旋启式止回阀结构特点：
SWING CHECK DESIGN FEATURES:

• 没有贯穿到外面的销钉，这是Velan的独特之处。
  有利于避免销钉密封处的泄漏，能够进行在线维护。
  No penetration of hinge pin to outside, a unique Velan feature.
  Eliminates pin seal leakage and provides in-line service.
• 紧凑的盒式结构。
  所有活动部件都安装在载体上，能够简易地拆卸下来维修。
  Compact cage unit.
  All moving parts are attached to the carrier and can be removed easily for service.
• 阀座采用锻造钨铬钴合金，并研磨和叠层成镜面光洁度，抗蚀能力最强，延长了使用寿命。它是通过密封焊接到阀体上的。
  Forged seat is Stellited, ground and lapped to a mirror finish for maximum erosion resistance and long service life. It is seal-welded to the body.
• 阀瓣具有钨铬钴合金阀座叠层镜面，并且通过精确引导与阀座接触。
  为了关闭紧密，可以部分旋转。在完全开启状态，阀瓣处于松弛性停止状态。
  Disc has a Stellited seat lapped to a mirror finish and accurately guided into seat contact.
  Can partially rotate for tight shutoff. In the fully open position, it rests against a stop.
• 起着销钉作用的钨铬钴合金轴承。
  在四个钨铬钴合金轴承上移动的坚固的阀瓣铰链，支撑着销钉，并且避免粘着。
  Stellite bearings for hinge pin.
  A sturdy disc hinge moves on four Stellite bearings, supporting the hinge pin and preventing binding.
• 易于在线维护。
  一旦拆卸掉盖子，就能够很容易维修所有部件。阀座表面能够重新叠层。
  Easy in-line service.
  Once the covers are removed, all parts are easily accessible for maintenance. Seating faces can be re-lapped.

翻转式阀瓣止回阀结构特点：
TILTING DISC CHECK DESIGN FEATURES:

　　这种翻转式阀瓣止回阀结构适用于管道流体流速很高，具有湍流，需要快速和安静关闭以防止“水锤”的场合。
　　This tilting disc check valve is designed for high piping velocities, turbulence flow, quick and quiet closing preventing "water hammer".

• 独特的盒式结构。
  在安装到阀体内部和进行密封焊接之前，全部的阀座-铰链-销钉-阀瓣总装可以在阀门外部进行测试。避免销钉密封泄漏。
  Unique cage unit.
  The entire seat-hinge-pin-disc assembly can be tested outside the valve before placing into the body and seal welding. Eliminates pin seal leakage.
• 易于在线维护。
  Easy in-line service.
• 操作效率高。
  销钉位于重力中心附近，能够让阀瓣的锥形阀座面在不发生滑动或磨损的情况下迅速进出阀座。阀瓣转轴通过一个小弧，避免流体倒流和“水锤”。
  Efficient operation.
  The hinge pin located near the center of gravity allows the conical seating face of the disc to move out and into the seat rapidly without sliding or wear. The disc pivots through a small arc preventing back flow and "water hammer".
• 优异的紧密型。
  锥形、叠层硬面阀座能够自我校对位置。即使在垂直管道，流体方向朝上的场合，也可以使用。
  Superior tightness
  Conical, lapped-in hardfaced seating is self-aligning. Valve can be used even in vertical piping with flow up.