Mechanical Ventilation System Safe Work Method Statement

Australian WHS guidelines recommend manual handling risk assessment for loads exceeding 15kg, with team lifting implemented where practical to eliminate or minimise musculoskeletal injury risk. For ductwork installation, implement mandatory two-person team handling for all duct sections exceeding 15kg or those with awkward dimensions exceeding 1.5 metres in any direction even if weight is less than 15kg. Overhead installation compounds manual handling risk as workers must support loads at shoulder height or above whilst making connections. Even relatively light duct sections become hazardous when held overhead for extended periods. The focus should be risk-based rather than absolute weight limits - consider load characteristics including weight, dimensions, balance, grip points, installation height, duration of holding, and confined space access. For large main duct trunks weighing 30-50kg or more, use mechanical lifting aids including chain hoists, gantries, or cranes eliminating manual lifting. Plan duct fabrication creating manageable section weights rather than maximising section length. Never allow single workers to install ductwork sections regardless of weight - team installation improves safety and efficiency.

A confined space under Australian WHS regulations is an enclosed or partially enclosed space not designed for continuous human occupancy, has restricted entry/exit, and may contain atmospheric hazards or engulfment risks. Large ductwork sections including main supply and return trunks typically meet this definition requiring confined space entry procedures. Factors indicating confined space status include: duct dimensions limiting movement or escape (typically requiring entry through opening less than 600mm), limited ventilation creating potential for oxygen deficiency or accumulation of contaminants, and restricted visibility. Before any personnel entry into ductwork, conduct atmospheric testing using calibrated multi-gas detector measuring oxygen (must be 19.5-23.5%), carbon monoxide, hydrogen sulphide, and combustible gases. Provide continuous forced ventilation introducing fresh air throughout entry period. Assign safety watch personnel maintaining constant communication with workers in duct - never allow lone worker entry. Provide rescue harness and retrieval line enabling emergency extraction without requiring rescuer entry. Ensure rescue equipment and trained personnel immediately available. If ductwork previously conveyed contaminated air or is located in areas where hazardous atmospheres may accumulate, additional controls including respiratory protection may be required. Prepare formal confined space entry permit documenting atmospheric testing, controls, emergency procedures, and authorisation before allowing entry.

Ductwork installation in mechanical and electrical rooms must maintain adequate clearances from electrical equipment to enable safe operation, maintenance access, and prevent physical contact creating electrical hazards. For electrical switchboards and main distribution boards, maintain minimum 600mm clear access space in front of equipment per AS/NZS 3000 electrical wiring standards - ductwork cannot be installed within this zone. Above electrical equipment, maintain minimum 300mm clearance allowing adequate heat dissipation and preventing dripping condensation onto energised equipment. For electrical cable trays and services, maintain minimum 150mm separation from ductwork preventing contact during installation or future maintenance. Where ductwork must cross above electrical equipment and minimum vertical clearances cannot be achieved, install protective barriers or drip trays preventing water damage from duct condensation or leaks. Do not support ductwork hangers from electrical equipment or conduits. Coordinate ductwork routes with electrical contractors during design phase ensuring adequate clearances can be maintained. If space constraints prevent achieving standard clearances, consult with electrical contractor and building owner to develop alternative solutions which may include relocating ductwork routes, installing additional protection, or modifying electrical equipment locations. Document final clearances in as-built drawings for future reference during maintenance activities.

AS 4254 Ductwork for air-handling systems in buildings specifies testing requirements based on ductwork pressure classification. For low-pressure ductwork (static pressure less than 1000Pa) serving typical commercial HVAC systems, visual inspection of joints and connections verifying appropriate sealing is standard minimum requirement. Medium-pressure ductwork (1000-2000Pa) and high-pressure ductwork (above 2000Pa) require air leakage testing to verify sealed systems meet specified maximum leakage rates. Air leakage testing involves pressurising completed duct sections using calibrated fan and measuring air flow required to maintain test pressure - leakage is calculated as percentage of system air flow or as leakage per square metre of duct surface area. Testing must be conducted before ductwork is concealed by ceiling or wall construction. For systems serving critical applications including hospital operating theatres, pharmaceutical clean rooms, or fume hood exhausts, additional testing may include smoke testing verifying no unexpected air paths, pressure decay testing, and airflow measurement verifying design air volumes delivered. Fire dampers and smoke dampers require operational testing verifying proper closure on signal from fire alarm system and self-closing action from thermal links. All testing should be documented in commissioning reports including test methodology, equipment used, results, and remedial actions for failed tests. Provide testing documentation to building owner for regulatory compliance verification and warranty purposes.

Mechanical plantrooms housing boilers, chillers, air handling units, and heat-producing equipment can experience temperatures exceeding 35-40°C creating serious heat stress risks for HVAC technicians performing installation, maintenance, or commissioning work. Before commencing work in plantrooms, measure ambient temperature using portable thermometer to assess conditions. When temperature exceeds 32°C, implement work-rest cycles adjusted for conditions: 45 minutes work with 15 minutes rest in cool environment when 32-35°C, reducing to 30 minutes work with 30 minutes rest when temperatures exceed 38°C. Provide portable cooling fans positioning near workers to improve air movement even if air temperature remains high - air movement enhances evaporative cooling improving thermal comfort. Ensure workers have unlimited access to cool drinking water - position insulated water containers in plantrooms and mandate drinking minimum 250ml every 20 minutes during work in hot conditions. Schedule high-intensity work including heavy lifting or sustained physical activity during cooler periods if plantroom temperature varies throughout day. Brief all workers on heat stress symptoms including headache, dizziness, nausea, confusion, and cessation of sweating - establish absolute requirement for workers to cease work immediately and move to cool environment if experiencing any symptoms. Implement buddy system where workers monitor each other for heat stress signs as affected persons may not recognise their own symptoms. For prolonged work in consistently hot plantrooms, consider engineering controls including installation of additional ventilation, portable air conditioning units for work areas, or scheduling work during facility shutdown periods when heat-producing equipment can be isolated.