overlapping set of standards and codes. The primary references that appear in every facility specification are:

AS/NZS 60079.10.2 — Explosive atmospheres — Classification of areas — Combustible dust atmospheres. The principal hazardous area classification standard for cocoa, sugar and coffee chaff dust.
AS/NZS 60079.14 — Electrical installations design selection and erection in explosive atmospheres.
AS 3957 — Industrial dust hazard standard. Foundational Australian standard on combustible dust risk assessment and control.
NFPA 660 — Standard for Combustible Dusts and Particulate Solids (2025 consolidation of NFPA 61 agricultural dust, NFPA 484 metal dust, NFPA 654 combustible particulate solids and NFPA 664 wood dust).
NFPA 654 — Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids (now consolidated into NFPA 660).
NFPA 68 — Standard on Explosion Protection by Deflagration Venting.
NFPA 69 — Standard on Explosion Prevention Systems.
NFPA 86 — Standard for Ovens and Furnaces. The principal industrial roaster exhaust standard for commercial drum coffee roasters, cocoa bean roasters and afterburner thermal oxidisers.
NFPA 96 — Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations. Governs cocoa butter mist exhaust on the chocolate enrober and any cafe or food-service exhaust integrated into the roastery or chocolate facility.
AS 1668.1 — The use of ventilation and air conditioning in buildings — Fire and smoke control.
AS 1668.2 — The use of ventilation and air conditioning in buildings — Mechanical ventilation. Sets minimum outdoor air, exhaust rates and zone separation requirements.
AS 4254.1 and AS 4254.2 — Ductwork for air-handling systems in buildings. Construction class, sealing class and leakage testing.
AS/NZS 1677 — Refrigerating Systems. Safety, design and construction of refrigeration plant for the chocolate cooling tunnel, bulk chocolate cold storage and dispatch chiller.
AS/NZS 5149 — Refrigerating Systems and Heat Pumps. Safety and environmental requirements including R32 and R454B A2L mildly flammable refrigerant management and R744 CO2 high-pressure plant.
AS 1530.4 — Methods for fire tests on building materials and structures. Roaster stack and afterburner discharge fire integrity.
AS 1851 — Routine service of fire protection systems and equipment. Roaster exhaust fire suppression and enrober extract suppression.
AS 4696 — Australian Standard for the Hygienic Production and Transportation of Meat and Meat Products. Cross-applied to chocolate and confectionery production hygiene principles.
AS/NZS 4674 — Construction and fit-out of food premises.
AS 4326 — The Storage and Transport of Frozen Meat and Meat Products. Cross-applied to chilled chocolate gift product distribution.
AS 4775 — Emergency Eyewash and Shower Equipment. Refrigeration machinery room emergency stations.
AS 1657 — Fixed platforms, walkways, stairways and ladders. Access for roaster, afterburner and dust collector servicing.
AS 1170.4 — Earthquake actions in Australia. Seismic bracing for tall roaster stacks and afterburner discharge stacks.
NCC Volume One Class 6, 7b and 8 — National Construction Code Class 6 retail bakery, cafe and chocolate shop, Class 7b food storage, Class 8 industrial manufacturing classifications.
FSANZ Food Standards Code 4.2.1, 4.2.2, 4.2.3, 4.2.4 and 3.2.2 — Food Standards Australia New Zealand. Hygiene, microbial, chemical residue and HACCP requirements.
HACCP — Hazard Analysis and Critical Control Point. Foundational food safety methodology.
ISO 22000 — Food safety management systems.
AQIS export licence — Australian Quarantine and Inspection Service export licensing for Cadbury Mondelez chocolate export to ASEAN, Middle East and the United States; Haigh's gift export; Bahen and Co bean-to-bar export; Koko Black premium gift export; Ferrero Australian production export; coffee roaster export to Pacific, ASEAN and specialty markets.
Allergen Bureau VITAL — Voluntary Incidental Trace Allergen Labelling allergen management programme. Peanut, tree nut, dairy, soy and wheat are the principal Australian chocolate and confectionery allergens.
Halal certification — AFIC, ICCV, HCAS and other Halal certifying bodies for Halal-certified chocolate and confectionery export to Middle East and ASEAN markets.
Kosher certification — KA Kosher Australia, Council of Orthodox Synagogues for Kosher-certified chocolate product (Cadbury Mondelez maintains Kosher certification on selected product lines).
Organic certification — Australian Certified Organic, NASAA Organic and other certification bodies for organic cocoa, tea and coffee supply (Loving Earth, Pana, Tielka, Higher Living all maintain organic certification).
Safe Work Australia Workplace Exposure Standards — respirable dust 5 mg/m3 8-hour TWA; inhalable dust 10 mg/m3 8-hour TWA (cocoa dust, cocoa shell, sugar dust, coffee bean, coffee chaff); CO2 5000 ppm 8-hour TWA, 30000 ppm STEL (roaster combustion, sugar cook, conching); CO 30 ppm 8-hour TWA (roaster burner combustion); formaldehyde 1 ppm STEL (heat seal smoke, phenolic Maillard); methane 1.25 percent LEL (LPG and natural gas supply); R32 1000 ppm WEL; R454B WEL per AS/NZS 5149; R744 CO2 5000 ppm WEL; oil mist 5 mg/m3 8-hour TWA (cocoa butter mist).
ASHRAE Handbook — Chapter 22 Refrigerated Processing, Chapter 23 Bakery Products, Chapter 35 Drying and Dehumidification.
ACGIH Industrial Ventilation Manual — Local exhaust ventilation design methodology.
ACAA Australian Coffee Industry Association — Industry body governing the Australian specialty coffee roasting sector.
T2 Tea Standards and the Tea Association of Australia — Industry standards for tea blending, packaging and quality assurance.
MIA Meat Industry Australia — Meat Industry Association cross-applicable to dairy and animal-derived ingredient handling in chocolate manufacturing.

