Butterfly valve refers to a type of valve in which the closing element (valve disc or butterfly plate) is a disc that rotates around the valve shaft to achieve opening and closing. It is mainly used for cutting off and throttling in pipelines. The butterfly valve opening and closing component is a disc-shaped butterfly plate that rotates around its own axis inside the valve body to achieve the purpose of opening, closing, or adjusting.

The fully open and fully closed butterfly valve is usually less than 90 °, and the butterfly valve and stem themselves do not have self-locking ability. In order to position the butterfly plate, a worm gear reducer should be installed on the stem. By using a worm gear reducer, not only can the butterfly plate have self-locking ability to stop at any position, but it can also improve the operational performance of the valve. 

The working principle of butterfly valve: The valve disc is a disc, and by rotating the valve stem, the disc rotates 90 ℃ within the valve seat range to achieve the opening and closing of the valve. It plays a shut-off role in the pipeline. It can also adjust the flow rate. 

The advantages of special butterfly valves are simple structure, lightweight volume, easy operation, and good sealing performance.

Classification of No.1 Butterfly Valve

Butterfly valves can be divided into offset plate, vertical plate, inclined plate, and lever type according to their structural forms. According to the sealing form, it can be divided into two types: soft sealing type and hard sealing type. Soft sealing type generally uses rubber ring sealing, while hard sealing type usually uses metal ring sealing.

01 Classified by structural form

(1) Center sealed butterfly valve

(2) Single eccentric sealing butterfly valve

(3) Double eccentric sealing butterfly valve

(4) Triple eccentric sealing butterfly valve

02 Classified by sealing surface material

(1) Soft sealed butterfly valve

   ① The sealing pair is composed of non-metallic soft materials.

   ② The sealing pair is composed of metal hard materials and non-metal soft materials.

(2) Metal hard sealed butterfly valve

The sealing pair is composed of metal hard materials.

Principles for selecting butterfly valves

1. Due to the relatively large pressure loss of butterfly valves compared to gate valves and ball valves, they are suitable for pipeline systems with less stringent pressure loss requirements.

2. Due to the fact that butterfly valves can be used for flow regulation, they are suitable for selection in pipelines that require flow regulation.

3. Due to the limitations of the structure and sealing materials of butterfly valves, they are not suitable for use in high-temperature and high-pressure pipeline systems. The general working temperature is below 300 ℃, and the nominal pressure is below PN40.

4. Due to the relatively short length of the butterfly valve structure and its ability to be made into a large bore, butterfly valves are recommended for situations where short structural length is required or for large bore valves (such as DN1000 or above).

5. Due to the fact that butterfly valves can be opened or closed by only rotating 90 degrees, it is appropriate to choose butterfly valves in fields that require fast opening and closing.