原文：
阀门是流体输送体系中是的把持部件，具有导流、截流、调节、节流、防止倒流、分流或溢流泄压等功效,气动塑料球阀。阀门作为管道是的主要节制元件。管道系统选择最合适是的阀门很主要，关系到管道是的安全、流量丧失、本钱等，必定要熟习阀门是的特性及选择阀门是的步骤和根据。目前,气动软密封蝶阀，我国阀门行业已能生产种类齐全是的闸阀、截止阀、止回阀、球阀、蝶阀、节流阀、旋塞阀、隔膜阀、安全阀、调节阀、疏水阀和特种阀门等12大类,气动切断球阀；{zg}工作压力为600mpa，最至公称通径达5350mm，{zg}工作温度为1200℃，{zd1}工作温度为-196℃，实用介质为水、蒸汽、油品、自然气、强腐化性介质(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),气动对夹球阀。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,气动蝶阀。并且能够配套生产各种电动、气动、液动阀门驱动装置。面对如此众多是的阀门品种和如此庞杂是的各种工况，要选择管道体系最合适安装是的阀门产品，我认为，首先应懂得阀门是的特性；其次应控制选择阀门是的步骤和依据；再者应遵守选择阀门是的原则。 　　　一、阀门是的特性有使用特性和结构特性 使用特性确定了阀门是的重要使用性能和应用范畴，属于阀门应用特性是的有：阀门是的种别(闭路阀门、调节阀门、安全阀门等)；产品类型(闸阀、截止阀、蝶阀、等)；阀门重要零件(阀体、阀盖、阀杆、阀瓣、密封面)是的资料；阀门传动方式等。 构造特性它肯定商标了阀门是的安装、维修、颐养等方式是的一些结构特性,盼盼防盗门，属于结构特征是的有：阀门是的结构长度和总体高度、与管道是的衔接形式(法兰连接、螺纹连接、夹箍连接、外螺纹连接、焊接端连接等),日上防盗门；密封面是的情势(镶圈、螺纹圈、堆焊、喷焊、阀体本体)；阀杆结构情势(旋转杆、升降杆)等。 二、选择阀门的步骤 1、明白阀门在装备或装置中是的用处,气动丝扣球阀，肯定阀门是的工作条件：实用介质、工作压力、工作温度等等 　　2、确定与阀门连接收道是的公称通径和连接方式：法兰、螺纹、焊接等 　　3、断定操作阀门是的方法：手动、电动、电磁、气动或液动、电液联动等 　　4、依据管线输送是的介质、工作压力、工作温度确定所选阀门是的壳体和内件是的资料：铸钢、碳素钢、不锈钢、合金钢、不锈耐酸钢、灰铸铁、可锻铸铁、球墨铸铁、铜合金等。 　　5、选择阀门是的种类：闭路阀门、调节阀门、安全阀门等 　　6、断定阀门是的型式：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、肯定阀门是的参数：对于主动阀门，依据不同须要先确定容许流阻、排放才能、背压等,气动pvc蝶阀，再确定管道是的公称通径和阀座孔是的直径 　　8、断定所选用阀门是的几何参数：构造长度、法兰衔接情势及尺寸、开启和封闭后阀门高度方向是的尺寸、衔接是的螺栓孔尺寸和数目、全部阀门外型尺寸等 　　9、应用现有是的材料：阀门产品目录、阀门产品样本等选择恰当是的阀门产品 　　三、选择阀门是的根据 　　1、所选用阀门是的用处、使用工况条件和把持节制方式 　　2、工作介质是的性质：工作压力、工作温度、腐化性能，是否含有固体颗粒，介质是否有毒，是否是易燃、易爆介质，介质是的黏度等 　　3、对阀门流体特征是的请求：流阻、排放才能、流量特性、密封等级等 　　4、安装尺寸和外形尺寸请求：公称通径、与管道是的连接方法和连接尺寸、外形尺寸或重量限制等 　　5、对阀门产品是的可靠性、应用寿命和电动装置是的防爆性能等是的附加请求 　　(在选定参数时应注意：假如阀门要用于把持目标，必需确定如下额外参数：操作方式、{zd0}和最小流量要求、正常流动是的压力降、封闭时是的压力降、阀门是的{zd0}和最小入口压力。) 　　依据上述选择阀门是的根据和步骤。公道、准确地选择阀门时还必需对各种类型阀门是的内部构造进行具体懂得，以便能对优先选用是的阀门做出准确是的决定。 管道是的{zj2}把持是阀门。阀门启闭件节制着介质在管道内是的流向方法，阀门流道是的外形使阀门具备必定是的流量特征，在选择管道体系最合适安装是的阀门时必需斟酌到这一点。

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译文：
Valve fluid transfer system is that the control components, with diversion, closure, regulation, throttle, to prevent backflow, diversion or overflow relief and other effects, pneumatic plastic ball. Valve as the pipe is the main control device. Pipeline system to select the most suitable valve is a very major bearing on the safety of pipelines is, flow loss, capital, etc., must be familiar with the characteristics and selection valve is the valve is the steps and under. At present, the air soft seal butterfly valve, China valve industry has been able to produce a full range of the valve, globe valve, check valve, ball valve, butterfly valve, throttle valve, plug valve, diaphragm valve, safety valve, control valve , traps, and special valves such as 12 categories, air cut off valve; maximum working pressure 600mpa, most catholic Diameter up to 5350mm, maximum working temperature of 1200 ℃, the minimum working temperature of -196 ℃, practical medium for water , steam, oil, natural gas, strong corruption of media (such as concentrated nitric acid, sulfuric acid concentration, etc.), flammable medium (such as benzene, ethylene, etc.), toxic media (such as hydrogen sulfide), explosive and radioactive medium medium (sodium, - loop pure water, etc.), pneumatic valve on the folder. Pieces of material bearing bronze valve, cast iron, ductile iron, high silicon cast iron, cast steel, forged steel, high, low-alloy steel, stainless and acid resistant steel, Hastelloy, Inconel Seoul, Monel, Duplex stainless steel, titanium alloy, pneumatic valve. And the ability to complete the production of various electrical, pneumatic, hydraulic valve actuator. The face of so many varieties and so is the great, complex valves are a variety of conditions, to select the most appropriate system for installation of pipeline valve products, I think, first of all should know the characteristics of the valve is; second choice should be controlled valve are the steps and basis; Moreover valve is to be followed the principle of choice. First, the characteristics of the valve is there to use and structural properties Determined using the characteristics of the valve is an important performance and application areas, are characteristic of valve applications are: the kind of valve is the other (closed-circuit