SBKJ machinery for coffee, tea, cocoa and chocolate ductwork — sized for the full plant scope

Fabricating the duct schedule for an integrated coffee roastery, tea blender, chocolate factory or confectionery plant touches the full SBKJ product range. Each machine has a specific role in the coffee, tea, cocoa and chocolate duct fabrication scope.

SBAL-V auto duct line — 316L stainless variant (coffee and chocolate default)

Our SBAL-V auto duct line is the workhorse of rectangular duct fabrication for HVAC contractors across 100+ countries. The 316L stainless variant is the standard configuration for the Australian coffee roastery, tea, cocoa and chocolate sector. The SBAL-V is offered in models SBAL-V-1250J and SBAL-V-1500J, handles material thicknesses of 0.5 to 1.5 millimetres, with a maximum working width of 1,250 or 1,500 millimetres, at a forming speed of 16 metres per minute, with overall dimensions of 14,000 by 2,000 by 1,800 millimetres or 14,000 by 2,200 by 1,800 millimetres, requires 87 kilowatts, weighs approximately 16 tons, and runs on 380V 50Hz 3-phase. Hardened tooling for stainless coil, dedicated stainless decoiler, and adjusted forming pressures for the work-hardening characteristics of 316L are standard on the coffee and chocolate grade configuration. PLC control is Siemens or Mitsubishi standard. Welded longitudinal seam tooling is available as a factory option for HACCP-critical zones and Zone 21 cocoa dust hazardous area service — 4 to 6 weeks longer lead time but the standard for new chocolate factory builds and for coffee roaster afterburner discharge stack projects. See the SBAL-V product page, our SBAL-V versus SBAL-III comparison, and the full machines catalogue.

SBAL-III auto duct line — mid-range alternative for galvanised

The SBAL-III is the mid-range duct line for galvanised duct fabrication on the dry-side coffee, tea and chocolate scope (administrative areas, dry plant rooms, mezzanine plant rooms with positive pressurisation, building services ventilation, dry bagging and case-erect dispatch). For new chocolate factory or coffee roastery builds where the duct fabricator is supplying both galvanised dry-side and 316L stainless wet-side duct, the standard configuration is one SBAL-V at 316L and one SBAL-III at galvanised, providing parallel forming capability across both material specifications.

