All of the following are safety measures to prevent the delivery of hypoxic gas mixture to the patient except –

Pin index system is to prevent incorrect cylinder attachment (not to prevent delivery of hypoxic gas mixture). Location of important parts :- Flow control valve and flow meter (rotameter) of oxygen should be in downstream position (most distal). Fail-valve is located downstream from N2O and other non-oxygen gas supply source, but not downstream from O2 supply source.