Duct Attenuator & Acoustic Treatment Install SWMS

HVAC duct attenuator and acoustic treatment installation is the mechanical trade that fits silencers and acoustic duct lining into air-handling systems at ceiling height, handling, hoisting and fixing heavy sheet-metal components. The dominant hazards are falls from platforms installing attenuators and duct overhead, musculoskeletal and crush injury handling and hoisting heavy units, severe laceration from sheet-metal edges and flanges, and respiratory and skin irritation from synthetic mineral-fibre acoustic lining. This SWMS covers the attenuator, duct and acoustic-lining installation; it does not cover the design of the air-handling system, the refrigerant or hydronic pipework, or the system commissioning, which are documented separately.

Under the model Work Health and Safety Act 2011 and the harmonised Work Health and Safety Regulations adopted in each state and territory, this is high risk construction work because attenuators and duct are installed from platforms above two metres and because handling and cutting acoustic lining create an area requiring respiratory protection; Victoria operates the equivalent provisions under the Occupational Health and Safety Act 2004 and Occupational Health and Safety Regulations 2017. The air-handling design context is set by AS 1668.1 and AS 1668.2, ductwork follows AS 4254, temporary edge protection follows AS/NZS 4994, and respiratory protective equipment is selected and used to AS/NZS 1715 and 1716.

Failure to meet the primary duty of care is prosecuted under the Category 1 to 3 offences in the Work Health and Safety Act (and the equivalent provisions in Victoria's Occupational Health and Safety Act 2004), with maximum penalties indexed in most jurisdictions, imprisonment available for individuals, and a separate industrial manslaughter offence; current figures follow the prevailing penalty schedule of the responsible state regulator. This document is structured to satisfy the safe work method statement content requirements of the harmonised regulations and documents safe attenuator and duct installation at height.

Hazards identified

10 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Engineering: Use a scissor lift or boom elevating work platform instead of a ladder, with guardrailed platforms to AS/NZS 4994, platform inspection and a harness where a residual fall risk remains.
2. 2Elimination: Mechanically hoist heavy units rather than lift them by hand, with lifting frames and platform-mounted supports, two-person handling and a 25 kg single-person limit for lighter parts.
3. 3Engineering: Use deburred edges and factory-formed flanges, handle cut metal with care, clear swarf, and wear cut-resistant gloves to AS/NZS 2161.3.
4. 4Substitution: Use pre-lined duct to limit on-site lining, ventilate during cutting and fitting, minimise dry handling and wash before breaks; wear a P2 respirator to AS/NZS 1715 and 1716.
5. 5Engineering: Use rated lifting gear and tag lines, an exclusion zone beneath the lift, a licensed dogger and no work under a suspended load; persons below wear a hard hat.
6. 6Administrative: Use adjustable platforms to keep work near shoulder height, with task rotation and micro-breaks.
7. 7Engineering: Use a rated platform on a firm level floor with overhead clearance checked, pre-start checks and no overreaching.
8. 8Engineering: Use low-noise cutting and fixing methods, limit continuous tool time against the 85 dB(A) eight-hour exposure standard to AS/NZS 1269, and provide hearing protection.
9. 9PPE: Capture debris where drilling overhead, keep the head clear of falling swarf, and wear sealed eye protection to AS/NZS 1337.1.
10. 10Engineering: Use guided lifting with tag lines and a defined landing point, keep hands clear of pinch points, control the lower and follow a communication protocol.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

A mechanical-services contractor is installing duct attenuators and acoustic lining in the air-handling system above a new ceiling, hoisting and fixing heavy sheet-metal silencers at ceiling height. The work is high risk construction work both because it is carried out from platforms above two metres and because handling and cutting the acoustic lining create an area requiring respiratory protection, so the supervisor builds the safe work method statement around fall protection, mechanical hoisting and the mineral-fibre exposure. A scissor lift with a guardrailed platform to AS/NZS 4994 is used in place of a ladder, the ground is checked firm and level, overhead clearance is confirmed, and pre-start checks are completed before the platform is raised. Heavy attenuators are hoisted with rated gear, tag lines and a defined landing point rather than lifted by hand, with an exclusion zone beneath the lift, a licensed dogger and no work under a suspended load, and the unit is guided into the duct run with hands clear of pinch points and a controlled lower. Pre-lined duct is used to limit on-site lining; where lining is cut and fitted the area is ventilated, dry handling is minimised, and a P2 respirator is worn with washing before breaks. Deburred edges, factory-formed flanges and cut-resistant gloves control the severe laceration risk from sheet metal, and adjustable platforms keep the overhead fixing near shoulder height with task rotation. Low-noise cutting and fixing with hearing protection manage saw noise within the 85 dB(A) exposure standard, and sealed eye protection with overhead capture controls swarf. Workers sign on to the statement before starting, the lift plan and platform checks are kept, and the signed statement is held on site for the responsible state regulator.

Related legislation

• Work Health and Safety Act 2011 (harmonised; enacted in all states and territories except Victoria, which applies the Occupational Health and Safety Act 2004), s.19 — Primary duty of care to workers and to other persons at or near the workplace
• Harmonised Work Health and Safety Regulations, section 291 — Defines high risk construction work (Victoria: Occupational Health and Safety Regulations 2017, Part 5.1)
• Harmonised Work Health and Safety Regulations, section 299 — Content and review requirements for a safe work method statement for high risk construction work (Victoria: regulation 327; Tasmania: regulation 312)
• Harmonised Work Health and Safety Regulations, Part 4.4 — Managing the risk of falls (work above two metres; Victoria applies the equivalent provisions of the Occupational Health and Safety Regulations 2017)
• Harmonised Work Health and Safety Regulations, Part 4.1 — Noise: the exposure standard of 85 dB(A) over eight hours and 140 dB(C) peak

Frequently asked questions