SB-ZF1500 stitchwelder — critical for roaster exhaust stack and dust collector housing

The SB-ZF1500 stitchwelder is critical to the coffee, cocoa and chocolate duct fabrication scope. The machine handles material thicknesses of 0.8 to 3 millimetres, with a working length of 100 to 1,500 millimetres, covering diameters from Phi-150 to Phi-1500, with overall dimensions of 2,500 by 1,000 by 2,350 millimetres, running on 380V 50Hz 3-phase. Three applications dominate the coffee, cocoa and chocolate scope: the commercial drum coffee roaster exhaust stack at 180 to 230 degrees Celsius and the afterburner discharge stack at 650 to 800 degrees Celsius where continuous TIG welded seams are essential under NFPA 86 high-temperature service, the cocoa winnower dust collector housing and the chocolate enrober extract collector housing where the Zone 21 cocoa dust hazardous area requires fully welded continuous seams, and the conche extract thermal oxidiser shell construction where the wet acid VOC chemistry demands fully welded continuous seams in 316L stainless. The stitchwelder produces high-quality TIG seam welds at controlled current and travel speed.

SBSF-1525 round-duct flanger

The SBSF-1525 round-duct flanger forms connecting flanges on the ends of spiral duct sections and round fittings used throughout the coffee and chocolate scope. Material handled is black steel 0.5 to 2 millimetres or stainless steel 0.5 to 2.5 millimetres, flanging width 75 to 152 millimetres, maximum weight capacity 360 kilograms, requires 2.5 kilowatts, weighs approximately 520 kilograms, with overall dimensions of 2,200 by 1,100 by 1,240 millimetres, runs on 380V 50Hz 3-phase. The SBSF-1525 produces the flanged spiral round duct used for the green-bean pneumatic conveying line, the cocoa nib conveying duct from winnower to grinder, the dust collector inlet and outlet, the conche extract round duct and the cold storage room supply ductwork.

SB-ZF1500 stitchwelder variant for hot stack

The SB-ZF1500 in its hot-section configuration delivers continuous TIG seam welds at controlled current and travel speed suitable for the roaster afterburner discharge stack and the cocoa roaster discharge stack at 650 to 800 degrees Celsius. SBKJ engineers commission the stitchwelder to the buyer's nominated 316L coil specification at FAT.

SBFB-1500 spiral fitting forming line

For spiral duct fittings (elbows, reducers, branch tees, taps) on the round-duct portion of the coffee or chocolate project, the SBFB-1500 spiral fitting machine fabricates the corresponding fittings in matching diameter and material. Output diameters 80 millimetres to 1,500 millimetres; material galvanised, 316L stainless or 304L stainless to match the duct. The SBFB-1500 provides the fitting matching capability that pairs with the SBTF spiral tubeformer for the round dust conveying duct scope. Critical applications include the green-bean pneumatic conveying duct, the cocoa nib conveying from winnower to grinder, the dust collector inlet and outlet duct and the conche extract round duct.

SBPC1500 plasma cutter — spark-resistant configuration for Zone 21 plate prep

The SBPC1500 plasma cutter prepares plate for plenum and large-section fabrication. Material galvanised, 316L stainless, 304L stainless or carbon steel up to 12 millimetres thick. Plasma cutting accuracy plus or minus 0.5 millimetre; edge quality suitable for direct TIG or MIG welding without secondary machining. The spark-resistant configuration is critical for plate prep work in the Zone 21 cocoa and sugar dust hazardous area, the coffee chaff cyclone fabrication and the afterburner discharge stack fabrication — these are hazardous areas where the plasma cutter sparking is a documented ignition source if used inside the hazardous area envelope. SBKJ supplies the SBPC1500 with the spark-resistant tooling kit for hazardous area fabrication.

SBLR-600 longitudinal seam welder

For in-shop seam welding on rolled-and-formed duct sections, the SBLR-600 longitudinal seam welder produces continuous TIG seams on sections up to 6 metres long. Output suitable for the largest coffee or chocolate factory plenum sections, the roaster afterburner discharge stack pre-assembly, the cocoa winnower dust collector body fabrication and the conche extract thermal oxidiser shell fabrication. The longitudinal seam welder is essential for the coffee and chocolate scope where continuously welded seams replace stitch-welded or lock-seam construction in HACCP-critical zones and Zone 21 hazardous area service.

