In the industrial automation instrument, the regulating valve is heavy, and the structure is simple, and it is often not paid attention to. However, it is in the process pipe, the working conditions are complex, once the problem occurs, people are busy with their hands. Because of its heavy weight, difficult to find the problem, often difficult to please, it also involves system transportation, system complete, quality control, environmental pollution and so on.

How to prevent the valve from jammed or blocked?
(6 methods)
Cleaning method
The most common faults: pipe welding slag, rust, slag in the throttle, steering parts, balance valve cover holes caused by blocked or stuck to the spool surface, surface oriented production strain and scratches, sealing surface indentation and so on. This often occurs in the new delivery system and in the early stages of the overhaul.
In this case, we must remove the cleaning, remove residue, such as the sealing surface should be ground by the injury; at the same time, open the bottom plug, to flush from the balance under the valve cover hole fall into the slag material, and pipe for flushing. Before the operation, let the regulating valve fully open, the medium flow after a period of time into normal operation.

External scour method
Some easy to precipitate solid particles of the medium containing the ordinary valve adjustment, often plugged in the throttle, guide, can be connected in eroding gas valve cover Cypriot department and steam. When the valve is jammed or jammed, it opens the external gas or steam valve and completes the washing operation under the condition of the non adjusting control valve, so that the valve can run normally.
Installation of pipe filter method
For the small caliber regulating valve, especially the ultra small flow regulating valve, the throttle gap is very small, and there can not be a little bit of slag in the medium. In this case, it is better to install a filter on the front of the valve to ensure the smooth passage of the medium.
With the regulating valve used by the locator, the positioner is not working properly, and the throttle blockage is the most common fault. Therefore, when the locator works, it is necessary to handle the gas source. The usual method is to install the air filter pressure relief valve on the front of the locator.

Enlargement of throttling method
Such as the medium of solid particles or pipe was washed away with things such as welding slag and rust caused by congestion, stuck fault because can not throttle, can use larger throttle throttle clearance — valve throttle sleeve, an area of open window, open class, because of the cutting area of focus and is not distributed on the circumference, the fault can easily be excluded.
If the single and double valve can be replaced by the plunger valve core to “ V” the valve core, or change to the sleeve valve. For example, a chemical plant has a double seat valve often stuck, recommended after the use of the sleeve valve, the problem is solved immediately.
Medium scour method
Using the energy of the medium's own scour to scour and take away the easily precipitated and clogged things, so as to improve the anti blocking function of the valve. The common methods are:
For the use of closed type flow;
Streamline valve body is used.
The throttle is placed in the most severe scouring place. This method should be used to improve the erosion resistance of the throttle material.
Straight through to angle method
Through the flow of inverted S, the flow path is complex and the dead zone of the upper and lower chamber is many, which provides a place for the precipitation of the medium. Angle connection, medium like flow over 90 degrees centigrade elbow, good scour performance, small dead zone, easy to design into a flow line. Therefore, the use of the angle valve can be changed when the direct regulating valve is slightly blocked.
How to prevent the leakage of the regulating valve?
(6 methods)

Increase the seal oil method
For valves that are not used for sealing oil, the sealing performance of the stem can be increased by adding sealing grease.
Adding packing method
In order to improve the sealing performance of the filler to the stem, a method of adding filler can be used. It is usually used in the form of double layer and multi-layer mixed packing, which increases the quantity simply, such as adding 3 pieces to 5 pieces, and the effect is not obvious.
Replacement of graphite packing method
Use a lot of PTFE packing, its operating temperature: +200 degrees centigrade range when the temperature in the upper and lower limits, change is large, the seal will be significantly decreased, aging fast, short life. Flexible graphite filler can overcome these shortcomings and have long service life.
Therefore, some factories have changed the fillers of tetrafluoroethylene into graphite filler, and even the newly bought adjustment valves also replace the tetrafluoro fillers into graphite fillers. However, the use of graphite filler has a large back difference and some creeping phenomena at the beginning, which must be considered.
Change the flow direction, set P2 in the stem end method
When a larger P, P1 and P1 than the larger, seal seal P2 difficult. Therefore, the method of changing the flow direction can be adopted to change the P1 in the stem end to the P2 in the stem end, which is more effective for the valve with high pressure and high pressure difference. If the bellows valve is usually considered to be sealed P2.
Using lens cushion seal method
Seal for upper and lower cover, seating of valve seat and upper and lower body. If the seal is flat, under high temperature and high pressure, the sealing ability is poor and the leakage can be caused. It can be replaced by the lens cushion seal, and the satisfactory effect can be obtained.
Replace the seal gasket
So far, most sealing gaskets are still used asbestos plate. Under high temperature, the sealing performance is poor and the life is short, causing leakage. In this case, it can be converted to winding gasket, &ldquo, O&rdquo, shape ring and so on, and now many factories have adopted it.
The source of this article: chemical 707;

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