It is mandatory to prevent the reverse flow of fire protection system substances, i.e. glycerin wetting agents, stagnant water and water of non-potable quality from being pumped or siphoned into the potable water line.

• 这种装置强制性防止消防系统物质，如湿甘油剂，停滞水和非饮用级的水通过泵吸或虹吸进入饮用水系统中。