一流的选型工程师都指定Duo-Chek II作为止回阀应用的首选产品，因为Duo-Chek II具有很好的性能。对所要求的性能进行大规模的研究和测试赢得了世界范围的认可，这一点在行业内是无可匹敌的。
　　Leading engineering specifiers specify the Duo-Chek II for check valve applications because it provides high performance. Extensive research and testing with demonstrated performance has earned worldwide recognition, unmatched in the industry.
　　和常规的旋启式止回阀相比，Duo-Chek II对夹式阀门结构通常更坚固，更轻，更小，更有效，也更便宜。这种阀门符合API 594的标准，对于大多数通径，这种阀门的面对面尺寸只是常规阀门的四分之一，重量是常规阀门的15%到20%，因此也比旋启式止回阀便宜。在标准垫圈和管道法兰之间也更加容易安装。由于容易搬运处理，且只需要一套法兰柱头螺栓，因此在安装期间也节省了部件需求，节约了安装成本和日常维护成本。
　　The Duo-Chek II wafer valve design is generally stronger, lighter, smaller, more efficient and less expensive than conventional swing check valves. Its design meets API 594 which is approximately one fourth the face to face dimension and 15% to 20% the weight, on most popular sizes, making them less expensive than a swing check valve. It is much easier to install between standard gaskets and line flanges. The savings compound during installation due to ease of handling and only one set of flange studs is required. Therefore, it is more cost effective to install, and also to maintain.
　　Duo-Chek II还具有特殊的结构特征，这使得这种阀门成为高性能无撞击止回阀。这些特征包括，免清洗开启，大多数通径的阀门配置独立的弹簧结构，以及独立的阀瓣支撑系统。这些特征在其它止回阀上可能并不具备。其它能够提供的配置包括凸耳，双法兰和加长阀体。
　　The Duo-Chek II also offers special design features that make it a high performance non-slam check valve. These include a scrub-free opening, and in most sizes a unique independent spring design as well as an independent plate support system. These features may not be found in other check valves. Other configurations offered include lug, double flange and extended body.

　　Duo-Chek II创新的双阀瓣结构采用两个弹簧负载阀瓣(半阀瓣)，悬挂在中心垂直的铰链销钉上。当流体开始流动时，阀瓣在作用在密封表面中心的合力(F)作用下开启。起着反作用的弹簧支架力(Fs)的作用点位于阀瓣面中心外的位置，使得阀瓣根部首先开启。这就避免了旧型常规阀门在阀瓣开启时所出现的密封表面摩擦现象，消除了部件的磨损。
　　The innovative dual-plate design of the Duo-Chek II employs two spring-loaded plates (disc halves) suspended on a central vertical hinge pin. As flow begins, the plates open in response to a resultant force (F) which acts as the center of the sealed surface area. The contact point of the reacting spring leg’s force (Fs) acts beyond the center of the plate area, causing the heel to open first. This prevents rubbing of the seal surface prior to normal plate opening, eliminating wear.
　　当流速减缓，扭转弹簧自动反作用，使得阀瓣关闭，向阀体阀座靠近，减少了关闭的行程距离和时间。当流体倒流时，阀瓣逐渐靠近阀体阀座，阀门的动态反应随之大大加速。这戏剧性地减小水锤现象的影响，从而实现无撞击性能。
　　As the velocity of flow decreases, torsion spring action reacts automatically. This moves the plates closer to the body seats, reducing the distance and time of travel for closure. By having the plates closer to the body seats at the time of flow reversal, the valve dynamic response is greatly accelerated. This dramatically reduces the water hammer effect for non-slam performance.

　　在关闭时，弹簧力作用点的作用使得阀瓣顶端首先关闭。这防止了阀瓣根部的出现咬模现象，使得阀门能够保持更长时间的密封整体性。
　　At closing, the point of spring force causes the toe of the plates to close first. This prevents dragging of the heels of the plates and maintains seal integrity for much longer periods.

独立的弹簧结构
Independent Spring Design

　　Duo-Chek II弹簧结构(通径DN150及以上)使得在每个阀瓣上能够施加更大的扭矩，并且随着工业液流的变化而独立关闭。实验证明这种作用使得阀门寿命延长了25%，水锤现象减少了50%.
　　A spring design of the Duo-Chek II (sizes 6" and larger) allows higher torque to be exerted against each plate with independent closing in response to the process stream. Testing has proved this action provides up to 25% improvement in valve life and 50% reduction in water hammer.

　　双阀瓣的每个部分都有自身的弹簧，这些弹簧提供独立的关闭作用力。这些独立的弹簧所经受的角度偏移比较小，只有140^o，而不是配置双支架的常规弹簧的350^o。
　　Each of the dual plates has its own spring or springs, which provide independent closing action. These independent springs undergo less angular deflection, only 140^o as compared to 350^o for conventional springs with two legs.

独立的阀瓣悬挂结构
Independent
Plate Suspension Design

　　Duo-Chek II独立的铰链结构减小摩擦力66%，这种结构极大地改善了阀门的反应作用。支撑套管从外侧铰链插入，使得上部铰链在阀门运行期间能够由下部套管独立支撑。这使得两个阀瓣能够迅速反应，并同时关闭，实现优异的动态性能。
　　The Duo-Chek II unique hinge design reduces friction forces by 66%, which improves valve response significantly. Support sleeves are inserted through the outboard hinges so that the upper hinge is independently supported by the lower sleeve during valve operation. This allows both plates to close at the same time for quick response, and exellent dynamic performance.