Safety alert for blast freezers

WorkCover NSW has published a safety alert to remind employers and those in control of workplaces to ensure the safety and stability of plenums, ceilings and other associated structures by having effective and appropriate inspection and maintenance programs.

This follows an incident where a worker suffered fatal injuries when a plenum made from expanded polystyrene (EPS) panels collapsed while he was working in a blast freezer. A plenum is a space inside a building used for airflow and often refers to the space between the dropped ceiling and the structural ceiling.

Contributing factor

A gradual build-up of ice on top of the plenum resulted in a number of panels collapsing under the weight.

Occupational health and safety requirements

The Occupational Health and Safety Act 2000 requires employers and those in control of workplaces to take all necessary steps to ensure that safe work systems are established and maintained, and that all staff are adequately informed, trained and supervised.

Clauses 9 to 12 of the Occupational Health and Safety Regulation 2001 provide specific obligations on the employer to manage the risk of any foreseeable hazard that may arise in their workplace.

Actions required

To ensure all components of a refrigeration system are operational and compliant, the employer or controller of the workplace should:

• Ensure inspection and maintenance regimes are in place, as per the manufacturer’s instructions - inspection and maintenance should cover:
  • the operation of refrigeration systems and other associated plant
  • the components associated with temperature and humidity control - eg, airflow and thermostat devices, door and joint seals, sensors and system alarms, such as ammonia leak detection, power interruption or abnormal pressures
  • removal of any ice build-up - and identify why it occurred (it is usually caused by high humidity and inadequate ventilation in the plenum)
  • the integrity of lamination
  • repairs in a timely and appropriate manner
• Monitor conditions to detect equipment failure or deterioration, and consider external factors that may affect the refrigeration process - eg, prolonged high temperatures, heatwaves and poor seals
• Review records of all work performed on, or associated with, the refrigeration plant and other equipment
• Provide appropriate training to all those who undertake inspections, maintenance and repairs

For more information, see AS/NZ 1170.1:2002, Structural design actions - Part 1: Permanent, imposed and other actions - this standard specifies the design of EPS panel ceilings, which allows for minor live loading to occur during maintenance and repair operations only.