Overview
The manual double eccentric valve, also known as a double offset butterfly valve, is engineered for industrial applications requiring reliable shut-off and throttling capabilities. Its design incorporates two offsets: the first positions the stem behind the disc centerline, while the second offsets the stem axis from the pipe center. This configuration eliminates sliding contact between the disc and seat during operation, significantly reducing wear. Unlike conventional butterfly valves, the double eccentric design allows for a cam-action during opening/closing, ensuring minimal friction and torque requirements. These valves are particularly suited for high-pressure systems (up to PN40) and critical services where long service life and low maintenance are prioritized.
Structure and Working Principle
The valve comprises a disc, stem, body, seat, and manual actuator (handwheel or gear operator). The disc rotates 90° between open and closed positions, with the double eccentricity causing the disc to lift clear of the seat immediately upon rotation. This 'lifting action' prevents abrasive contact, making it ideal for particulate-laden fluids. Sealing is achieved through a resilient seat (EPDM, PTFE, or metal) that compresses against the disc's conical periphery. The stem is typically protected by bushings to prevent media ingress. Larger sizes (DN300+) often incorporate a gearbox to reduce operating torque by 80-90% compared to direct handwheel operation.
Key Features
1. **Wear Resistance**: The non-rubbing motion extends seat life 3-5x longer than concentric designs, especially in abrasive services like slurry transport. 2. **Bidirectional Sealing**: Properly designed models achieve bubble-tight shut-off in both flow directions (tested per ISO 5208). 3. **Low Torque**: Requires 30-50% less operating torque than single eccentric valves, enabling smaller actuators. Additional features may include fire-safe designs (API 607), anti-blowout stems, and position indicators. High-performance variants use metal seats with graphite seals for temperatures up to 600°C.
Application Areas
Primary industries include: - **Water Treatment**: Pump discharge control in desalination plants (seawater-resistant materials like Super Duplex) - **Oil & Gas**: Pipeline isolation valves for crude oil (API 609 compliant) - **Chemical Processing**: Corrosive media handling with PTFE-lined bodies - **Power Generation**: Cooling water systems in thermal plants These valves excel in applications requiring frequent operation (200+ cycles/year) or where space constraints rule out gate valves. They are not recommended for throttling below 15° open position due to potential cavitation damage.
Maintenance and Precautions
**Routine Maintenance**: - Lubricate stem bushings quarterly with high-temperature grease (e.g., lithium-based) - Inspect seat surfaces annually for erosion (replace if compression set exceeds 10%) - Verify bolt torque on flange connections during shutdowns **Critical Precautions**: - Never force the valve closed against solid particles—this may deform the seat - Ensure proper pipeline supports to avoid stress on valve body - For cryogenic services (-50°C and below), specify extended stem designs to prevent packing freeze
B2B Procurement Guide
1. **Technical Specifications**: Clearly define pressure class (PN16/25/40), end connections (RF flanges, wafer, or lug type), and material grades (e.g., ASTM A351 CF8M for corrosive media). 2. **Certifications**: Require third-party inspection reports for critical applications (e.g., NACE MR0175 for sour gas service). 3. **Supplier Evaluation**: Prioritize manufacturers with in-house testing facilities for seat leakage (Class VI per ANSI FCI 70-2) and pressure testing. Lead times typically range 4-12 weeks for custom configurations. Consider stocking spare seats and seals for high-availability operations.
