原文：
         1、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。

 　　2、为什么双密封阀不能当作切断阀使用？平衡阀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。

 　　3、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。

 　　4、为什么直行程调节阀阀杆较细？水力控制阀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，最好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，电站阀门其摩擦力矩反而小、回差小。

 　　5、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。

　　6、为什么脱盐水介质使用衬胶蝶阀、低温阀门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。现在最好的办法是用水处理专用球阀，它可以使用到5～8年。

 　　7、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，软密封阀的泄漏是最低的，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。

　　8、为什么套筒阀代替单、双座阀却没有如愿以偿？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，过滤器并非如此，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。

 　　9、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精确度，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。

      10、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。

“ How to solve small problems common valve ”是由中国闸阀网提供的阀门行业新闻，译文仅供参考。另外，中国闸阀网还提供相关产品搜索： 电动闸阀、 手动闸阀、 气动闸阀、 不锈钢闸阀、 美标凸耳闸阀等。

译文：
       1 Why a small two-seater valve opening is easy oscillation work? On single-core, when the medium is open stream type, the valve stability; when the medium is the flow of closed type, the valve of the poor stability. There are two spool valve seat, the next in a flow valve closed, the valve is open 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 work for small opening reason. 2, why not double sealing valve used as a cut off valve? Seat valve spool force balance the advantages of the structure,Plug Valves allowing a large pressure difference, but it highlights the shortcomings of the two can not both be a good contact with the sealing surface, causing a large leak. If it artificially, mandatory for cutting off occasion, obviously not good, even if it made a lot of improvements (such as double-sealed sleeve valve), is also undesirable. 3, what direct attempts to prevent poor performance valve stroke, rotary valve attempts to prevent the performance is good? Straight trip throttle valve spool is vertical, while the medium is the level of flow into the outflow valve cavity flow must turn back street, so that the valve flow path becomes quite complex (such as the shape of inverted "S" type). Thus, there are many dead, as the medium of precipitation provides a spaceReducing Valves for the long run, causing blockage. Throttle valve angle of the direction of travel is the horizontal direction, the level of flow into the medium, the level of outflow, easy to medium is not clean away, a simple flow path at the same time, media space and few precipitation, so rotary valve attempts to prevent the performance is good. 4 stroke valve stem straight Why smaller? It involves a simple mechanical principle: a large sliding friction, rolling friction small. Linear actuator valve stem up and down movement, packing slightly compressed that it will stem a very tight package, have a greater backlash. To this end, stem design very small, another commonly used filler of PTFE packing friction coefficient in order to reduce backlash, but this fine to send the question stem, is easily bent, packing too short life. Solve this problem, the best way is to turn valve stem with a trip that travel Lei control valve angle, its stem straight trip Fagan rough than 2 to 3 times, and choose long-lived graphite packing, valve stem stiffness Good, filling long life, but a small friction torque, hysteresis small. 5, why cut off the rotary valve type pressure greater? Rotary type valve to cut off large pressure difference is due to media in the spool or the valve on a board together on the shaft torqueSafety valves produced by very small, so it can withstand greater pressure. 6, Why desalination water medium using rubber lined butterfly valve, fluorine diaphragm short life? Desalination of water medium containing low concentrations of acid or base, they have more corrosive to rubber. Rubber for the expansion of the corrosion performance, aging, low intensity, with a rubber lined butterfly, diaphragm use results are poor, in essence, rubber impatient corrosion. After the rubber lined diaphragm valve to improve the corrosion resistance of a good fluorine for the diaphragm, but the fluorine diaphragm diaphragm up and down then stand up to fold folding was broken, causing mechanical damage, shorter valve life. Now the best way to deal with special ball valve water, it can use to 5 ~ 8 years. 7, why use a hard shut-off valve shouldBalance Valves be closed? Shut-off valve required leakage the lower the better, soft-sealing valve leakage is the lowest cut off the effect is good, but not wear and poor reliability. From leakage and small, sealed double standards and reliable, soft sealing off sealing off the good as hard. Such as full-featured ultra-light valve, seal and protect the heap are resistant alloys, high reliability, leakage rate of 10-7, has been able to satisfy the requirements of cut off valves. 8, why replace the single sleeve valve, two-seat valve has not got his wish? Come out of the sleeve valve 60's, 70's heavy use at home and abroad, introduction of 80 petrochemical plants in the sleeve valve, the proportion greater then, many people think that the sleeve valve can replace a single, two-seat valve , a second-generation products. By now, it is not the case, single-seat valve, double seat valves, sleeve valves have been the same use. This is because only improved throttle valve sleeve form, stability, and safeguard the single seat valve, but it is weight, aiming to halt and leakage targets with single, double seat valve line, how can it replace the single, double seat valves what? Therefore, it can only be shared. 9, Why is that selection is more important than the calculation? Calculations and selection of comparison, the selection to be far more important to far more complex. Because the calculation is a simple formula, which in itself is not the accuracy of the formula, but inAPI Cast Steel Valves the given parameters is accurate. More related to the content selection, a little careless, would lead to selection of inappropriate, not only causes human, material and financial resources of the waste, and use the results not satisfactory, bring some use, such as reliability, life, running Quality and so on. 10, why in the pneumatic piston valve actuator using more and more? The pneumatic valve, the piston actuator can take advantage of the pressure gas source, the executing agency of the size smaller than the diaphragm, greater thrust, piston O-ring in reliable than film, so its use will become increasingly more.

原文来源：http://www.1zhafa.com/

2010-07-29 06:58

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