Compressed Air Systems SWMS

Compressed air systems in HVAC and industrial plant environments operate at pressures commonly between 700 kPa and 1.4 MPa, storing significant potential energy in receivers, reticulation piping, hoses and pneumatic tooling. Commissioning, modification, isolation and maintenance of these systems exposes workers to stored pressure release, hose whip, projectile fittings, noise, oil-mist aerosols and inadvertent air injection into tissue. Under WHS Regulation 2025, pressure equipment classified under AS 4343 hazard levels A-D is notifiable plant, and any work involving its installation, alteration or maintenance is High Risk Construction Work triggering a mandatory Safe Work Method Statement before work commences. The PCBU must ensure the SWMS is prepared in consultation with workers, available at the workplace, and reviewed whenever controls change or an incident occurs. This SWMS documents the task-specific hazards, hierarchy controls, isolation and lock-out procedures, competency requirements and verification steps required to meet WHS Regulation 2025 obligations and AS 4774 compressed air code compliance.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

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

1. 1Elimination — Where reticulated air is only needed intermittently, eliminate permanent pressurisation by using battery-electric tools or task-end depressurisation and bleed-down to atmosphere.
2. 2Elimination — Remove condemned or unregistered air receivers from service and replace rather than repair where AS 4458 in-service inspection identifies critical wall-thickness loss.
3. 3Substitution — Substitute oil-flooded compressors with oil-free scroll units in breathing-air and sensitive HVAC applications to remove aerosol and CO contamination pathways.
4. 4Substitution — Replace standard blow guns with OSHA-compliant venturi nozzles limiting dead-end pressure to below 200 kPa per AS 4024 safeguarding principles.
5. 5Engineering — Install pressure relief valves, rupture discs, automatic drain traps and hose whip-check restraints on every reticulation branch in accordance with AS 4041 piping code.
6. 6Engineering — Fit lockable isolation valves, downstream bleed points and tagout stations at every maintenance access node to enable zero-energy verification before work.
7. 7Administrative — Implement a written permit-to-work, isolation certificate and pre-start SWMS sign-on briefing reviewed daily by the HVAC supervisor and signed by all workers.
8. 8Administrative — Schedule competency verification for pressure equipment work, AS 3873 in-service inspection records, and operator training documented in the project HSE plan.
9. 9PPE — Issue impact-rated safety glasses to AS/NZS 1337.1, Class 5 hearing protection to AS/NZS 1270, cut-5 gloves and long-sleeve flame-retardant coveralls for compressor room entry.
10. 10PPE — Provide face shields and arc-rated gauntlets when breaking pressurised joints, supplemented by respiratory protection to AS/NZS 1716 when oil-mist aerosols are detected.

Applicable Codes of Practice

High-Risk Construction Work triggered

Worked example

On a refurbishment of a mid-rise commercial building plantroom, a mechanical services subcontractor is engaged to recommission a 1,200-litre air receiver and replace corroded discharge piping feeding pneumatic VAV actuators. At the 6:30 am pre-start brief, the leading hand opens the Compressed Air Systems SWMS on a site tablet and walks the four-person crew through the hazard register. The team identifies that stored pressure in the receiver (currently at 950 kPa) and three downstream isolation points pose the highest risk, matching the SWMS hazard line on uncontrolled release of stored pneumatic energy. Following the control sequence, the supervisor confirms the electrical isolation of the compressor at the MCC, applies personal locks and tags, opens the bleed-down valve, and verifies zero pressure on the gauge for two minutes before authorising disconnection. Each worker signs the SWMS sign-on register acknowledging the isolation certificate number and confirms PPE — impact glasses, Class 5 earmuffs and cut-5 gloves. Mid-task, the crew detects a residual 80 kPa reading at a downstream actuator branch not listed on the isolation drawing. Work stops; the supervisor amends the SWMS in the field, adds the additional bleed point as a new control entry, re-briefs the crew, and obtains fresh signatures before resuming. The amended document is uploaded to the project HSE register that evening.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• AS/NZS 5149 — Refrigerating systems; AS 1668 — Mechanical ventilation