If the butterfly valve is required to be used as flow control, the main thing is to correctly select the size and type of the valve. The structure principle of butterfly valve is particularly suitable for making large diameter valves. Butterfly valves are not only widely used in petroleum, gas, chemical, water treatment and other general industries, but also used in the cooling water system of thermal power stations.???

1. The valve rod of straight stroke pneumatic control valve is thin
It involves a simple mechanical design basis: large rolling friction, small rolling friction. The stem of the straight travel valve keeps fit from left to right. If the packing is slightly tightened, it will wrap the stem too tightly, causing a large backlash. Therefore, the valve rod design scheme is very subtle, and tetrafluoro packing with small friction resistance is common in the packing, which is convenient to reduce the return difference. However, the difficulty of dispatching is that the valve rod is thin, which is easy to bend, and the service life of the packing is also short. The effective way to deal with this problem is to use the travel valve stem, that is, the angle travel regulating valve stem. Its stem is 2 to 3 times thicker than the straight travel valve stem. In addition, it uses high-purity graphite packing with a long life. The bending stiffness of the stem is good, the packing has a long life, and its friction torque is small and the backlash is small.