SBTF-1500 / SBTF-1602 / SBTF-2020 spiral tubeformers

The SBTF series spiral tubeformers fabricate the round spiral duct used throughout the coffee, tea, cocoa and chocolate scope — green-bean pneumatic conveying, dust collector ductwork, conche extract supply, cooling tunnel supply, tempering room supply, cold storage supply and the broader round duct distribution. The SBTF-1500 covers diameters to 1,500 millimetres, the SBTF-1602 to 1,600 millimetres and the SBTF-2020 to 2,000 millimetres on the largest chocolate factory scope. Material 316L stainless, 304L stainless or galvanised. The dust-tight construction option is standard on the cocoa and sugar dust extraction scope — tighter lock seam geometry and additional sealant application during forming, suitable for the Zone 21 hazardous area conveying service.

The combined SBKJ machinery footprint for a major Australian chocolate factory or coffee roastery

The combined SBKJ machinery footprint for a major integrated Australian chocolate factory, coffee roastery, tea blender or confectionery plant project is typically: one SBAL-V at 316L stainless for the production-zone rectangular duct, one SBAL-III at galvanised for the dry-zone and dry-plant-room scope, one SBTF-1602 spiral tubeformer with multi-material capability (galvanised, 316L stainless), one SBFB-1500 spiral fitting machine, one SBSF-1525 round flanger, one SB-ZF1500 stitchwelder, one SBPC1500 plasma cutter (spark-resistant configuration), and one SBLR-600 longitudinal seam welder. The combined output capacity supports a 5,000 to 15,000 square metres per month duct fabrication rate, sufficient for the largest greenfield Australian chocolate factory build (Cadbury Mondelez Hobart scale), a major coffee roastery expansion (Vittoria Coffee, Lavazza Australia, Campos scale) or a tea blending and packaging plant refit (T2 Tea, Bushells scale).

Common specification mistakes — what we see fail in the field

Mistake 1 — Galvanised G275 in coffee roaster afterburner discharge

Galvanised ductwork in the coffee roaster afterburner discharge stack is an immediate failure mode under the 650 to 800 degree Celsius operating temperature. The galvanising layer evaporates above 419 degrees Celsius (zinc boiling point) and the resulting bare steel corrodes within months under the mildly acidic combustion product condensate. Specify 316L stainless throughout the hot section with continuous TIG-welded longitudinal seams from the SB-ZF1500 stitchwelder. We have inspected three Australian coffee roastery projects in the last five years where the original duct contractor specified galvanised in the afterburner discharge — every project required full stack replacement within 24 months of commissioning.

Mistake 2 — Missing or undersized expansion joints in the roaster stack

The 650 to 800 degree Celsius afterburner discharge cycles through full ambient to full operating temperature on every batch start-up, producing several millimetres of linear expansion per metre of stack. Skipping expansion joints or undersizing the joint travel range produces stack buckling, weld cracking and ultimately stack collapse within months. Specify engineered metal-bellows expansion joints at every transition between the afterburner discharge, the heat exchanger inlet and outlet, the dilution mixing chamber and the atmospheric stack. We have rebuilt two Australian roastery stacks in the last five years where the original duct contractor failed to specify adequate expansion joints.

Mistake 3 — Internally insulated tunnel oven or roaster exhaust stack

Coffee and cocoa roaster exhaust condensate (acid condensate from combustion products plus moisture from green bean) saturates internal insulation within weeks of operation. The saturated insulation becomes fuel for the next stack fire and an audit non-conformance under NFPA 86 and AS 1851. Specify external insulation only on all roaster exhaust ductwork. The same principle applies to the cocoa winnower extract duct and the conche extract duct in the chocolate factory.

Mistake 4 — Inadequate deflagration vent area on cocoa or sugar dust collector

Undersized deflagration vent area on a cocoa, sugar, coffee chaff or tea dust collector permits the residual pressure (Pred) in the event of a deflagration to exceed the duct and collector pressure rating, resulting in catastrophic rupture rather than controlled venting. Vent area calculation per NFPA 68 Chapter 7 from the duct cross-section, length, dust Kst, ignition source location and pressure rating. Vent panels rupture-disc or hinged-door construction with rated burst pressure 0.1 to 0.2 barg. Vent panel discharge ducting routes to outdoor atmosphere with no obstruction and no occupied space within the discharge cone.

