Importance

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Abstract

An automatic regulating valve apparatus comprises a main valve unit, and a pilot valve unit operatively connected to the main valve unit to control the main valve unit. The main valve unit comprises a main valve casing, a main valve element disposed in the main valve casing, and a main valve driving member disposed in the main valve casing together with the main valve element and having a pressure receiving area greater than that of the main valve element, the main valve element is disposed on the upstream side of a valve seat so as to form a restricting passage between the main valve element and the main valve seat, and the main valve driving member is disposed for sliding movement in a space defined by a cylindrical wall formed in the main valve casing so as to define a main valve driving pressure chamber together with the cylindrical wall. The pilot valve unit comprises pilot valves A and B which are operated for opening and closing operations according to the variation of a pressure difference across an orifice included in the main valve unit, a pressure difference across the main valve unit, liquid level on the downstream side of the main valve unit or the pressure on the upstream side of the main valve unit. The pilot valve A and the pilot valve B are arranged in series and connected between the upstream and the downstream side of the main valve unit by connecting passages with a chamber between the pilot valves A and B connected to the main valve driving pressure chamber. The pressure in the main valve driving pressure chamber is varied by the coordinated operations of the pilot valves A and B to regulate the opening of the main valve unit. Thus, the automatic regulating valve apparatus 4 exercises automatic control functions including a constant-flow control function, an emergency shutoff function, a liquid level control function and an upstream pressure control function.

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First Claim