译文：
在流体管道系统中，阀门是控制元件，其主要作用是隔离设备和管道系统、调节流量、防止回流、调节和排泄压力。由于管道系统选择最适合的阀门显得非常重要，所以，了解阀门的特性及选择阀门的步骤和依据也变得至关重要起来。 阀门行业到目前为止，已能生产种类齐全的闸阀、截止阀、节流阀、旋塞阀、球阀、电动阀、隔膜阀、止回阀、安全阀、减压阀、蒸汽疏水阀和紧急切断阀等12大类、3000多个型号、4000多个规格的阀门产品；{zg}工作压力为600MPa，{zd0}公称通径达5350mm，{zg}工作温度为1200℃，{zd1}工作温度为-196℃，适用介质为水、蒸汽、油品、天然气、强腐蚀性介质（如浓硝酸、中浓度硫酸等）、易燃介质（如笨、乙烯等）、有毒介质（如硫化氢）、易爆介质及带放射性介质（金属钠、-回路纯水等）。阀门承压件材质铸铜、铸铁、球墨铸铁、高硅铸铁、铸钢、锻钢、高、低合金钢、不锈耐酸钢、哈氏合金、因科镍尔、蒙乃尔合金、双相不锈钢、钛合金等。并且能够生产各种电动、气动、液动阀门驱动装置。面对如此众多的阀门品种和如此复杂的各种工况，要选择管道系统最适合安装的阀门产品，我以为，首先应了解阀门的特性；其次应掌握选择阀门的步骤和依据；再者应遵循选择阀门的原则。 1．阀门的特性一般有两种，使用特性和结构特性。 使用特性：它确定了阀门的主要使用性能和使用范围，属于阀门使用特性的有：阀门的类别（闭路阀门、调节阀门、安全阀门等）；产品类型（闸阀、截止阀、蝶阀、球阀等）；阀门主要零件（阀体、阀盖、阀杆、阀瓣、密封面）的材料；阀门传动方式等。 结构特性：它确定了阀门的安装、维修、保养等方法的一些结构特性，属于结构特性的有：阀门的结构长度和总体高度、与管道的连接形式（法兰连接、螺纹连接、夹箍连接、外螺纹连接、焊接端连接等）；密封面的形式（镶圈、螺纹圈、堆焊、喷焊、阀体本体）；阀杆结构形式（旋转杆、升降杆）等。 2．选择阀门的步骤和依据大体如下： ⑴ 选择步骤 ① 明确阀门在设备或装置中的用途，确定阀门的工作条件：适用介质、工作压力、工作温度等等。 ② 确定与阀门连接管道的公称通径和连接方式：法兰、螺纹、焊接等。 ③ 确定操作阀门的方式：手动、电动、电磁、气动或液动、电气联动或电液联动等。 ④ 根据管线输送的介质、工作压力、工作温度确定所选阀门的壳体和内件的材料：灰铸铁、可锻铸铁、球墨铸铁、碳素钢、合金钢、不锈耐酸钢、铜合金等。 ⑤ 选择阀门的种类：闭路阀门、调节阀门、安全阀门等。 ⑥ 确定阀门的型式：闸阀、截止阀、球阀、蝶阀、节流阀、安全阀、减压阀、蒸汽疏水阀、等。 ⑦ 确定阀门的参数：对于自动阀门，根据不同需要先确定允许流阻、排放能力、背压等，再确定管道的公称通径和阀座孔的直径。 ⑧ 确定所选用阀门的几何参数：结构长度、法兰连接形式及尺寸、开启和关闭后阀门高度方向的尺寸、连接的螺栓孔尺寸和数量、整个阀门外型尺寸等。 ⑨ 利用现有的资料：阀门产品目录、阀门产品样本等选择适当的阀门产品。 ⑵ 选择阀门的依据 在了解掌握选择阀门步骤的同时，还应进一步了解选择阀门的依据。 ① 所选用阀门的用途、使用工况条件和操纵控制方式。 ② 工作介质的性质：工作压力、工作温度、腐蚀性能，是否含有固体颗粒，介质是否有毒，是否是易燃、易爆介质，介质的黏度等等。 ③ 对阀门流体特性的要求：流阻、排放能力、流量特性、密封等级等等。 ④ 安装尺寸和外形尺寸要求：公称通径、与管道的连接方式和连接尺寸、外形尺寸或重量限制等。 ⑤ 对阀门产品的可靠性、使用寿命和电动装置的防爆性能等的附加要求。 （在选定参数时应注意：如果阀门要用于控制目的，必须确定如下额外参数：操作方法、{zd0}和最小流量要求、正常流动的压力降、关闭时的压力降、阀门的{zd0}和最小进口压力。） 根据上述选择阀门的依据和步骤，合理、正确地选择阀门时还必须对各种类型阀门的内部结构进行详细了解，以便能对优先选用的阀门做出正确的抉择。 管道的最终控制是阀门。阀门启闭件控制着介质在管道内的流束方式，阀门流道的形状使阀门具备一定的流量特性，在选择管道系统最适合安装的阀门时必须考虑到这一点。 如下为选择阀门应遵循的原则： ⑴ 截止和开放介质用的阀门 流道为直通式的阀门，其流阻较小，通常选择作为截止和开放介质用的阀门。向下闭合式阀门（截止阀、柱塞阀）由于其流道曲折，流阻比其他阀门高，故较少选用。在允许有较高流阻的场合，可选用闭合式阀门。 ⑵ 控制流量用的阀门 通常选择易于调节流量的阀门作为控制流量用。向下闭合式阀门（如截止阀）适于这一用途，因为它的阀座尺寸与关闭件的行程之间成正比关系。旋转式阀门（旋塞阀、蝶阀、球阀）和挠曲阀体式阀门（夹紧阀、隔膜阀）也可用于节流控制，但通常只能在有限的阀门口径范围内适用。闸阀是以圆盘形闸板对圆形阀座口做横切运动，它只有在接近关闭位置时，才能较好地控制流量，故通常不用于流量控制。 ⑶ 换向分流用的阀门 根据换向分流的需要，这种阀门可有三个或更多的通道。旋塞阀和球阀较适用于这一目的，因此，大部分用于换向分流的阀门都选取这类阀门中的一种。但是在有些情况下，其他类型的阀门，只要把两个或更多个阀门适当地相互连接起来，也可作换向分流用。 ⑷ 带有悬浮颗粒的介质用阀门 当介质中带有悬浮颗粒时，最适于采用其关闭件沿密封面的滑动带有擦拭作用的阀门。如果关闭件对阀座的来回运动是竖直的，那末就可能夹持颗粒，因此这种阀门除非密封面材料可以允许嵌入颗粒，否则只适用于基本清洁的介质。球阀和旋塞阀在启闭过程中对密封面均有擦拭作用，故适宜用在带有悬浮颗粒的介质中。 目前，无论在石油、化工，还是在别的行业的管道系统，阀门应用、操作频率和服务千变万化，要控制或杜绝那怕是低微的泄漏，最重要、最关键的设备还数阀门。管道的最终控制是阀门，阀门在各个领域的服务和可靠表现是{dywe}的。

“ The importance of pipeline valves ”是由提供的国际阀门新闻，译文仅供参考。另外，中国止回阀网还提供相关产品搜索：、、、、等。

原文：
In fluid piping systems, valves to control the components, whose main role is to isolate equipment and piping systems to regulate the flow, to prevent the return of the pressure regulation and excretion. Because the pipeline system to select the most suitable valve is very important, therefore, to understand the characteristics of the valve and choose the valve becomes essential steps and based on them. Valve industry so far has been able to produce the full range of gate valve, globe valve, throttle valve, plug valves, ball valves, electric valves, diaphragm valves, check valve, safety valve, pressure reducing valve, steam trap and emergency shut-off valve in 12 categories, over 3000 models, more than 4000 specifications of valve products; maximum working pressure of 600MPa, the largest nominal diameter up to 5350mm, maximum operating temperature of 1200 ℃, the lowest operating temperature of -196 ℃, for medium is water, steam, oil, natural gas, strong corrosive media (such as concentrated nitric acid, sulfuric acid concentration, etc.), flammable medium (such as stupid, ethylene, etc.), toxic medium (such as hydrogen sulfide), explosive media and radioactive medium (metallic sodium, - loop pure water, etc.). Pieces of material cast copper pressure valve, cast iron, ductile iron, high silicon cast