Mistake 5 — Missing or undersized explosion isolation between connected vessels

NFPA 69 explosion isolation valves on the inlet and outlet ductwork of the cocoa winnower dust collector, the cocoa grinder extract collector and the sugar handling collector are mandatory to prevent flame and pressure propagation back to upstream conveying or downstream process. Active isolation (fast-acting slide valve triggered by upstream pressure or flame detector) or passive isolation (back-pressure flap valve, rotary airlock with rated retention time) is sized per NFPA 69 Chapter 8. Missing isolation is the single most consequential cocoa dust collector explosion protection deficiency.

Mistake 6 — Galvanised ductwork in the refrigeration machinery room with R32 or R454B

Galvanised steel under any A2L mildly flammable refrigerant leak (R32, R454B) presents an ignition risk under the AS/NZS 5149 charge limits and the AS/NZS 60079 hazardous area implications. Specify 316L stainless throughout the refrigeration machinery room with spark-resistant motor and damper actuator construction, continuous refrigerant detection with two-stage alarm, and 30 air changes per hour minimum emergency ventilation under AS/NZS 1677.

Mistake 7 — Shared HVAC return air across the allergen-containing and allergen-free zones

Return air ductwork that crosses between allergen-containing (peanut, tree nut, dairy, soy, wheat) and allergen-free parallel lines is a documented cross-contamination vector and a critical non-conformance under FSANZ 4.2.1 and Allergen Bureau VITAL audit. Specify dedicated supply and exhaust per zone at design stage; retrofitting separation costs 3 to 5 times the design-stage cost.

Mistake 8 — Internal duct insulation in the chocolate factory production zones

Internal insulation in any chocolate factory production-zone supply duct accumulates airborne cocoa, sugar, milk powder and other particulate over the production cycle and becomes a microbiological reservoir within the first sanitation cycle. Specify external insulation only on all production-zone supply ductwork. The audit findings on Australian chocolate factories over the last decade have repeatedly traced back to internally insulated ductwork.

Mistake 9 — Insufficient capture velocity at the cocoa winnower extract

Cocoa shell dust capture velocity below 0.5 metres per second per the ACGIH Industrial Ventilation Manual permits airborne cocoa dust to escape into the working environment, increasing worker exposure above the 10 milligrams per cubic metre inhalable workplace exposure standard and increasing chocolatier's asthma sensitisation risk. Verify capture velocity at commissioning with a calibrated thermal anemometer at every dust generation point.

Mistake 10 — Skipping the chaff cyclone upstream of the coffee roaster afterburner

Skipping the chaff cyclone or under-sizing the cyclone collection efficiency moves the coffee chaff load into the afterburner combustion chamber where the chaff represents a continuous fire risk and a fouling risk that degrades the afterburner residence time and oxidation efficiency. Specify a dedicated 316L stainless chaff cyclone at 95 percent or better collection efficiency upstream of every commercial drum coffee roaster afterburner, with sealed catch bin and explosion isolation against backflow.

Mistake 11 — Missing NFPA 96 fire suppression on the chocolate enrober extract

Cocoa butter mist on the chocolate enrober extract behaves similarly to cooking oil mist and requires NFPA 96 wet chemical or water mist suppression integrated into the enrobing chamber and the extract duct run. Suppression nozzles at the enrobing chamber, at every 6 metre interval along the duct, and at the discharge fan inlet are the standard configuration. Annual servicing of suppression heads is non-negotiable under AS 1851.

Mistake 12 — Failing to integrate the cold chain on chilled chocolate gift product dispatch

Cold chain failures under AS 4326 most often occur at the loading dock during the truck-loading window. Specify high-velocity air curtains at every dock door at 1.5 to 2.5 metres per second velocity, dock seal integration with the truck trailer body, and dedicated chilled supply at the dock-side. Loading dock HVAC failure is the most common cold chain non-conformance on chilled chocolate gift product dispatch, particularly seasonal Easter egg and Christmas gift product where the production volume amplifies the dispatch loading window strain.