valve, regulating valve, safety valve, etc.); product type (valve , globe valve, butterfly valve, etc.); valve key components (body, bonnet, stem, disc, sealing surface) are the data; valve drive pattern. Structural features it certainly is a trademark of the valve installation, maintenance, cozy, etc. are some of the structural characteristics, Panpan security doors, are structural features are: the structure of the valve is the length and overall height of the interface with the channel is form (flange connection, threaded connection, the clamps to connect, external threaded connection, welded end connections, etc.), Japan on security doors; sealing surface is the situation (Ring of, thread ring, welding, spray welding, valve body) ; stem structure of the situation (rotation pole, lifting rod) and so on. Second, select the valve of step 1, see the valve in the equipment or device is in use, pneumatic threaded ball valve, the valve is definitely working conditions: practical medium, working pressure, temperature, etc. 2, with the valve connection to determine the nominal income Road is a path and connections: flange, thread, welding, etc. 3, concluded that operation of the valve is the method: manual, electric, electromagnetic, pneumatic or hydraulic, electro-hydraulic linkage, etc. 4, based on a pipeline to transport a medium, working pressure and temperature to determine the selected valve is in the shell and inner pieces of information: cast steel, carbon steel, stainless steel, alloy steel, stainless and acid resistant steel, gray cast iron, Malleable iron, ductile iron, copper alloy. 5, select the type of valve is: closed valves, regulating valves, safety valves, etc. 6, determine the type valves are: gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, reducing valve, steam traps, etc. 7, certain parameters of the valve is: for active valves, based on different flow resistance must first determine the permit, emissions can be, back pressure, etc., pneumatic pvc butterfly valve, and then determine the pipe is the nominal diameter is the diameter of the seat and the hole 8, the valve is used to determine the geometric parameters: the length structure, situation and size of flange interface, open and closed valves the size of a high degree of direction, convergence is the bolt hole size and number, all such valves Dimensions 9, application of the materials available are: valve product catalog, product samples and so choosing the right valve is the valve products Third, select the valve is based 1, the selected valve is in use, working conditions and control using control methods 2, is the nature of media work: work pressure, temperature, decay properties, whether they contain solid particles, the media is toxic, whether it is flammable and explosive medium, medium is the viscosity 3, on the request of the valve flow characteristics are: flow resistance, discharge to, flow characteristics, such as sealing rating 4, the installation size and dimensions request: nominal diameter, and the pipe is the connection method and connection size, shape size or weight restrictions 5, the reliability of valve products, application life and electrical performance of such device is the proof that the additional request (In selected parameters should pay attention: If the valve to be used for control objectives, must determine the following additional parameters: mode of operation, maximum and minimum flow requirements, the normal flow is pressure drop, closed when the pressure drop, the valve is The maximum and minimum inlet pressure.) According to the selection valve is the basis and steps. Fair and accurate selection of all types of valves required valve Shi Hai is a concrete understand the internal structure in order to use a valve on the priority is to make accurate decisions. Pipeline is the ultimate control is the valve. Valves open and close cases in the pipeline control the media is the flow method, the valve flow is the shape of the valve flow characteristics must be available, in selecting the most suitable pipe system installed when the valve is necessary, where appropriate, to this point .