应用推荐
Service Recommendation

1. 旋转式止回阀应该以适当的方式运行，以避免下列问题：
   The swing check valve shall be operated in a manner to avoid the following troubles:
   1. 在阀门关闭时，形成过高的冲击压力，以及
      formation of excessive high surge pressure as a result of valve closing, and
   2. 阀门关闭部件的快速升降运动。
      　　通过足够快速地关闭阀门来避免在关闭阀门时产生过高的冲击压力。此时不会由于突然的关闭而产生巨大的逆流，这种逆流是产生冲击压力的根源。因此，阀门的关闭速度应该与顺流减速的速度相一致。
      　　必须避免阀门关闭部件的快速升降运动， 以防止阀门的活动部件过度磨损，从而导致阀门过早失效。通过根据计算产生使阀门关闭部件运动的力的流量来确定阀门通径，可以避免开速升降运动的出现。
      rapid fluctuating movement of valve closing member. 　　The excessively high surge pressure by valve closing is prevented by closing the valve fast enough not to develop a significant reverse flow on a sudden shutoff which is a source of the surge pressure. Thus, the closing speed of valve should match closely with the speed of forward flow retard.
      　　The rapid fluctuating movement of valve closing member must be avoided to prevent the moving valve parts from excessive wear which may result in early failure of valve. Such movements can be precluded by sizing the valve to a flow rate which forces the closure member not to move.
2. 旋转式止回阀也可以安装在垂直位置，此时阀瓣应该无法达到阀门的位置。但是，在全开位置，阀瓣靠重力进行关闭运动的作用很小。为了克服对于流量减速的迟缓反应，这种阀瓣可能要配置杠杆或弹簧负载来帮助止回阀的启闭。
   The swing check valve can also be mounted to the vertical position, provided the disc should not reach the valve position. However, the closing moment of disc by weight is very low in fully-opened position, so the valve tends to close late. In order to overcome such slow response to flow retardation, the disc may be supplied with a levermounted or with spring loaded.

美国太平洋阀门公司保留对产品设计或结构进行改进或修改的权利，孰不另行通知，并不为因产品的改进或修改而对以前或以后销售的产品承担任何的责任。
Pacific Valves reserves the right to change or modify product design or construction without prior notice and without incurring any obligation to make such changes and modifications on products previously or subsequently sold.

注意：
NOTES:

1. 焊接端口阀门的阀体材料为ASTM A351等级CF3M (316L).
   Body material for weld end valves will be ASTM A351 GR CF3M (316L).
2. ANSI等级2500阀门的阀体的垫圈区域嵌入309不锈钢是一种标准配置。而其它压力等级只是作为一个选项，需要这种特殊配置时，请在型号后加上一个后缀“H”加以指定。
   A 309 SS inlay is standard in the gasket area of the body on ANSI class 2500 valves. For this option on other pressure classes, specify special features suffix H.
3. WCC阀门的阀帽何阀内件采用300系列不锈钢和/或2¹/₄铬制造。
   WCC valve bonnets and internals will be manufactured with 300 series SS and/or 2¹/₄ CR.