Selection
Industry pump is a large faceted, wide volume general-purpose mechanical equipment, it is widely used in petroleum, chemical, electric power, metallurgy, mining, shipbuilding, light industry, agriculture, civil and defense departments, occupies an important position in the national economy. According to 79 years statistics, China's production of pump are 1256 thousand sets. Industrial pump electricity consumption accounts for above 21% of electricity consumption. Therefore greatly reduce pump used energy consumption is a great significance to energy saving.
At present in the national economy domain, due to the unreasonable selection, many pumps are in unreasonable operational condition, low operation efficiency and lost a large number of energy. Some industrial pump because unreasonable selection, can't use, or usd maintenance cost increased, and the economic benefit is low. Thus, reasonable choosing pump also has an important significance for energy conservation.
So-called reasonable pump selection, which means comprehensive consideration of pump units and the pumping station investment and running costs and other integrated technical and economic indexes, to fit for economy, safe and applicable principles. Specifically, have the following respects：
Must satisfy the used flow and head requirements, which requires pump operating conditions points (device characteristic curve and pump performance curve intersection) often operate maintain in high efficiency interval, it saves power and not easy damage parts
The selected pump should not only small volume, light weight, cheap, and have good properties and higher efficiency
Has good anti-cavitation performance, it can reduce pump body platform build strength, and do not let the pump body cavitation, smooth operation and long life.
According to selected pump built pump station, less engineering investment, low operating cost
selecting steps
一 list basic data:
1、 medium characteristics: medium name, proportion, viscosity, corrosivity, toxicity, etc.
2、 medium contained solid particle diameter, amount.
3、 medium temperature（℃）
4、 needed flow
General industrial pumps used in technologic process can be neglected pipe system leakage, but must consider the effect to flow when process changed. If agriculture pumps used for water channel, must consider leakage and evaporation
5、 pressure: suction pressure, drain tank pressure, pipeline system pressure drop (head losses).
6、 piping system data (diameter, length and piping fittings types and number, absorb pool to pressure pool geometric elevation, etc.).
If needed, we also should make device characteristic curve
When designing layout pipe, should pay attention to the following items:
A. rational selection of pipe diameter, large pipe diameter, under the same flow, liquid flow speed is small, resistance loss is small, but the price is high, the pipe diameter is small, can cause resistance losses increased rapidly, make the selected pump head increased, equipped power increased, cost and operation cost is also increased. So we need to comprehensive consider from the technical and economic respects.
B. discharge pipe and pipe joint should be considered the supported maximum pressure.
C. piping layout should as far as possible to minimize decorate straight pipe and try best to narrow pipe accessory and lessen pipe length, when turning, elbow bend radius should be3 ~ 5 times of the pipe diameter, angle should as far as possible larger than 90℃.
D. pump discharge side must furnish valve (ball valves or globe valve, etc) and non-return valve. The valve is used to regulate the pump operation points, non-return valve can prevent pump reveral when liquid backflows and make pump avoid water hammer attacking. (when the liquid backflows, will have a huge reverse pressure, make pump damaged) determine the flow head.
二. flow determination
a. if producing process has given the smallest and normal, the maximum flow, should according to the maximum flow consideration.
b. if producing process just give normal flow, should consider to leave a certain allowance.
To ns&100 large flow low head pump, flow allowance takes 5%, to ns<50 small flow higher head pump, flow allowance takes 10%, 50≤ns≤100 pumps, flow allowance also takes 5%, to inferior quality and poor operating conditions pump, flow allowance should take 10%.
c if the basic data only give weight flow, should convert to volume flow.
Although most industry pumps always according to different used environment, but customers requirements of product service life and efficiency are increasingly growth, each manufacturer engineers are improving existing technology, provide the best solution for engineering and projects.
