A butterfly valve refers to a valve whose closing part (valve or butterfly plate) is a disc and rotates around the valve axis to achieve opening and closing. It mainly cuts and throttles the pipeline. The butterfly valve opening and closing part is a disc-shaped butterfly plate, which rotates around its own axis in the valve body, so as to achieve the purpose of opening, closing or adjusting. When the butterfly valve is fully open to fully closed, it is usually less than 90 °. The butterfly valve and the butterfly rod itself have no self-locking ability. For the positioning of the butterfly plate, a worm gear reducer must be added to the valve rod. The use of worm gear reducer can not only make the butterfly plate self-locking, stop the butterfly plate at any position, but also improve the valve performance.
The characteristics of industrial special butterfly valve can withstand high temperature, the applicable pressure range is also high, the valve nominal diameter is large, the valve body is made of carbon steel, and the sealing ring of the valve plate uses a metal ring instead of a rubber ring. Large high-temperature butterfly valves are manufactured by welding steel plates, and are mainly used for flue gas ducts and gas pipes of high-temperature media.
The advantages of butterfly valve are as follows:
1. Opening and closing is convenient and quick, labor saving, low fluid resistance, and can be operated frequently.
2. Simple structure, small size and light weight.
3. It can transport mud and has the least liquid accumulation at the pipe mouth.
4. Under low pressure, a good seal can be achieved.
5. Good adjustment performance.
The disadvantages of butterfly valves are as follows:
The operating pressure and operating temperature range are small.
Poor tightness.
Butterfly valves can be divided into offset plate type, vertical plate type, inclined plate type and lever type according to the structure. According to the form of sealing, it can be divided into two types: relatively sealed type and hard sealed type. The soft seal type generally uses a rubber ring seal, and the hard seal type usually uses a metal ring seal.
According to the connection type, it can be divided into flange connection and wafer connection; according to the transmission mode, it can be divided into manual, gear transmission, pneumatic, hydraulic and electric.
Butterfly valve installation and maintenance should pay attention to the following:
During installation, the disc should stop in the closed position.
The opening position should be determined according to the rotation angle of the butterfly plate.
Butterfly valves with bypass valves should be opened before opening.
The installation should be in accordance with the manufacturer's installation instructions. The heavy butterfly valve should be set up with a solid foundation.
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