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The closing of the butterfly valve online (disc) in the middle of the medium, when the design should consider the influence of the convective resistance. About the structure of large diameter butterfly plate, the American association of water supply engineering standards, the butterfly plate should not have transverse reinforcement; the thickness shall not be greater than 2125 times the diameter of the stem. Butterfly plate into the water and the surface should be streamlined, internal screw not bulge on the outside of the butterfly plate, so as not to increase the area.
A foreign company produces the butterfly valve online in order to reduce the flow resistance will made discus butterfly plate shape, there are also firms that will be small butterfly valve online butterfly plate do very thin, and the water pipe network in butterfly valve online in full open position when the butterfly plate has a diversion, is to reduce the flow resistance. Our standard JB/T 5317121999 will also be international standards ISO/TC 153 / SC1GT 8237 included the flow resistance and flow coefficient, this suggests that the flow resistance is an important index.
Sometimes rubber butterfly valve online service life is short, this is related to quality of rubber and seal face width. The sealing ring of the rubber sealing butterfly valve online should choose high quality rubber materials, the pressure molding process should be strictly abided by during the procedures cannot arbitrarily raise the curing temperature, shorten the time, otherwise easy to cause seal aging and cracking. Application of electric actuators , and the width of the rubber sealing ring with metal seal face should be enough, otherwise the rubber sealing ring is not easy to embed. In addition, the form of the valve body and disc position tolerances, symmetry, the precision and smoothness, seal pressure capacity, etc. also influence the service life of rubber seal.
Stiffness is butterfly valve the important issues in the design of the online with butterfly plate, valve shaft and connecting factors.
1) Valve shaft size: AWWA C504 specified in the valve shaft size. Valve shaft size cannot meet the requirements, may appear not enough stiffness, and reverse seal leakage, the phenomenon such as open torque. The size of the valve spindle generally calculated on twisted into, it is not only related to the torque, and mainly related to the bending moment. Compared with torque, the bending moment of large diameter butterfly valve online is bigger.
(2) Shaft hole cooperates: AWWA C504 specified in the old version, butterfly valve shaft is a straight through the shaft. After the 1980 version, can make two short axis is put forward. AWWA C504 and GB12238 regulations, shaft and hole of the embedded length should be 115 - d. Japan butterfly valve body in the axial size edge with the butterfly plate bearing clearance between (C value), generally related to the diameter size, between 25 ~ 45 mm, or minimize the distance between the bearings (C value), so as to reduce the bending moment and deformation of the shaft.
(3) The butterfly valve online structure: butterfly plate structure and the stiffness is directly related to, so in addition to the flat shape more into a pot or truss profile. In short, in order to increase the moment of inertia of cross section, in order to improve the stiffness.
(4) The body structure: in the design of the large diameter butterfly valve online body stiffness problems, too. Generally have circle muscle and transverse reinforcement, transverse reinforcement is actually increase stability, should not be too many, mainly circle tendons. If I can add U steel is more advantageous to stiffness, but the problems of poor manufacturability.