Document ID: chunk:federal_register_of_legislation:F2016L00419:body:0:p21
Version: federal_register_of_legislation:F2016L00419
Segment Type: other
Provision Reference: 
Character Range: 53212–56105

A local exhaust system may comprise the elements listed:
    * a hood which captures the contaminant close to its point of generation
    * a duct system to move contaminant away from the work area
    * an air cleaning system to prevent pollution of the general atmosphere
    * an exhaust fan to provide air flow
    * a stack or other means of discharging the decontaminated air into the atmosphere.
Local exhaust ventilation systems should be designed to provide a minimum capture velocity at the fume source of 0.5m/second away from the welder. Inlets and outlets should be kept clear at all times. Air from a local exhaust ventilation system should not be re-circulated into the workroom. This air should be discharged into the outside air away from other work areas and away from air conditioning inlets or compressors supplying breathing air.
Examples of local exhaust ventilation suitable for welding operations include:
    * fixed installations, such as side-draught or down-draught tables and benches, and partially or completely enclosed booths
    * portable installations, such as movable hoods that are attached to flexible ducts
      (for example, see Figure 1)
    * low volume high velocity fume extractors attached directly to the welding gun (for example,
      see Figure 2).

Forced dilution ventilation
An elevated concentration of atmospheric contaminants can be diluted with a sufficient volume of clean air. Successful dilution ventilation depends not only on the correct exhaust volume but also on control of the airflow through the workplace. Although forced dilution ventilation systems are not as effective in controlling atmospheric contaminants as local exhaust ventilation systems, they may be useful to control minor emissions of low toxicity contaminants.

Figure 1 Local Exhaust ventilation in confined space welding

Figure 2 Fume extraction attached to the welding gun

Natural ventilation
Natural ventilation should only be used for general comfort not as an engineered control
measure for atmospheric contaminants and fumes. Natural ventilation can assist with the transfer of contaminants from the work area however it is not a reliable way of diluting or dispersing contaminants. For example, if a worker is working in a fixed position and the natural wind
velocity is mild or wind is in a direction towards the worker, the worker may remain exposed
to contaminants that have not been removed from the worker's breathing zone.

4.2 Personal protective equipment (PPE)

Regulation 44: If personal protective equipment is to be used at the workplace, the person conducting the business or undertaking must ensure the equipment is selected to minimise risk to health and safety including by ensuring that the equipment is:
    * suitable for the nature of the work and any hazard associated with the work
    * a suitable size and fit and reasonably