几个经批准的组件可用于防回流保护。它们是减压回流总成、减压检测器总成、双止回阀总成、双止回检测器总成、压力真空断路器总成和大气真空断路器。此外，一些供应商可能允许使用一些特殊的应用设备，如双重检查或带有大气通风口的双重检查。所用防回流阀的类型取决于存在的危险程度。

Several approved assemblies may be used for backflow protection. They are the reduced pressure backflow assembly, reduced pressure detector assembly, double check valve assembly, double check detector assembly, pressure vacuum breaker assembly and atmospheric vacuum breaker. In addition, some purveyors may allow the use of some special application devices such as the dual check or dual check with atmospheric vent. The type of backflow preventer used will depend upon the degree of hazard present.