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、焊接等确定操作阀门的方式：手动、电动、电磁、气动或液动、电液联动等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：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。选择阀门的种类：闭路阀门、调节阀门、阀门等确定阀门的型式：闸阀、截止阀、球阀、蝶阀、节流阀、阀、减压阀、蒸汽疏水阀等确定阀门的参数：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三、选择阀门的依据

Clarify the purpose of the valve in the equipment or device, determine the working conditions of the valve: applicable medium, working pressure, working temperature, etc. Determine the nominal diameter and connection method of the pipeline connected to the valve: flange, thread, welding, etc. Determine the operation method of the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electro-hydraulic linkage, etc. Based on the medium transported by the pipeline, working pressure, working temperature, etc. Determine the materials of the selected valve's shell and internal components: cast steel, carbon steel, stainless steel, alloy steel, stainless acid resistant steel, gray cast iron, malleable cast iron, ductile iron, copper alloy, etc. Selection of valve types: closed circuit valve, regulating valve, safety valve, etc. Determine the type of valve: gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, steam trap valve, etc. Determine the parameters of the valve: For automatic valves, first determine the allowable flow resistance, discharge capacity, back pressure, etc. according to different needs, and then determine the nominal diameter of the pipeline and the diameter of the valve seat hole. Determine the geometric parameters of the selected valve: structural length, flange connection form and size, size of the valve height direction after opening and closing, size and quantity of connecting bolt holes, and overall external size of the valve. Utilize existing information: valve product catalog, valve product samples, etc. Select appropriate valve products. III. Basis for selecting valves

所选用阀门的用途、使用工况条件和操纵控制方式工作介质的性质：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、大和小流量要求、正常流动的压力降、关闭时的压力降、阀门的大和小进口压力。)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。

The purpose, operating conditions, and control method of the selected valve. The properties of the working medium include working pressure, working temperature, corrosion performance, whether it contains solid particles, whether the medium is toxic, whether it is flammable or explosive, and the viscosity of the medium. The requirements for the fluid characteristics of the valve include flow resistance, discharge capacity, flow characteristics, sealing level, etc. Installation dimensions and external dimensions requirements include nominal diameter, connection method and size with the pipeline, external dimensions or weight limitations. Additional requirements for the reliability, service life, and explosion-proof performance of the valve product and the electric device must be determined. When selecting parameters, attention should be paid to: if the valve is to be used for control purposes, the following additional parameters must be determined: operating method, large and small flow requirements, pressure drop for normal flow, closing. According to the above criteria and steps for selecting valves, it is necessary to have a detailed understanding of the internal structure of various types of valves in order to make the right decision on the preferred valve.

管道的终控制是阀门。阀门启闭件控制着介质在管道内的流向方式，阀门流道的形状使阀门具备一定的流量特性，在选择管道系统适合安装的阀门时必须考虑到这一点。

The final control of pipelines is valves. The valve opening and closing components control the flow direction of the medium in the pipeline, and the shape of the valve flow channel gives the valve certain flow characteristics. When selecting a valve suitable for installation in the pipeline system, this must be considered.

正确选用阀门的意义

The significance of correctly selecting valves

正确选用阀门，对保证装置生产，提高阀门使用寿命，满足装置长周期运行是关重要的。许多阀门事故的主要原因是阀门选用不当，如在寒冷地区使用了铸铁阀门，因油中含水积于阀体中，冬季结冰很容易冻裂阀门。在一些泵体出口阀门中，由于某些原因，所需流程较低而用泵功率较大的场合，常常采用管小闸阀来调节流量的方法，由于闸阀板局部打开，产生振动，加速了闸板与阀座密封表面的磨损，很容易造成阀门的泄露。另外，阀门质量的好坏对生产使用也有很大影响。

The correct selection of valves is crucial for ensuring the safe production of the device, improving the service life of valves, and meeting the long-term operation of the device. The main cause of many valve accidents is improper valve selection, such as using cast iron valves in cold areas. Due to the accumulation of water in the oil in the valve body, the valve is prone to freezing and cracking during winter. In some pump outlet valves, due to certain reasons, small pipe gate valves are often used to regulate flow in situations where the required process is low and the pump power is high. Due to the local opening of the gate valve plate, vibration is generated, which accelerates the wear of the sealing surface between the gate plate and the valve seat, making it easy to cause valve leakage. In addition, the quality of valves also has a significant impact on production and use.

如某化肥厂发生特大爆炸事故，事故原因查明，是一起由阀门存在严重质量问题造成的责任事故。爆炸原因是：二段出口阀门承受不住正常工作压力突然爆裂，止回阀失灵，系统内0.75MPa的半水煤气迅速溢出，与周围空气混合形成爆炸性气体空间，发生气体化学爆炸。据检测该阀门有多项指标不符合有关标准。另外，这两种均为以水、蒸汽和油类为介质的阀门，非可燃气体专用阀门，设计部门选型也是错误的。因此，正确选择阀门对装置生产、、长周期运行，提率都显得非常重要。

If a major explosion accident occurs in a fertilizer plant, the cause of the accident is determined to be a responsibility accident caused by serious quality issues with the valve. The cause of the explosion was that the second stage outlet valve could not withstand normal working pressure and suddenly burst, causing the check valve to malfunction. The 0.75MPa semi water gas in the system quickly overflowed and mixed with the surrounding air to form an explosive gas space, resulting in a gas chemical explosion. According to testing, multiple indicators of the valve do not meet the relevant national standards. In addition, both of these are valves that use water, steam, and oil as media, and are non combustible gas specific valves. The design department's selection was also incorrect. Therefore, the correct selection of valves is crucial for device production, safety, long-term operation, and improving efficiency.