| 摘要 |
A back flow preventer is provided that is made of at least two different materials. The back flow preventer includes a housing that has a passageway configured for the transport of a fluid therethrough. The housing has both an inlet and an outlet that define at least a portion of the passageway. The inlet is made of a different material than the outlet. A first and second check valve are disposed in the passageway. Both of the check valves allow fluid to flow through the passageway in the direction from the inlet to the outlet of the housing.
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