Police Forensic Lab, Crime Scene Investigation, DVI, Coronial Pathology & Mortuary HVAC Ductwork — Australian Engineering Guide

A note on the work this building does

An Australian forensic laboratory is the last room a piece of physical evidence enters before it becomes the basis of a verdict. A coronial mortuary is the last room many Australians pass through before their family is told what happened. A DVI centre is the room a country runs to when the news breaks — a Bali nightclub, a bushfire front in the Kinglake ranges, a passenger aircraft over a wheat field in eastern Europe. The HVAC ductwork inside those buildings is not glamorous. It is not the headline cost on the project. It is the silent equipment that determines whether the people who do the work go home healthy, whether the evidence holds up at trial, and whether the family is told the right name on the right body.

This guide is written for the engineers, mechanical contractors and fabrication shops who make those buildings work. The vocabulary is technical because the failure modes are technical — formaldehyde overexposure under Safe Work Australia limits, cross-contamination of a DNA sample on a recirculated air path, lead deposition in a ballistics ductwork, pressure-cascade collapse in an autopsy room during a fire-mode override, refrigerated body storage failing during a 45-degree heatwave in the days after a mass-casualty event. Each failure is preventable at design and fabrication stage. Each is a discipline of materials, seam construction, ventilation rate, pressure relationship and machinery capability.

The Australian forensic network is small, professional and well known to itself. The Victorian Institute of Forensic Medicine at Southbank is the national lead for DVI and Australia's largest forensic medical institute, combining autopsy, post-mortem CT, toxicology, anthropology, odontology and radiology under one roof. The Victoria Police Forensic Centre at Macleod is the state's biggest forensic facility, integrating DNA, ballistics, drug analysis, fingerprint, document examination, digital forensics, chemistry, criminalistics and toxicology. NSW Forensic Pathology operates from the Glebe Coroner's Court mortuary under NSW Health Pathology, working closely with the Royal Prince Alfred Hospital. Queensland Health Forensic and Scientific Services runs from Coopers Plains in Brisbane. Forensic Science SA serves Adelaide. PathWest Forensic serves Perth from the QEII Medical Centre and Royal Perth Hospital. Forensic Science Tasmania operates from Hobart. Northern Territory Forensic Services operates from Darwin. ACT Government Analytical Laboratory serves Canberra. The Australian Federal Police Forensics operates nationally from Canberra and regional and international embassy postings. The Australia New Zealand Policing Advisory Agency National Institute of Forensic Science — ANZPAA NIFS — is the peak coordinating body. The state coroners’ courts in Southbank, Lidcombe, Brisbane, Adelaide, Perth, Hobart, Canberra and Darwin sit at the head of the chain. This guide is for the buildings that house all of them.

1. The Australian regulatory stack — how the standards fit together

A forensic, coronial or mortuary HVAC design in Australia sits at the intersection of healthcare ventilation, laboratory biocontainment, occupational hygiene, fire engineering, environmental discharge and accredited testing quality systems. There is no single document that covers it. The job of the consultant is to layer the standards into one coherent design. The job of the duct fabricator is to execute the design without introducing leakage paths, condensation traps or galvanic incompatibilities. The job of the machinery — the auto duct line, the seam welder, the spiral former, the plasma cell — is to make that fabrication economic at the volumes Australian projects actually deliver.

The operative stack runs as follows. Treat it as a stack, not a menu. Every project applies the whole stack, with state-by-state variation on coroners’ legislation, on EPA discharge licences and on NATA scope of accreditation.

• AS 1668.2 — The use of ventilation and airconditioning in buildings, Part 2: Mechanical ventilation in buildings. Section 5 contaminant exhaust is the Australian baseline for any room with a chemical or biological hazard — autopsy suite, histopathology grossing station, toxicology fume cupboard, ballistics test-fire chamber, drug squad clandestine lab decontamination, fumigation chamber, refrigerated body storage. Tabulated air change rates, capture velocities and discharge location requirements all start here.
• AS 1668.1 — Fire and smoke control in buildings. Applies wherever ductwork penetrates a fire-rated compartment boundary — between forensic laboratory and corridor, between evidence vault and the rest of the facility, between the DVI surge cool-room and the routine mortuary.
• AS 4254 — Ductwork for air-handling systems in buildings. The Australian construction standard cited in every mechanical specification for sheet metal duct, supports, fittings, leakage classes and pressure ratings.
• AS 1530.4 — Methods for fire tests on building materials, components and structures. The fire-resistance test method referenced when a duct must be rated to 250 degrees Celsius for two hours through a fire compartment.
• AS 1851 — Routine service of fire protection systems and equipment. Sets the annual routine service of fire and smoke dampers in the forensic facility.
• ASHRAE 170 — Ventilation of Health Care Facilities. The operative international design-intent reference for autopsy, mortuary, isolation and laboratory spaces. Australian forensic and coronial design routinely cites ASHRAE 170 alongside AS 1668.2 because ASHRAE 170 is the more granular document on negative-pressure cascade, recirculation prohibition in autopsy and exhaust discharge geometry.
• AS/NZS 2243.3 — Safety in laboratories — Microbiological aspects and containment facilities. Defines Physical Containment levels PC1 to PC4. Forensic biology, autopsy and post-mortem laboratories handling unfixed human tissue work to PC2 equivalent — aerosol-generating procedures in a controlled-airflow room with biological safety cabinets.
• AS/NZS 2243.10 — Safety in laboratories — Storage of chemicals. And AS/NZS 2982 — Laboratory design and construction. Cover fume cupboard performance, local exhaust ventilation, chemical storage cabinetry and laboratory bench layout.
• AS/NZS 2243.9 — Safety in laboratories — Recirculation of laboratory exhaust. The fume cupboard performance verification standard — face velocity, smoke visualisation, tracer-gas containment testing, with NATA witness for laboratories holding ISO/IEC 17025 accreditation.
• ISO/IEC 17025 — General Requirements for the Competence of Testing and Calibration Laboratories. The accreditation standard administered by NATA — the National Association of Testing Authorities — that every Australian forensic laboratory operates under. Environmental conditions, including HVAC, are explicitly within scope of the testing method.
• AS/NZS 4187 — Reprocessing of reusable medical devices in health service organisations. Covers sterile reprocessing of forensic and post-mortem instruments where the laboratory operates an in-house sterilisation suite.
• AS 1428.1 — Design for access and mobility. The Disability Discrimination Act DDA-derived standard that applies to family viewing areas, witness suites and public access elements of coroners’ courts.
• AS 1670 — Fire detection, warning, control and intercom systems. Sets the detection design for the building shell.
• AS 4214 — Gaseous fire-extinguishing systems. Used for clean-agent suppression in irreplaceable evidence stores, digital forensics laboratories with sensitive electronics and high-value document examination archives.
• AS 2118 — Automatic fire sprinkler systems. Applies to occupied wet zones of the building — offices, corridors, family viewing — with bypass arrangements at the clean-agent zones.
• AS/NZS 60079 — Explosive atmospheres. Applies in narrow scope — chemistry and toxicology gas cylinder reception (hydrogen, propane), solvent stills in toxicology, chloroform extraction legacy lines, explosive and arson investigation chambers and drug squad clandestine lab decontamination where solvent vapour can accumulate.
• ARPANSA RPS 11 and RPS 14 — Radiation protection in forensic photography and in the medical industry. Applies to forensic radiology, post-mortem CT, X-ray and any radioisotope work.
• State Coroners Acts (Vic, NSW, Qld, SA, WA, Tas, ACT, NT). The statutory framework under which a coronial mortuary operates — chain of custody, body identification, the powers of the coroner, the order in which examinations may proceed.
• Crimes Act, Customs Act, Privacy Act 1988 and the Australian Privacy Principles. Federal legislation framing evidence chain of custody, controlled-substance handling and the sensitivity of forensic data.
• State Police Acts and Royal Commission into Institutional Responses to Child Sexual Abuse 2017 recommendations. Operational and ethical frameworks influencing the design of evidence handling and child-protection-related forensic facilities.
• AS/NZS 2107 — Acoustics — Recommended design sound levels and reverberation times. Sets the acoustic targets — NC-25 for audio enhancement laboratories where degraded recordings are re-mastered for court, NC-30 for general laboratory and analytical space, NC-35 for office and administrative zones, NC-30 for family viewing and witness suites.
• AS 3580 — Methods for sampling and analysis of ambient air. Referenced where stack discharge from autopsy, histopathology or drug-squad decontamination must be characterised under EPA licence.
• Safe Work Australia Workplace Exposure Standards (WES). The numerical exposure limits that the HVAC must hold below at the operator’s breathing zone. The key values for this facility class are listed in detail in Section 4 below.

2. The eight ventilation zones — how a forensic and coronial facility breaks up

A modern Australian forensic, coronial and DVI facility breaks into eight distinct ventilation zones, each on its own air handling unit, each with a defined pressure relationship to the others. The discipline of the design is enforcing those relationships everywhere the air can move — through doors, through pass-through hatches, through unsealed cable penetrations, through the ceiling void if it shares with another zone.

