通径：DN65 - DN250
Sizes: 2¹/₂" – 10" (65 to 250 mm)

　　系列757，757N双止回阀总成用于防止非健康危害、不能采用，但是无毒的污染物回流进入饮用水供应系统中。系列757，757N可以安装在持续压力应用中，并且可能与反压力和反虹吸相关。系列757，757N由两个独立运行的止回阀、两个关闭阀和四个测试旋塞构成。
　　Series 757, 757N Double Check Valve Assemblies are used to prevent backflow of non-health hazard pollutants that are objectionable but not toxic, from entering the potable water supply system. Series 757, 757N may be installed under continuous pressure service and may be subjected to backpressure and backsiphonage. Series 757, 757N consists of two independently operating check valves, two shutoff valves, and four test cocks.

特点
Features

• 结构非常紧凑
  Extremely compact design
• 比传统设计轻70%
  70% Lighter than traditional designs
• 304（目录40）不锈钢外壳和套筒
  304 (Schedule 40) Stainless steel housing & sleeve
• 槽状连接件，允许整体管道调整
  Groove fittings allow integral pipeline adjustment
• 专利三连接止回阀提供最低的压力损失
  Patented tri-link check provides lowest pressure loss
• 特别容易维修
  Unmatched ease of serviceability
• 可提供槽状连接蝶阀为关闭阀
  Available with grooved butterfly valve shutoffs
• 可提供水平，垂直或N形安装方式
  Available for horizontal, vertical or N pattern installations
• 可更换止回阀阀瓣橡胶
  Replaceable check disc rubber
• 通径DN65和DN80可提供四分之一转球阀为关闭阀
  Sizes 2¹/₂" and 3" available with quarter-turn ball valve shutoffs

规格说明
Specifications

　　这种双止回阀总成应该由在一个外壳内两个独立的三连接止回阀模块，套筒进入端口，四个测试旋塞和两个不透水关闭阀构成。三连接止回阀应该是可拆卸和可维修的，不需要采用特殊工具。外壳应该由304目录40不锈钢管结构，配置槽状端口连接。三连接止回阀应该配置双向合成橡胶阀瓣，运行时对于由于反压力或发虹吸产生的反向流动具有不透水的密封性。这种总成应该是美国瓦茨调节阀公司系列757，757N。
　　The Double Check Valve Assembly shall consist of two independent tri-link check modules within a single housing, sleeve access port, four test cocks and two drip tight shut-off valves. Tri-link checks shall be removable and serviceable, without the use of special tools. The housing shall be constructed of 304 Schedule 40 stainless steel pipe with groove end connections. Tri-link checks shall have reversible elastomer discs and in operation shall produce drip tight closure against reverse flow caused by backpressure or backsiphonage. Assembly shall be a Watts Regulator Company Series 757, 757N.

757OSY

757NBFG

757OSY
（垂直）
(Vertical)