Pump selection should follow the following general rules:
1. Should use low-noise, energy-saving pumps, non-use eliminated products.
2. According to the actual flow, lift election pump. Consider due to wear and tear causes the pump output decreased, according to the calculation of the lift multiplied by 1.05 to 1.1 after the pump. Pumps should operate in high-efficiency areas. In general, it is not appropriate to choose a pump with a rising section of the QH curve. If it is operated in parallel, you have to use it.
3. Water tank, water tower pump should be reduced to minimize the number of units, with one preparedness appropriate; when a run to meet the requirements, it is not appropriate to use more than one pump in parallel; if you must use more than one parallel operation or size Pump with the way, its model, the number of units should not be too much, generally not more than two models, the pump lift range should be similar; parallel operation of each pump should still be operating within the high-efficiency zone.
4. If using frequency control feed pump, should meet the following conditions:
1) reliable power supply should be dual power or dual-loop power supply.
2) The most unfavorable operating point of the design should be at the right end of the high efficiency section of the pump characteristic curve, and the working range of the pump speed regulation can be within the high-efficiency section of the pump as far as possible.
3) Pump speed range should be within the range of 0.75 ~ 1.0.
4) Uneven water, large flow changes should be used when more than one water pump combination (usually not more than 3 to 4 units, you can press a speed control for the rest of the way for constant speed), should be equipped with small flow pumps and small pressure tank.
5) Equipment should have water level control. Ultra-high water level alarm, down to the design of the lower limit of water level, automatic shutdown; to restore the pump water level, the automatic start.
5. Equipment pumps, spare pumps should not be less than the maximum water supply capacity of a running pump, the pump should automatically switch, alternating operation.
6. Pump equipped with the pressure of the motor should be the same.