Structure Principle Classification Introduction and Troubleshooting of Butterfly Valve

Butterfly valve is often used in water system. Because of its small volume and high cost performance, it has become a commonly-used valve in pipelines. The main products of butterfly valve are wafer soft seal butterfly valve and flange butterfly valve. Although the types of butterfly valve are fewer than those of gate valve, there are many differences in the ability to adapt to different working conditions.

According to the structure, the butterfly valve is mainly divided into central type and eccentric type. The eccentric types are divided into single eccentric, double eccentric and triple eccentric.

The working principle of butterfly valve is as follows:

1. The principle of butterfly valve

The butterfly valve adopts the structure that the valve plate rotates along the center line, so the valve volume is small. Turn the handle or worm gear 90 degrees to make the valve plate parallel to the flow direction of the medium, and then open the valve. Therefore, a butterfly valve has the characteristics of simple structure, small volume, light weight, small installation size, convenient operation, quick opening and closing, etc. It also has sealing and flow regulation characteristics. However, due to the large disc resistance, the medium pressure has a great impact on the opening and closing of the valve, so it is not suitable to be used in a high-pressure environment.

2. The advantages of butterfly valves

  • Small volume
  • Simple structure
  • Quick opening and closing

2. 1The disadvantages of butterfly valves

The pressure loss of its pipeline flowing medium is large, so it is difficult to open and close under a high pressure environment.

3. Different structures of butterfly valves

The sealing performance and service life of centerline butterfly valve, single-eccentric butterfly valve, double-eccentric butterfly valve and triple-eccentric butterfly valve are improved in turn. But then, the difficulty and the cost of structural shortage increase. Unless there are special working conditions, we often choose more economical and appropriate butterfly valves.

Troubleshooting of butterfly valve

When there is a failure of butterfly valves, how to eliminate it in time?

  • 1. The leakage at both ends of butterfly valve is caused by the gasket at both sides. The pressing force of the pipe flange is uneven or not compacted. We can change the gasket so that the flange bolts are pressed evenly.
  • 2. The leakage of butterfly valve bonnet is caused by butterfly valve plate. There are sundries in the sealing ring. The sealing position of butterfly valve and sealing ring is not correct, and the bolts of outlet flange are pressed unevenly. The pressure test deviation does not meet the requirements. We need to remove impurities including valve cavity, adjust turbine or electric actuator, limit screw to achieve the accurate position of valve closing. If the pressure test deviation does not meet the requirements, we should rotate it according to the deviation of the arrow.
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