译文：
本文开门见山地回答了阀门使用过程中常见地10个问题，希望对相关技术人员有帮助。 　　一、为什么双座阀小开度工作时容易振荡　　对单芯而言，当介质是流开型时，阀稳定性好；当介质是流闭型时，阀的稳定性差。双座阀有两个阀芯，下阀芯处于流闭，上阀芯处于流开，这样，在小开度工作时，流闭型的阀芯就容易引起阀的振动，这就是双座阀不能用于小开度工作的原因所在。　　二、为什么双密封阀不能当作切断阀使用　　双座阀阀芯的优点是力平衡结构，允许压差大，而它突出的缺点是两个密封面不能同时良好接触，造成泄漏大。如果把它人为地、强制性地用于切断场合，显然效果不好，即便为它作了许多改进（如双密封套筒阀），也是不可取的。　　三、什么直行程调节阀防堵性能差，角行程阀防堵性能好　　直行程阀阀芯是垂直节流，而介质是水平流进流出，阀腔内流道必然转弯倒拐，使阀的流路变得相当复杂（形状如倒“S”型）。这样，存在许多死区，为介质的沉淀提供了空间，长此以往，造成堵塞。角行程阀节流的方向就是水平方向，介质水平流进，水平流出，容易把不干净介质带走，同时流路简单，介质沉淀的空间也很少，所以角行程阀防堵性能好。　　四、为什么直行程调节阀阀杆较细　　它涉及一个简单的机械原理：滑动摩擦大、滚动摩擦小。直行程阀的阀杆上下运动，填料稍压紧一点，它就会把阀杆包得很紧，产生较大的回差。为此，阀杆设计得非常细小，填料又常用摩擦系数小的四氟填料，以便减少回差，但由此派出的问题是阀杆细，则易弯，填料寿命也短。解决这个问题，{zh0}的办法就是用旅转阀阀杆，即角行程类的调节阀，它的阀杆比直行程阀杆粗2～3倍，且选用寿命长的石墨填料，阀杆刚度好，填料寿命长，其摩擦力矩反而小、回差小。　　五、为什么角行程类阀的切断压差较大？　　角行程类阀的切断压差较大，是因为介质在阀芯或阀板上产生的合力对转动轴产生的力矩非常小，因此，它能承受较大的压差。　　六、为什么脱盐水介质使用衬胶蝶阀、衬氟隔膜阀使用寿命短？　　脱盐水介质中含有低浓度的酸或碱，它们对橡胶有较大的腐蚀性。橡胶的被腐蚀表现为膨胀、老化、强度低，用衬胶的蝶阀、隔膜阀使用效果都差其实质就是橡胶不耐腐蚀所致。后衬胶隔膜阀改进为耐腐蚀性能好的衬氟隔膜阀，但衬氟隔膜阀的膜片又经不住上下折叠而被折破，造成机械性破坏，阀的寿命变短。现在{zh0}的办法是用水处理专用球阀，它可以使用到5～8年。　　七、为什么切断阀应尽量选用硬密封　　切断阀要求泄漏越低越好，软密封阀的泄漏是{zd1}的，切断效果当然好，但不耐磨、可靠性差。从泄漏量又小、密封又可靠的双重标准来看，软密封切断就不如硬密封切断好。如全功能超轻型调节阀，密封而堆有耐磨合金保护，可靠性高，泄漏率达10～7，已经能够满足切断阀的要求。　　八、为什么套筒阀代替单、双座阀却没有如愿以偿　　20世纪60年代问世的套筒阀，70年代在国内外大量使用，80年代引进的石化装置中套筒阀占的比率较大，那时，不少人认为，套筒阀可以取代单、双座阀，成为第二代产品。到如今，并非如此，单座阀、双座阀、套筒阀都得到同等的使用。这是因为套筒阀只是改进了节流形式、稳定性和维护好于单座阀，但它重量、防堵和泄漏指标上与单、双座阀一致，它怎能取代单、双座阀呢？所以，就只能共同使用。　　九、为什么说选型比计算更重要　　计算与选型比较而言，选型要重要得多，复杂得多。因为计算只是一个简单的公式计算，它的本身不在于公式的xx度，而在于所给定的工艺参数是否准确。选型涉及到的内容较多，稍不慎，便会导致选型不当，不仅造成人力、物力、财力的浪费，而且使用效果还不理想，带来若干使用问题，如可靠性、寿命、运行质量等。 十、为什么在气动阀中活塞执行机构使用会越来越多　　对于气动阀而言，活塞执行机构可充分利用气源压力，使执行机构的尺寸比薄膜式更小巧，推力更大，活塞中的O型圈也比薄膜可靠，因此它的使用会越来越多。

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原文：
This straight to the point answers to common land use process valve 10 problems in the hope of the relevant technical staff helpful. One, why is a small two-seater valve opening hours of work likely oscillation Pairs of single-core, when the medium is open-type flow, the valve stability; when the medium is a closed-type flow, the valve of the stability of the difference. There are two spool valve seat, the next spool in the flow of closed, open on the spool in the flow, so that a small opening in the work, the flow of closed-type valve spool is easy to cause vibration, which is two-seat valve can not be used for the work of a small opening reason. Second, why can not double-sealing valve used as a shut-off valves Two-seat valve spool force balance the advantages of the structure, allowing large differential pressure, and its obvious drawback is that two sealing surface can not be good contacts at the same time, resulting in large leakage. If it is artificially Mandatory used to cut off occasion, apparently ineffective, even if it made a lot of improvements (such as the double-sealed sleeve valve), is also undesirable. Third, what straight poor performance, aiming to halt the stroke control valve, angle valve, prevent the travel of good performance Direct travel is vertical throttle valve spool, while the medium is the level of flow into the outflow valve cavity flow channel bound to turn down Shui Po, so that the valve flow path becomes quite complex (shape such as the inverted "S" type). In this way, there are many dead zone, in order to provide a space for the precipitation media, long run, causing blockage. The direction of travel throttle valve angle is the horizontal direction, the level of flows into the medium, the level of outflow, easy to clean media is not removed, flow path at the same time simple and very little room for medium precipitation, therefore, prevent the valve angle stroke of good performance. Fourth, why do straight stroke adjustment valve stem smaller It involves a simple mechanical principle: sliding friction, rolling friction small. Trip valve stem straight up and down movement, packing slightly pressed a little, it will stem bag tightly, resulting in a larger backlash. To this end, valve stem is designed to be very small, they often fill a small friction coefficient of PTFE packing, in order to reduce hysteresis, but the resulting problem is that stem thin sent, then the easy to bend, filling a shorter life expectancy. To solve this problem, the best way is to turn valve stem with the brigade, namely, the class trip valve angle, and its stem stroke than the straight stem crude 2 ~ 3 times, and the selection of long-lived graphite packing, valve stem stiffness Well, filling long life, but its friction torque is small, a small hysteresis. 