Principles and steps for the selection of the hott

Principles and steps of pump selection

selection principles

pump is a wide range of general-purpose mechanical equipment, which is widely used in petroleum, chemical industry, electric power metallurgy, mining, shipbuilding, light industry, agriculture, civil and national defense departments, and plays an important role in the national economy. According to statistics in 2002, the output of pumps in China reached more than 2 million, and the electric energy consumption of pumps accounted for more than 21% of the national electric energy consumption. Therefore, it is of great significance to reduce the energy consumption of pumps

at present, in various fields of the national economy, due to the unreasonable type selection, many pumps are in unreasonable operation conditions, with low operation efficiency and waste of a lot of energy. Some pumps cannot be used at all due to unreasonable model selection, or the use and maintenance costs increase, resulting in low economic benefits. It can be seen that reasonable pump selection is also of great significance to energy conservation

the so-called reasonable pump selection is to comprehensively consider the stc8800 Universal Experimental card of the pump unit measurement and control system, which is a microcomputer built-in PCI experimental card based on PCI interface, and the comprehensive technical and economic indicators such as the investment and operating costs of the pump station, so as to make it conform to the principles of economy, safety and applicability. Specifically, there are the following aspects:

the requirements for the use of flow and head must be met, that is, the operating point of the pump (the intersection of the device characteristic curve and the pump performance curve) is often maintained in the high-efficiency range, which saves power and is not easy to damage the parts

the selected pump should not only be small, light and cheap, but also have good characteristics and high efficiency

it has good anti cavitation performance, which can not only reduce the construction intensity of the pump platform, but also prevent the pump body from cavitation, with stable operation and long service life

the pump station is built according to the selected pump, so the project investment is small and the operation cost is low

selection steps

first, list the basic data:

1. Characteristics of the medium: medium name, specific gravity, viscosity, corrosivity, toxicity, etc

2. The particle diameter and content of solids in the medium

3. Medium temperature: (℃)

4. Required flow rate

generally, the leakage in the pipeline system can be ignored in the process flow of industrial pumps, but the impact of process changes on the flow rate must be considered. If agricultural pumps use open channels for water delivery, leakage and evaporation must also be considered

5. Pressure: suction pool pressure, drainage pool pressure, pressure drop in the pipeline system (head loss)

6. Pipeline system data (pipe diameter, length, type and number of pipeline accessories, geometric elevation from suction pool to pressure pool)

if necessary, the device characteristic curve should also be made

when designing and arranging pipelines, the following matters should be paid attention to:

a. reasonably select the pipeline diameter. The pipeline diameter is large. Under the same flow rate, the liquid flow speed is small, and the resistance loss is small. However, the high price and small pipeline diameter will lead to a sharp increase in resistance loss, which will increase the lift of the selected pump, increase the matching power, and increase the cost and operating expenses. Therefore, we should consider comprehensively from the perspective of technology and economy

b. the maximum pressure that the discharge pipe and its pipe joint can bear should be considered

c. the pipeline shall be arranged as a straight pipe as far as possible to minimize the accessories in the pipeline and the length of the pipeline. When turning is necessary, the bending radius of the elbow shall be 3 ~ 5 times the diameter of the pipeline, and the angle shall be greater than 90 ℃ as far as possible

d. the discharge side of the pump must be equipped with valves (ball valves or stop valves, etc.) and check valves with large market space for the development of the reverse extruder industry. The valve is used to adjust the working point of the pump. The check valve can prevent the pump from reversing when the liquid flows back, and prevent the pump from being hit by water hammer. (when the liquid flows back, it will generate huge reverse pressure and damage the pump)

determine the flow head

II. Determine the flow

A. if the minimum, normal and maximum flow have been given in the production process, the maximum flow should be considered

b. if only normal flow is given in the production process, a certain margin should be considered

for NS 100 high flow and low head pumps, in the shipbuilding market, the flow margin is taken as 10% for NS 50 low flow and high head pumps, and 5% for 50 ≤ ns ≤ 100 pumps. For pumps with poor quality and poor operating conditions, the flow margin should be taken as 10%

c. if the basic data only gives weight flow, it should be converted into volume flow

although most pumps are always determined according to different use environments, customers' requirements for product service life and efficiency are increasing. Our engineers are experts with rich experience in design, material selection and monitoring system. In addition to developing new designs, they also often exchange experience with users, constantly improve our existing technical level, and provide the best design scheme for customers' projects and projects

many customers have benefited from the experienced and correct choice of Zhejiang Deke pump and valve manufacturing Co., Ltd. with a wide range of product series and strong engineering and technical force, we can "Chen Linsen, President of the Institute of high tech industry of Suzhou University, said that it is enough to provide economical and durable water pumps to ensure that you have no worries when using our products