Zone 1 — The autopsy and post-mortem suite. NCC Class 9a healthcare or Class 8 laboratory. ASHRAE 170 negative pressure, minus 15 to minus 20 Pa relative to corridor. 12 to 15 air changes per hour, 100 percent outside air, no recirculation, downdraft airflow. Stainless 316L wash-down body table. Sub-table source-capture and overhead capture canopy. Temperature held at 16 to 20 degrees Celsius to slow decomposition. HEPA H13 or H14 on the exhaust before discharge above roof line. The most chemically and biologically loaded room in the facility, and the room with the lowest tolerance for HVAC failure.

Zone 2 — The DVI surge mortuary and refrigerated body storage. A 10 to 30 body capacity routine refrigerated mortuary at plus 4 degrees Celsius, expandable through pre-installed flange connections and dedicated extract capacity to absorb mass-casualty surge events. Isolation and a separate climate zone from the routine autopsy. Independent supply air and a separate decontamination loop. The DVI surge capacity is the engineering legacy of Bali 2002, Black Saturday 2009, MH17 2014 and Lindt Cafe 2014 — each event tested the limits of the routine mortuary and each forced an increment of surge engineering.

Zone 3 — The histopathology, anthropology, odontology and radiology laboratories. Mid-level laboratory ventilation, mostly outside air, with downdraft grossing benches, fume cupboards for xylene, toluene, ethanol, methanol, formalin and DCM, post-mortem CT bunker with lead shielding and dedicated exhaust, and gentle airflow at the bone-fragment anthropology benches where draught would scatter small skeletal evidence.

Zone 4 — The forensic biology and DNA molecular laboratories. Clean-room engineering, positive pressure relative to corridor (pre-PCR), strict separation from the autopsy suite, ISO Class 5 to Class 7 air quality, HEPA H14 supply, unidirectional downdraft over the workstations. The post-PCR amplification side runs at neutral to slight negative because the amplicon-bearing air is the contamination threat to the pre-PCR side. Stainless ductwork throughout so the interior can be decontaminated with sodium hypochlorite and ultraviolet.

Zone 5 — The chemistry, toxicology and trace evidence laboratories. Fume cupboard-dominated workspace. HPLC, UPLC, LC-MS/MS, GC-MS, GC-FID, ICP-MS and AAS analytical instruments. Source-capture local exhaust at every active station. Gas cylinder reception room for oxygen, hydrogen, argon, helium, nitrogen, carbon monoxide and propane — a small Class I Zone 1 hazardous area under AS/NZS 60079 where solvent vapour or flammable gas can accumulate. Chemical-resistant epoxy floor, wash-down geometry.

Zone 6 — The firearms, ballistics, tool-mark and gunshot residue laboratories. Sound-proofed test-fire chamber with bullet trap, downdraft extract for lead and propellant residue, HEPA H14 on discharge, scanning electron microscope with energy-dispersive X-ray spectroscopy (SEM-EDX) for GSR characterisation, microspectrometer for paint and fibre, and acoustic treatment to NC-25 for tool-mark audio analysis. Acoustic engineering carries equal weight with HVAC.

Zone 7 — The drug squad, explosive, arson and clandestine lab decontamination rooms. The most hazardous zone in the building. AS/NZS 60079 Zone 1 hazardous-area rating. Heavy local exhaust at every active station. Sodium hypochlorite-resistant 316L stainless ductwork throughout. HEPA plus activated carbon polishing on every discharge. Drug-squad clandestine lab decontamination handles seized methamphetamine labs — P2P, ephedrine, lithium, anhydrous ammonia, sodium hydroxide, ether, acetone, red phosphorus and trace fentanyl — each acutely dangerous at the personal exposure level. Explosive and arson investigation handles nitroglycerine, TNT, RDX, HMX and ANFO traces with remote handling and blast shielding.

Zone 8 — The digital forensics, document examination, evidence storage and family viewing zones. ESD-safe digital forensics laboratory with Faraday cage and air-gapped network, climate-stable document examination room, secured evidence storage with clean-agent suppression, refrigerated biological evidence chiller, and family viewing and witness suites under AS/NZS 2107 NC-30 acoustic with dignity-grade comfort engineering. Positive pressure relative to working corridors so no chemical, biological or odour signature can drift from the laboratory side into the family space.

A common older facility mistake is sharing a return air path across two or more of these zones — the autopsy with the histopathology, the histopathology with the chemistry, the DNA pre-PCR with the post-PCR. Within five years the laboratory cannot maintain a NATA-accredited contamination control regime and the entire HVAC has to be rebuilt with proper zonal separation. The discipline at design stage is to insist on eight independent zones from day one and to budget for it accordingly.

3. Police forensic lab HVAC duct — the operator landscape

The eight ventilation zones above translate differently into the building of each Australian operator. A short tour through the network is worth doing because the engineering brief is shaped by who runs the building and what work they do.

Victorian Institute of Forensic Medicine (VIFM), Southbank. Australia’s largest forensic medical institute. Co-located with the Victorian Coroner’s Court on the south bank of the Yarra. Operates autopsy, post-mortem CT, toxicology, anthropology, odontology and radiology under one roof. National DVI lead. The HVAC brief is the most demanding in the country — ASHRAE 170 autopsy with downdraft tables, post-mortem CT bunker with lead shielding, anthropology benches for skeletal sex, race, age and stature reconstruction, dedicated DVI surge capacity that has been activated for Bali 2002, the 2004 Boxing Day tsunami response, Black Saturday 2009, MH17 2014 and the Lindt Cafe 2014. Every duct is 316L stainless from the autopsy and DVI surge zones; the family viewing and counselling zones are conventional commercial in galvanised with rigorous acoustic separation.

Victoria Police Forensic Centre (VPFC), Macleod. The state’s biggest forensic facility. Integrates DNA, ballistics, drugs, fingerprint, document examination, digital forensics, chemistry, criminalistics and toxicology. The HVAC engineering covers all eight zones above, with particular emphasis on DNA clean rooms (pre-PCR positive pressure, post-PCR neutral-to-negative), the ballistics test-fire chamber with downdraft lead extract, the drug squad clandestine lab decontamination, the document examination room with ESDA electrostatic detection and climate-stable conditions, and the digital forensics suite with Faraday cage and air-gap.

NSW Forensic Pathology — Glebe Coroner’s Court Mortuary. Run under NSW Health Pathology, working closely with the Royal Prince Alfred Hospital. ASHRAE 170 autopsy suite, refrigerated body storage, histopathology, toxicology, and DVI capability through partnership with NSW Health Pathology DVI. The Glebe site sits adjacent to the NSW Coroner’s Court at Lidcombe in operational terms — the Coroner directs work between the two locations depending on case load.

Queensland Health Forensic and Scientific Services (QHFSS), Coopers Plains, Brisbane. Co-located mortuary and laboratory campus. Autopsy suite, refrigerated body storage, histopathology, toxicology, drug analysis, DNA, ballistics and digital forensics on one site. The HVAC engineering follows the standard eight-zone model with significant attention to the tropical-summer cooling load — Brisbane summer outside air temperatures above 35 degrees Celsius with relative humidity above 70 percent stress refrigerated body storage hard.

Forensic Science SA (FSSA), Adelaide. Smaller campus footprint than VIFM or VPFC but covers the same disciplines for South Australia — autopsy, mortuary, histopathology, toxicology, DNA, drugs, ballistics, documents. The HVAC engineering is the same model, scaled to a single coronial jurisdiction.

PathWest Forensic, Perth. Operates autopsy and toxicology services from QEII Medical Centre and Royal Perth Hospital, working with WA Police Forensics. The HVAC engineering is hospital-co-located — the autopsy suite sits within a Class 9a healthcare building, with the laboratory side at Class 8.

Forensic Science Tasmania, Hobart. Co-located with Royal Hobart Hospital. Single-state coronial jurisdiction. Eight-zone HVAC model scaled to the case-load.

Northern Territory Forensic Services, Darwin. The most thermally challenging Australian forensic site. Darwin’s wet-season ambient regularly exceeds 35 degrees Celsius with relative humidity above 80 percent. Refrigerated body storage carries a double-redundant cooling load and the HVAC ductwork is externally insulated end-to-end to prevent condensation drip onto bodies.

ACT Government Analytical Laboratory and AFP Forensics, Canberra. The Australian Federal Police Forensics operates nationally from Canberra with regional and international postings, supporting Commonwealth investigations and overseas embassy work. ACT Government Analytical Laboratory provides chemistry and analytical reference. Both run the standard eight-zone model.

National Measurement Institute (NMI), Lindfield NSW. The national analytical reference laboratory — provides reference materials and analytical confirmation for state forensic toxicology. Specialist chemistry zone with extreme fume cupboard density and a full AS/NZS 2982 laboratory build.

