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 area; 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, the vibration 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 the pump of choice, but the ideal situation is usually not very few, usually run into the following situations:
A, the first: the intersection point in the characteristic curve above, indicating that the flow to meet the requirements, but the lift is not enough, at this time, if the lift is about the same, or a difference of about 5%, can still be used, if the lift a lot of difference, 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.
A, such as: to the level of liquid must be maintained to maintain a certain height of the container,
B, this time thinning
C, looking at the larger changes, however
D, small change in head,
E, should be used for the second smooth HO curve pump.
F, such as: the oil sent to the tube furnace,
G, if the work flow changes small,
H, the tube is easy to produce coking phenomenon. To avoid this situation,
I, hope but a slight decrease in traffic,
J, the oil pressure in the tube has increased greatly,
K, just to be formed by the scorch higher pressure flow away,
L, at this moment,
M, should choose QH curves more sub-drop pump.
7, the pump model is determined, the pump or transport medium similar to the physical and chemical water pump, need to go to the relevant product catalog or sample, according to the model performance chart or performance curve correction to see whether the normal working point falls on the Pump priority work area? The effective NPSH is greater than (NPSH). Can also be reversed in order to NPSH geometric installation height?
8, for the delivery of liquid pump viscosity greater than 20mm2 / s, must be the experimental curve of water pump performance curve converted to the viscosity, in particular, to suction or performance such as careful calculation of nuclear.
9, to determine the number of pumps and spare rate:
The normal operation of the pump, generally only one, because a large pump and parallel work of two small pumps, (referring to the head, the same flow), the pump efficiency is higher than the small pump, so from the point of view of energy-saving options rather Ning Taiwan big pump, rather than two small pumps, but in the case of the following circumstances, consider the two pumps in parallel cooperation:
A lot of traffic, a pump can not reach this traffic.
For large pumps requiring a 50% standby rate, two smaller pumps can be changed to work, with two spares (total of three)
For some large pumps, the pump with 70% of the flow rate can be selected for operation in parallel without a spare pump. When one pump is undergoing maintenance, the other pump still takes 70% of the production.
On the need for 24 hours of continuous operation of the pump, spare pump should be three, running, a spare, a maintenance.
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