這四種蝶閥的核心區別在于閥桿軸線與蝶板、閥體中心的相對位置設計，即“偏心”的數量和方式。偏心設計的根本目的是為了解決傳統蝶閥啟閉時蝶板與閥座持續摩擦的問題，從而提升密封性能、降低操作扭矩并延長閥門壽命。簡單來說，偏心數量越多，結構越復雜，性能也越優越，能適應的工況也越嚴苛。中線蝶閥 (同心蝶閥)這是最基礎的結構，閥桿軸心、蝶板中心和閥體中心都在同一條線上。工作原理：在啟閉過程中，蝶板的整個密封面會持續地與閥座擠壓和刮擦。特點：結構簡單，成本低。但由于摩擦嚴重，閥座容易磨損，通常采用橡膠、聚四氟乙烯等軟質材料來保證密封。因此，它不適用于高溫、高壓或有顆粒物的介質。適用場景：低壓、常溫的清潔介質，如市政供水、空調系統、食品工業等。

　　The core difference between these four butterfly valves lies in the design of the relative position between the stem axis and the center of the butterfly plate and valve body, that is, the number and method of "eccentricity". The fundamental purpose of eccentric design is to solve the problem of continuous friction between the butterfly plate and the valve seat during the opening and closing of traditional butterfly valves, thereby improving sealing performance, reducing operating torque, and extending valve life. Simply put, the more eccentricities there are, the more complex the structure, the superior the performance, and the more demanding the working conditions that can be adapted to. The centerline butterfly valve (concentric butterfly valve) is the most basic structure, with the stem axis, butterfly plate center, and valve body center all on the same line. Working principle: During the opening and closing process, the entire sealing surface of the butterfly plate will continuously press and scrape against the valve seat. Features: Simple structure and low cost. However, due to severe friction, the valve seat is prone to wear, and soft materials such as rubber and polytetrafluoroethylene are usually used to ensure sealing. Therefore, it is not suitable for media with high temperature, high pressure, or particulate matter. Applicable scenarios: Low pressure, room temperature cleaning media, such as municipal water supply, air conditioning systems, food industry, etc.

　　單偏心蝶閥這是為了解決中線蝶閥摩擦問題而做的初步改進。

　　The single eccentric butterfly valve is a preliminary improvement made to solve the friction problem of the centerline butterfly valve.

　　工作原理：閥桿軸心偏離了蝶板的中心。這使得蝶板在開啟時能比中線蝶閥更早地脫離閥座，減少了部分摩擦。特點：相比中線蝶閥，摩擦和磨損有所減輕，但并未完全消除，在啟閉的大部分行程中，蝶板與閥座仍存在刮擦。適用場景：與中線蝶閥類似，多用于對密封要求不高的低壓、常溫工況。

　　Working principle: The axis of the valve stem deviates from the center of the butterfly plate. This allows the butterfly plate to detach from the valve seat earlier than the centerline butterfly valve when opened, reducing some friction. Characteristics: Compared to the centerline butterfly valve, friction and wear have been reduced, but not completely eliminated. During most of the opening and closing strokes, there is still friction between the butterfly plate and the valve seat. Applicable scenarios: Similar to the centerline butterfly valve, it is commonly used in low-pressure and room temperature conditions where sealing requirements are not high.

　　雙偏心蝶閥這是在單偏心基礎上的重大升級，應用非常廣泛。

　　The double eccentric butterfly valve is a significant upgrade from the single eccentric foundation and has a wide range of applications.

　　工作原理：擁有兩個偏心。第一偏心：閥桿偏離蝶板中心。第二偏心：閥桿偏離閥體中心。

　　Working principle: It has two eccentricities. First eccentricity: The valve stem deviates from the center of the butterfly plate. Second eccentricity: The valve stem deviates from the center of the valve body.

　　這兩個偏心共同作用，產生類似“凸輪”的效應，使得蝶板在開啟的瞬間（通常是前10°-15°）就能迅速、完全地脫離閥座。特點：實現了啟閉過程中的“零摩擦”或“低摩擦”，大大延長了閥座壽命，操作扭矩也更小。它可以采用軟密封實現零泄漏，也可以采用金屬硬密封來適應更高的溫度和壓力。適用場景：中低壓、中溫的液體或氣體，如污水處理、化工、電力、城市燃氣管網等。

　　These two eccentricities work together to produce a cam like effect, allowing the butterfly plate to quickly and completely detach from the valve seat at the moment of opening (usually the first 10 ° -15 °). Features: It achieves "zero friction" or "low friction" during the opening and closing process, greatly extending the service life of the valve seat and reducing the operating torque. It can use soft seals to achieve zero leakage, or metal hard seals to adapt to higher temperatures and pressures. Applicable scenarios: Liquid or gas with medium low pressure and medium temperature, such as sewage treatment, chemical industry, power, urban gas pipeline network, etc.

　　三偏心蝶閥這是蝶閥技術的高端形式，專為苛刻工況設計。

　　Triple eccentric butterfly valve is a high-end form of butterfly valve technology designed specifically for harsh working conditions.

　　工作原理：在雙偏心的基礎上，增加了第三個偏心——將蝶板的密封面加工成一個傾斜的錐面。特點：零摩擦：繼承了雙偏心的優點，啟閉全程無摩擦。金屬硬密封：密封原理從“擠壓密封”變為“扭力密封”或“楔形效應”。關閉時，蝶板的錐面與閥座錐面越壓越緊，形成金屬對金屬的密封。零泄漏：能夠實現氣泡級的零泄漏，密封性能極佳。耐高溫高壓：由于采用金屬密封，可適用于高溫（可達600℃）、高壓（PN100以上）和強腐蝕性介質。適用場景：高溫高壓蒸汽、油氣、酸堿等惡劣介質，常見于石油化工、核電、冶金等關鍵系統。

　　Working principle: On the basis of double eccentricity, a third eccentricity is added - the sealing surface of the butterfly plate is machined into an inclined conical surface. Features: Zero friction: Inheriting the advantages of double eccentricity, there is no friction throughout the opening and closing process. Metal hard seal: The sealing principle has changed from "extrusion sealing" to "torque sealing" or "wedge effect". When closed, the conical surface of the butterfly plate and the conical surface of the valve seat become tighter as they are pressed, forming a metal to metal seal. Zero leakage: capable of achieving bubble level zero leakage and excellent sealing performance. High temperature and high pressure resistance: Due to the use of metal sealing, it can be applied to high temperatures (up to 600 ℃), high pressures (PN100 or above), and highly corrosive media. Applicable scenarios: High temperature and high pressure steam, oil and gas, acid and alkali and other harsh media, commonly used in key systems such as petrochemicals, nuclear power, metallurgy, etc.

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