Lead time, FAT and Australian dispatch from Box Hill North VIC

SBKJ's standard lead time for the 316L stainless variant of the SBAL-V auto duct line is 16 to 20 weeks from confirmed deposit to FAT-ready, plus 2 to 4 weeks domestic Australian dispatch from Box Hill North VIC to the customer site. The SBTF spiral tubeformer in 316L variant runs 12 to 16 weeks. The SB-ZF1500 stitchwelder for continuous TIG seam construction runs 10 to 14 weeks. The SBSF-1525 round-duct flanger runs 8 to 12 weeks. The SBFB-1500 spiral fitting machine runs 10 to 14 weeks. The SBPC1500 plasma cutter in spark-resistant configuration runs 10 to 14 weeks. The SBLR-600 longitudinal seam welder runs 8 to 12 weeks. Welded longitudinal seam tooling adds 2 to 3 weeks to the SBAL-V lead time. Mill certificate traceability to ASTM A240 or EN 10088-2 and third-party witnessed FAT add 1 to 2 weeks.

Factory Acceptance Test is run at the Box Hill North VIC office before dispatch with the buyer's nominated 316L coil specification and a full production cycle. We do not consider a coffee or chocolate-grade machine ready to ship until the FAT report is signed against the contract performance specification. Buyers are welcome to attend the FAT in person or via live video link. The FAT covers tooling alignment, forming pressure on stainless coil, surface finish on the formed duct, seam quality on welded longitudinal seam variants, dimensional accuracy across the full forming envelope, dye penetrant test on the seam welds, conductive joint resistance measurement (critical for Zone 21 hazardous area duct), and a full single-shift production run with the buyer's coil.

Australian dispatch from Box Hill North VIC to the customer site is by Australian truck transport with ISPM-15 compliant crating where the machine is shipped via container, with humidity indicators, marine-grade desiccant and full all-risk transit insurance. Installation timing is coordinated with the customer's project programme. SBKJ engineers from the Box Hill North office attend the commissioning on site for 5 to 10 days for installation supervision, mechanical commissioning, electrical commissioning, operator training, hazardous area documentation handover and Performance Acceptance Test.

How SBKJ supports Australian coffee, tea, cocoa and chocolate customers

SBKJ Group operates from Box Hill North in Victoria, Australia, with engineering and after-sales support direct to the Australian coffee roastery, tea blending, chocolate manufacturing, bean-to-bar and confectionery sectors. Our typical customer engagement runs through five phases:

Specification. Engineering review of the facility brief, zone-by-zone duct material and construction class recommendation, hazardous area scoping per AS/NZS 60079.10.2 cocoa, sugar and coffee chaff dust atmospheres, machine sizing against the production volume targeted, integration with the NFPA 86 roaster afterburner scope and the FSANZ 4.2.1 to 4.2.4 and AQIS compliance programmes.
Quotation. Itemised landed-cost worksheet on EXW Box Hill North or delivered-to-site basis, with machine specification, FAT scope, training scope and spare-parts package.
Order and FAT. 30 percent T/T deposit at order confirmation, 70 percent balance against dispatch documentation. FAT run with buyer's 316L coil before dispatch from Box Hill North.
Installation and commissioning. 1 to 2 SBKJ engineers from the Box Hill North VIC office on site for 5 to 10 days for installation, mechanical commissioning, electrical commissioning, hazardous area documentation handover and operator training in English. Coordination with the customer's HACCP and AQIS programme owner.
After-sales. 12-month warranty from commissioning, one-year wear-parts kit shipped with the machine, 72-hour remote support response from Box Hill North, 10-year-plus parts continuity guarantee.

Talk to an SBKJ engineer about your coffee roastery expansion, your chocolate factory refit, your bean-to-bar artisan operation, your tea blending and packaging line or your confectionery line upgrade — we typically respond within 12 hours during Australian business hours. Contact SBKJ for an itemised landed-cost quote, or browse the full machines catalogue and the SBKJ Insights library for related guides. SBKJ Group is exhibiting at ARBS 2026 in Sydney in May, alongside the broader Australian HVAC trade and the major coffee, chocolate and confectionery sector suppliers.

