7. Introduction of pneumatic control valve positioner
Valve positioners: after different periods of development, there are mechanical, intelligent, and other types in the early days. Valve positioners are the main accessories of the control valve, usually used together with the pneumatic control valve. It receives the output signal of the control system, and then uses its output signal to control the pneumatic control valve. When the control valve acts, The displacement of the valve stem is fed back to the valve positioner through the mechanical device. The valve position status can be transmitted to the industrial control system through electrical signals or additional valve position switches, or it can not be transmitted.

Four reasons for the breakage of pneumatic butterfly valve in daily use
Pneumatic butterfly valves often break in daily use, and we mainly have the following four reasons:
First, the quality of pneumatic butterfly valves. Some people may have quality problems when they buy pneumatic butterfly valves at the beginning, so they should buy them when they buy them.
Second, there is dislocation vibration between the pneumatic butterfly valve and the cylinder head, and mechanical fatigue in daily use, there will be dislocation vibration between the pneumatic butterfly valve and the bar head.
Third, the injection pressure of the pneumatic butterfly valve is wrong
Fourth, oil return of pneumatic butterfly valve is blocked
In the daily use of pneumatic butterfly valve, if it is used for a long time, the oil return will be blocked!