Medical Gas and Mechanical Services
What the exam expects
This domain covers medical gas pipeline systems and mechanical services installations, with medical gas work being tightly controlled in NSW. Candidates should understand AS 2896 for medical gas systems, AS/NZS 5601 for gas installations where relevant, and the requirements for competent persons and licensing for medical gas work. Mechanical services covers heating, ventilation and air conditioning pipework, refrigerant systems and associated controls.
Concepts to master
For medical gases, know the gases involved (oxygen, medical air, nitrous oxide, nitrogen, carbon dioxide, vacuum and anaesthetic gas scavenging), the colour coding of cylinders, pipework and outlets, and the role of the medical gas supply system. Understand the sequence of installation, pressure testing, purging and commissioning, and why brazing under nitrogen purge is used to prevent oxidation inside copper. Know that medical gas systems require verification by an accredited verifier before handover, with documented test results. Understand zone valves, alarm systems, terminal units and the non-interchangeability principle that prevents cross-connection of different gases. For mechanical services, know refrigerant handling obligations, pressure testing of pipework, insulation and condensate drainage, and the interaction between HVAC and building services.
Traps the exam sets
Questions often test colour coding and terminal unit identification, or ask who may verify a medical gas installation. Another trap is treating medical gas pipework like ordinary gas pipework, ignoring the verification and documentation requirements. Refrigerant handling and the need for appropriate licences are also commonly tested.
Worked example
Rule of thumb: no medical gas system is commissioned until the verifier signs off. Plan the sequence as install, pressure test, purge, verify, commission. If a question offers commissioning before verification, it is wrong.