Abstract: A rotary noise attenuating valve is provided which utilizes noise attenuation technology previously utilized with linear valves. The arrangement includes an impedance assembly in which the area with the impedance assembly which is accessed by the flow downstream of a rotary closure element flow is varied upon opening of the rotary closure element, with an interface assembly disposed between the rotary closure element and the impedance assembly. As a result, benefits previously realized only in linear valves are attainable utilizing a rotary valve, while the benefits attendant to rotary valves (such as greater capacity, variable .DELTA.p and/or minimum .DELTA.p under max flow) are also attainable. Attenuator assemblies are also provided in which the attenuator or impedance structure is mounted within the valve, either downstream of the closure member, or mounted to the closure member.

Abstract: A rotary noise attenuating valve is provided which utilizes noise attenuation technology previously utilized with linear valves. The arrangement includes an impedance assembly in which the area with the impedance assembly which is accessed by the flow downstream of a rotary closure element flow is varied upon opening of the rotary closure element, with an interface assembly disposed between the rotary closure element and the impedance assembly. As a result, benefits previously realized only in linear valves are attainable utilizing a rotary valve, while the benefits attendant to rotary valves (such as greater capacity, variable .DELTA.p and/or minimum .DELTA.p under max flow) are also attainable.

Abstract: The invention concerns a ball or plug valve for dividing differential pressure into several stages during opening or closing operation of the valve.The valve (1) comprises a body (2) defining a housing (2') for a movable member (3) consisting of a ball (4) or plug (5), and provided with a substantially cylindrical channel (6). The said valve (1) comprises a substantially cylindrical tubular insert (10) received in the said channel (6) and defining at least one inlet chamber (11) and at least one outlet chamber (12). These chambers are diametrically opposite and consist of two longitudinal recesses (13) formed in the wall of the insert (10) parallel to the longitudinal axis (14) of the channel (6). The chambers (11) and (12) communicate via two or more resistords (15) in two cylindrical sectors defined by the said chambers at the periphery of the insert.

Abstract: The present invention relates to a butterfly type control valve.This valve (30) comprises a body (31) defining a housing (32) for a mobile plug (13), rotating about an axis (14). The housing (32) is extended by an inlet channel (15) and an outlet channel (16), thus defining a connection passage between the inlet channel and the outlet channel. The effective cross section of this passage and therefore the flow rate of the fluid flowing through the valve are controlled according to the angular position of the plug (13). Furthermore, this valve comprises an element which generates a drop in pressure (18) provided with several calibrated passages (19) with a small diameter, located between the inlet channel (15) and a part of the housing, in a peripheral area of said housing (32).The valve makes it possible to reduce cavitation, noise and wear and tear of the valve by creating a considerable drop in pressure when the valve is slightly open, whilst allowing a greater control range.