4. The Workplace Exposure Standards that drive the engineering

Every Australian forensic HVAC design starts from the Safe Work Australia Workplace Exposure Standard for the chemicals and biological agents present in the work. The HVAC is the silent equipment that keeps the operator’s breathing-zone concentration below the limit. The numbers below are the operative limits at the time of writing. They drive the air change rate, the source capture face velocity, the choice of recirculation versus once-through, the filtration strategy and the stack discharge geometry.

Formaldehyde (HCHO) — 1 ppm STEL, 0.3 ppm TLV-TWA. The killer. IARC Group 1 carcinogen. The principal fixative chemistry of autopsy gross dissection, anatomical pathology and histopathology embedding. Used as 10 percent buffered formalin — 3.7 percent formaldehyde — for tissue preservation. Every Australian autopsy room runs under a formaldehyde control regime that combines downdraft body table capture, overhead canopy, fume below table, downdraft histopathology grossing stations, real-time personal monitoring badges, and a written exposure-management plan reviewed annually.

Ethanol — 1000 ppm TWA. Tissue and specimen preservation, chemistry and toxicology. Less acute than formaldehyde but volume-loading drives the air change rate at the chemistry bench.

Methanol — 200 ppm TWA. Tissue chemistry and toxicology HPLC mobile phase. Acute neurotoxic and optic-nerve hazard. Fume cupboard or downdraft capture required at any open transfer.

Dichloromethane (DCM, methylene chloride) — 50 ppm STEL. Legacy paint stripper and chromatography solvent. IARC Group 2A. Being phased out of Australian laboratory chemistry but still present in older procedures. Fume cupboard mandatory.

Chloroform (CHCl3) — 10 ppm STEL. Legacy extraction solvent. IARC Group 2B. Phasing out but still present in some toxicology procedures. Fume cupboard mandatory.

Mercury (Hg) — 0.025 mg per cubic metre TWA, organomercury 0.01 mg per cubic metre STEL. Legacy laboratory thermometers, dental amalgam in odontology, button battery and electronic device recovery. Being phased but still present. Local exhaust at handling points, vapour suppression on storage.

Formic acid — 5 ppm STEL. Acetic acid — 10 ppm STEL. Chemistry, forensic toxicology, tissue staining. Source-capture at the bench.

Xylene — 50 ppm STEL. Toluene — 50 ppm STEL. The dominant solvents in histopathology embedding and staining — Histo-Tek, Leica TP1020, Sakura Tissue-Tek, Hacker Knives equipment. Downdraft grossing station and dedicated extract.

n-Hexane — 50 ppm STEL. Laboratory solvent extraction. Fume cupboard.

Acetone 250 ppm, isopropanol 400 ppm, methyl ethyl ketone 200 ppm, ethyl acetate 200 ppm, methyl isobutyl ketone 50 ppm. General chemistry and laboratory clean solvents. Cumulative loading drives the air change rate.

Hydrochloric acid (HCl) 5 ppm STEL, hydrofluoric acid (HF) 1.8 ppm STEL, nitric acid (HNO3) 4 ppm STEL, sulfuric acid (H2SO4) 1 mg per cubic metre STEL. Chemistry, sample preparation, silica digestion. Fume cupboard mandatory with corrosion-resistant duct material — 316L stainless or, in extreme HF service, polypropylene-lined.

Potassium and sodium cyanide (KCN, NaCN) — 5 mg per cubic metre STEL. Forensic toxicology sample preparation. Fume cupboard with dedicated discharge.

Peracetic acid — 0.4 ppm STEL. Autopsy table and instrument sterilisation. The room is washed down with peracetic and the ductwork interior must accept the residual.

Ozone (O3) — 0.1 ppm STEL. UV decontamination and laser printers. Source-capture at the active surface.

Chlorine (Cl2) — 0.5 ppm STEL. Sterrad, ethylene oxide and chlorine sanitation. Local exhaust at the sterilisation rack.

Sodium hydroxide, potassium hydroxide alkali fume. Sample digestion. Local exhaust and corrosion-resistant ductwork.

Benzene — 1 ppm STEL. Legacy solvent and IARC Group 1 carcinogen. Phasing out of laboratory chemistry but residual presence requires fume cupboard.

Respirable particulate — 5 mg per cubic metre. Inhalable particulate — 10 mg per cubic metre. The general dust standards. Apply to bone dust at the anthropology and osteology bench, desiccated tissue handling and any dry-procedure laboratory.

Carbon monoxide (CO) — 30 ppm STEL. Carbon dioxide (CO2) — 5000 ppm TWA. General gas standards.

Hydrogen sulfide (H2S) — 10 ppm STEL. Decomposition off-gas at body recovery and at autopsy of advanced post-mortem cases. Acute neurotoxic.

Ammonia (NH3) — 25 ppm TWA, plus amines, putrescine and cadaverine. Decomposition off-gas and autopsy odour. Drives the downdraft body table extract requirement.

VOC organic accelerant residue. Arson investigation samples carry petrol, kerosene, diesel and similar. Gasoline carries roughly 0.5 ppm benzene as a sub-component. Nitroglycerine and TNT explosive residue handled remotely by AFP Forensics. Canine training samples carry trace explosive.

Prussic acid (HCN), arsenic (As), lead (Pb 0.05 mg per cubic metre), thallium (Tl), barium (Ba), selenium (Se), chromium (Cr VI), mercury (Hg), manganese (Mn). Forensic toxicology heavy-metal sample preparation. ICP-MS and AAS analysis. Fume cupboard with HEPA on discharge.

Street drug residue. Methamphetamine hydrochloride, heroin, cocaine, fentanyl, THC and MDMA — fentanyl in sub-nanogram per cubic metre airborne quantity is acutely dangerous and is the dominant occupational risk in modern drug squad seizure rooms. HEPA H14 plus activated carbon polishing on the extract.

Refrigerant gases R32, R454B and R744 (CO2). Mortuary cool-room at plus 4 degrees Celsius and cold storage at minus 20 degrees Celsius. R744 carbon dioxide and R454B mildly-flammable refrigerant carry Class I Zone 2 hazardous-area implications around plant rooms.

Every number above is a duty cycle for the HVAC. The design satisfies the standard by combining air change rate, source capture at the point of generation, dilution ventilation in the room, and stack discharge geometry that prevents re-entrainment. The duct fabricator’s responsibility is the integrity of the path from source to stack — no leakage into the breathing zone, no condensation traps for biological growth, no galvanic corrosion that opens a fugitive emission path.

5. Autopsy room ASHRAE 170 negative pressure — the centre of the design

If every other zone is engineered correctly and the autopsy room is not, the building fails on staff exposure, on family trust and on the coronial evidence chain. Get the autopsy room right and most of the rest of the design follows.

The standard. ASHRAE 170 Ventilation of Health Care Facilities is the operative reference for the autopsy room in every Australian forensic and coronial design. ASHRAE 170 specifies the autopsy room at 12 air changes per hour minimum, 100 percent outside air, no recirculation, minus 0.025 inches water gauge (about minus 6.2 Pascals) below the corridor as the absolute pressure floor. Australian practice routinely targets 15 ACH and a deeper pressure differential of minus 15 to minus 20 Pa for engineering margin — the deeper differential absorbs door-opening transients, fan-curve variation and filter-loading drift between maintenance intervals. AS 1668.2 Section 5 contaminant exhaust principles layer over ASHRAE 170 with the additional Australian-specific requirements.

Air change rate. 12 ACH minimum, 15 ACH preferred. For a typical 50 cubic metre autopsy room with two tables, that is 600 to 750 cubic metres per hour of supply air, all 100 percent outside, all exhausted to atmosphere. No return air, no recirculation, no shared duct with the adjacent histopathology or DVI surge zones.

Airflow pattern. Downdraft. Supply diffusers at high level above the operator, sized for low face velocity (under 0.3 metres per second at the diffuser face) so as not to disturb the source-capture flow. Exhaust at low level behind the body table at 200 to 300 mm above floor finish, distributed so that the room has uniform downward flow and no stagnant zones. The intent is that any aerosol generated at the body — bone saw, oscillating saw, formalin pour, organ retrieval — is swept downward and toward the extract before it can rise.

Source capture. Three layers. (1) An overhead canopy hood above the body table, 1.2 metres wide and 0.6 metres deep, suspended 0.4 to 0.5 metres above the table, at 0.5 to 0.7 metres per second face velocity. (2) A sub-table slot or downdraft body table where the table surface itself is perforated stainless and air is drawn down through the body. (3) A local capture arm at any wet station where formalin is poured or organs are weighed. Together the three layers capture more than 95 percent of formaldehyde and biological aerosol at source, with the room dilution ventilation handling only the residual.

Body table. 316L stainless 1.5 mm wash-down construction. Continuous TIG-welded seams. Drainage with full S-trap and air break. Perforated work surface where the downdraft configuration is used. Wash-down with peracetic acid or sodium hypochlorite at the end of every case.

