Selection points of horizontal high pressure centrifugal water pump
Centrifugal pump is a kind of positive displacement pump. It is designed mainly by the principle of centrifugal force. The high-speed rotating impeller blades drive the water to rotate and throw the water out to achieve the purpose of transportation. There are many types of centrifugal pumps, which can be divided into civil and industrial pumps in terms of use; and can be divided into clean water pumps, impurity pumps, and corrosion-resistant centrifugal pumps from the transportation medium. The horizontal high-pressure centrifugal water pump of Zoomlion Pump is mainly composed of pump body, main shaft, impeller, mechanical seal, bearing and other parts.
Reasonable selection of horizontal high-pressure centrifugal water pumps requires comprehensive consideration of comprehensive technical and economic indicators such as pump units, pumping station investment and operating costs, so that it conforms to the principles of economy, safety and application. The key points of selection of horizontal high pressure centrifugal water pump include the following aspects:
1). High-efficiency, low-noise, energy-saving water pumps should be selected, and it is strictly forbidden to choose obsolete products.
2). The pump should be selected according to the design flow and the required head, and considering that the pump output is reduced due to wear and tear of the pump, the pump can be selected after the calculated head H is multiplied by a coefficient of 1.05 to 1.10; the characteristic curve should be selected as the flow increases. Larger pumps whose heads gradually drop are stable and reliable when working in parallel; and the operating point of the pump should be kept in a high-efficiency range, which saves energy and is not easy to damage the parts.
3) When the water supply network has no regulating facilities, it is advisable to use speed-regulating pump sets or rated speed pump sets to run water supply. The maximum water output of the pump set should not be less than the design flow of the community water supply, and should be checked according to the fire fighting conditions.
4). The number of pumps should be minimized when selecting water tanks and water towers. It is advisable to use one for one; when a single pump can meet the requirements, it is not advisable to use multiple units in parallel; if multiple units must be operated in parallel or with large and small pumps When operating in parallel, the model and number of units should not be too many, and generally should not exceed two models. The pump head range should be similar; each pump should still operate in the high-efficiency zone when operating in parallel.
5) The designed water supply flow of the variable-frequency speed-regulating pump (group) should ensure that it meets the requirements of the maximum designed second flow 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 should be selected in the efficient working area of the pump characteristic curve (QH curve), and not on the extension line of the QH curve. The most unfavorable working point of the design should be At the right end of the high-efficiency section of the pump characteristic curve, that is, the point where the pump has the largest output and lower head but can meet the requirements, that is, the intersection of the low point of the high-efficiency section of the pump characteristic curve and the pipeline characteristic curve. The working range of the pump speed adjustment can be as far as possible within the high-efficiency section of the pump; the speed adjustment range should be set between 25% and 100% of the water supply volume of the pump; the equipment should have the function of automatic water level control.
6) The water pump unit of the domestic pressurized water supply system should be equipped with a standby pump. The water supply capacity of the standby pump should be greater than the water supply capacity of the largest running water pump. The water pumps should automatically switch and operate alternately.
7) The voltage of the motor equipped with the water pump should be the same, and the power supply system should be the same as the power supply system of the national grid.
