The backflow preventer must be supported and is not designed to carry full weight of the stand pipe. 防回流阀必须有所支撑，不能用于承载立管的全部重量。
The installation of vertical water supply pipes on some floors does not consider the space necessary for the installation of fire and water protection items. 部分楼层的给水立管的安装没有考虑防火防水密封材料的安装空间。
