| 摘要 |
PURPOSE:To perform the titled control by alternate switchover between controllable flow rate and zero flow rate to effect omitting extra pipings and control valves, etc. for use in low flow rate. CONSTITUTION:In case the divergence of a flow control valve for attaining the target flow rate is below the virtual lower limit of flow-controllable range for said control valve, switchover is made alternately between controllable flow and zero flow rate so that the time-average flow rate be equal to the target one. Thus, as the divergence control itself for the flow control valve is carried out within the controllable range, a flow control of high precision can virtually be accomplished below the flow controllable range.
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