Reasonable pump selection requires comprehensive consideration of comprehensive technical and economic indicators such as pump unit, pump station investment and operation cost, so as to make it meet the requirements of economy, safety

Applicable principles. It includes the following aspects:

1) High efficiency, low noise and energy-saving water pumps shall be selected, and obsolete products are strictly prohibited.

2) The pump shall be selected according to the design flow and required head. Considering the decrease of pump output due to wear and other reasons, the pump can be selected after multiplying the calculated head h by a factor of 1 05 ~ 1.10; The pump whose characteristic curve is the pump whose head decreases gradually with the increase of flow shall be selected, so that the pump can work stably and reliably in parallel; Moreover, the operating point of the water pump should be kept in the high-efficiency range, which is energy-saving and not easy to damage the parts.

3) When there is no regulation facility in the water supply network, the speed regulating pump group or the rated speed pump group should be used for water supply. The maximum water output of the pump unit shall not be less than the design flow of water supply in the community, and shall be checked according to the fire-fighting conditions.

4) Select the lifting pump of water tank and water tower, and try to reduce the number of pumps, one for use and one for standby; When a single pump can meet the requirements, it is not suitable to adopt multiple parallel pumps; If it is necessary to adopt multiple parallel operation or matching mode of large and small pumps, the model and number should not be too many, generally not more than two models, and the head range of the water pump should be similar; When running in parallel, each pump should still operate within the high efficiency area.

5) The design water supply flow of variable frequency speed regulating pump (set) shall meet the requirements of the maximum design flow per second in the domestic water supply system. The power supply must be reliable (dual power supply or dual circuit power supply); The working point of the pump shall be selected in the high-efficiency working area of the pump characteristic curve (Q-H curve), and shall not be selected on the extension line of the Q-H curve. The most unfavorable working point shall be designed at the right end of the high-efficiency section of the pump characteristic curve, that is, the outlet of the pump; The point where the water volume is the largest and the head is low but can meet the requirements, that is, the intersection of the low point of the high-efficiency area of the pump characteristic curve and the pipeline characteristic curve. The working range of water pump speed regulation can be within the high-efficiency section of the water pump as far as possible; The speed regulation range should be set between 25% and 100% of the water supply of the pump; The equipment shall have automatic water level control function.

6) The water pump unit of domestic pressurized water supply system shall be equipped with standby pump. The water supply capacity of the standby pump shall be greater than that of the largest operating pump. The water pump shall be switched automatically and operate alternately.

7) The voltage of the motor equipped with the water pump shall be the same, and the power supply system shall be the same as that of the State Grid.