Temperature and humidity. 16 to 20 degrees Celsius room temperature to slow decomposition during the case. Relative humidity 35 to 55 percent for staff comfort and to limit microbial growth. Cooling and dehumidification by 100 percent outside air conditioning, never by recirculation, because recirculation is forbidden.

HEPA on the exhaust. H13 (99.95 percent at 0.3 micron) or H14 (99.995 percent at 0.3 micron) HEPA filtration on the exhaust before discharge to atmosphere. Bag-out filter housings so the technician handling a contaminated filter never touches the filter media. Discharge stack minimum 7 metres above local roof line, positioned to avoid re-entrainment into any outside air intake on the building.

Pressure cascade verification. Calibrated digital manometer at the room door reading continuously, with audible alarm at any rise above minus 5 Pa. Verified at NATA surveillance audit and at the laboratory’s six-monthly self-verification cycle.

Stainless 316L ductwork end to end. Every duct downstream of the autopsy room is 316L stainless, 1.5 mm sheet, continuously TIG-welded longitudinal seam. The interior accepts sodium hypochlorite, peracetic acid and formalin contact without substrate damage. The transverse joints are TDF flange or bolted angle with full-perimeter EPDM gasket on a 100 mm fastener pitch. SMACNA Class A leakage — under 0.5 percent of design airflow at 250 Pa — verified by leakage test at commissioning.

6. DVI disaster victim identification HVAC — surge engineering for mass-casualty events

The Victorian Institute of Forensic Medicine at Southbank is the national DVI lead for Australia, working under Interpol DVI Standing Committee protocols and in partnership with the Asia-Pacific Forensic Anthropology Centre and the Australian Society of Forensic Medicine. The Royal Australian Air Force operates a DVI capability from Williamtown for repatriation and mass-evacuation logistics. NSW Health Pathology operates a DVI partnership. State-by-state, every coronial mortuary in Australia has a defined surge protocol and a pre-engineered HVAC configuration to absorb a mass-casualty event.

The historical record. Australia’s DVI engineering legacy is built on a series of events. The 2002 Bali bombings — 88 Australians dead, repatriated to VIFM Southbank for identification. The 2004 Boxing Day tsunami — Australian victims processed through VIFM. The 2009 Black Saturday bushfires — 173 dead across Victoria, every case through VIFM. The 2011 Christchurch earthquake — Australian victims and cross-jurisdictional cooperation. The 2014 MH17 shootdown — 38 Australians dead, repatriated and identified through VIFM and Dutch counterparts. The 2014 Lindt Cafe Sydney siege — three dead through NSW Forensic Pathology. The Truro killings in South Australia processed through Forensic Science SA. Each event tested the routine mortuary capacity and each forced an increment of pre-engineered surge capability.

The engineering brief. The DVI surge mortuary is a separate ventilation zone from the routine autopsy and the routine mortuary — Zone 2 in the eight-zone model from Section 2. It carries a 10 to 30 body capacity in pre-installed refrigerated holding at plus 4 degrees Celsius, with the ability to expand within hours of a declared event by bringing in portable refrigerated containers, RAAF C-130 mass-evacuation logistics and dedicated additional cooling plant. The HVAC ductwork serving the DVI surge zone is sized for the expanded capacity from day one — under-sized day-one ductwork is the most common DVI engineering failure mode.

Independent supply and separate decontamination. The DVI surge zone is on its own air handling unit with no shared return air. The supply duct is 316L stainless from the AHU to the room, continuously TIG-welded, fully accessible internally for decontamination. The decontamination loop is independent of the routine mortuary — spray-down decontamination of the entire interior surface with peracetic acid or sodium hypochlorite at the end of each DVI activation, with the spray-down chemistry venting through dedicated HEPA H14 filtered extract.

Plug-and-play surge expansion. Pre-installed flange connections at the building envelope allow portable refrigerated containers to be brought on-site within hours of a mass-casualty declaration. Each container connects to a pre-routed power feed and a pre-installed ducted supply and extract. The HVAC engineering brief is to have the flange points already there, with terminating blanking plates that can be removed and replaced with active duct in under two hours.

The associated suites. A DVI activation requires not just refrigerated holding but every supporting laboratory function in surge mode. Anthropology and odontology benches for skeletal and dental antemortem comparison. CT and X-ray for post-mortem imaging. DNA extraction and PCR for relationship identification against family reference samples. Each supporting suite has a HVAC carrying capacity sized for the surge load, not just the routine baseline.

7. Histopathology xylene fume cupboard — the daily chemistry hazard

Histopathology is the highest-volume chemical hazard in the day-to-day operation of a forensic and coronial laboratory. Every autopsy generates tissue specimens that are fixed in formalin, processed through ascending ethanol, cleared in xylene or toluene, embedded in paraffin wax, sectioned on a microtome and stained with hematoxylin and eosin or by immunohistochemistry. The Australian histopathology workflow is dominated by Histo-Tek, Leica TP1020, Sakura Tissue-Tek and Hacker Knives equipment, supplemented by manual grossing benches.

The grossing station. The grossing bench is where the pathologist receives the wet specimen from the autopsy, examines it, cuts it into representative sections and submits the sections to the embedding cassettes. The bench is a downdraft station — perforated stainless work surface with air drawn down through the surface at 0.5 metres per second face velocity, captured in a plenum below the bench and extracted via dedicated 316L stainless duct. The downdraft configuration is the design intent because the formalin and xylene vapour are heavier than air and naturally sink — a conventional overhead capture canopy fights physics; the downdraft works with it.

The fume cupboard. The fume cupboard at the histopathology bench handles the heavier chemistry — bulk formalin transfer, xylene clearing, IHC immunohistochemistry reagent preparation. Specified to AS/NZS 2243.10 and AS/NZS 2982. Face velocity 0.5 metres per second at the sash open position with NATA-witnessed annual performance verification under AS/NZS 2243.9. Construction in phenolic resin or 316L stainless. Single-pass extract to dedicated stack discharge above roof line, never recirculated.

The extract duct. 316L stainless 1.5 mm coil, run through the SBAL-V configured for stainless. Continuously TIG-welded longitudinal seam, transverse joints TDF flange with EPDM gasket, SMACNA Class A leakage. Routed externally where practicable to avoid running formaldehyde-bearing extract through occupied ceiling voids. Discharge stack 7 metres minimum above local roof line, with EPA stack-emission characterisation under AS 3580 where the EPA licence requires.

Monitoring. Personal monitoring of histopathology operators on a representative working day, comparing 8-hour TWA against the 0.3 ppm formaldehyde TWA and the 50 ppm xylene STEL limits. Real-time data-logging badges, with the data archived as part of the laboratory’s ISO/IEC 17025 quality record.

Tissue processor. The Histo-Tek or Leica TP1020 tissue processor runs overnight, cycling specimens through formalin, ethanol, xylene and paraffin. The processor is plumbed to a dedicated local exhaust hood above the loading door so that vapour released at the start and end of each cycle is captured.

8. DNA PCR clean room HEPA — positive pressure and contamination control

Forensic DNA is the most contamination-sensitive analytical workflow in the building. A single skin cell from an analyst contaminating a pre-PCR workstation is a result that has to be excluded from the court record. The HVAC ductwork is the silent partner in DNA result reliability — a leak in the pre-PCR supply path, a shared return air with any other zone, a contaminated HEPA filter, and the entire batch is compromised.

The clean cascade. The forensic DNA workflow runs as a strict directional cascade. Sample reception → extraction → quantification → pre-PCR setup → PCR amplification → post-PCR analysis → instrument detection. Each stage is in a separate room or separate biological safety cabinet, with positive pressure on the clean (pre-PCR) side, neutral or slight negative on the dirty (post-PCR) side, air locks and material pass-throughs at every boundary, and a strict no-shared-airflow rule. The HVAC design enforces the cascade by physical separation of the air handling units, with the pre-PCR AHU pulling 100 percent fresh air through HEPA H14 and discharging via the post-PCR side’s extract or directly to atmosphere.

Positive pressure pre-PCR. Plus 15 to plus 20 Pa relative to corridors. ISO Class 5 to Class 7 air quality at the workstation surface under ISO 14644. HEPA H14 supply capturing 99.995 percent of 0.3 micron particulates. Unidirectional downward airflow at 0.35 to 0.45 metres per second at the working plane. Stainless ductwork throughout the supply path so the interior can be decontaminated with sodium hypochlorite and ultraviolet without substrate damage. PCR workflows include PowerPlex, GlobalFiler and Identifiler, feeding the National Criminal Investigation DNA Database and providing CODIS-compatible STR profiles for international cooperation.

Neutral-to-negative post-PCR. The post-PCR room contains amplicon — PCR-amplified DNA at concentrations that are easily transferred and that would compromise any pre-PCR sample. The post-PCR room runs at neutral to slight negative pressure relative to the corridor and is air-locked from the pre-PCR side. The HVAC extract on the post-PCR side carries the amplicon-bearing air to dedicated discharge, never recirculated.