Related Manufacturers
- 主营：温控阀、浮球阀、刀闸阀、双法兰、手动蝶阀、角座阀门、气动笼、铝合金、止回阀、背压阀、供氮阀、过滤器、空气阀、排渣阀、调节阀、疏水阀、斜灰阀、钢衬氟、铸钢刀、放料阀、插板阀、法兰闸阀、高温球阀、焊接球阀、调节球阀
- 主营：固定球阀、硬碰硬旋球阀、调流调压阀、偏心半球阀、V型球阀、卸灰球阀
- 主营：卫生级蝶阀、卫生级球阀、卫生级隔膜阀、手动球阀、气动膨胀蝶阀、三片式快装球阀、罐底隔膜阀、三片式焊接蝶阀、AB阀、气动隔膜阀、快装三通球阀、U型隔膜阀
- 主营：耐腐蚀阀门、自来水开关、法兰暗杆闸阀、铸铁软密封闸阀
- 主营：球阀、闸阀、截止阀、丝扣阀门、三偏心硬密封蝶阀、止回阀、蝶阀、y型过滤器、气动球阀、电动球阀、气动蝶阀、电动蝶阀、气动闸阀、气动截止阀、气动调节阀、涡轮球阀、涡轮蝶阀、对夹蝶阀、电动法兰球阀、电动法兰不锈钢球阀、气动法兰球阀、气动执行器、不锈钢法兰暗杆闸阀、不锈钢法兰闸阀、法兰止回阀
- 主营：电磁阀、紧急切断阀、电磁式燃气紧急切断阀、防爆电磁阀、高压电磁阀、高温高压电磁阀
- 主营：焊接阀、电动球阀、法兰球阀、双向二通式法兰球阀、内外丝球阀、不锈钢球阀、内螺纹球阀
- 主营：不锈钢刀闸阀、陶瓷球阀、陶瓷摆动阀、陶瓷双闸板、偏心半球阀、方形闸门、铸铁镶铜闸门、盲板阀、螺旋闸门、水力控制阀、调流调压阀、三开插板阀
- 主营：软密封、铸钢球阀、美标锻钢、手动固定球阀、固定球阀、浮动球阀、锻钢球阀、焊接球阀、气动球阀、管线球阀、电动球阀、国标锻钢、蜗轮球阀、国标球阀、美标球阀、卸灰球阀、燃气球阀、不锈钢球阀、硬密封球阀
- 主营：博雷Bray、奥兰斯AULANS、巴蝶TOMOE、气动双偏心阀门、开滋Kitz
- 主营：星型卸料器、螺旋输送机、散装机、手动双向棒条阀、空气斜槽、刮板输送机、粉尘加湿搅拌机、斗式提升机、插板阀、通风蝶阀、三通分料阀、布袋除尘器、催化燃烧设备、活性炭吸附箱、除尘布袋、除尘骨架、脉冲阀、重锤翻板阀、鄂式扇形阀、星型卸灰阀
- 主营：矿浆阀、耐磨矿浆阀、高压矿浆阀、双向密封刀闸阀、双向密封矿浆阀、电动双向密封刀闸阀、双向密封浆液阀、不锈钢刀闸阀、刀型闸阀、电动刀闸阀、电动矿浆阀、全衬聚氨酯矿浆阀、聚氨酯耐磨矿浆阀、两片式刀闸阀、不锈钢插板阀、电液动刀闸阀、不锈钢矿浆阀、高抗磨矿浆阀、不锈钢浆闸阀、插板阀、闸板阀、耐磨插板阀、浆闸阀、渠道闸门、无凹槽插板阀
- 主营：多功能水泵控制阀、200x减压阀、100x遥控浮球阀、500x泄压阀、微阻缓闭止回阀、角式液动快开排泥阀、排气阀、管力阀、消声止回阀、静音止回阀、橡胶瓣止回阀、球形止回阀、液力自动阀、调流调压阀
- 主营：球阀、蝶阀、闸阀、截止阀、止回阀、电磁阀、排气阀
- 主营：刀闸阀、渣浆阀、闸板阀、污水阀门、玻璃钢阀门、气动陶瓷双闸板阀、半球阀、陶瓷阀、排渣阀、减压阀、出料阀、法兰闸阀、陶瓷蝶阀、陶瓷球阀、陶瓷闸阀、100摆动阀、搪瓷管件、不锈钢球阀、气动圆盘阀、陶瓷浆液阀、耐腐蚀球阀、排渣止回阀、陶瓷止回阀、圆顶阀、库顶阀
- 主营：法兰盘、法兰片、管道配件、带颈法兰、对焊法兰、高压法兰、方形法兰、厚壁法兰、异径三通、焊接三通、定做封头、钢制三通、凹凸法兰、螺纹丝扣、船标法兰、盲板法兰、国标法兰、平焊法兰、高压封头、球形封头、高颈法兰、异形法兰、平底封头、法兰蝶阀、合金法兰