Pneumatic ball valve is widely used in industrial automation, gas equipment and pipeline flow control system equipment.  Because of the pneumatic control ball valve simple structure, reliable quality, low price, good quality, many applications.  However, in the complex working conditions of process pipeline, once there are problems, it will cause a lot of problems;  Because the pneumatic ball valve is installed inside the pipe, there is no choice of problem.  In addition, it also involves system operation, system A integrity, quality adjustment, environmental pollution and other issues。

One. Pneumatic control ball valve wide open work  

Allow the regulating pneumatic ball valve to operate at the widest opening possible (e.g. 90%) at the beginning.  In this way, evaporation, wear and other damage to the spool head can occur.  With the damage of the spool, the flow increases and gradually closes, prompting the entire spool to be fully utilized until the spool root and surface are damaged.  You can't use it. At the same time, the throttle clearance of the open work is large, the wear is sharp, and the service life of the valve is 1-5 times more than that of the middle open and small open work at the beginning.

Two, Reduce the specification, increase the working openness  

Increase operating opening according to reduced valve specifications. Specific measures are as follows: Replace a small size valve, such as DN40 to DN32. The valve body shall remain unchanged, and the small diameter valve core seat shall be replaced. For example, the throttling parts DN8 during overhaul in the chemical plant shall be replaced with DN6, and the service life shall be doubled.

Three, why the pneumatic control ball valve can not work in a small opening?  

Pneumatic control ball valve in the small opening of the work has severe flow resistance, flow rate, pressure changes/will bring the following problems.  

1. The throttle clearance Z is small, the flow rate is large, and the flushing Z is serious, which seriously endangers the service life of the valve.  

2. The flow rate is fast, the pressure changes fast, exceeds the valve stiffness, the valve stability is poor, and even produces serious oscillation.  

3. For the valve working under the state of flow closure, there will be a bouncing close or bouncing pneumatic situation, the regulator can not be adjusted in this opening.  

4. The opening degree is small, and the spool protruding surface is close to the throttle orifice, which damages the spool protruding surface.  

5. Some valves are not suitable for small opening. For disc valves, a small opening is an unbalanced torque that can lead to disconnection and tripping. For example, two-seat valve, two spool one in the flow close, one in the flow close, small opening stability is poor, easy to produce shock.