良工阀门作为流体控制系统的关键部件，其选型是否合理直接影响管道系统的运行效率、安全性与使用寿命。选购时需综合考虑应用场景、介质特性、压力温度等因素，从类型、材质、参数到性能验证，每一步都需精准匹配，才能确保阀门在长期使用中发挥稳定作用，避免因选型不当导致泄漏、堵塞或损坏等问题。

　　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.

　　明确阀门类型是选购的第一步，需根据系统功能需求选择适配种类。闸阀适合作为切断阀使用，其阀板垂直移动实现全开或全关，流阻小（全开时阻力系数接近 0），适合大口径管道（DN50 以上）的主管道控制，如自来水厂、污水处理厂的主干管，但不宜用于频繁启闭的场景（每月启闭次数建议不超过 10 次）。球阀凭借 90 度旋转的阀芯结构，启闭迅速（通常 1-2 秒完成操作），适合需要快速切断或调节流量的场合（如油品输送管道），尤其适用于粘度较高的介质（如糖浆、润滑油），不易造成介质滞留。截止阀通过阀瓣升降控制流量，调节精度高，适合蒸汽、热水等需要精确控制流量的系统，但流阻较大，能耗略高于闸阀，多用于支线管道或换热器进出口。止回阀则依靠介质自身压力自动启闭，防止介质倒流（如水泵出口防止水锤冲击），选购时需明确介质流向和工作压力，避免安装后失效。

　　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.

　　材质选择需适配介质特性，防止腐蚀、磨损或污染。铸铁阀门成本较低，适合输送水、空气等无腐蚀性介质的低压系统（工作压力≤1.6MPa），但抗冲击性较差，不宜用于振动剧烈的管道。铸钢阀门（如碳钢、铬钼钢）耐温性强（可承受 425℃以上高温），抗冲击性能优异，适合蒸汽管道、热油系统等中高压场景（压力 1.6-10MPa），在化工、电力行业应用广泛。不锈钢阀门（304、316 材质）耐腐蚀性突出，304 材质可应对弱酸碱介质（如食品工业的盐水、果汁），316 材质则适合强腐蚀性环境（如海水、硝酸溶液），但成本较高，需根据介质腐蚀性等级合理选用。对于食品、医药行业，需选择卫生级阀门（内壁抛光 Ra≤0.8μm），材质需符合食品接触标准，避免介质被污染。

　　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.

　　参数匹配是确保阀门正常工作的核心，需与管道系统参数一致。公称直径（DN）需与管道口径匹配，偏差不宜超过 1 个规格（如 DN100 管道可配 DN100 或 DN80 阀门，但需通过变径管件连接），过大或过小都会导致流阻异常或调节失灵。公称压力（PN）需大于系统工作压力的 1.2 倍，如工作压力 1.0MPa 的系统，应选择 PN1.6MPa 的阀门，预留安全余量应对压力波动。工作温度需在阀门材质的耐受范围内，如铸铁阀门适用温度 - 10℃至 200℃，超过此范围需选用铸钢或不锈钢材质，防止高温下阀体变形或低温下脆裂。对于介质为蒸汽、热油的系统，还需考虑阀门的密封面材质（如硬质合金密封可耐高温磨损），避免密封失效导致泄漏。

　　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.

　　性能验证关注阀门的密封、操作与耐用性，确保长期可靠运行。密封性能可通过静压试验验证，在公称压力 1.1 倍的试验压力下，阀体、阀盖及密封面无渗漏为合格，软密封阀门（如橡胶密封）的泄漏量需≤0.1mL/h，硬密封阀门（如金属密封）允许微量泄漏（≤0.5mL/min）。操作性能方面，手动阀门的启闭力矩需均匀，无卡阻现象，电动或气动阀门需测试控制信号响应速度（≤1 秒）和行程准确性（偏差≤1%）。耐用性可参考阀门的启闭次数（一般要求≥10000 次），频繁启闭的场景（如灌装生产线）需选择高频率阀门，其阀芯、阀座采用耐磨材料（如陶瓷），延长使用寿命。

　　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.

　　安装与维护便利性影响后期使用成本，选购时需提前考虑。阀门的连接方式需与管道匹配，法兰连接适合大口径、高压力场景，安装拆卸方便；螺纹连接适合小口径（DN50 以下）低压管道，安装紧凑；焊接连接则用于高压、高温管道，密封性好但拆卸困难。阀门的操作方式需符合现场条件，空间狭小的位置适合选用手柄或齿轮箱操作，远程控制场景需选择电动、气动阀门，并确保控制线路或气源管路便于布置。维护方面，选择结构简单、易拆卸的阀门，如阀盖采用螺栓连接（而非焊接），便于更换密封件；阀芯、阀座可单独更换的阀门，能降低后期维修成本。

　　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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