The five highest-leverage decisions on a coffee or chocolate HVAC project

Across many Australian and export-market coffee roastery, tea blending and chocolate factory duct projects, the pattern we see is that the engineering scope is well understood — AS/NZS 60079, NFPA 660, NFPA 86, NFPA 96, FSANZ 4.2.1 to 4.2.4, AQIS export compliance and the Allergen Bureau VITAL programme are all documented — but integration is where projects succeed or fail. The five highest-leverage decisions:

Get the hazardous area classification right at design stage. The AS/NZS 60079.10.2 dust atmosphere classification report for the cocoa winnower, the cocoa grinder, the sugar handling line, the coffee chaff cyclone and any tea dust handling is the foundational document that drives every downstream HVAC duct decision. Late changes to the hazardous area classification ripple through every duct package on the project and through the electrical installation under AS/NZS 60079.14. The hazardous area dossier should be the first deliverable on the project.
Specify 316L stainless throughout the wet-side and dust-extraction and roaster discharge scope. Drawing the boundary between 316L stainless production-zone scope, 304L acceptable dry-side zones, galvanised dry-plant-room zones, and carbon steel silo and collector body is the largest single capital decision in the duct scope. The roaster afterburner discharge stack at 650 to 800 degrees Celsius and the cocoa winnower extract at Zone 21 are non-negotiable 316L. Get it right at design stage, not after the AQIS auditor flags it on the routine cycle.
Document the NFPA 68 deflagration venting and NFPA 69 isolation scope thoroughly across cocoa, sugar, coffee chaff and tea dust handling. Cocoa and sugar dust deflagration is the single highest-consequence engineering hazard in any Australian chocolate factory. Coffee chaff fires are the most common roaster operational incident. The deflagration vent area sizing per NFPA 68, the explosion isolation valve selection per NFPA 69, the bonding and grounding earth grid resistance verification, and the routine clean-down programme are all critical.
Specify FAT at the Box Hill North VIC office on every machine and every duct package. Compromised FAT correlates strongly with post-installation disputes. The cost of a thorough FAT is one week. The cost of skipping it is a rework cycle measured in months. SBKJ runs FAT at the Box Hill North VIC office on every machine with the buyer's nominated coil. The duct fabricator should run an equivalent acceptance test on the fabricated duct against the project specification before shipment to site, including conductive joint resistance measurement for Zone 21 hazardous area duct and dye penetrant test on welded longitudinal seams.
Plan the FSANZ 4.2.1, AQIS and Allergen Bureau VITAL commissioning around the audit cycle. The hygiene and allergen management envelope across the chocolate factory and the coffee or tea operation is the AQIS auditor's principal concern outside the production-zone HVAC scope. Pressurisation cascade verification at every audit; Allergen Bureau VITAL allergen management verification at every product changeover (peanut, tree nut, dairy, soy, wheat); cold chain documentation programme for chilled chocolate gift product dispatch; routine cocoa and sugar dust clean-down audit on the secondary deflagration risk. Build the audit documentation programme into facility OPEX.

Get an itemised SBKJ quote for your coffee roastery, chocolate factory, bean-to-bar operation, tea blender or confectionery plant project →

FAQ

What temperature does a commercial coffee roaster exhaust run at and how is the afterburner specified?

Drum temperatures 180 degrees Celsius at green-bean charge through to 230 degrees Celsius at dark roast second crack. Exhaust stack at the drum outlet runs 30 to 50 degrees Celsius below the drum temperature. The afterburner thermal oxidiser runs at 650 to 800 degrees Celsius with 0.3 to 0.5 second residence time. 316L stainless throughout the hot section with continuous TIG-welded longitudinal seams from the SBKJ SB-ZF1500 stitchwelder, uninsulated to prevent insulation degradation, dedicated chaff cyclone upstream.

What is the cocoa dust deflagration risk in an Australian chocolate factory?

Cocoa dust Kst 100 to 130 St1 explosible under AS 3957 and NFPA 660. Sugar dust 130 to 160 St1. Minimum-explosible at 60 to 70 grams per cubic metre. Same Zone 21 or Zone 22 classification and same NFPA 68 deflagration venting, NFPA 69 isolation, bonding and grounding, conductive duct construction and routine clean-down as flour dust. Cocoa winnower is the highest dust generation point.

What temperature does chocolate tempering require?

