Valve ten common problems in use: First, why the small opening of two-seat valve easy to oscillate Work on a single core, when the medium is open type, the valve stability is good; when the medium is flow closed, the valve Poor stability. Double-seated valve has two spools, the lower spool in the flow closed, the valve spool is open, so that work in a small opening, the flow-closure valve spool is easy to cause the valve vibration, which is double seat valve Can not be used for a small degree of work reason. Second, why double seal valve can not be used as a shut-off valve The advantage of using two-seater valve spool is force balance structure, allowing pressure, and its prominent drawback is that the two sealing surfaces can not be both good contact, resulting in large leaks. If it is artificially and purposely used to cut the occasion, apparently ineffective, even for it made many improvements (such as double seal sleeve valve), is not desirable. Third, what is the straight-stroke control valve anti-blocking performance is poor, the anti-blocking valve performance is good Stroke valve is a vertical straight throttle, while the medium is the level of flow in and out of the valve cavity must turn around the flow channel, so that the valve The flow path becomes quite complex (the shape is inverted "S"). In this way, there are many dead zones that provide space for the precipitation of the medium over time, causing clogging. Angle valve stroke direction is the horizontal direction, the media into the level, the level of outflow, easy to clean media away, while the flow path is simple, medium precipitation space is also small, so the anti-blocking performance of the angular stroke valve. Fourth, why the straight stroke adjustment valve stem thin It involves a simple mechanical principle: sliding friction, rolling friction small. Straight travel valve stem up and down movement, the packing a little bit tight, it will be very tight stem package, resulting in greater backlash. To this end, the valve stem is designed to be very small, packing and PTFE friction coefficient is often small PTFE packing, in order to reduce backlash, but the problem is sent stem thin, easy to bend, filler life is short. Solve this problem, the best way is to travel with the valve stem, which is the type of angular travel control valve, the valve stem than the straight travel valve stem thick 2 to 3 times, and the choice of long life graphite packing, stem stiffness Good, long filler life, but the friction torque on the contrary, small backlash. Fifth, why the angular stroke valve cut off the larger pressure? Angle stroke valve to cut off the larger pressure differential is because the media in the valve core or valve plate together on the torque generated by the rotating shaft is very small, therefore, it can withstand greater pressure. Six, why desalinated water medium using rubber lined butterfly valve, lined diaphragm valve life is short? Desalinated water medium contains a low concentration of acid or alkali, they are more corrosive to rubber. Corrosion of rubber is manifested as swelling, aging, low strength, with rubber lining butterfly valve, diaphragm valve are poor effect is essentially the result of rubber intolerance corrosion. Liner rubber diaphragm valve improved corrosion-resistant performance of fluorine-lined diaphragm valve, but lined with fluorine diaphragm valve can not withstand the collapse of the upper and lower folded, resulting in mechanical damage, valve life shorter. Now the best way is to use special ball valve water treatment, it can be used to 5 to 8 years. Seven, why cut-off valve should be used as hard seal cut-off valve as required to leak the lower the better, soft-sealed valve leakage is the lowest, of course, cut off the effect, but not wear-resistant, poor reliability. From the leakage is small, sealed and reliable double standards, the soft seal cut off as good as the hard seal cut off. Such as full-featured ultra-light control valve, sealed and piled with wear-resistant alloy protection, high reliability, leakage rate of 10 to 7, has been able to meet the requirements of shut-off valve. Eight, why the sleeve valve instead of a single, two-seater valve did not get one's wish came in the 20th century, 60 sleeve valve, the 70's extensive use at home and abroad, the introduction of the petrochemical plant in the 1980s sleeve valves accounted for a larger ratio, that When many people think that sleeve valve can replace single, double seat valve, a second generation products. Until now, not so, single-seat valve, seat valve, sleeve valve are the same use. This is because the sleeve valve is only improved throttle mode, stability and maintenance better than a single seat valve, but its weight, anti-blocking and leakage indicators with the single, double seat valve, how can it replace single, double seat valve What? So, can only be used together. Nine, why the selection is more important than the calculation Calculation and selection comparison, the selection is much more important, much more complex. Because calculation is just a simple formula calculation, it does not depend on the accuracy of the formula itself, but on the accuracy of the given process parameters. Selection involves more content, a little carelessness, it will lead to improper selection, not only resulted in human, material and financial waste, and the use of results are not satisfactory, bringing a number of use problems, such as reliability, life expectancy, operation Quality and so on. X. Why Piston Actuators in Pneumatic Valves Will Become More and More For Pneumatic Valves, Piston Actuators can make full use of the pressure of gas source to make the size of actuator smaller and thinner than the diaphragm, The O-ring is also more reliable than the film, so it will be used more and more.
