MSMWHS217 – Gas test atmospheres

This unit of competency covers the skills and knowledge required to test the working atmosphere, using electronic test apparatus, to find out if it is safe for the proposed work.

It applies to situations where an individual may be required to carry out gas testing of an atmosphere prior to entering a specific area or workspace. The competency requires the person to interpret readings and take actions based on the interpretation.

Working environment may be hazardous, unpredictable, subject to time pressure, chaotic and expose responders to risk, on land or water, by day or night. Workplace atmospheres may include visible and invisible hazards and hazardous surfaces.

The unit is suitable for use in the following situations:

  • confined spaces
  • enclosed and partially enclosed spaces
  • hot work
  • storage tanks, silos, pits, pipes, shafts, ducts, transport vehicles and ships
  • testing as part of issuing a work permit
  • monitoring as part of working under a work permit
  • open areas
  • holding the gas tester by hand
  • lowering the gas tester into a space, e.g. on a line.

This unit of competency applies to an individual working alone or as part of a team or group and working in liaison with other shift team members and the control room operator, as appropriate.

Course Content

The course covers the following;


  • Introduction
  • Case studies
  • Common confined spaces
  • Statistics
  • Risk management
  • Hierarchy of control measures
  • Plan and prepare for working in a confined space
  • Work in accordance with procedures
  • Classification of confined spaces
  • Confined space operations
  • The confined space risk assessment form
  • Communications and consultation
  • Collect information and instructions
  • Confined space hazard control
  • Risks, Hazards and controls with confined spaces
  • Hazard identification
  • How are hazards controlled in confined spaces?
  • Where will the gases accumulate?
  • Vapour density and relative density
  • Explosive atmospheres in confined spaces
  • The flammable range
  • LEL and UEL
  • Purging and ventilation
  • Inerting
  • Types of ventilation
  • Calculating the purge time
  • Positive ventilation¬†
  • Manual handling
  • Musculoskeletal injuries
  • Standard operating procedures
  • Instruction and guidance
  • Ceasing confined space operations
  • Returning the confined space to service



4 Hour