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| Need to know for selection of vertical centrifugal pump
As we all know, the vertical centrifugal pump is used to transport clean water and other basic liquids with physical and chemical properties similar to clean water. It is suitable for industrial and urban water supply and drainage, pressurized water supply for high-rise buildings, garden sprinkler irrigation, fire pressurization, long-distance transmission, and HVAC refrigeration cycle. So the use of different industries is not completely the same, so we can not choose the same product when we choose vertical centrifugal pump, so how do we choose vertical centrifugal pump reasonably?
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 conform to the principles of economy, safety and applicability. It includes the following aspects:
1) Water pumps with high efficiency, low noise and energy conservation shall be selected, and obsolete products are strictly prohibited.
2) . The pump shall be selected according to the design flow and the required lift, and considering that the pump output decreases due to wear and other reasons, the pump can be selected by multiplying the calculated lift H by a coefficient of 1.05~1.10; The pump with the characteristic curve of gradually decreasing head as the flow increases shall be selected, so that the pump can work stably and reliably in parallel; And the operating point of the water pump should be kept in the high efficiency range, which is not only energy-saving but also not easy to damage the parts.
3) When there is no regulating facility in the water supply network, it is better to use the speed regulating pump set or the rated speed pump set for marshalling operation of water supply. The maximum water output of the pump unit shall not be less than the design water supply flow of the community, and shall be checked according to the fire fighting conditions.
4) . The number of lifting pumps for water tank and water tower shall be reduced as far as possible, and one for use and one for standby; When a single pump can meet the requirements, it is not suitable to use multiple parallel pumps; If multiple pumps must be operated in parallel or matched with large and small pumps, their models and numbers should not be too many. Generally, they should not exceed two types, and the lift range of pumps should be similar; When running in parallel, each pump should still operate within the high efficiency zone.
5) The design water supply flow of the variable frequency speed regulating pump (group) 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 efficient working area of the pump characteristic curve (Q-H curve), and not in the extension line of the Q-H curve. The most unfavorable working point shall be designed at the right end of the efficient section of the pump characteristic curve, that is, the point where the pump has the largest water output, but the head is low but can meet the requirements, that is, the intersection point between the low point of the efficient section of the pump characteristic curve and the pipe characteristic curve. The working range of water pump speed regulation shall be within the high efficiency range of 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 the domestic pressurized water supply system shall be equipped with a standby pump. The water supply capacity of the standby pump shall be greater than the water supply capacity of the largest operating pump. The pump shall be automatically switched and operated 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 national grid.
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Need to know for selection of vertical centrifugal pump
