6 ways to address clogging in self-acting control valves

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　　The six methods for preventing clogging and sticking in self-acting control valves are as follows: 1. Cleaning method: Weld slag, rust, debris, etc. in the pipeline can cause blockages or sticking at the throttle openings, guide sections, and balance holes in the lower valve cover, resulting in scratches and damage to the surface of the valve core and its guide surfaces. In such cases, it is necessary to disassemble the component for cleaning in order to remove debris. If the sealing surface is damaged, it must be ground as well. At the same time, the plug should be removed to flush out any debris that has fallen into the lower valve cover from the balance hole, and the pipelines should also be cleaned. Before putting it into operation, open the control valve fully; allow the medium to flow for a while before proceeding with normal operation. 　　2. Medium scouring method: Utilizing the scouring energy of the medium itself to wash away and remove substances that tend to settle or cause blockages, thereby enhancing the valve’s resistance to blockage. Common methods include: a) converting it to a flow-blocking design; b) using a streamlined valve body; c) placing the throttle opening in the area most subject to erosion. When using this method, it is important to enhance the erosion resistance of the throttling element. 　　3. Change from straight-through to corner method: The straight-through configuration involves an inverted S-shaped flow pattern, resulting in a complex flow path and numerous dead zones in the upper and lower chambers, which provide areas for the deposition of the medium. Angular connection: the medium flows as if through a 90° elbow, offering good scouring performance, a small dead zone, and allowing for easy design in a streamlined shape. 　　4. Method of increasing the throttling gap: Solid particles in the medium, or weld slag and rust that have been washed away in the pipes, can cause blockages and other problems due to their inability to pass through the throttling opening. In such cases, it is possible to use throttling elements with a larger throttling gap – valve cores or sleeves with window-like or open-shaped throttling areas. Since the throttling area is concentrated rather than distributed around the circumference, such problems can be easily resolved. For single or double-seat valves, the plunger-type valve core can be replaced with a valve core having a “V”-shaped port, or it can be changed to a cartridge valve or similar. 　　5. External flushing method: When using ordinary valves to regulate media that tend to precipitate and contain solid particles, blockages often occur at the throttling ports and guide areas; in such cases, flushing gas and steam can be supplied externally at the bottom plug of the lower valve cover. When the control valve becomes clogged or stuck, opening the external gas or steam valve allows for flushing to be carried out without moving the control valve itself, thereby restoring its normal operation. 　　6. Pipeline filter installation method: For small-diameter control valves, especially those with extremely low flow rates, the throttling gap is very small; even a small amount of debris in the fluid can cause blockages. It is advisable to install a filter on the pipeline ahead of the valve to ensure smooth flow of the fluid. For control valves used with positioners, when the positioner does not function properly, the most common fault is a blockage in the air circuit throttle.