Zhuopu will answer the common problems that fluorine lined valves are prone to

I often encounter friends who use fluorine lined valves and ask various questions. Next, I will summarize some common problems and define them as the top ten fluorine lined valves. I hope it can help everyone: 1. Why should hard seals be used as much as possible for shut-off valves? The requirement for cutting off valves is that the lower the leakage, the better. The leakage of soft sealed valves is low, and the cutting effect is of course good, but it is not wear-resistant and has poor reliability. From the dual standards of small leakage and reliable sealing, soft seal cutting is not as good as hard seal cutting. As a fully functional ultra light regulating valve, it is sealed and stacked with wear-resistant alloy protection, with high reliability and a leakage rate of 10-7, it can already meet the requirements of a shut-off valve. 2. Why can't double sealed valves be used as shut-off valves? The advantage of a dual seat valve core is its force balance structure, which allows for a large pressure difference. However, its prominent disadvantage is that the two sealing surfaces cannot make good contact at the same time, resulting in large leakage. If it is artificially and forcibly used in cutting situations, the effect is obviously not good, and even if many improvements are made to it (such as double sealed sleeve valves), it is not advisable. 3. Why is it easy for a double seat valve to oscillate when working with a small opening? For a single core, when the medium is a flow open type, the valve has good stability; When the medium is flow closed, the stability of the valve is poor. A double seat valve has two valve cores, with the lower valve core in the flow closed position and the upper valve core in the flow open position. This makes it easy for the flow closed valve core to cause valve vibration when working at a small opening. This is why double seat valves cannot be used for small opening operations. 4. What kind of straight stroke control valve has poor anti blocking performance, while angle stroke valve has good anti blocking performance? The valve core of a straight stroke valve is vertically throttled, while the medium flows horizontally in and out. The flow path inside the valve chamber will inevitably turn and turn, making the flow path of the valve quite complex (shaped like an inverted S-shape). In this way, there are many dead zones that provide space for the precipitation of the medium, which can lead to blockage over time. The throttling direction of the angle stroke valve is in the horizontal direction. The medium flows in and out horizontally, which easily takes away unclean medium. At the same time, the flow path is simple, and there is little space for medium sedimentation, so the angle stroke valve has good anti blocking performance. 5. Why is the stem of a straight stroke control valve thinner? The straight stroke regulating valve involves a simple mechanical principle: high sliding friction and low rolling friction. The stem of a straight stroke valve moves up and down, and if the packing is slightly tightened, it will wrap the stem tightly, resulting in a large backlash. For this reason, the valve stem is designed to be very small, and PTFE packing with low friction coefficient is commonly used to reduce backlash. However, the problem arising from this is that the valve stem is thin, making it easy to bend, and the packing life is also short. A good way to solve this problem is to use a rotary valve stem, which is an angle stroke regulating valve. Its stem is 2-3 times thicker than the straight stroke stem, and graphite packing with a long service life is used. The stem stiffness is good, the packing life is long, and its friction torque is small and the backlash is small. 6. Why is the cut-off pressure difference of angle stroke valves relatively large? The cutting pressure difference of angle stroke valves is relatively large because the combined force generated by the medium on the valve core or valve plate has a very small torque on the rotating shaft. Therefore, it can withstand a large pressure difference. 7. Why did sleeve valves replace single and double seat valves but not achieve their desired results? The sleeve valve, which was introduced in the 1960s, was widely used both domestically and internationally in the 1970s. In the petrochemical plants introduced in the 1980s, the proportion of sleeve valves was relatively high. At that time, many people believed that sleeve valves could replace single and double seat valves and become second-generation products. Until now, this is not the case. Single seat valves, double seat valves, and sleeve valves are all used equally. This is because the sleeve valve only improves the throttling form, stability, and maintenance compared to single seat valves, but its weight, anti clogging, and leakage indicators are consistent with single and double seat valves. How can it replace single and double seat valves? So, it can only be used together. 8. Why do desalinated water media use rubber lined butterfly valves and fluorine lined diaphragm valves with short service life? The desalinated water medium contains low concentrations of acids or bases, which have significant corrosiveness to rubber. The corrosion of rubber manifests as expansion, aging, and low strength. Butterfly valves and diaphragm valves lined with rubber have poor performance, which is essentially due to the lack of corrosion resistance of rubber. The rear rubber lined diaphragm valve has been improved to a fluorine lined diaphragm valve with good corrosion resistance, but the diaphragm of the fluorine lined diaphragm valve cannot withstand up and down folding and is broken, causing mechanical damage and shortening the valve's lifespan. The best solution now is to use specialized ball valves for water treatment, which can be used for 5-8 years. 9. Why is the use of piston actuators increasing in pneumatic valves? For pneumatic valves, the piston actuator can fully utilize the air source pressure, making the size of the actuator smaller and more thrust than the diaphragm type. The O-ring in the piston is also more reliable than the diaphragm, so its use will be increasing. 10. Why is selection more important than calculation? Compared to selection, selection is much more important and complex. Because calculation is just a simple formula calculation, it is not about the degree of the formula itself, but about whether the given process parameters are accurate. The selection involves a lot of content, and a slight carelessness can lead to improper selection, which not only causes waste of manpower, material resources, and financial resources, but also results in unsatisfactory usage effects, leading to several usage problems such as reliability, lifespan, and operational quality.