Valve common problem elimination, maintenance low pressure ADAMS valve fast closing time setting method
1. Why should the cut-off valve be hard sealed as far as possible?
Cut off the valve leakage requirements of the lower the better, the leakage of the soft seal valve is the lowest, cut off the effect of course is good, but not wear-resistant, poor reliability. From the leakage and small, sealing and reliable double standard, soft seal cut off is better than hard seal cut off. Such as full-function ultra-light regulating valve, sealed and stacked with wear-resistant alloy protection, high reliability, leakage rate of 10-7, has been able to meet the requirements of the cut-off valve.
2. Why can’t the double seal valve be used as a cut-off valve?
The advantage of the two-seat valve spool is the force balance structure, allowing a large pressure difference, and its outstanding disadvantage is that the two sealing surfaces can not be good contact at the same time, resulting in large leakage. If it is artificially and forcibly used to cut off the occasion, obviously the effect is not good, even if it has made many improvements (such as double seal sleeve valve), it is not desirable.
3. Why is it easy to oscillate when the two-seat valve is small open?
For the single core, when the medium is flow open type, the valve stability is good; When the medium is flow closed, the stability of the valve is poor. The double seat valve has two spool, the lower spool is in the flow closed, the upper spool is in the flow open, so, in the small opening work, the flow closed type spool is easy to cause the vibration of the valve, this is the reason why the double seat valve can not be used for the small opening work.
4, what straight stroke regulating valve blocking performance is poor, Angle stroke valve blocking performance is good?
Straight stroke valve spool is vertical throttling, and the medium is horizontal flow into and out of the valve chamber flow channel must turn back, so that the valve flow path becomes quite complex (shape such as inverted S-type). In this way, there are many dead zones, which provide space for the precipitation of the medium, and in the long run, cause blockage. The direction of the Angle stroke valve throttling is the horizontal direction, the medium flows in and out horizontally, and it is easy to take away the unclean medium. At the same time, the flow path is simple, and the medium precipitation space is very little, so the Angle stroke valve has good blocking performance.
5, why the straight stroke control valve stem is thinner?
Straight stroke regulating valve it involves a simple mechanical principle: large sliding friction, small rolling friction. Straight stroke valve stem up and down movement, packing slightly pressed a little, it will put the valve stem wrapped very tight, produce a large back difference. For this reason, the valve stem is designed to be very small, and the packing is commonly used with a small coefficient of friction PTFE packing, in order to reduce the backdifference, but the problem is that the valve stem is thin, easy to bend, and the packing life is short. To solve this problem, the best way is to use the travel valve stem, that is, the Angle stroke of the valve stem, its valve stem is 2 ~ 3 times thicker than the straight stroke of the valve stem, and the choice of long-life graphite packing, stem stiffness is good, packing life is long, the friction torque is small, small return difference.
6. Why is the cut off pressure difference of the Angle stroke valve large?
Angle stroke type valve cut off pressure difference is large, because the medium in the spool or valve plate resultant force on the rotation shaft torque is very small, therefore, it can withstand a large pressure difference.
7. Why did the sleeve valve replace the single and double seat valve but not achieve its goal?
The sleeve valve, which came out in the 1960s, was widely used at home and abroad in the 1970s. In the petrochemical plant introduced in the 1980s, the sleeve valve accounted for a larger ratio. At that time, many people believed that the sleeve valve could replace the single and double seat valve and become the second generation of products. Today, this is not the case, single seat valve, double seat valve, sleeve valve are used equally. This is because the sleeve valve only improves the throttling form, stability and maintenance better than the single seat valve, but its weight, blocking and leakage indicators are consistent with the single and double seat valve, how can it replace the single and double seat valve? So, it has to be shared.
8. Why is the service life of the desalting water medium lined with rubber butterfly valve and fluorine lined diaphragm valve short?
Desalting water medium contains low concentration of acid or alkali, they have a greater corrosion to rubber. The corrosion of rubber is characterized by expansion, aging and low strength. The use effect of butterfly valve and diaphragm valve lined with rubber is poor. The essence is that rubber is not corrosion resistant. After the rubber lining diaphragm valve is improved to the corrosion resistance of fluorine lined diaphragm valve, but the diaphragm of fluorine lined diaphragm valve can not stand up and down folding and broken, resulting in mechanical damage, the life of the valve is shorter.
Now the best way is to use water treatment ball valve, it can be used for 5 to 8 years.
9, why in the pneumatic valve piston actuator use will be more and more?
For pneumatic valve, the piston actuator can make full use of the air source pressure, the size of the actuator is smaller than the film, the thrust is greater, the O-ring in the piston is more reliable than the film, so it will be used more and more.
10. Why is selection more important than calculation?
Calculation and selection compared, selection is much more important, much more complex. Because the calculation is only a simple formula calculation, its itself does not depend on the degree of the formula, but depends on the accuracy of the given process parameters. The selection involves more content, a little careless, will lead to improper selection, do not cause the waste of manpower, material resources, financial resources, and the use of the effect is not ideal, bring a number of use problems, such as reliability, life, operation quality, etc.
In the quick closing test of a low pressure valve on site, the quick closing time of some stop valves is not qualified. The inlet of the quick release valve is adjusted on site to make the quick closing time of all valves meet the requirements.
In THE quick closing test OF a low-pressure valve on site, the quick closing time of a few stop valves is not qualified. The inlet of the quick release valve is adjusted on site to make the quick closing of all valves meet the requirements.
The inlet of the low-pressure Adams valve to the quick-release valve is changed by changing the number of front and rear gaskets. The moving effect of thin section is ±0.15s, and the moving effect of thick section is ±0.3s, as shown in the picture below.
According to the mechanical structure of the device, the principle is simply drawn as follows:
Combined WITH the schematic diagram and photos, it can be seen that the adjustment method is to change the gaskets on both sides of the boss to adjust the length of the entire slide deep into the oil circuit. There are two kinds of slider, one thin and one thick.
The following two diagrams show the position of the slider during normal operation and quick shutdown.
As can be seen from the figure, when working normally, the slider is pushed forward, and the unloading road is closed; When rapid shutdown of jumping occurs, the slider is outward and the unloading oil circuit is opened.
Change the number of gaskets behind the slide block, can change the back seat of the slide block, out to the length of the unloading oil road, on the outside to add a gasket, can make the fast closing time extended 0.15s, on the outside to add a thick gasket, can make the fast closing time extended 0.3s.
When the washer is placed inside, it does not change the time. It is used for backup storage.
Post time: Jul-29-2022
