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How do we choose butterfly valves

The selection of butterfly valve

The butterfly valve’s butterfly plate is installed in the direction of the pipeline’s diameter. The butterfly valve is simple in structure, small in size, and it is light in weight. It consists of only a few parts and can be opened and closed quickly by rotating only 90°. As a result, it is simple to operate, and the valve has good fluid control characteristics. When the butterfly valve is in the fully open position, the thickness of the butterfly plate is the resistance to the flow of the medium through the valve body. As a result, the pressure drop through the valve is minimal and has good flow control characteristics.

Wafer-type butterfly valve&Flange-type butterfly valve

If a butterfly valve is required for use as flow control, it is essential to note that we need to select the correct size and type of valve. The construction principle of the butterfly valve is especially appropriate for producing valves of large diameter. There are two types of butterfly valves in common use, the wafer-type butterfly valve and the flange-type butterfly valve. A wafer-type butterfly valve is a valve that is connected between two pipe flanges using double-headed bolts. A flanged butterfly valve is a valve with a flange on it. It uses bolts to connect the flanges on both ends of the valve to the pipeline flanges in the use process.

Butterfly valve as a pipeline system used to achieve the flow control components have been in the petroleum, chemical, metallurgical, hydropower, and many other fields have been extremely widely used. In the known butterfly valve technology, the seal form is mostly used to seal the structure. It is sealed with rubber, PTFE, etc. Due to the limitations of the structural features, it is not adapted to high-temperature, high pressure and corrosion resistance, anti-wear, and other industries.

Triple Eccentric Metal Hard Seal Butterfly Valve

The Triple Eccentric Metal Hard Seal Butterfly Valve is a more advanced type of butterfly valve. Its valve body and seat are connected together. Its seat sealing surface is superimposed with welded temperature and corrosion-resistant alloy material. It uses multiple layers of soft laminated sealing rings and is fixed to the valve plate. Compared to conventional butterfly valves, this butterfly valve has the advantage of high-temperature resistance and light operation. It opens and closes without friction and compensates for the seal as the torque of the drive mechanism increases during closure. It also has the advantage of improving the sealing performance of the butterfly valve and extending its service life.

However, butterfly valve still have the following problems in the use process.

1.As the multi-layer soft and hard stacked seal ring is fixed on the valve plate, the medium will form a frontal scouring on its sealing surface when the valve plate usually is open. The soft sealing tape in the metal plate sandwich will directly influence the performance of the seal after being scraped.

2.Restricted by the structural conditions of the valve structure is not suitable for doing the valve diameter DN200 below. The reason is that the overall frame of the valve plate is too thick, and the flow resistance is large.

3.Due to the theory of triple eccentric construction, the sealing between the sealing surface of the valve plate and the valve seat is achieved by the torque of the drive unit pressing the plate against the valve seat.In the positive flow state, the higher the medium pressure, the tighter the seal squeeze. When the flow channel media counterflow, with the increase of medium pressure between the valve plate and the valve seat unit positive pressure, is less than the medium pressure, the seal begins to leak.

High-performance three eccentric two-way hard seal butterfly valve

High-performance three eccentric two-way hard seal butterfly valve, characterized in that the seat sealing ring is composed of a soft T-shaped sealing ring on both sides of a multi-layer stainless steel sheet. The valve plate and the sealing surface of the valve seat is an angled pyramid structure. We will overlay weld temperature and corrosion-resistant alloy material on the oblique cone surface of the valve plate. The spring fixed between the adjusting ring pressure plate is a structure assembled with the adjusting bolt on the pressure plate.

This structure effectively compensates for the tolerance zone between the sleeve and the valve body and the elastic deformation of the valve stem under medium pressure. It solves the problem of sealing the valve in bi-directional interchangeable media transport. The butterfly valve uses a soft T-shaped multi-layer stainless steel plate to form a sealing ring on both sides. It offers the dual benefits of a hard and soft metal seal. The valve has a zero leakage sealing performance at both low and high temperatures.

In the positive flow state (the direction of media flow is the same as the rotation direction of the butterfly plate), the pressure on the sealing surface is generated by the torque of the transmission device and the action of the media pressure on the valve plate. When the positive medium pressure increases, the tighter the valve plate’s oblique cone surface is squeezed with the sealing surface of the valve seat. The better the sealing effect at this point. When the reverse flow state, the sealing between the valve plate and the valve seat relies on the torque of the drive device to make the valve plate pressed to the valve seat. As the reverse medium pressure increases, the unit pressure between the valve plate and the valve seat is less than the medium pressure. At this time, the spring of the adjustment ring can compensate for the deformation of the valve plate and the tight stress of the sealing surface of the valve seat after being loaded, thus playing an automatic compensation role.

What are the critical points of butterfly valve selection?

  1. The butterfly valve’s main control parameter is the specification’s size.
  2. Butterfly valve is a single plate type air valve. It has a simple structure, easy processing, low cost, and easy operation. However, it has poor adjustment accuracy and is only suitable for ventilation and air-conditioning systems for switching or coarse adjustment.

The butterfly valve can be operated manually, electrically, or by zipping. You can also fix it at any angle within the 90° range.

  1. Due to the single shaft and single valve plate, the butterfly valve has a limited capacity. As a result, the valve has a short service life when under enormous differential pressure and flow rate conditions. The valve has closed type and ordinary type, insulation, and non-insulation.
  2. Electric butterfly valve has only two-position control.The electric actuator is identical to the multi-leaf valve.

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