通径：DN80 - DN250
Sizes: 3" – 10" (80 – 250mm)

　　系列709DCDA双止回阀检测器总成专用于满足水主管部门的密封要求的应用场合。这种装置强制性防止消防系统物质，如湿甘油剂，停滞水和非饮用级的水通过泵吸或虹吸进入饮用水系统中。
　　Series 709DCDA Double Check Detector Assemblies are designed exclusively for use in accordance with water authority containment requirements. It is mandatory to prevent the reverse flow of fire protection system substances, i.e. glycerin wetting agents, stagnant water and water of non-potable quality from being pumped or siphoned into the potable water line.
　　优点：检测泄漏……特别重视无控制的水所带来的成本；配置一个水表，使得自来水公司能够：
　　Benefits: Detects leaks . . . with emphasis on the cost of unaccountable water; incorporates a meter which allows the water utility to:

• 检测地下泄漏，这种泄漏每年造成巨大的浪费。
  detect leaks underground that historically create great annual cost due to waste.
• 对于未经许可的用水提供一个监测点。这种装置有助于确定非法使用的龙头位置。
  provide a detection point for unauthorized use. It can help locate illegal taps.

　　模块止回设计概念有助于日常维护和总成的维修。所有通径的标准配置都包括弹性阀座外阀杆轭架关闭阀，DN16 x DN20水表和球型测试旋塞。
　　Modular check design concept facilitates maintenance and assembly access. All sizes are standardly equipped with resilient seated OSY shutoff valves, ⁵/₈" x ³/₄" (16 x 19mm) meter and ball type test cocks.

特点
Features

• 阀体结构材料为熔融环氧树脂涂敷铸铁制造
  Body construction fused epoxy coated cast iron
• 可更换的青铜阀座
  Replaceable bronze seats
• 低压降下实现最大流量
  Maximum flow at low pressure drop
• 结构紧凑，性价比高
  Compact for economy combined with performance
• 结构简单，易于维护
  Design simplicity for easy maintenance
• 配置DN16 x DN20青铜仪表
  Furnished with ⁵/₈" x ³/₄" (16 x 19mm) bronze meter
• 维修时不需要特殊工具
  No special tools required for servicing

规格说明
Specifications

　　在消防系统连接到饮用水供应系统的地方，需要安装一个双止回阀检测器总成。危险等级应该由当地有关主管部门确定。这种装置应该是一个完整的总成，包括UL认证弹性阀座外阀杆轭架关闭阀和测试旋塞。这种装置应该通过UL/FM认证，并配置UL/FM认证的外阀杆轭架关闭阀。辅助管路应该由通过认证的防回流阀和水表构成。这种装置应该符合美国卫生工程师协会（ASSE）1048标准的基本要求，美国自来水厂协会（AWWA）标准C510关于双止回阀的标准。通过位于美国南加州大学内的美国交叉连接管理和水研究基金会的认证。这种总成应该是美国瓦茨调节阀公司系列709DCDA。
　　A Double Check Detector Assembly shall be installed on fire protection systems when connected to a potable water supply. Degree of hazard present is determined by the local authority having jurisdiction. The unit shall be a complete assembly including UL listed resilient seated OSY shutoff valves and test cocks. The unit shall be UL/FM approved with UL/FM approved OSY shutoff valves. The auxiliary line shall consist of an approved backflow preventer and water meter. The assembly shall meet the basic requirements of ASSE 1048; AWWA Std. C510 for Double Check Valves. Approved by the Foundation for Cross-Connection Control and Hydraulic Research at the University of Southern California. Assembly shall be a Watts Regulator Company Series 709DCDA.

709DCDA外阀杆轭架
709DCDA OSY

止回总成模块
Check Assembly Module

　　特点在于模块设计概念，通过保持弹簧负载促使日常维护和总成的完善。第一和第二止回阀弹簧模块不能互换。
　　Features a modular design concept which facilitates complete maintenance and assembly by retaining the spring load. First and second check valve spring modules are not interchangeable.