常見例句雙語(yǔ)例句The backflow preventer must be installed upstream of the regulator.防倒流裝置必須安裝在調(diào)節(jié)閥的上游位置。The relief valve may be serviced while on or off the backflow preventer valve.可以在防回流閥上維修安全閥,或?qū)⑵鋸姆阑亓鏖y拆卸下來(lái)維修。 返回 backflow preventer