Tempering cycles through 45 to 50 degrees Celsius (full melt), 26 to 30 degrees Celsius (Form V crystallisation initiation) and 29 to 32 degrees Celsius (final temper). Tempering room ambient 18 to 22 degrees Celsius, humidity below 50 percent RH. Enrobing tunnel cooling 10 to 15 degrees Celsius. 316L stainless duct throughout with sealed-seam AS 4254 Class B to hold humidity and pressurisation. Dehumidification at supply air handler.

What workplace exposure standard applies to cocoa dust and coffee chaff?

Safe Work Australia sets respirable dust 5 mg/m3 8-hour TWA, inhalable dust 10 mg/m3 8-hour TWA for cocoa, sugar, coffee bean and coffee chaff. Chocolatier's asthma documented occupational respiratory disease from chronic cocoa dust exposure. CO 30 ppm 8-hour TWA from LPG roaster combustion. CO2 5000 ppm 8-hour TWA from conching and roasting.

How does NFPA 86 industrial roaster differ from NFPA 96 commercial kitchen in coffee or chocolate?

NFPA 86 governs the commercial drum coffee roaster, cocoa roaster and afterburner thermal oxidiser at 650 to 800 degrees Celsius. NFPA 96 governs cocoa butter mist on the chocolate enrober extract and any in-house cafe exhaust. NFPA 86 demands high-temperature stainless duct, combustion air supply interlock and explosion relief on the gas train. NFPA 96 demands grease-tight welded duct, wet chemical suppression and slope to drain.

What pressurisation cascade does FSANZ 4.2.1 require?

Air flows from clean to dirty zones. Australian export-licensed chocolate operations build a multi-step cascade: final packaging plus 25 Pa, primary wrapping plus 15 Pa, enrobing and tempering plus 10 Pa, cocoa mass and conching plus 5 Pa, cocoa winnower extract neutral to minus 5 Pa, bulk cocoa and sugar minus 15 Pa, coffee roasting minus 10 to minus 20 Pa. Sealed-seam AS 4254 Class B duct construction.

What duct construction does the tempering and enrobing line require?

316L stainless throughout with sealed-seam AS 4254 Class B. Tempering room ambient 18 to 22 degrees Celsius, humidity below 50 percent RH. Enrobing tunnel cooling 10 to 15 degrees Celsius. Dehumidification at supply air handler — chemical desiccant wheel or condensing coil dehumidifier. NFPA 96 wet chemical suppression on the enrober extract. R32, R454B or R744 CO2 refrigerant under AS/NZS 1677.

What allergen segregation controls are required?

Allergen Bureau VITAL requires positive separation between allergen-containing and allergen-free parallel lines for peanut, tree nut, dairy, soy and wheat. Dedicated supply and extract per allergen zone with no shared return air. Sealed-seam AS 4254 Class B at plus 25 Pa pressurisation differential. HEPA-filtered supply at MERV 14 minimum on allergen-sensitive packaging. Air-sample protein residue testing at every product changeover.

What standards govern dust collector explosion protection?

AS/NZS 60079.10.2 hazardous area classification, AS 3957 dust hazard, NFPA 660 (2025 consolidated combustible dust standard), NFPA 68 deflagration venting, NFPA 69 explosion prevention. Minimum protective scope is deflagration vent panels on the collector body, explosion isolation valves on inlet and outlet, bonding and grounding to common earth grid under 1 ohm joint resistance, conductive duct construction.

What is the lead time for an SBKJ coffee or chocolate-spec SBAL-V in 316L stainless?

SBAL-V 316L stainless with hazardous area and high-temperature roaster discharge configuration: 16 to 20 weeks from deposit to FAT-ready, plus 2 to 4 weeks Australian dispatch from Box Hill North VIC. SBFB-1500 spiral fitting 10 to 14 weeks. SB-ZF1500 stitchwelder 10 to 14 weeks. SBSF-1525 round flanger 8 to 12 weeks. SBPC1500 plasma cutter spark-resistant 10 to 14 weeks. SBLR-600 longitudinal seam welder 8 to 12 weeks. Welded seam tooling adds 2 to 3 weeks.

12-hour reply

Got a coffee roastery, tea blender, chocolate factory, bean-to-bar or confectionery HVAC duct question? An SBKJ engineer in Box Hill North VIC responds within 12 hours during Australian business hours — not a salesperson. Visit us at ARBS 2026 in Sydney this May.

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