iron, cast steel, forged steel, high, low-alloy steel, stainless acid-resistant steel, Hastelloy, Inconel Seoul, Monel, Duplex stainless steel, titanium alloy and so on. And can produce a variety of electric, pneumatic and hydraulic valve actuators. The valve face of so many varieties and such a complex variety of working conditions, to select the most suitable for piping system valve product, I think, first of all should understand the characteristics of the valve; Secondly, we should master the steps and the basis for selection of the valve ; Furthermore, the valve should follow the principle of choice. 1. There are two general characteristics of the valve, use the properties and structural characteristics. The use of features: it identifies the main use of the valve performance and the use of the scope of the use of properties belonging to the valve are: valve type (closed valves, regulating valves, safety valves, etc.); product type (valve, cut-off valve, butterfly valve, ball valve, etc.); valve main parts (valve, valve cover, valve stem, valve flap, sealing surface) of the material; valve drive pattern. Structural characteristics: it identifies the valve installation, repair, maintenance and other methods some of the structural characteristics, belonging to structural characteristics are: the length of the valve structure and overall height, and piping connections form (flange connection, threaded connection, clip hoop connection, external threaded connection, welding end connections, etc.); sealing surface of the form (inlay ring, thread ring, welding, spray welding, valve body); stem structure (rotation pole, lifting rod) and so on. 2. Select Valve steps and based on general as follows: ⑴ Select Step ① valve in the device or devices specifically in the use of the valve to determine the working conditions: for medium, working pressure, working temperature and so on. ② connecting pipes and valves to determine the nominal path and connections: flange, thread, welding and so on. ③ determine the operation of the valve mode: manual, electric, electromagnetic, pneumatic or hydraulic, electrical or electro-hydraulic linkage, etc. linkage. ④ According to pipeline transportation of the medium, working pressure, working temperature to determine the selection of the valve housing and internal parts of the material: gray cast iron, malleable iron, ductile iron, carbon steel, alloy steel, stainless acid-resistant steel, copper alloy. ⑤ Select the type of valve: closed valves, regulating valves, safety valves and so on. ⑥ determine the type of valve: gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, steam trap, et al. ⑦ determine the parameters of the valve: For automatic valves, depending on the need to determine the permitted flow resistance, discharge capacity, back pressure and so on, and then determine the nominal pipe diameter and the valve seat hole diameter. ⑧ determine the choice of geometric parameters of the valve: the structure length, flange connection form and size, opening and closing the valve after the height of the direction of the size of the connection bolt hole size and quantity, the entire valve dimensions and so on. ⑨ use of existing information: valve product catalog, product samples and other valves select the appropriate valve products. ⑵ the basis for selection valve Understand the steps in the selection valve while the valve should be the basis for a better understanding of choice. ① the selected use of the valve, use the working conditions and manipulation control mode. ② working fluid in nature: working pressure, temperature, corrosion, whether they contain solid particles, medium is toxic, whether it is flammable, explosive medium, the medium viscosity and so on. ③ The valve flow characteristics requirements: flow resistance, discharge