Technical Code for fire water supply and hydrant system
Technical Code for fire water supply and hydrant system
The fire pump should be directly started by the low pressure switch on the main outlet pipe of the pump, the flow switch on the outlet pipe of the High Position Fire Tank, or the pressure switch of the alarm valve.The low pressure switch is mounted on the main outlet pipe of the fire pump. The position of the switch depends on your system. The setting value of the pressure switch depends on the height of your floor.
Standard 11.0.4 of GB50974-2014 stipulates that the signals for direct starting fire pumps are flow switches and pressure switches,Because both of them are high reliability. The reliability of the flow indicator is poor, and the misoperation is high, the water level signal of high water tank has hysteresis phenomenon, and the signal can only be used as alarm signal.
The provisions stipulate that flow switches and pressure switches shall be used as direct start signals for fire pumps,The flow switch is set in a certain range of flow value. When the water level of the high water tank drops to a certain pressure, the pump is started with the assistance of the pressure switch. Interlock is also possible.In order to reduce false movement, the flow switch and pressure switch (pressure switch will act when the water level in the tank or the pressure-stabilizing pump can not support the fire water consumption, and the pressure of the high-level tank drops to the setted value) operate simultaneously as a reliable measure to start the pump directly.The flow switch and the pressure switch start successively to achieve the direct start of double insurance, thus the set-up should be "high tank flow switch control and start fire pump device. ".
The setting value of low-pressure switch is not uniform. It should be adjusted according to the site working condition and calculated according to the floor height. A BAR is a water column of 10 meters height. Therefore, a 12-story building needs to set the pressure switch of 1.6 MPA.
To make sure the pressure in the pipe is within the normal range, we need to set two values, pressure-stabilizing pump will start when pressure dropped to setted value and stop automatically when the pressure reaches a certain value.
