Types and classification of butterfly valves

Butterfly valve according to the structure can be divided into offset plate, vertical plate, inclined plate and lever type. According to the sealing form, it can be divided into two types: relatively sealed type and hard sealed type. The soft seal butterfly valve generally adopts rubber ring seal, while the hard seal butterfly valve usually adopts metal ring seal. According to the connection type, it can be divided into flange connection and pair clamp connection. According to the transmission mode, it can be divided into manual, gear transmission, pneumatic, hydraulic and electric.

There are many kinds of butterfly valves, and in special working conditions, the corresponding butterfly valve products are also different. Therefore, for this kind of valve, we should select another type with the engineer. According to the common types and classifications, butterfly valves can be divided into the following forms:

（1） Classification by structural form

1. Center seal butterfly valve

2. Single eccentric sealing butterfly valve

3. Double eccentric sealing butterfly valve

4. Triple eccentric sealing butterfly valve

（2） Classified by link mode

1. Wafer butterfly valve

2. Flange butterfly valve

3. Lug type butterfly valve

4. Welded butterfly valve

（3） Classification by operating temperature

1. High temperature. t> 450 ° C butterfly valve.

2. Medium temperature butterfly valve. 120 C < + < 450 ° C butterfly valve.

3. Normal temperature butterfly valve- 40C < T < 120 ° C butterfly valve.

4. Low temperature butterfly valve- 100 < T < – 40 ° C butterfly valve.

（4） Classified by sealing surface material

1. Soft seal butterfly valve.

(1) The sealing pair is composed of non-metallic soft material to non-metallic soft material.

(2) The sealing pair is composed of hard metal material and soft non-metal material.

2. Metal hard seal butterfly valve. The sealing pair is composed of metal hard material to metal hard material.

（5） Classification by work pressure

1. Vacuum butterfly valve, butterfly valve whose working pressure is lower than atmospheric pressure of standard reactor.

2. Low pressure butterfly valve, nominal pressure PN < 1.6Mpa butterfly valve.

3. Medium pressure butterfly valve nominal pressure PN 2.5-6.4mpa butterfly valve（ 2) External torque sealing butterfly valve. The seal specific pressure is generated by the torque applied to the valve shaft.

4. High pressure butterfly valve, nominal pressure PN 10 — 80MPa butterfly valve.

5. Ultra high pressure butterfly valve with nominal pressure PN > 100MPa.

（6） Classified by seal type

1. Forced seal butterfly valve.

1 elastic seal butterfly valve. The sealing specific pressure is produced by the elasticity of the valve seat or valve plate when the valve plate is squeezed against the valve seat when it is closed.

2. Pressure sealing butterfly valve. The sealing specific pressure is generated by the charging pressure of spring sealing element on the valve seat or valve plate.

3. Automatic sealing butterfly valve. The sealing pressure is automatically generated by the medium pressure.