1, according to the layout of the device, topography, water conditions, operating conditions, economic programs and many other factors. 2, consider the choice of horizontal, vertical and other types (pipe, right angle, variable angle, angle, parallel, vertical, vertical, submersible, demolition, Self-priming, gear-type, oil-filled, water-filled temperature). Horizontal pump disassembly and assembly convenience, 3, easy to manage, but bulky, 4, the price is more expensive, 5, need a large footprint; vertical pump, 6, in many cases the impeller submerged in water, 7, Start, 8, for automatic ç› or remote control, 9, and compact, 10, small installation area, 11, cheaper prices. 3, according to the nature of the liquid medium to determine the water pump, hot water pump also pump, chemical pump or corrosion-resistant pump or impurity pump, or not blocked pump. Pumps installed in the explosive area should be explosion-proof motor according to the explosion area level. 4. Vibration volume is divided into: pneumatic, electric (electric divided into 220v voltage and 380v voltage). 5, according to the size of the flow, suction pump or double suction pump menu: According to the level of the head, the pump suction or suction pump, high speed pump or low speed pump (air conditioning pump), multi-stage pump efficiency than single-stage pump, Pumps and multi-stage pump can also be used when the same, should choose a single-stage pump. 6, to determine the specific type of pump, the pump used in what series of options, you can press the maximum flow, enlarge the 5% - 10% head lift the performance of these two main parameters in the spectrogram or series of characteristic curve Determine the specific model. Use the pump characteristic curve to find the desired flow value on the abscissa and the desired lift value on the ordinate. Draw the vertical or horizontal lines from the two values, respectively, and the intersection of the two lines falls exactly on the characteristic curve. The pump is to be selected pump, but this ideal situation generally not rare, usually encounter the following situations: A, the first: the intersection point in the characteristic curve above, indicating that the flow to meet the requirements, but not enough head, At this point, if the lift is about the same, or a difference of about 5%, can still be used, if a lot of head difference, then choose a larger head pump. Or try to reduce the pipeline resistance loss. B, the second: the intersection of the curve below the characteristic curve in the fan characteristic trapezoidal trapezoidal range, the initial set under this model, and then according to how much head difference to decide whether to cut the impeller diameter, if the difference is small head, it does not cut , If the head is very different, according to the required Q, H, according to its ns and cutting formula, cutting impeller diameter, if the intersection does not fall within the range of fan-shaped trapezoidal, should choose a smaller pump head. Pump selection, and sometimes have to consider the production process requirements, choose different shape QH characteristic curve.