UV decontamination. The pre-PCR workstation and the supply ductwork accept ultraviolet decontamination on a daily or shift-end cycle. UV-C at 254 nm denatures DNA and is the laboratory’s primary defence against carry-over contamination. The HVAC ductwork interior is specified for compatibility — stainless 316L surface with no organic coating that would degrade under UV-C exposure.

ESD-safe handling. The DNA workstation is ESD-safe to protect the analytical instruments. The HVAC ductwork is bonded to building earth at every transition and at every register box, with conductive supports avoiding any floating metal surface that could discharge into the instrumentation.

9. Chemistry, toxicology and trace evidence — analytical-grade ventilation

The chemistry and toxicology laboratory is fume cupboard-dense. HPLC, UPLC, LC-MS/MS, GC-MS, GC-FID, ICP-MS and AAS analytical instruments line the bench. Each is supported by a fume cupboard or local exhaust hood. The HVAC ductwork ties the entire space together into a coherent contaminant-exhaust system.

The fume cupboard population. A working forensic toxicology laboratory carries 8 to 20 fume cupboards depending on case load. Each is specified to AS/NZS 2243.10 and AS/NZS 2982, with annual NATA-witnessed face-velocity verification under AS/NZS 2243.9. Construction phenolic resin or 316L stainless for the most aggressive chemistry — HF, HNO3, perchloric acid digestion.

The gas cylinder reception. A separate small room handles incoming gas cylinders — oxygen, hydrogen, argon, helium, nitrogen, carbon monoxide and propane. The room is AS/NZS 60079 Zone 1 hazardous-area rated because hydrogen and propane can accumulate. Local exhaust ventilation at 6 ACH minimum, with low-level extract for heavier-than-air gases and high-level for lighter-than-air hydrogen. Detection sensors for hydrogen, oxygen depletion and carbon monoxide.

The trace evidence room. Trace evidence — fibre, paint, glass, soil, pollen — is analysed under microscope, SEM-EDX and microspectrometer. The room is clean to ISO Class 7 under ISO 14644 because extraneous particulate would contaminate the comparison. HEPA H13 supply, downward unidirectional airflow at the bench, no shared return with any other zone, ESD-safe at the SEM and microspectrometer.

Chemical-resistant floor. Epoxy floor coating across the entire chemistry zone with coved skirtings and wash-down geometry. Floor drains piped to chemical-resistant waste holding for batch neutralisation before sewer discharge.

10. Firearms test fire chamber Pb fume — lead, propellant residue and acoustics

The firearms and ballistics laboratory carries a test-fire chamber where seized firearms are discharged into a deceleration trap for comparison microscopy. The chamber generates airborne lead from primer combustion (lead styphnate primer being the legacy formulation, with lead-free formulations now common but lead still dominant in older ammunition) and propellant residue. Safe Work Australia sets the inorganic lead workplace exposure standard at 0.05 mg per cubic metre 8-hour TWA, with periodic biological monitoring of operators.

Chamber construction. Steel-lined acoustic chamber with bullet trap — steel deceleration plate for low-velocity small calibre, sand trap for general handgun rounds, water tank for high-velocity rifle to preserve the bullet for comparison. Chamber wall construction layered for acoustic attenuation to AS/NZS 2107 NC-25 outside the chamber.

Downdraft extract. Air drawn downward from the firer’s position toward a perforated floor or low-level extract behind the trap. Face velocity at the firing position above 0.5 metres per second to capture combustion gas before it can rise into the firer’s breathing zone. Extract sized so the chamber air exchanges in under 60 seconds between consecutive shots — the operational cadence is shot, wait for clearance, shot.

HEPA H14 on discharge. The extract carries sub-micron lead particulate that would deposit fugitive lead anywhere downwind of an unfiltered discharge. HEPA H14 with bag-out housing immediately downstream of the chamber extract. The HEPA captures 99.995 percent of 0.3 micron particulate.

316L stainless extract ductwork. Continuously TIG-welded longitudinal seam, transverse joints TDF flange with high-temperature EPDM gasket. The duct interior accepts periodic wipe testing as part of the lead-exposure management program. The duct is sized for the peak airflow during the post-shot clearance cycle, not the lower routine.

Acoustic treatment for audio enhancement. The tool-mark comparison and audio enhancement laboratory adjacent to the test-fire chamber works at NC-25 acoustic for the comparison microphone signal-to-noise. The HVAC ductwork serving the audio room carries internal acoustic lining for the first 5 metres downstream of the supply diffuser, with attenuators in both supply and extract, and isolation hangers between the duct and the structure.

Scanning electron microscope with EDX. The SEM-EDX used for gunshot residue characterisation sits in a separate clean room at ISO Class 7 with vibration isolation and tight temperature control (plus or minus 0.5 degrees Celsius). The HVAC supply is conditioned to the required precision through a dedicated trim coil in the supply ductwork immediately upstream of the room diffuser.

11. VIFM Southbank Melbourne HVAC — the national reference design

The Victorian Institute of Forensic Medicine campus at Southbank is the de facto reference design for an Australian integrated forensic, coronial and DVI facility. The HVAC ductwork engineering that supports the institute carries every zone discussed in this guide.

The autopsy suite. Multi-table autopsy under ASHRAE 170 negative pressure, 15 ACH, downdraft tables, sub-table source capture, overhead canopies, 316L stainless ductwork end to end, HEPA H14 on the extract before discharge above the roof line. Dedicated extract stack on the southern aspect to take advantage of prevailing wind for dispersion.

The post-mortem CT suite. Post-mortem CT scanning is the modern forensic imaging modality — non-destructive whole-body imaging that complements traditional autopsy. The CT scanner sits in a lead-shielded bunker under ARPANSA RPS 14 with dedicated ventilation isolated from the autopsy and laboratory zones. The HVAC supply maintains room temperature to plus or minus 1 degree Celsius and relative humidity in the 45 to 55 percent band for instrument stability.

The anthropology and odontology laboratories. Skeletal and dental analysis. Working with the University of Adelaide and Murdoch University in Perth on research-grade case work. Fume hood and local exhaust for the chemistry, gentle airflow at the bench so delicate skeletal fragments are not disturbed by draught. The HVAC supply enters at high level with low face velocity diffusers (under 0.2 metres per second at the diffuser face) and extracts at low level along the room perimeter.

The DVI Centre. The national DVI lead. Pre-engineered surge capacity for 30 bodies routine and 100-plus bodies under activation. Independent AHU. Pre-installed envelope connections for portable refrigerated containers. The HVAC ductwork sized from day one for the surge load.

The Coroner’s Court interface. The Victorian Coroner’s Court is co-located with VIFM. The HVAC ductwork serves the court chamber, the witness room, the family viewing area and the public gallery. Acoustic engineering to AS/NZS 2107 NC-30 in the court room, NC-30 in the family viewing area, NC-35 in administrative offices. Positive pressure relative to the working corridors so no chemical or biological signature can drift from the institute side into the court side.

12. Drug squad clandestine lab decontamination, fumigation chambers and the explosive ATEX zone

The most operationally hazardous zone in any Australian forensic facility is the drug squad clandestine laboratory decontamination room. Seized methamphetamine clandestine labs are dismantled in this room — meth oil, P2P phenyl-2-propanone, ephedrine, lithium metal, anhydrous ammonia, sodium hydroxide, ether, acetone and red phosphorus. Each of the precursor chemistries is either acutely toxic, acutely flammable, acutely reactive or all three. Trace fentanyl on a seized clandestine lab can carry sub-microgram airborne quantity, which is acutely dangerous at the personal exposure level.

The decontamination room HVAC. 100 percent outside air at 15 ACH minimum, downdraft airflow over the work bench, source-capture local exhaust at every active station, AS/NZS 60079 Zone 1 hazardous-area rating on the extract fan and electrical fittings, 316L stainless ductwork with continuously TIG-welded seams, HEPA H14 plus activated carbon polishing on the extract before discharge, separate dedicated extract stack discharged above roof line and away from any outside air intake on any zone of the building.

Fumigation chambers for fingerprint development. Cyanoacrylate superglue fuming, ninhydrin, iodine fuming, DFO and vacuum metal deposition are the principal latent fingerprint development techniques. Each chamber is a sealed unit under negative pressure relative to the evidence-processing room outside. The ductwork serving the chamber extract is 316L stainless, continuously TIG-welded, sized for cyanoacrylate vapour clearance, with HEPA H14 and activated carbon polishing on the discharge.

Explosive and arson investigation. The AFP Forensics and VIFM share explosive and arson investigation capability. Incendiary device residue, nitroglycerine, TNT, RDX, HMX and ANFO ammonium nitrate fuel oil traces are handled in extreme blast-shielded chambers with remote handling. The HVAC ductwork follows AS/NZS 60079 Zone 1 with extreme attention to fan isolation, motor protection and electrical earth bonding. The fan motors are positioned outside the hazardous envelope wherever practicable, with the fan itself driven by extended shaft through a gas-tight gland.

