Sanitary Butterfly Valve What points should be paid attention to during the installation process?
Pneumatic butterfly valves are widely used in automatic control systems, just like pneumatic ball valves. Pneumatic butterfly valves are equipped with GT cylinders, AT cylinders, or AW cylinders, supplemented by pneumatic accessories (solenoid valves, filter pressure reducing valves, limit switch boxes, quick exhaust valves, position-holding valves, etc.), and are used for two-position switch control. Because of the good approximate equal percentage flow characteristics of the three-eccentric butterfly valve, the pneumatic three-eccentric butterfly valve is often equipped with an electrical valve positioner to adjust the process control.
Installation requirements for pneumatic butterfly valves:
1. Pay attention to the direction of the medium fluid and the direction of the arrow when installing pneumatic butterfly valves
2. Pneumatic butterfly valves with rising stems cannot be installed geographically to prevent the valve stem from rusting. In trenches with cover plates, the valves should be installed and maintained and inspected and operated
3. When installing pneumatic butterfly valves in horizontal pipelines, the valve stem should be vertically upward, or tilted at a certain angle, and the valve stem is not allowed to be installed downward
4. Valves connected with flanges and threads should be closed during installation. Install flange valves to ensure that both ends of the flanges are parallel and concentric to each other.
Notes:
1. The relationship between the opening and flow of pneumatic butterfly valves is basically linear. If used to control flow, its flow characteristics are also closely related to the flow resistance of the piping. For example, if the valves installed on two pipelines have the same diameter and form, but the pipeline loss coefficients are different, the flow of the valves will also be very different.
2. If the valve is in a state of large throttling range, cavitation is prone to occur on the back of the valve plate, which may damage the valve. It is generally used outside 15°.
3. When the pneumatic butterfly valve is in the middle opening, the opening shape formed by the valve body and the front end of the butterfly plate is centered on the valve shaft, and the two sides form different states. The front end of the butterfly plate on one side moves in the direction of the water flow, and the other side moves in the direction of the water flow. Therefore, the valve body and the valve plate on one side form a nozzle-shaped opening, and the other side is similar to a throttling hole-shaped opening. The nozzle side has a much faster flow rate than the throttling side, and negative pressure will be generated under the valve on the throttling side, and the rubber seal will often fall off.
4. The operating torque of the pneumatic butterfly valve varies with the opening and the opening and closing direction of the valve. For horizontal pneumatic butterfly valves, especially large-diameter valves, the torque generated by the difference in water head between the upper and lower ends of the valve shaft due to the water depth cannot be ignored. In addition, when an elbow is installed on the inlet side of the valve, a biased flow is formed, and the torque will increase. When the valve is in the middle opening, the operating mechanism needs to be self-locking due to the action of the water flow torque.