Among all types of valves, there is a particular one with the most beautiful name—the butterfly valve. How did the name come from? In answering this question, we could use analogy. For example, the ball valve looks like a ball, so can we guess that the butterfly valve looks like a butterfly? Well, it seems a little funny, but I have to say: “Bingo, right answer!” The butterfly valve is a regulating valve with simple structure, and it can be used for switching control of a low pressure pipeline medium. The opening and closing member (valve or disc) of the butterfly valve is a disc that rotates around the valve…