Splitting Ratio Vaporiser — FRCA Primary MCQ
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Correct answer: B — The ratio of gas that flows through the vaporising chamber to gas that bypasses it
In a variable bypass (plenum) vaporiser the total fresh gas flow is split: a small proportion flows through the vaporising chamber (becoming saturated with vapour) and the majority bypasses it. The ratio is adjusted by the concentration dial. The splitting ratio determines the final output concentration. Temperature compensation adjusts this ratio to maintain constant output.
Reference: Al-Shaikh Stacey 2019 Essentials of Anaesthetic Equipment