13. Refrigerated body storage, mortuary cool room and frozen body storage

Every Australian forensic and coronial facility operates refrigerated body storage at plus 4 degrees Celsius for routine holding and minus 20 degrees Celsius for extended forensic, coronial and repatriation cases. The refrigeration plant uses R744 carbon dioxide as the primary refrigerant in modern installations (low global warming potential, narrow Class I Zone 2 hazardous-area implication around the plant room) or R454B (mildly flammable A2L refrigerant with similar hazardous-area implications). Ammonia secondary refrigerant is occasionally used for the cold-side circuit in larger installations.

The plus 4 mortuary cool room. 316L stainless ductwork supply with closed-cell PIR or PVA foam external insulation 50 mm minimum, vapour-tight foil tape at every joint. The room runs at 80 to 90 percent relative humidity because the cooling coils condense moisture from the recirculated air. Drainage from the coil pan piped to floor tundish with air break.

The minus 20 frozen storage. Freezer-room panel construction with 150 mm insulation, vapour-tight membrane, cold-resistant door seals. 316L stainless ductwork because the chloride-bearing condensate that forms during defrost cycles is aggressive to lesser materials. Defrost cycles release condensate that must drain to a heated tundish so the drain line itself does not freeze.

Tropical-summer ambient. Darwin in the wet season, Brisbane in summer and Perth in summer all stress refrigerated body storage hard. Outside air temperatures above 38 degrees Celsius with relative humidity above 70 percent for weeks at a time drive the supply duct insulation specification end-to-end. A bare cold supply duct in a 35-degree ambient roof space will condense litres of water per hour. The Australian convention is closed-cell PIR or nitrile foam, 25 mm minimum on cold supply ducts, taped at every joint with foil tape rated for the service temperature.

Refrigerated biological evidence chiller. A separate chiller within the secured evidence storage zone holds biological evidence — sexual assault kits, blood swabs, fibre transfer evidence — at plus 4 degrees Celsius until DNA analysis. The ductwork is 316L stainless, externally insulated, with continuous temperature logging and alarm to the security desk on any excursion.

14. Material selection — why galvanised fails and why 316L stainless wins

The default sheet metal material across Australian commercial HVAC is galvanised steel, typically G2 or G3 zinc coating on cold-rolled mild steel, snaplock or button-punch seams, fabricated on a standard SBAL-V configured for galvanised coil. For the contaminant-bearing extract in autopsy, histopathology, toxicology, drug squad decontamination, ballistics and fumigation, galvanised fails in five distinct mechanisms.

Mechanism 1 — formaldehyde and amine corrosion of zinc. Formaldehyde in the presence of moisture hydrolyses to formic acid. Formic acid attacks zinc directly. Within 18 to 36 months of operation, internal duct surfaces show characteristic white zinc bloom, then pinhole perforation along the bottom of horizontal runs where condensate pools. The fugitive emission path through the perforation is a NATA non-conformance event.

Mechanism 2 — chloride disinfection chemistry. Sodium hypochlorite at 1000 to 5000 ppm available chlorine and quaternary ammonium chlorides at much higher concentrations are aggressive to zinc. Australian forensic mortuaries wash down after every case — sometimes multiple times daily. Galvanised ductwork inside the room and the first three metres downstream accumulates damage cycle by cycle.

Mechanism 3 — acid digestion chemistry from toxicology. HCl, HNO3, H2SO4 and HF in fume cupboard extract attack any non-stainless duct material. Even small leakage volumes from the fume cupboard envelope load the extract duct interior.

Mechanism 4 — peracetic acid sterilant. Modern Australian autopsy practice uses peracetic acid for table and instrument sterilisation. Peracetic acid is aggressive to zinc and to lower grades of stainless. 316L is required.

Mechanism 5 — thermal cycling and saline condensate in refrigerated storage. Refrigerated body storage cycles between plus 4 routine and minus 20 defrost. The condensate that forms during defrost carries saline from body contact and chloride from the disinfection chemistry. Galvanised in this service is corroded through within five years.

The Australian engineering response is unambiguous. 316L stainless steel for every duct surface in contact with autopsy extract, histopathology extract, toxicology fume cupboard discharge, drug squad decontamination extract, ballistics extract, fumigation chamber extract and refrigerated body storage supply and extract. 304 stainless steel acceptable for clean-room supply in DNA, trace evidence and digital forensics where the air is clean by design. Galvanised G2 or G3 acceptable for general office, family viewing, witness suite, court chamber and administrative HVAC where the air is clean and the chemistry is absent.

Sheet thickness typically 1.5 mm in 316L stainless for the contaminant-bearing extract, 0.8 to 1.2 mm in galvanised for the general office supply, 1.6 mm and heavier on the fire-rated duct serving the ballistics and evidence vault. Sheet thickness drives the choice of fabrication machine — the SBAL-V handles 0.8 to 1.5 mm in galvanised and 304 stainless, the SBAL-V configured for stainless handles 316L at 1.5 mm, the SBSF-1525 super auto duct line handles 1.6 mm fire-rated, and the SB-ZF1500 produces the welded-seam stainless for chemistry-bearing extract.

15. Seam construction — SMACNA Class A and continuously welded

SMACNA — the Sheet Metal and Air Conditioning Contractors’ National Association — publishes the duct construction standards used as reference across Australian commercial HVAC. SMACNA sets four leakage classes from Class A (tightest) through Class C and into uncategorised. Most Australian commercial ductwork is built to roughly Class C, which permits leakage of around 12 percent of design airflow at 250 Pa static pressure. For office cooling that is acceptable. For an autopsy room or a DNA clean room that is not — every cubic metre per second of leakage is a cubic metre per second that bypasses the source capture or the pressure cascade.

Forensic and coronial contaminant-bearing ductwork is built to SMACNA Class A — under 0.5 percent of design airflow at 250 Pa. Class A is achieved only through continuously welded longitudinal seams. Snaplock, button-punch, Pittsburgh lock and flat-S slip joints all leak at the seams, no matter how careful the fabrication. The only way to hit Class A reliably is to TIG-weld the longitudinal seam on the SBAL-V configured for stainless or on the SB-ZF1500 sealed welded longitudinal seam duct line, and to use TDF flange or fully gasketed bolted angle at the transverse joints.

This is where the duct machinery decision becomes load-bearing. A standard SBAL-III or galvanised SBAL-V will roll-form, notch, fold and snaplock galvanised coil at 30 metres per shift, but it will not weld a continuous seam. To produce 316L stainless ductwork with continuously welded seams at any economic rate, the line needs an integrated TIG seam welder downstream of the roll-former. The SBAL-V configured for stainless and the SB-ZF1500 are built specifically for this — stainless coil handling, TIG seam welder with argon shielding gas, auto bead crimping, integrated TDF flange, run-out and packaging — replacing the SBAL-III plus manual fabrication workflow that older Australian sheet metal shops use for stainless work.

For the heaviest gauge construction — the fire-rated duct serving the ballistics chamber, the secured evidence vault corridor and the DVI surge mass-evacuation route — the SBSF-1525 super auto duct line handles 1.6 mm mild steel and 1.5 mm stainless with a continuous longitudinal seam and produces duct rated to AS 1530.4 250 degree Celsius two-hour fire resistance for fire compartment penetration. The fire-rated duct carries fire and smoke dampers at every compartment boundary, sized and certified to AS 1668.1 and routine-serviced to AS 1851.

For clean-room recirculation — the DNA pre-PCR supply path, the trace evidence ISO Class 7 supply, the digital forensics climate-controlled supply — the SBFB-1500 round spiral former produces 304 or 316L stainless round duct with continuous spiral lock seam. Round duct is the optimum geometry for clean-room recirculation — minimum surface area for a given cross-section means minimum particulate deposition, the spiral lock seam is inherently low-leakage, and the geometry handles HEPA H14 housing transitions cleanly.

For the heaviest plate transitions feeding the ballistics chamber bullet trap, the post-mortem CT shielded bunker, the firearms tool-mark comparison chamber and any refractory-lined high-temperature stack, the SBPC1500 plasma cutting cell profiles 4 mm to 20 mm stainless and mild steel plate to drawing tolerance with refractory anchor stud capability.

For the highest-class chemistry exhaust — toxicology fume cupboard discharge where every joint must be gas-tight for chain-of-custody integrity — the SBLR-600 laser-welded round duct produces 304 and 316L stainless round duct with a continuous laser-welded longitudinal seam, achieving leakage below Class A by a comfortable margin.

For the transverse flange — SBTF-1500 for ducts up to 1500 mm, SBTF-1602 for ducts to 1600 mm, SBTF-2020 for ducts up to 2000 mm — the SBTF range forms TDF profile rolled directly into the duct end. The bolted joint with EPDM gasket on a 100 mm fastener pitch achieves Class A leakage when correctly torqued without continuous welding at every transverse joint, which would be uneconomic on a 50 metre duct run.

