Butterfly valve

Butterfly valve is also known as disc valve, the opening and closing parts of the disc disc and can rotate around the axis of the valve body. It is mainly composed of valve body, valve stem, disc and sealing ring. Valve body cylindrical, short axial length, built-in disc. The disc is driven by the valve stem and can be opened and closed once if it is turned 90°. Changing the deflection Angle of the plate can control the flow rate of the medium. The main seal is the sealing ring, the material according to the use and media commonly used butterfly valve wafer butterfly valve and flange butterfly valve two. Wafer butterfly valve is connected between two pipe flanges with double-head bolts, flanged butterfly valve is a valve with flanges, with bolts on both ends of the valve flanges are connected to the pipe flanges.

Butterfly valve is suitable for furnace, gas, natural gas, liquefied petroleum gas, city gas, hot and cold air, chemical smelting and power generation environmental protection engineering systems to transport a variety of corrosive and non-corrosive fluid media on the pipeline, used to regulate and cut off the flow of media.

Butterfly valve refers to the closing parts (disc or butterfly plate) for the disc, revolving around the valve shaft to open and close a valve, in the pipeline mainly cut off and throttling effect. Butterfly valve opening and closing part is a disc disc, in the valve body around its own axis rotation, so as to achieve the purpose of opening and closing or regulating. Butterfly valve fully open to fully closed is usually less than 90°, butterfly valve and butterfly rod themselves do not have self-locking ability, in order to butterfly plate positioning, worm gear reducer should be installed on the valve stem. The worm gear reducer can not only make the disc have self-locking ability, make the disc stop at any position, but also improve the operation performance of the valve.

The relationship between butterfly valve opening and flow is basically linear proportional change. If used to control the flow, the flow characteristics and pipe flow resistance is also closely related, such as the two pipeline installation valve diameter, form, etc., are all the same, and the pipeline loss coefficient is different, the valve flow will be very different.

If the valve is in a large throttling range state, the back of the valve plate is prone to cavitation, there is a possibility of damage to the valve, generally used outside 15°.

Butterfly valve in the middle of the opening, valve body and butterfly plate front formed by the opening shape of the valve shaft as the center, the formation of different states on both sides, one side of the butterfly plate front flow water direction and the other side of the countercurrent water

To move, therefore, one side of the valve body and valve plate to form a nozzle shaped opening, the other side is similar to the throttle hole shaped opening, the nozzle side is much faster than the throttle side flow rate, and the throttle side valve will produce negative pressure, often rubber seals fall off.

Butterfly valve operating torque, due to the opening and valve opening and closing direction of different values, horizontal butterfly valve, especially large caliber valve, due to water depth, valve shaft, water head produced by the torque can not be ignored. In addition, the valve inlet side device elbow, the formation of deflection, torque will increase. When the valve is in the middle opening, the operating mechanism needs to be self-locked due to the water flow torque.