5, why cut off the angle valve pressure class travel more? Angle type valve to cut off travel greater pressure because of media in the spool or the valve plate force generated by the rotational axis of the torque produced is very small, so it can withstand a greater pressure differential. 6, why the use of desalination water medium rubber lined butterfly valve, lined diaphragm valves and short service life? Desalination of water medium containing low concentration of acid or alkali, they have a greater corrosive to rubber. Rubber showed expansion of corrosion, aging, low intensity, with the rubber lining of the butterfly valve, diaphragm use the results are worse in essence, rubber corrosion caused by impatience. After the rubber lining for Diaphragm Valves to improve corrosion resistance of a good Lining diaphragm valves, diaphragm valves of the diaphragm, but lined up and down then stand up to collapse were broken off, resulting in mechanical damage to valves shorter life expectancy. Now the best way to deal with specific water valve, it can use to 5 ~ 8 years. 7, why use a hard shut-off valve should be sealed Required shut-off valve leakage as low as possible, soft-sealing valve leakage is the lowest cut off the effect is good, but not wear and poor reliability. From the leakage volume is small, sealed and reliable double standards, not as hard on the soft sealing off sealing off well. As a full-featured ultra-light control valve, sealing the heap are wear-resistant alloy protection, high reliability, leakage rate of 10 ~ 7, have been able to meet the shut-off valve requirements. 8, why sleeve valves instead of a single, two-seat valve did not wish fulfilled The 20th century advent of the sleeve valve 60's, 70's heavy use at home and abroad, and 80 years the introduction of the sleeve valve petrochemical plant accounted for a larger proportion of that time, many people think that the sleeve valve can replace a single, double seat valve, to become the second-generation products. By now, is not the case, single-seat valves, seat valves, sleeve valves have been the same use. This is because the sleeve valve is throttling the form of improved stability and maintenance of better than single-seat valve, but it's weight, aiming to halt and leakage targets with single-seat valve in line, how can it replace the single-seat valve it? So, the only shared use. 9, Why is selection is more important than the calculation Calculation and selection of comparison, the selection should be much more important, much more complex. Because the calculation is a simple formula, which itself does not lie in the accuracy of the formula, but rather by the given parameters are correct. Selection related to the contents of the large, slightly careless, would lead to selection of properly, not only causes human, material and financial resources to waste, and use the result was unsatisfactory, and has brought a number of user issues, such as reliability, life, running quality. 10, why in the pneumatic valve in the piston will be more and more by implementing agencies For the pneumatic valve, the piston executing agencies may make full use of gas supply pressure, so that the executing agency of the size smaller than the membrane, a greater thrust piston in the O-ring and reliable than the film, so its use will become increasingly more.