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How to explain the adjustable ratio if the pneumatic control valve is not closed tightly


Release time:

2021-07-14

How to explain the adjustable ratio if the pneumatic control valve is not closed tightly

Pneumatic control valveComposed of pneumatic actuator and regulating valve. First of all, the pneumatic actuator is to accept the control system to transmit signals, drive the valve core action, adjust the flow, pressure and temperature of the process device. So sometimes there will be loose seals in use.
1. When the output of the pneumatic actuator, the output power of the pneumatic actuator, as the driving force for adjusting the movement of the valve core, is greater than the force required to close the valve, otherwise the valve can be closed lax, so why is this situation, open the valve core, because the medium pressure pneumatic valve will form a leakage phenomenon, so how can we prevent this kind of accident? Therefore, it is necessary for the user to pay attention to the check of the pressure difference when selecting the process pipeline and ensure that the pneumatic actuator has a satisfactory output force to close the valve.
2. If the control valve is selected incorrectly, it will also lead to lax sealing. The specification of each model is different from the specification of the differential pressure regulating valve itself, sleeve regulator and double-seat regulator. Compared with the V-shaped regulating ball valve and eccentric rotary valve with larger differential pressure angle stroke allowed by the single-seat regulating valve, the differential pressure will be larger. Under the condition of larger differential pressure, it is very important to reasonably select pneumatic regulating valve and electric regulating valve.
The quality of the automatic control process, the closure of the pneumatic control valve will lose the automatic control process of high-quality adjustment, the difference in flow characteristics will affect the quality of the adjustment, the leakage is large, the action is not reliable, the adjustment action will be disabled, these will be in the production process to form a great loss, add labor intensity, so the selection and application of pneumatic control valve has been paid more and more attention.
The control accuracy of the pneumatic control valve can be realized by changing the energy of flow and logistics. The control valve can adopt the control energy of adjustable share. The adjustable share refers to the control valve with the pressure difference between the two sides of the control valve as a fixed value. The control valve can control the ratio of large flow and small flow. When the regulator is in series pipeline, the adjustable ratio is proportional to the square root of the pressure drop ratio, the smaller the control capacity, when there are two or more than two regulators in parallel and work together, it is necessary to pay attention to the bypass degree. In actual production, in addition to the regulating valve, there will be other pipelines, so the pressure difference before and after the valve will change, which is called the operation flow characteristic. Specifically, there are linear valves, percentage valves and parabolic valves. The percentage valves are widely used and have strong adaptability.