CONTROL VALVE DEVICE

摘要

In a control valve device according to the invention, a pilot valve device for driving of a main valve is such that a pilot valve device (A) adapted to close when pressure on a downstream side of the main valve becomes higher that a predetermined value, and a pilot valve device (B) adapted to open when pressure on the downstream side of the main valve becomes higher than the predetermined value, communicate with each other in series between flow passages upstream of and downstream of a main valve device with a main valve driving pressure chamber therebetween to be interlockingly by operated to keep pressure on the downstream side of the main valve at a predetermined value. A pilot valve device (C) adapted to close when a pressure difference across an orifice provided in a flow passage in the main valve device becomes higher than a predetermined value is provided in series with a communication passage portion across the pilot valve device (A), to thereby limit a flow rate supplied to the downstream side of the main valve to a predetermined amount. Valve disks of both the pilot valve device (A) and the pilot valve device (B) may be formed to interlock with each other on a single valve rod. Also, the orifice may be a variable one. Further, provided on the communication passage portion across the pilot valve device (A), are valve means for opening and closing the communication passage according to vertical movement of a liquid surface level on the downstream side, and valve means for closing the communication passage when abnormality is detected by abnormality detecting means.