常見例句Four required per backflow preventer. 每個防回流閥需要四個。Winterization of backflow preventers. 防回流閥的過冬處理。For use with backflow preventer test cocks to protect from damage. 用于防回流閥測試旋塞,防止受到破壞。A check valve may be required ahead of the backflow preventer. 此時在防回流閥前面可能需要安裝一個止回閥。This would create an air gap to eliminate any possible backflow. 這將產(chǎn)生一個氣隙以消除任何可能的回流。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。 返回 backflowing