Views: 227 Author: Site Editor Publish Time: 2021-08-02 Origin: Site
Common pneumatic valve products include pneumatic control valves, pneumatic wafer type butterfly valves, air actuated diaphragm valve, among which pneumatic control valve is a more important one. It is inevitable that this kind of products will cause clog due to improper maintenance during use. Don’t worry! Here are some preventive measures:
There are weld slag, rust, slag, etc. in the pipeline, which will cause blockages or jams in the orifice, guide part, and balance hole of the lower valve cover, causing strain and scratches on the valve core surface and guide surface. In this case, it must be unloaded for cleaning to remove the slag. If the sealing surface is damaged, it should be ground; at the same time, the bottom plug should be opened to wash away the slag falling into the lower valve cover from the balance hole, and the pipeline should be flushed. Before putting it into operation, let the regulating valve be fully opened, and the medium will flow for a period of time before being brought into normal operation.
When ordinary valves are used to adjust some media that are easy to precipitate and contain solid particles, they are often blocked at the orifice and guide. The flushing gas and steam can be connected to the bottom plug of the lower valve cover. When the air actuator valve is blocked or stuck, we should open the external gas or steam valve to complete the flushing work without moving the regulating valve. And the valve will operate normally.
For small-diameter valve with pneumatic actuator working, especially ultra-small flow air actuated control valve, the throttling gap is extremely small, even if there is a little slag in the medium, it will be blocked. It is best choice to install a filter on the pipe before the valve. For globe control valve with pneumatic actuator and smart positioners, if the positioners are not working properly, the air passage orifice will be always blocked. That is the most common fault.
These things includes the solid particles in the medium, the welding slag, rust that have been washed away from the pipeline, will cause blockage, jamming and other failures due to the inability to pass the orifice. We can use a throttle with a large throttle gap—the throttle area is the window, open valve cores and sleeves, because their throttling area is concentrated instead of circumferentially distributed, the fault can be easily eliminated. If it is a single or double acting actuator valve, the plunger valve core can be changed to a "V" shaped valve core or a sleeve valve.
We can use the scouring force of the medium itself to flush and the medium can take away things that are easy to precipitate and block, thereby improving the anti-blocking function of the valve. The common methods are: ① change to flow-closed use; ② adopt streamlined valve body; ③ place the orifice at the most severe scouring point if we use this method, we need pay attention to improving the erosion resistance of the throttle.
The straight flow is inverted S flow, this flow path is complicated. So there are many dead zones in upper and lower chambers, which provide a place for the precipitation of the medium. But if we use angle seat piston valve or pneumatic angle seat valve, the medium will be like flow through a 90℃ elbow with good scouring performance.
