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:

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:

特点 Features	型号/系列 Model/Series
	7	L7	O7S	7B	7C	CU7
中心阀杆引导 Center Stem Guides	·	·	·	·	·	·
边缘引导 Edge Guides	·		·	·	·	·
抗氯胺腐蚀部件 Chloramine Resistant Components	·	·	·	·	·	·
模块化结构 Modular Design	·		·	·	·	·
限制止动装置 Limit Stops	·	·	·			·
不锈钢弹簧 Stainless Steel Springs	·	·	·	·	·	·
可更换阀座 Replaceable Seats	·		·	·	·	·
没有暴露的螺丝或螺纹 No Exposed Screws Or Threads	·	·	·	·	·	·

最大压力：175 psi (12 bars).

最小压力： 10 psi (69 kPa).

工作温度：持续温度0.6^oC to 60^oC；间歇温度82.2^oC