Don't underestimate the butterfly valve! With a rotating valve plate in the pipeline, it can easily switch and adjust the water flow. From household to industrial use, this "flow control expert" can be found everywhere. Today, let's take a detailed look at the "butterfly valve"~

　　1、 What is butterfly valve

Butterfly valve, also known as flap valve, is a structurally simple regulating valve that can be used for on/off control of low-pressure pipeline media. Butterfly valve refers to a valve whose closing element (valve disc or butterfly plate) is a disc that rotates around the valve axis to achieve opening and closing.

The butterfly valve structure includes: valve body, ball, valve seat, valve stem, and driving device (manual/electric/pneumatic).

Butterfly valves can be divided into flange butterfly valves and clamp butterfly valves according to different connection forms; According to their structural form, butterfly valves can be divided into centerline butterfly valves and eccentric butterfly valves.

The structure of a butterfly valve is very simple, consisting of a valve body, valve stem, valve seat, butterfly plate, and transmission mechanism. Common transmission methods include handle, turbine, pneumatic, and electric.

　　2、 What are the types of butterfly valves

1. Flange butterfly valves are suitable for pipelines in metallurgy, chemical, power, municipal engineering, and water plants where the medium is water, oil, and air. They play a role in cutting off fluids or regulating the flow rate of the medium. The specific design structure is novel, the overall size is small, and the weight is light; The butterfly plate adopts double eccentricity, quick opening and closing, and is easy to operate and labor-saving.

2. The butterfly valve is mainly composed of a valve body, valve plate, valve shaft, and sealing components. Its working principle relies on the rotating valve plate to control the opening and closing of the valve, thereby achieving control over the flow of medium in the pipeline. Valve shafts are usually made of stainless steel or carbon steel and can withstand high pressures.

3. Welded butterfly valves use precision J-shaped elastic sealing rings and three eccentric multi-level metal hard sealing structures, which are widely used in industrial pipelines such as metallurgy, power, petrochemicals, water supply and drainage, and municipal construction where the medium temperature is ≤ 425 ℃, for regulating flow and carrying fluids.

The welded butterfly valve adopts a three eccentric structure, and the valve seat and disc sealing surface are made of different hardness and stainless steel, which has good corrosion resistance and long service life. This valve can have bidirectional sealing function.

4. The ventilation butterfly valve is designed and manufactured using a new structural form of welding a midline disc plate and a short structural steel plate. It has a compact structure, light weight, easy installation, low flow resistance, large flow capacity, avoids the influence of high temperature expansion, and is easy to operate. No connecting rods, bolts, etc. inside, reliable operation, long service life. It can be installed in multiple workstations without being affected by the flow direction of the medium.

5. The telescopic butterfly valve combines the functions of a flange butterfly valve and a pipeline expansion joint, which can not only act as a cut-off and regulating device, but also solve the problem of eliminating internal forces caused by temperature differences, thus playing a telescopic role.

This butterfly valve can be used for regulating and cutting off in power, metallurgy, petroleum, chemical, gas, urban heating, water supply and drainage, energy, and all non corrosive gas, liquid, and solid powder pipelines. In addition, it can adjust the distance between two flanges.

3、 What are the advantages of butterfly valves?

● Simple structure

The number of parts is small, the volume is compact, and it does not take up too much space during installation, making it suitable for most pipelines.

● Easy to operate

The valve plate only needs to be rotated 90 degrees to complete the switch, which is easy to operate and can quickly adjust the flow rate.

● Lower cost

Low manufacturing difficulty and low cost; Subsequent maintenance is simple, and there is no need to spend too much money on replacing parts.

● Good liquidity

The internal flow channel is unobstructed, and the resistance to water flow or medium passing through is small, which will not significantly affect the conveying efficiency.

● Wide applicability

It can adapt to various media such as water, air, and oil, and can be used in low-pressure to medium pressure scenarios.

　　4、 How to choose a butterfly valve suitable for working conditions

　　(1) Basic selection elements

▲ Medium characteristics

Low corrosive media such as ordinary water, air, and gas can choose soft sealed butterfly valves (such as nitrile rubber, EPDM rubber); Corrosive media (acid, alkali, salt) should be made of stainless steel or polytetrafluoroethylene material; It is recommended to use hard sealed butterfly valves (such as D343H, D943H) for steam media.

▲ Pressure level

Low pressure (≤ 1.6MPa): ordinary carbon steel or cast iron valve body; Medium pressure (1.6-6.4MPa): Carbon steel or stainless steel; High pressure (≥ 6.4MPa): The valve body and sealing structure need to be strengthened.

▲ Connection method

Flange connection (≥ DN300): suitable for large diameters and high pressures;

Clamp connection (≤ DN300): Easy to install, but attention should be paid to the interference between the butterfly plate and the valve seat hole.

(2) Special scenario supplement

▲ Large diameter pipeline

Consider the issues of valve stem support and axial positioning, and recommend horizontal installation with sufficient space reserved; The reverse sealing pressure of the eccentric butterfly valve should be lower than the selected direction.

▲ Flow regulation

Mid line butterfly valves are suitable for precise adjustment of small diameters; Eccentric butterfly valves (double/triple eccentric) are suitable for large-diameter flow regulation due to their soft seals that are easy to maintain.

▲ Special medium treatment

Oil/gas main pipeline: full bore welding or flange connection; Oxygen pipeline: degreasing treatment is required, and it is recommended to fix the ball butterfly valve.