| 摘要 |
A rotary control valve is provided with a variable area orifice in the control element that communicates with a bypass channel, which contains noise silencing means, when the valve is in the less than full-open position. This arrangement minimizes cavitation and noise when the valve is not in the full-open position while providing maximum flow with minimum friction and pressure drop when the valve is in the full-open position. The removable bypass channel configured with a single variable orifice in the control element allows for in-line maintenance of, or modification to, either the noise silencing means in the removable bypass channel or the valve body itself through top entry to the valve. The cross-sectional void area of the upstream and downstream ports as a means of further reducing noise and controlling velocities. The silencing means located within the bypass channel can be a multiplicity of balls or other such means that can be placed within the bypass channel. The through bore and the elongated variable orifice slot may be constructed latitudinally from any point below or above the equator of the control element. In addition, the bypass channel housing may be constructed, in whole or part, of a translucent material. The bypass channel housing may also have a separate, normally closed access to the channel for modification to, or maintenance of, the bypass channel or the noise suppression means contained therein.
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