| 摘要 |
A precision digital flow rate control system particularly suitable for controlling the flow of an inert gas into the atomizing furnace of an atomic absorption spectrometer. The selection of the desired flow rate is made by switching the flow through one or more of the plurality of tubes having restrictors that limit the flow according to digital steps. The flow is switched by directional control solenoid valves that direct the flow either through a flow restrictor to the atomizing furnace or through an identical flow restriction to a vent. Therefore, there will always be a constant flow through each valve and, since the inlet pressure regulator will always see a constant load, it can maintain a very constant pressure to the valves.
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