The Differences Between Butterfly Valve and Ball Valve

The biggest difference between butterfly valve and ball valve is that the opening and closing part of butterfly valve is a plate, while the ball valve is a ball. Both the butterfly plate and the spool of ball valve rotate around their axes. The plate of sluice valve moves up and down along the axis. Both butterfly valve and sluice valve can adjust flow through opening degree; while ball valves are not easy to do this.

Figure 1: Different types of ball valves.

1. Butterfly Valve

Butterfly valve has the characteristics of fast opening and closing speed, simple structure, and low manufacturing cost, but is poor in tightness and pressure bearing capacity. The characteristics of ball valve are similar to sluice valve’s characteristics, but is difficult to produce large-diameter type under the restriction of size and opening and closing resistance.

The structural principle of butterfly valve is particularly suitable for making large-diameter valves. The butterfly plate of the butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis with a rotation angle from 0 degree to 90 degree. When it rotates to 90 °, the valve is fully open. It has the advantages of simple structure, low cost and large adjustable range.

2. Ball Valve

Ball valves are generally applicable to liquids and gases without particle impurities, with small fluid pressure loss, good sealing performance and high cost. Compared with butterfly valve, ball valve is better in sealing performance. Sealing of ball valve is pressed on the spherical surface by the valve seat for a long time. It must wear faster than the semi-ball valve. Ball valve is usually sealed with flexible materials, and thus it is difficult to be used in high temperature and high-pressure pipelines. The sealing of butterfly valve is mediated by rubber, which is far from the metal hard sealing performance of semi-ball valve, ball valve and sluice valve.

Figure 2: Diagram of internal structure of ball valve.

After long-term use of the semi-ball valve, the valve seat will also produce a small amount of wear, which can also continue to be used through adjustment. The valve rod and packing only need to be rotated 90 degrees during the opening and closing process. If there is any sign of leakage, press a few bolts of the packing gland to ensure that there is no leakage at the packing. However, other valves are still used even with small leakage and replaced until there is much leakage.

Ball valve operates under the holding force of the valve seats at both ends during the opening and closing process. Compared with semi-ball valve, it is large in opening and closing torque, and the larger the nominal diameter is, the more obvious the difference of opening and closing torque is. The opening and closing of butterfly valve are realized by overcoming the deformation of rubber, and the torque is greater, but the sluice valve and stop valve is hard and time-consuming in operation.

Figure 3: Ball valve is used in the practical chemical field.

Ball valve and plug valve belong to the same type of valve. Only its closing part is a sphere. The sphere rotates around the axis of the valve body to open and close. The ball valve is mainly used to cut off, distribute and change the flow direction of media in the pipeline.

3. Differences

3.1 Differences in Names

Ball valve: its opening and closing part, driven by valve rod, rotates around the axis of ball valve.
Butterfly valve: it, also called flap valve, is a kind of adjusting valve with simple structure. The butterfly valve that can be used for switch control of low-pressure pipeline media refers to a valve whose closing part (valve clack or butterfly plate) is a disc and rotates around the valve axis to open and close.

3.2 Differences in Characteristics

Ball valve: the fluid resistance is small, and its resistance coefficient is equal to that of the pipe section with the same length. It is simple in structure, small in size and light in weight. It is compact and reliable, and the sealing surface of the ball valve is widely made of plastic, with good sealing performance. It has also been widely used in the vacuum system. In addition, it is easy to operate, quick to open and close, only rotate 90 degrees from full opening to full closing, convenient for long-distance control.

Butterfly valve: the butterfly valve has the characteristics of simple structure, small size, light weight, less material consumption, small installation size, fast switching, 90 degree’s reciprocating rotation, small driving torque, etc. It is used to cut off, connect and adjust the media in the pipeline, and has good fluid control characteristic and sealing performance.

3.3 Differences in Applications

Ball valve: it can be used to adjust and control fluid. The hard sealing V-shaped ball valve has a strong shearing force between its V-shaped ball core and the metal valve seat welded with cemented carbide, particularly suitable for media containing fiber and micro solid particles. The multi-way ball valve can not only flexibly control the confluence, diversion and flow direction switching of media in the pipeline, but also close any channel to connect the other two channels.

Figure 4: Diagram of electrical ball valve used in automation control system.

Butterfly valve: this valve can be used to control the flow of air, water, steam, various corrosive media, mud, oil, hydraulic metal, radioactive media, and various types of fluid, mainly playing the role of cutting off and throttling in the pipeline. The opening and closing part of butterfly valve, which is a disc-shaped butterfly plate, rotates around its axis in the valve body to achieve the purpose of opening and closing or adjustment.

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