O2 Critical Temp -118°C — FRCA Primary MCQ

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ModeratePhysics & Clinical MeasurementO2 Critical Temp -118°CFRCA Primary

The critical temperature of oxygen is approximately:

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Correct answer: B — -118°C

Critical temperature of O2 is -118°C. Since room temperature is far above this O2 cannot exist as a liquid in cylinders at room temperature and is stored as compressed gas. The gauge pressure therefore falls linearly with use (unlike N2O). Liquid O2 is stored in vacuum-insulated evaporators (VIE) for hospital bulk supply at -183°C (its boiling point).

Reference: Al-Shaikh Stacey 2019 Essentials of Anaesthetic Equipment