良工閥門作為流體控制系統的關鍵部件，其選型是否合理直接影響管道系統的運行效率、安全性與使用壽命。選購時需綜合考慮應用場景、介質特性、壓力溫度等因素，從類型、材質、參數到性能驗證，每一步都需精準匹配，才能確保閥門在長期使用中發揮穩定作用，避免因選型不當導致泄漏、堵塞或損壞等問題。

　　As a key component of fluid control systems, the selection of Lianggong valves directly affects the operational efficiency, safety, and service life of pipeline systems. When selecting, it is necessary to comprehensively consider factors such as application scenarios, medium characteristics, pressure and temperature. From type, material, parameters to performance verification, each step needs to be accurately matched to ensure that the valve can play a stable role in long-term use and avoid problems such as leakage, blockage or damage caused by improper selection.

　　明確閥門類型是選購的第一步，需根據系統功能需求選擇適配種類。閘閥適合作為切斷閥使用，其閥板垂直移動實現全開或全關，流阻小（全開時阻力系數接近 0），適合大口徑管道（DN50 以上）的主管道控制，如自來水廠、污水處理廠的主干管，但不宜用于頻繁啟閉的場景（每月啟閉次數建議不超過 10 次）。球閥憑借 90 度旋轉的閥芯結構，啟閉迅速（通常 1-2 秒完成操作），適合需要快速切斷或調節流量的場合（如油品輸送管道），尤其適用于粘度較高的介質（如糖漿、潤滑油），不易造成介質滯留。截止閥通過閥瓣升降控制流量，調節精度高，適合蒸汽、熱水等需要精確控制流量的系統，但流阻較大，能耗略高于閘閥，多用于支線管道或換熱器進出口。止回閥則依靠介質自身壓力自動啟閉，防止介質倒流（如水泵出口防止水錘沖擊），選購時需明確介質流向和工作壓力，避免安裝后失效。

　　Clarifying the valve type is the first step in purchasing, and the appropriate type should be selected based on the system's functional requirements. Gate valves are suitable for use as shut-off valves, with their valve plates moving vertically to achieve full opening or full closing. They have low flow resistance (the resistance coefficient is close to 0 when fully opened) and are suitable for controlling the main pipeline of large-diameter pipelines (DN50 or above), such as the main pipeline of water plants and sewage treatment plants. However, they are not suitable for frequent opening and closing scenarios (it is recommended to open and close no more than 10 times per month). The ball valve, with its 90 degree rotating valve core structure, opens and closes quickly (usually within 1-2 seconds), making it suitable for situations that require quick cutting or flow adjustment (such as oil delivery pipelines), especially for media with high viscosity (such as syrup and lubricating oil), and less likely to cause medium retention. Globe valves control flow through valve disc lifting and lowering, with high adjustment accuracy, suitable for systems such as steam and hot water that require precise flow control. However, they have high flow resistance and slightly higher energy consumption than gate valves. They are mostly used for branch pipelines or inlet and outlet of heat exchangers. Check valves rely on the pressure of the medium itself to automatically open and close, preventing medium backflow (such as preventing water hammer impact at the outlet of a water pump). When selecting, it is necessary to clarify the flow direction and working pressure of the medium to avoid failure after installation.

　　材質選擇需適配介質特性，防止腐蝕、磨損或污染。鑄鐵閥門成本較低，適合輸送水、空氣等無腐蝕性介質的低壓系統（工作壓力≤1.6MPa），但抗沖擊性較差，不宜用于振動劇烈的管道。鑄鋼閥門（如碳鋼、鉻鉬鋼）耐溫性強（可承受 425℃以上高溫），抗沖擊性能優異，適合蒸汽管道、熱油系統等中高壓場景（壓力 1.6-10MPa），在化工、電力行業應用廣泛。不銹鋼閥門（304、316 材質）耐腐蝕性突出，304 材質可應對弱酸堿介質（如食品工業的鹽水、果汁），316 材質則適合強腐蝕性環境（如海水、硝酸溶液），但成本較高，需根據介質腐蝕性等級合理選用。對于食品、醫藥行業，需選擇衛生級閥門（內壁拋光 Ra≤0.8μm），材質需符合食品接觸標準，避免介質被污染。

　　The material selection should be adapted to the characteristics of the medium to prevent corrosion, wear, or contamination. Cast iron valves have lower costs and are suitable for low-pressure systems that transport non corrosive media such as water and air (working pressure ≤ 1.6MPa), but they have poor impact resistance and are not suitable for pipelines with severe vibrations. Cast steel valves (such as carbon steel and chromium molybdenum steel) have strong temperature resistance (able to withstand high temperatures above 425 ℃), excellent impact resistance, and are suitable for medium and high pressure scenarios (pressure 1.6-10MPa) such as steam pipelines and hot oil systems. They are widely used in the chemical and power industries. Stainless steel valves (made of 304 and 316 materials) have outstanding corrosion resistance. 304 material can handle weak acidic and alkaline media (such as salt water and fruit juice in the food industry), while 316 material is suitable for highly corrosive environments (such as seawater and nitric acid solution), but the cost is relatively high and needs to be selected reasonably according to the corrosiveness level of the medium. For the food and pharmaceutical industries, sanitary grade valves (inner wall polished Ra ≤ 0.8 μ m) should be selected, and the material should meet food contact standards to avoid contamination of the medium.

