译文：
阀门的流量系数和气蚀系数是阀的重要参数，这在先进工业国家生产的阀门资料中一般均能提供，甚至在样本里也印出。我国生产的阀门基本上没有这方面资料，因为取得这方面的资料需要做实验才能提出，这是我国和世界先进水平的阀门差距的重要表现之一。? 阀门的流量系数? 阀门的流量系数是衡量阀门流通能力的指标，流量系数值越大，说明流体流过阀门时的压力损失越小。? 按KV值计算式 式中：KV—流量系数?? Q—体积流量m3/h? ΔP—阀门的压力损失bar? P—流体密度kg/m3?? 阀门的气蚀系数? 用气蚀系数δ值，来选定用作控制流量时，选择什么样的阀门结构型式。 式中：H1—阀后(出口)压力m? H2—大气压与其温度相对应的饱和蒸气压力之差m? ΔP—阀门前后的压差m? 各种阀门由于构造不同，因此，允许的气蚀系数δ也不同。如图所示。如计算的气蚀系数大于容许气蚀系数，则说明可用，不会发生气蚀。如蝶阀容许气蚀系数为2.5，则：? 如δ＞2.5，则不会发生气蚀。? 当2.5＞δ＞1.5时，会发生轻微气蚀。? δ＜1.5时，产生振动。? δ＜0.5的情况继续使用时，则会损伤阀门和下游配管。 阀门的基本特性曲线和操作特性曲线，对阀门在什么时候发生气蚀是看不出来的，更指不出来在那个点上达到操作极限。通过上述计算则一目了然。所以产生气蚀，是因为液体加速流动过程中通过一段渐缩断面时，部分液体气化，产生的气泡随后在阀后开阔断面炸裂，其表现有三：? (1)发生噪声? (2)振动(严重时可造成基础和相关构筑物的破坏，产生疲劳断裂)? (3)对材料的破坏(对阀体和管道产生侵蚀)? 再从上述计算中，不难看出产生气蚀和阀后压强H1有极大关系，加大H1显然会使情况改变，改善方法：? a.把阀门安装在管道较低点。 b.在阀门后管道上装孔板增加阻力。? c.阀门出口开放，直接蓄水池，使气泡炸裂的空间增大，气蚀减小。? 综合上述的分析、探讨，归纳起来对闸阀、蝶阀主要特点和参数列表便于选用。两个重要参数在阀门运用中。
“ Valve applications need to pay attention to two important parameters ”是由中国气动阀门网提供的国际阀门新闻，译文仅供参考。另外，中国气动阀门网还提供相关产品搜索：气动阀门型号、气动阀门价格、气动阀门技术、气动阀门新闻、气动阀门生产商等。
原文：
The valve flow coefficient and gas-loss coefficient of valve important parameter, which in the advanced industrial countries the production of valves of information generally can provide, even in the samples of are also printed. China's production of the valve is basically no information in this regard, since access to information in this regard need to do experiments in order to put forward, this is ourFilter country and the world advanced level in the valve gap between the major manifestations. ? The valve flow coefficient ? Of the valve flow coefficient is a measure of the valve flow capacity of the indicators, flow coefficient greater, indicating fluid flow through the valve when the pressure loss smaller. ? By KV value calculation formula Where: KV-flow coefficient ? ? Q-volumetric flow rate m3 / h ? ΔP-valve pressure loss in bar ? P-fluid density, kg/m3 ? ? Valve cavitation coefficient ? With the cavitation coefficient δ values, to select as a control flow, choose what kind of valve structure type. Formula: H1-valve after (exit) pressure m ? H2-atmospheric pressure with the temperature corresponding to the saturated vapor pressure difference m ? ΔP-valve before and after the pressure m ? A variety of valves due to structural differences, therefore, permissible cavitation coefficient δ is also different. As shown. Such as the calculation of cavitation coefficient isBellow Seal Valves larger than allowed cavitation coefficient, then available, does not occur cavitation. Such as the butterfly valve to allow cavitation coefficient is 2.5, then: ? If δ> 2.5, will not occur cavitation. ? When the 2.5> δ> 1.5 when a minor cavitation. ? δ <1.5, the resulting vibrations. ? δ <0.5 the situation continues to use, it will damage the valve and downstream piping. Valve basic characteristics curve and operating characteristic curve, right valve at what time of the cavitation is not apparent, but that does not come out at that point to reach operational limits. Through the above calculation is clear. Therefore generate cavitation, because the liquid accelerating flow process through a tapered section, some of the liquid gasification, the resulting bubbles followed by valve after the open cross-section burst, their performance has three: ? (1) took place the noise ? (2) Vibration (in severe cases may result in the foundation and related structures destroyed, resulting in fatigue fracture) ? (3) the material damage Automatic Control Valves (to the valve body and pipe corrosion) ? And then from the above calculation, it is easy to see produce cavitation and valve after the pressure of H1 have great relationships, increase H1 obviously make the situation change, ways of improvement: ? a. the valve installed in the pipeline much lower. b. In the valve, piping coat plates increased resistance. ? c. valve outlet open, direct reservoir, so that bubble burst of space increases, cavitation decreases. ? The above analysis, study, sum up to the gate valve, butterfly valve main features and list of parameters easy to use. Two important parameters in the valve in operation.
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