Hutton P, Boaden R W
Br J Anaesth. 1986 Aug;58(8):919-24. doi: 10.1093/bja/58.8.919.
The pressure-flow characteristics of needle valves used on anaesthetic equipment were investigated. It was found that, under normal conditions of use, the valves behaved in a manner similar to convergent nozzles with sonic velocity at the throat. This means that, once the valve has been set, the mass flow rate of gas is effectively independent of the downstream changes in resistance and compliance encountered in normal anaesthetic practice. The error in a preset flow induced by the permissible variations in the upstream pipeline pressure was measured.
对麻醉设备上使用的针形阀的压力-流量特性进行了研究。结果发现，在正常使用条件下，这些阀门的行为类似于喉部具有声速的渐缩喷嘴。这意味着，一旦阀门设定好，气体的质量流量实际上与正常麻醉操作中遇到的下游阻力和顺应性变化无关。测量了上游管道压力允许变化引起的预设流量误差。