16. NATA, ISO/IEC 17025 and the HVAC quality dossier

Every Australian forensic laboratory operates under NATA accreditation against ISO/IEC 17025 General Requirements for the Competence of Testing and Calibration Laboratories. Accreditation has a direct bearing on the HVAC ductwork because environmental conditions — temperature, relative humidity, particulate count, pressure cascade, fume cupboard performance, exhaust integrity — are explicitly within scope of the testing method and must be controlled, monitored and recorded.

Practical HVAC implications include continuous logging of supply and return temperature and relative humidity in every analytical zone, particle counting and HEPA integrity testing on an annual cycle under ISO 14644 for clean-room spaces, fume cupboard performance verification under AS/NZS 2243.9 with NATA-witnessed face velocity and containment testing, room pressure cascade verification under ASHRAE 170 with calibrated digital manometers, and a documented HVAC commissioning and re-verification dossier as part of the laboratory’s quality manual. Any HVAC change — duct replacement, AHU upgrade, filter change, fume cupboard reconfiguration — is a change-control event in the laboratory’s quality system.

The HVAC quality dossier carried at handover typically contains: the full set of as-built drawings, the SMACNA Class A leakage test results with NATA witness where in scope, HEPA integrity certificates for every HEPA in the building, the pressure cascade log over a representative working day, fume cupboard performance certificates against AS/NZS 2243.9 face velocity and containment, NATA witness statements on the contamination-control test work, the operating and maintenance manual with filter-change schedule, the change-control register, and the response procedure if any room loses negative pressure or any fume cupboard loses face velocity.

17. Commissioning, leakage testing and pressure cascade verification

Before handover, the forensic and coronial HVAC ductwork is commissioned through a formal verification sequence that aligns with the NATA quality dossier above.

Leakage testing. Run a SMACNA Class A leakage test on every contaminant-bearing duct system at design pressure. The test pressurises the duct to 250 Pa and measures the leakage flow, with the pass criterion at under 0.5 percent of design airflow. Sectional testing on long runs — a 60 metre extract from a histopathology bench to the roof stack is tested in three to four sections so any failure is localised.

Pressure cascade verification. Calibrated digital manometers at every boundary between zones, reading continuously through a representative 24-hour working day including door-opening events. Verify the cascade — autopsy at minus 15 to minus 20 Pa relative to corridor, DNA pre-PCR at plus 15 to plus 20 Pa, toxicology and chemistry at slight negative, refrigerated body storage at neutral to slight negative, viewing chapel and family room at plus 5 to plus 10 Pa.

HEPA integrity testing. Every H13 and H14 HEPA in the building tested with DOP (di-octyl phthalate) or PAO (poly-alpha olefin) aerosol challenge under ISO 14644-3, with leak detection on the downstream face under a calibrated photometer. Annual repeat through the laboratory’s life.

Fume cupboard performance. Every fume cupboard tested to AS/NZS 2243.9 with smoke visualisation, face velocity at 0.5 metres per second across the sash open position, and tracer-gas containment testing where the laboratory’s scope requires.

Particle counting. Every clean-room zone tested under ISO 14644-1 for the target class — ISO Class 5 at the DNA pre-PCR workstation, ISO Class 7 at the trace evidence room, ISO Class 8 at the digital forensics climate-controlled supply.

Personal monitoring during a working day. On a representative working day, fit operators in autopsy, histopathology and chemistry with personal monitors and run a full shift. Compare measured 8-hour TWA against the Safe Work Australia limits — formaldehyde 0.3 ppm TWA, xylene 50 ppm STEL, lead 0.05 mg per cubic metre TWA in the ballistics room, fentanyl trace below detection limit in the drug squad.

Tracer-gas room decay testing. In the autopsy and DVI surge rooms, run a tracer-gas decay test (sulfur hexafluoride or carbon dioxide step-up and step-down) to verify achieved air change rate against the 12 to 15 ACH design target.

18. The SBKJ machine package for an Australian forensic HVAC duct fabricator

The fabrication of forensic and coronial HVAC ductwork is a discipline of materials, seam construction and machinery capability. The SBKJ machine package described below is the configuration we recommend for fabricators serving this market because it is the configuration that produces the seam quality, the leakage class and the construction speed that the work requires.

SBAL-V auto duct line for general HVAC supply. Galvanised coil 0.8 to 1.2 mm for the family viewing, witness suite, court chamber and administrative HVAC. Standard roll-form, notch, fold and snaplock fabrication. SMACNA Class C acceptable for the clean-air supply paths where the contaminant load is zero. Auto-output at 30 metres per shift, integrated with TDF flange former for the transverse joint.

SBAL-V configured for 316L stainless at 1.5 mm. The dedicated stainless configuration of the SBAL-V handles 1.5 mm 316L coil for the autopsy room extract, the formaldehyde-bearing histopathology extract, the chemical fume cupboard discharge, the drug squad decontamination extract and the fumigation chamber extract. Higher-tension roll-formers, integrated TIG seam welder with argon shielding gas, auto bead crimping for the longitudinal seam, integrated stainless TDF flange. Output at 15 to 20 metres per shift on 1.5 mm stainless, slower than galvanised because the welding pace controls.

SBSF-1525 super auto duct line for fire-rated heavy-gauge work. The SBSF-1525 carries mild steel coil up to 1.6 mm with a continuous longitudinal seam, producing duct rated to AS 1530.4 250 degree Celsius two-hour fire resistance for compartment penetration around the ballistics chamber, the secured evidence vault and the DVI surge mass-evacuation route. Fire and smoke dampers integrated at every compartment boundary, certified to AS 1668.1.

SB-ZF1500 sealed welded longitudinal seam stainless duct line. For the chemical fume cupboard exhaust, the toxicology stack and any gas-tight evidence-processing chamber extract, the SB-ZF1500 produces a continuously TIG-welded longitudinal seam in 316L coil up to 1500 mm circumferential blank with argon shielding gas. Achieves SMACNA Class A leakage reliably with visual inspection of every seam and dye-penetrant testing on a sampling basis for the most critical chemistry-bearing ducts.

SBFB-1500 round spiral former for clean-room recirculation. For the DNA PCR clean-room recirculation duct, the trace-evidence ISO Class 7 supply path and the digital forensics climate-controlled supply, the SBFB-1500 produces 304 or 316L stainless round duct with a continuous spiral lock seam. Round geometry is the optimum for clean-room recirculation — minimum surface area for a given cross-section means minimum particulate deposition.

SBPC1500 plasma cutting cell for heavy plate. The SBPC1500 plasma cuts 4 mm to 20 mm stainless and mild steel plate, profiles to drawing tolerance, and supports refractory anchor stud welding for thermally insulated stack construction. Used for the heavy-gauge plate transitions feeding the ballistics chamber bullet trap, the firearms tool-mark comparison chamber discharge, the post-mortem CT shielded bunker exhaust and any refractory-lined high-temperature stack in the facility.

SBLR-600 laser-welded round duct for highest-class chemistry exhaust. The SBLR-600 produces 304 and 316L stainless round duct with a continuous laser-welded longitudinal seam. Used for the toxicology fume cupboard discharge stack where every joint must be gas-tight for chain-of-custody integrity, achieving leakage below SMACNA Class A by a comfortable margin.

SBTF-1500, SBTF-1602 and SBTF-2020 transverse duct flange formers. The SBTF range forms the TDF profile rolled directly into the duct end. The SBTF-1500 handles ducts up to 1500 mm, the SBTF-1602 up to 1600 mm and the SBTF-2020 up to 2000 mm. The bolted joint with full-perimeter EPDM gasket on a 100 mm fastener pitch achieves Class A leakage when correctly torqued, without the cost of continuously welding every transverse joint on a long duct run.

For a deeper treatment of the SBAL-V versus SBAL-III decision and the line capability for stainless work, see the SBKJ SBAL-V versus SBAL-III comparison. For the welding-method options across the package — TIG, plasma, laser, resistance seam — and where each is appropriate, see the SBKJ guide on welding methods for HVAC duct fabrication. For the parallel design questions in clinical and pharmaceutical clean rooms, see the pharmaceutical cleanroom HVAC duct guide. For the hospital theatre and ICU baseline that the autopsy ASHRAE 170 design extends, see the hospital and healthcare HVAC duct guide. For the funeral and routine mortuary baseline that the coronial mortuary extends, see the funeral, mortuary and cremation HVAC duct guide.

19. The supporting infrastructure — evidence storage, digital forensics, family viewing

The forensic facility carries supporting zones that do not generate chemical or biological contaminant but that still have HVAC engineering implications.

Secured evidence storage. The chain-of-custody evidence room holds physical evidence from active and historical cases. Climate-controlled at plus 18 to plus 22 degrees Celsius and 35 to 55 percent relative humidity for long-term stability of paper, fabric, electronic and biological evidence. Clean-agent suppression under AS 4214 (typically FM-200 or Novec 1230 inert gas) rather than water sprinkler under AS 2118, because water damage to evidence is the worse outcome. Access-controlled with full audit trail through the security desk.

