The total volume of anti-fire water pressure tank is divided into three parts, namely the fire water storage volume (adjust volume), buffered water volume and water volume regulator, shown in Figure 2. Pressure system usually provided by the regulator pump, when the pressure rises, reaching a high level of water volume regulator, the regulator pump automatically stops running; when the pressure decreases, reaching a low level of water volume regulator, the regulator pump automatically open, the volume of water regulator regulator to the highest level. So the cycle in order to keep the pressure on the state of the system. In the event of a fire, with the fire hydrant into use, the system pressure begins to drop, when the fire water storage volume to a minimum level, stopping regulator pump, fire pump automatically open fire.