| 摘要 |
PURPOSE:To prevent vibration and variation of pressure due to a check valve by increasing the sectional area of a fluid passage at the part between the inside surface of a casing and a ball valve body at a regulated position, in the front in the direction of fluid flow larger than the sectional area at the back of the ball valve body. CONSTITUTION:The sectional area of a water flow passage at the part between the inside surface of a valve casing 10 and a ball valve body 11 in the front in the direction of flow of water with respect to the ball valve body 11 is designated phid1, and the sectional area in the vicinity of the center of the ball valve body 11 is designated phid2, and the sectional area at the back of the ball valve body 11 is designated phid3, and the diameter phiD of the ball valve body 11 and the dimension of a rib 11 are determined so that the following equation is established: phid1>phid2>phid3. Therefore, when each flow-speed at each sectional part phid1, phid2, phid3 is determined as V1, V2, V3, the following equation is established: V1<V2<V3, and contracted vein is formed at the front and back of the ball valve body 11. Therefore, eddy current is hardly generated, and development and exfoliation of boundary layer are hardly generated, and thus generation of vibration, noise, and variation of pressure can be prevented. |
