Butterfly valve definition:
Butterfly valve [ 1] (English: butterfly valve) refers to a closure (valve or disc) is a disc, a valve that rotates around the valve shaft to open and close, mainly used for cutting and throttling on the pipeline. The butterfly valve opening and closing member is a disc-shaped butterfly plate that rotates around its own axis in the valve body to achieve the purpose of opening and closing or adjusting. The butterfly valve is normally less than 90° from full opening to full closing. The butterfly valve and the butterfly rod have no self-locking ability. For the positioning of the butterfly plate, a worm gear reducer is added to the valve stem. The use of a worm gear reducer not only enables the disc to have a self-locking capability, but also stops the disc at any position and improves the valve's operating performance.
The characteristics of the industrial special butterfly valve can withstand high temperature, the applicable pressure range is also high, the valve has a large nominal diameter, the valve body is made of carbon steel, and the sealing ring of the valve plate uses a metal ring instead of the rubber ring. Large high temperature butterfly valves are manufactured by steel plate welding and are mainly used for flue ducts and gas pipes of high temperature media.
Ball valve definition:
Ball valve , GB/T21465-2008 "Valve Terminology" is defined as: the opening and closing member (sphere) is driven by the valve stem and rotates around the axis of the valve stem. It is mainly used to cut off or turn on the medium in the pipeline, and can also be used for fluid regulation and control. The hard seal V-shaped ball valve has a strong shear between the V-shaped ball core and the metal valve seat of the hardfacing alloy. Shear force, especially suitable for media containing fibers, tiny solid particles. The multi-way ball valve not only can flexibly control the switching of the merge, split, and flow directions of the medium, but also can close any channel and connect the other two channels.
The main features of the ball valve are its compact structure, simple sealing, simple structure and convenient maintenance. The sealing surface and the spherical surface are often closed, not easily eroded by the medium, easy to operate and repair, suitable for water, solvent, acid and natural gas. Working medium, but also suitable for medium with harsh working conditions, such as oxygen, hydrogen peroxide, methane and ethylene, which are widely used in various industries. The ball valve body may be integral or combined.
The difference between the two:
The biggest difference between the two is that the opening and closing part of the butterfly valve is a plate, and the ball valve is a ball. The valve plate of the butterfly valve and the valve core of the ball valve are rotated around their own axes; the valve plate of the gate valve is moved up and down along the axis. Butterfly valves and gate valves can regulate flow through opening; ball valves are not easy to do this. The sealing surface of the ball valve is a spherical surface, and the sealing surface of the butterfly valve is a circular cylindrical surface.
The butterfly valve is characterized by quick opening and closing speed, simple structure and low cost, but the tightness and pressure bearing capacity are not good. The characteristics of the ball valve are similar to those of the gate valve, but it is difficult to achieve a large diameter due to the limitation of the volume and the opening and closing resistance.
The structural principle of the butterfly valve is especially suitable for making the butterfly plate of the large-diameter valve butterfly valve installed in the diameter direction of the pipe. In the cylindrical passage of the butterfly valve body, the disc-shaped disc rotates around the axis, and the rotation angle is between 0° and 90°. When the rotation is 90°, the valve is fully open. The utility model has the advantages of simple structure, low cost and large adjustable range. Ball valves are generally suitable for liquids and gases without particulate impurities, with low fluid pressure loss, good sealing performance and high cost. In comparison, the ball valve seal is better than the butterfly valve. The ball valve seal is * the valve seat is squeezed on the spherical surface for a long time. It is definitely faster to wear than the hemispherical valve. The seal of the ball valve is usually made of flexible material and is difficult to use in high temperature and high pressure pipes. The butterfly valve seal is based on rubber, which is far from the hard metal sealing performance of the hemispherical valve, ball valve and gate valve. After the long-term use of the hemispherical valve, the valve seat will also produce a small amount of wear. It can be used continuously by adjustment. The valve stem and the packing need only be rotated by 90° during the opening and closing process. When there is any indication of leakage, the packing gland is pressed again. A little bolt can achieve no leakage at the packing, while other valves are still used for small leaks and large leaks.
During the opening and closing process, the ball valve is operated under the tight force of the valve seat at both ends. It is larger than the opening and closing torque of the hemispherical valve. The larger the nominal diameter, the more obvious the difference between the opening and closing torque. The opening and closing of the butterfly valve is to overcome the deformation of the rubber. To achieve, the torque is greater. The gate valve and the shut-off valve operate for a long time and are laborious.
The ball valve and the plug valve are the same type of valve, only the closing member of which is a ball, and the ball rotates around the center line of the valve body to open and close a valve. The ball valve is mainly used in the pipeline to cut, distribute and change the flow direction of the medium.
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