Refrigerated biological evidence chiller. A separate chiller at plus 4 degrees Celsius within the secured evidence zone holds biological evidence pending DNA analysis. Sexual assault kits, blood swabs, fibre and hair transfer evidence. 316L stainless ductwork, externally insulated, continuous temperature logging and alarm.

Digital forensics laboratory. Computer, mobile phone and encrypted media analysis. ESD-safe at every workstation. Faraday-cage-shielded mobile device examination chamber to isolate target devices from cellular networks during analysis. Air-gap network with separate physical cable plant. Climate-controlled at plus 20 to plus 22 degrees Celsius for instrument stability. The HVAC ductwork is bonded to building earth at every transition.

Document examination room. Climate-stable at plus 20 to plus 22 degrees Celsius and 45 to 55 percent relative humidity. Light-controlled with full UV and IR photography capability. ESDA Electrostatic Detection Apparatus for indented writing recovery. The HVAC supply enters at very low face velocity through perforated ceiling diffusers so that paper documents are not disturbed by airflow.

Family viewing and witness suite. Acoustic target AS/NZS 2107 NC-30. Comfort cooling and heating, generous outside air for occupant freshness, slight positive pressure relative to the working corridors so no chemical or biological signature can drift from the laboratory side. No shared return air with any laboratory zone — fully ducted return back to the family-area air handler.

Crime scene investigation vehicle bay. CSI vehicle bay holds Forensic CSI vans, SMARTKIT mobile laboratories, drone vehicles and other deployable equipment. Mechanical ventilation at 6 ACH to manage vehicle exhaust, with carbon monoxide detection and alarm. Lighting and power for vehicle preparation and equipment maintenance.

Refrigerated body transport vehicle bay. Mortuary vans, ambulances and RAAF C-130 mass-evacuation logistics interface. Drive-through layout with airlock between the vehicle bay and the routine mortuary, so the body transfer happens in a controlled-airflow space. The bay itself runs at 6 ACH with downward airflow to capture vehicle exhaust at floor level.

20. Closing — engineering as quiet competence in service of justice

The HVAC ductwork in a forensic laboratory, a coronial mortuary, a DVI centre or a police forensic facility is engineering that nobody outside the operation should ever notice. The autopsy room holds its formaldehyde limit on a busy day. The DNA pre-PCR room holds its positive pressure through a door cycle that opens 200 times in a shift. The ballistics chamber clears its lead within 60 seconds between shots and the operator goes home at the end of the day with a personal-monitor reading well below the limit. The DVI surge zone sits at plus 4 degrees Celsius month after month, waiting for an activation that may never come and that, when it does, has to absorb 100 bodies in 24 hours. The family in the viewing suite smells nothing and feels still.

Each outcome is built on engineering decisions made at design stage and held to at fabrication and commissioning. The decisions are not glamorous — material grade, seam construction, pressure relationship, source-capture face velocity, leakage test pass criterion, the choice between an SBAL-III configured for galvanised and an SBAL-V configured for stainless on the fabricator’s shop floor. Each decision is technical. Each consequence is human. The discipline of getting them right is the closest thing the engineering community has to a contribution to the justice system that the building serves.

SBKJ engineers have been involved in HVAC ductwork for forensic, coronial and DVI facilities across more than a decade of operator and consultant projects in Australia and across 100+ export markets. The machinery package covered above — the SBAL-V auto duct line in dual galvanised and stainless configuration, the SBSF-1525 super auto duct line for fire-rated heavy-gauge work, the SB-ZF1500 sealed welded stainless duct line for chemistry-bearing extract, the SBFB-1500 round spiral former for clean-room recirculation, the SBPC1500 plasma cell for heavy plate, the SBLR-600 laser-welded round duct line for the highest-class chemistry exhaust, and the SBTF-1500 through SBTF-2020 transverse flange formers — is the configuration we recommend for Australian fabricators serving this market.

SBKJ will be at ARBS 2026 in Sydney in May. If you are working on a forensic, coronial or DVI HVAC ductwork project — design stage, fabrication stage, commissioning stage or retrofit — the SBKJ engineering team will be on the floor to talk through the machinery package and the seam-construction options that the work requires. Bring a drawing. The conversation is more productive when there is geometry to look at.

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FAQ

What negative pressure does an Australian forensic autopsy room require under ASHRAE 170?

ASHRAE 170 specifies minus 0.025 inches water gauge (about minus 6.2 Pa) below the corridor as the floor, with Australian practice targeting minus 15 to minus 20 Pa for engineering margin. 12 ACH minimum with 15 ACH preferred, 100 percent outside air, no recirculation, downdraft airflow, three layers of source capture at the body table, HEPA H13 or H14 on the exhaust before discharge above roof line.

What is the Safe Work Australia formaldehyde exposure standard in a forensic mortuary?

1 ppm short-term exposure limit (15-minute STEL) and 0.3 ppm time-weighted average over 8 hours. Formaldehyde is IARC Group 1 carcinogenic. The HVAC response is downward airflow at the body table, sub-table and overhead source capture, downdraft histopathology grossing stations, real-time personal monitoring, and a written exposure-management plan.

How much mortuary surge capacity does an Australian DVI centre need?

10 to 30 body routine refrigerated holding at plus 4 degrees Celsius, expandable through pre-installed flange connections and dedicated extract capacity to absorb mass-casualty surge events. The VIFM Southbank DVI Centre is the national lead, working under Interpol DVI Standing Committee protocols, with operational legacy across Bali 2002, Black Saturday 2009, MH17 2014 and Lindt Cafe 2014.

What fume cupboard standards apply to an Australian histopathology xylene grossing station?

AS/NZS 2243.10 and AS/NZS 2982 cover construction. Face velocity 0.5 metres per second with annual NATA-witnessed performance verification under AS/NZS 2243.9. Downdraft grossing configuration with perforated stainless work surface drawing xylene, toluene, ethanol, methanol and formalin vapour away from the operator. 316L stainless extract ductwork, continuously TIG-welded, discharged via dedicated stack 7 metres minimum above local roof line.

How is DNA PCR clean-room contamination prevented through the HVAC ductwork?

Pre-PCR side at plus 15 to plus 20 Pa positive pressure with ISO Class 5 to Class 7 air, HEPA H14 supply, unidirectional downdraft. Post-PCR side at neutral to slight negative. Strict separation of air handling units. Stainless ductwork throughout for sodium hypochlorite and UV decontamination compatibility. Air locks and material pass-throughs at every boundary.

What SBKJ machines does an Australian forensic HVAC duct fabricator need?

SBAL-V auto duct line in galvanised and 316L stainless configurations, SBSF-1525 super auto duct line for fire-rated 250 degree Celsius two-hour duct, SB-ZF1500 sealed welded longitudinal seam stainless duct line for chemistry-bearing extract, SBFB-1500 round spiral former for clean-room recirculation, SBPC1500 plasma cell for heavy plate transitions, SBLR-600 laser-welded round duct for highest-class chemistry exhaust, SBTF-1500 through SBTF-2020 transverse duct flange formers.

What NATA accreditation requirements affect HVAC ductwork in a forensic laboratory?

NATA accreditation under ISO/IEC 17025 brings HVAC into scope of the testing method. Continuous logging of temperature and relative humidity, annual particle counting and HEPA integrity testing under ISO 14644, annual fume cupboard verification under AS/NZS 2243.9, pressure cascade verification under ASHRAE 170, and a documented HVAC commissioning dossier as part of the laboratory’s quality manual.

How is firearms test-fire chamber lead fume managed through the ductwork?

Sealed test-fire chamber with bullet trap, downdraft extract at above 0.5 metres per second face velocity at the firing position, HEPA H14 on the discharge to capture sub-micron lead particulate, 316L stainless extract ductwork continuously TIG-welded, no recirculation, discharge above roof line. Safe Work Australia inorganic lead workplace exposure standard 0.05 mg per cubic metre 8-hour TWA, with periodic biological monitoring.

What ductwork governs a forensic drug squad clandestine laboratory decontamination room?

100 percent outside air at 15 ACH minimum, downdraft airflow, source-capture local exhaust at every active station, AS/NZS 60079 Zone 1 hazardous-area rating, 316L stainless ductwork continuously TIG-welded, HEPA H14 plus activated carbon polishing on the extract, separate dedicated discharge stack away from any outside air intake. The hazard inventory includes P2P, ephedrine, lithium, anhydrous ammonia, sodium hydroxide, ether, acetone, red phosphorus and trace fentanyl.

What is the role of fumigation chambers in forensic evidence processing and how is the ductwork built?

Cyanoacrylate superglue fuming, ninhydrin, iodine fuming, DFO and vacuum metal deposition for latent fingerprint development. Each chamber is sealed under negative pressure, with 316L stainless extract ductwork continuously TIG-welded, sized for cyanoacrylate vapour clearance, with HEPA H14 and activated carbon polishing on the discharge. Independent of the autopsy, histopathology, toxicology and DNA zones.