Variable bypass vaporiser — FRCA Primary MCQ
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Correct answer: B — Temperature-compensated splitting ratio
Variable bypass vaporisers split fresh gas between bypass and vaporising chambers, and temperature compensation adjusts the splitting ratio as saturated vapour pressure changes. A fixed output independent of flow is not how conventional plenum vaporisers behave across their full operating range. Reservoir bags and pressure relief valves are not the key mechanism. Vaporisers are agent-specific because saturated vapour pressure differs between agents.
Reference: Dorsch and Dorsch Understanding Anesthesia Equipment; Primary FRCA physics texts