　　參數匹配是確保閥門正常工作的核心，需與管道系統參數一致。公稱直徑（DN）需與管道口徑匹配，偏差不宜超過 1 個規格（如 DN100 管道可配 DN100 或 DN80 閥門，但需通過變徑管件連接），過大或過小都會導致流阻異常或調節失靈。公稱壓力（PN）需大于系統工作壓力的 1.2 倍，如工作壓力 1.0MPa 的系統，應選擇 PN1.6MPa 的閥門，預留安全余量應對壓力波動。工作溫度需在閥門材質的耐受范圍內，如鑄鐵閥門適用溫度 - 10℃至 200℃，超過此范圍需選用鑄鋼或不銹鋼材質，防止高溫下閥體變形或低溫下脆裂。對于介質為蒸汽、熱油的系統，還需考慮閥門的密封面材質（如硬質合金密封可耐高溫磨損），避免密封失效導致泄漏。

　　Parameter matching is the core of ensuring the normal operation of valves and must be consistent with the parameters of the pipeline system. The nominal diameter (DN) should match the diameter of the pipeline, and the deviation should not exceed one specification (for example, DN100 or DN80 valves can be equipped for DN100 pipelines, but they need to be connected through variable diameter fittings). Being too large or too small can cause abnormal flow resistance or adjustment failure. The nominal pressure (PN) should be greater than 1.2 times the system working pressure. For systems with a working pressure of 1.0 MPa, valves with a PN of 1.6 MPa should be selected, with a safety margin reserved to cope with pressure fluctuations. The working temperature should be within the tolerance range of the valve material. For example, cast iron valves are suitable for temperatures ranging from -10 ℃ to 200 ℃. If this range is exceeded, cast steel or stainless steel materials should be used to prevent deformation of the valve body at high temperatures or brittle cracking at low temperatures. For systems with steam or hot oil as the medium, the sealing surface material of the valve should also be considered (such as hard alloy seals that can withstand high temperature wear) to avoid leakage caused by seal failure.

　　性能驗證關注閥門的密封、操作與耐用性，確保長期可靠運行。密封性能可通過靜壓試驗驗證，在公稱壓力 1.1 倍的試驗壓力下，閥體、閥蓋及密封面無滲漏為合格，軟密封閥門（如橡膠密封）的泄漏量需≤0.1mL/h，硬密封閥門（如金屬密封）允許微量泄漏（≤0.5mL/min）。操作性能方面，手動閥門的啟閉力矩需均勻，無卡阻現象，電動或氣動閥門需測試控制信號響應速度（≤1 秒）和行程準確性（偏差≤1%）。耐用性可參考閥門的啟閉次數（一般要求≥10000 次），頻繁啟閉的場景（如灌裝生產線）需選擇高頻率閥門，其閥芯、閥座采用耐磨材料（如陶瓷），延長使用壽命。

　　Performance validation focuses on the sealing, operation, and durability of valves to ensure long-term reliable operation. The sealing performance can be verified through static pressure testing. Under a test pressure of 1.1 times the nominal pressure, the valve body, valve cover, and sealing surface are qualified if there is no leakage. The leakage rate of soft sealed valves (such as rubber seals) should be ≤ 0.1mL/h, and hard sealed valves (such as metal seals) are allowed to have a slight leakage rate (≤ 0.5mL/min). In terms of operational performance, the opening and closing torque of manual valves should be uniform and free of jamming, while electric or pneumatic valves should be tested for control signal response speed (≤ 1 second) and stroke accuracy (deviation ≤ 1%). Durability can refer to the opening and closing times of the valve (generally required to be ≥ 10000 times). For frequent opening and closing scenarios (such as filling production lines), high-frequency valves should be selected, and their valve cores and seats should be made of wear-resistant materials (such as ceramics) to extend their service life.

　　安裝與維護便利性影響后期使用成本，選購時需提前考慮。閥門的連接方式需與管道匹配，法蘭連接適合大口徑、高壓力場景，安裝拆卸方便；螺紋連接適合小口徑（DN50 以下）低壓管道，安裝緊湊；焊接連接則用于高壓、高溫管道，密封性好但拆卸困難。閥門的操作方式需符合現場條件，空間狹小的位置適合選用手柄或齒輪箱操作，遠程控制場景需選擇電動、氣動閥門，并確保控制線路或氣源管路便于布置。維護方面，選擇結構簡單、易拆卸的閥門，如閥蓋采用螺栓連接（而非焊接），便于更換密封件；閥芯、閥座可單獨更換的閥門，能降低后期維修成本。

　　The convenience of installation and maintenance affects the cost of later use, and should be considered in advance when selecting. The connection method of the valve needs to match the pipeline, and the flange connection is suitable for large-diameter and high-pressure scenarios, with easy installation and disassembly; Threaded connections are suitable for small-diameter (below DN50) low-pressure pipelines and can be installed compactly; Welding connections are used for high-pressure and high-temperature pipelines, with good sealing but difficult disassembly. The operation mode of the valve should meet the site conditions, and the location with small space is suitable for using a handle or gearbox for operation. For remote control scenarios, electric and pneumatic valves should be selected, and the control circuit or gas source pipeline should be easy to arrange. In terms of maintenance, choose valves with simple structures and easy disassembly, such as bolted connections (rather than welding) for valve covers, which facilitate the replacement of seals; Valves with replaceable valve cores and seats can reduce maintenance costs in the later stages.

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