保护公用水供应系统
Protecting the Public Water Supply

　　公用水供应官员和消费者都需要共同保护安全的饮用水的公共供应。由于共用水供应的专业性，人们应该尽力保护与下列情况有关的回流：
　　Both public water supply officials and consumers need to protect the public supply of safe drinking water. As a public water supply professional, you need to do everything in your power to prevent the reverse flow associated with:

• 主管道冲洗(维护)
  Main line flushing (maintenance)
• 消防(紧急)
  Firefighting (emergency)
• 主管道破裂或爆裂(灾难)
  Main line rupture or blowout (disaster)

　　这种情况和事故可能会对生活用水产生虹吸作用，将每种可能的连接用户系统的液体抽回到公用水供应系统中。
　　Such activities and occurrences can siphon domestic water systems, drawing every conceivable fluid connected to the user's system back into the public water supply.
　　系列7防回流阀提供性价比高的、符合当地或州管道有关规定要求的公用水供应防回流保护装置。作为综合性密封规划的一部分，用户应该需要安装系列7装置作为用户接受共用水供应系统服务的条件。理想的规划包括下列三个步骤：
　　The Series 7 Backflow Preventers provide cost-effective backflow protection of the public water supply when used according to the local or state plumbing code requirements. As part of your comprehensive containment program, you should require the installation of a Series 7 unit as a condition for the user to receive service from the public water system. This three-step program should ideally include:

　　第一保护规划
　　The first line of defense

　　用户要确保室内水系统符合当地管道的有关规定。
　　The user certifies that his/her domestic water system complies with the local plumbing codes.

　　第二保护规划
　　The second line of defense

　　用户要由安全饮用水供应商在水表处安装法定的双止回防回流阀。
　　The user installs a dual check backflow preventer at the water meter as prescribed by the supplier of safe drinking water.

　　第三保护规划
　　The third line of defense – education

　　水供应商提供指导资料，指导用户在出现污染物进入室内水系统时如何避免污染饮用水。
　　The supplier of water provides educational material that teaches the user how to avoid contaminating or polluting the drinking water once it has entered his domestic water system.

　　为了保证饮用水的安全，不能有任何的妥协方案。这就是美国瓦茨提供无以伦比的双止回安全性的系列7防回流阀的原因。安装在住宅水表入口处的系列7防回流阀具有下列性能：
　　To ensure the safety of drinking water, there can be no room for compromise.That's why Watts provides the incomparable Series 7 Backflow Preventers with dual check security. Installed at the residential water meter or service entrance, the Series 7 Backflow Preventers offer:

• 低压降
  Low pressure drop.
• 易于维护和维修
  Easy maintenance and service.
• 在类型、通径和连接方式方面具有多种选择方案
  Wide selection of types, sizes, and connections.

　　我们独特的止回模块结构使得我们的系列7防回流阀住宅保护装置方面明显处于领先地位。由于其各项创新设计，大多数系列7型号都具有全系列的特点，包括：
　　Our unique check modules put our Series 7 Backflow Preventers distinctly ahead of other residential containment devices.With their innovative design, most Series 7 models offer a full range of features, including:

• 抗氯胺腐蚀 - 在最严酷的水环境下能够维持很长的使用寿命。
  Chloramine resistance – for long life under the harshest water conditions.
• 完善的木块性 - 易于维护
  Complete modularity – for easy maintenance.
• 限制止动装置 - 避免由于热膨胀导致的破坏
  Limit stops – to prevent damage from thermal expansion.
• 中心和边缘引导 - 确保密封可更换和将局部磨损降到最小程度
  Center and edge guides – to ensure repeatable seating and minimize localized wear.
• 没有暴露的螺丝和螺纹 - 消除潜在的腐蚀，改善可维修性
  No exposed screws or threads – to eliminate corrosion potential and improve serviceability.

　　当然，系列7双止回防回流阀还是世界阀门技术领头羊的美国瓦茨质量工程的具体体现。了解系列7是通过ASSE 1024和CSA B64.6认证的产品，将增加用户的信心。所以，当用户需要确保使用的是最可靠的住宅防污染系统，则指定美国瓦茨系列7防回流阀。
　　Of course, the Series 7 Dual Check Backflow Preventers embody the quality engineering of Watts, a world leader in valve technology. And you have the confidence of knowing the Series 7 are ASSE 1024 and CSA B64.6 Certified. So when you need to be sure you have the most reliable residential containment
products, specify the Watts Series 7 backflow preventers.