capacity, flow characteristics, sealing rating and so on. ④ Install size and form factor requirements: nominal diameter, and pipe connections and connection size, shape size or weight restrictions. ⑤ of the valve product reliability, service life and performance of explosion-proof electrical equipment such as additional requirements. (In the selected parameters should pay attention: If the valve to be used for control purposes, we must determine the following additional parameters: methods of operation, maximum and minimum flow requirements, the normal flow of the pressure drop, shut down when the pressure drop, the valve of the largest and Minimum inlet pressure.) Based on the above basis and procedures for selection of the valve, reasonable, correct selection of the valve must also be of various types of valves to learn more about the internal structure so that the preferred valve can make the right choices. Pipeline is the ultimate control valve. Valves open and close control of the media pieces in the pipeline within the jet way, the shape of the valve flow channel so that the valve have a certain flow characteristics, in selecting the most suitable for piping system must be considered when the valve into it. The valve should be followed for the selection of the following principles: ⑴ medium used for closing and opening the valve Flow channel for the straight-through valve, its flow resistance small, often choose to use as a cut-off valve and open media. Closed down valve (cut-off valve, plunger valve) because of its tortuous flow channel, flow resistance than other valves, hence less use. Allowing a higher flow resistance of the occasion, the choice of closed-type valve. ⑵ control flow valve used in Often choose easy-to-adjust flow valve used as the control flow. Closed down valve (such as the cut-off valve) is suitable for this purpose because of its size and close the valve seat between the pieces of the trip is proportional to the relationship. Rotary valve (plug valves, butterfly valve, ball valve) and the deflection valve type valve (clamp valves, diaphragm) can also be used for throttle control, but usually only in a limited range of the valve diameter to apply. Gate valve is a disc-shaped gate cross-section of the circular seat I do exercise, it is only near the closed position, in order to better control traffic, it is not normally used for flow control. ⑶ reversing valve used to divert According to the need for change to the diversion, this valve may have three or more channels. Plug valves and ball valves are more applicable to this purpose, therefore, mostly used for the shunt valve is selected in one of these valves. However, in some cases, other types of valves, as long as two or more valves connected to each other properly, but also can be used for the diversion to use. ⑷ media with suspended particles with valve When the medium with suspended particles, the most appropriate use of its off pieces along the sealing surface of the slide valve with a wipe effect. If you turn off parts of the seat back and forth movement is vertical, and then may be gripping grain, so the valve sealing surface material can be allowed unless the embedded particles, or only applies to basic cleaning of the media. Ball and plug valves in the open and close during the course of both the sealing surface cleaning effect, it is suitable for use in the medium with suspended particles. At present, both in petroleum, chemical, or in another trade piping system, valves applications, operating frequency and service the ever-changing, it is necessary to control or eliminate even the low-leakage, the most important, the most critical devices also the number of valves. The ultimate control is the pipeline valves, valves in various fields of service and reliable performance is unique.