Pneumatic butterfly valve opening and flow, the relationship between the linear scale change basically. If used to control the flow, the flow characteristics and distribution pipe flow resistance also have close relations, such as two pipe installation valve size, form and all the same, and line loss coefficient is different, the flow valves difference also will be very big. If pneumatic butterfly valve in the throttled to a larger extent state, valve plate at the back of the vulnerable to cavitation, there is the possibility of damage to the valve, the general is in 15 ° external use. Pneumatic butterfly valve is in the open degree, body and butterfly plate front formation of open shape to valve shaft as the center, on both sides of the form complete different state, side of the butterfly plate front downstream water direction and moving, the other side of the water flow direction and moving, therefore, the side of the body and the valve plate form like nozzle shape open, the other side of the similar throttle aperture openings, nozzle side than throttle lateral velocity much faster, and throttle side valve below will produce negative pressure, often can appear rubber seal off. Dynamic butterfly valve operation torque, for opening and valve opening and closing direction different its value each different, horizontal pneumatic butterfly valve, especially large diameter valve, due to water depth, valve shaft, water head difference generated by the torque is also not allow to neglect, general large-size butterfly valves need to install into pneumatic butterfly valve, pneumatic butterfly valve has the switch quickly, large output torque, etc. In addition, the valve inlet side device bend, form drift, moment there will be increased. The valve is in middle opening, due to water flow moment function, operating mechanism need self-locking.
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