明確閥門在設備或裝置中的用途，確定閥門的工作條件：適用介質、工作壓力、工作溫度等等確定與閥門連接管道的公稱通徑和連接方式：法蘭、螺紋、焊接等確定操作閥門的方式：手動、電動、電磁、氣動或液動、電液聯動等根據管線輸送的介質、工作壓力、工作溫度確定所選閥門的殼體和內件的材料：鑄鋼、碳素鋼、不銹鋼、合金鋼、不銹耐酸鋼、灰鑄鐵、可鍛鑄鐵、球墨鑄鐵、銅合金等。選擇閥門的種類：閉路閥門、調節閥門、閥門等確定閥門的型式：閘閥、截止閥、球閥、蝶閥、節流閥、閥、減壓閥、蒸汽疏水閥等確定閥門的參數：對于自動閥門，根據不同需要先確定允許流阻、排放能力、背壓等，再確定管道的公稱通徑和閥座孔的直徑確定所選用閥門的幾何參數：結構長度、法蘭連接形式及尺寸、開啟和關閉后閥門高度方向的尺寸、連接的螺栓孔尺寸和數量、整個閥門外型尺寸等利用現有的資料：閥門產品目錄、閥門產品樣本等選擇適當的閥門產品三、選擇閥門的依據

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

所選用閥門的用途、使用工況條件和操縱控制方式工作介質的性質：工作壓力、工作溫度、腐蝕性能，是否含有固體顆粒，介質是否有毒，是否是易燃、易爆介質，介質的黏度等對閥門流體特性的要求：流阻、排放能力、流量特性、密封等級等安裝尺寸和外形尺寸要求：公稱通徑、與管道的連接方式和連接尺寸、外形尺寸或重量限制等對閥門產品的可靠性、使用壽命和電動裝置的防爆性能等的附加要求(在選定參數時應注意：如果閥門要用于控制目的，必須確定如下額外參數：操作方法、大和小流量要求、正常流動的壓力降、關閉時的壓力降、閥門的大和小進口壓力。)根據上述選擇閥門的依據和步驟，合理、正確地選擇閥門時還必須對各種類型閥門的內部結構進行詳細了解，以便能對優先選用的閥門做出正確的抉擇。

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.

管道的終控制是閥門。閥門啟閉件控制著介質在管道內的流向方式，閥門流道的形狀使閥門具備一定的流量特性，在選擇管道系統適合安裝的閥門時必須考慮到這一點。

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.

正確選用閥門的意義

The significance of correctly selecting valves

正確選用閥門，對保證裝置生產，提高閥門使用壽命，滿足裝置長周期運行是關重要的。許多閥門事故的主要原因是閥門選用不當，如在寒冷地區使用了鑄鐵閥門，因油中含水積于閥體中，冬季結冰很容易凍裂閥門。在一些泵體出口閥門中，由于某些原因，所需流程較低而用泵功率較大的場合，常常采用管小閘閥來調節流量的方法，由于閘閥板局部打開，產生振動，加速了閘板與閥座密封表面的磨損，很容易造成閥門的泄露。另外，閥門質量的好壞對生產使用也有很大影響。

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.

如某化肥廠發生特大爆炸事故，事故原因查明，是一起由閥門存在嚴重質量問題造成的責任事故。爆炸原因是：二段出口閥門承受不住正常工作壓力突然爆裂，止回閥失靈，系統內0.75MPa的半水煤氣迅速溢出，與周圍空氣混合形成爆炸性氣體空間，發生氣體化學爆炸。據檢測該閥門有多項指標不符合有關標準。另外，這兩種均為以水、蒸汽和油類為介質的閥門，非可燃氣體專用閥門，設計部門選型也是錯誤的。因此，正確選擇閥門對裝置生產、、長周期運行，提率都顯得非常重要。

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.