Pipeline Pump Selection Steps

May. 15, 2024

Relatively speaking, pipeline pumps do not have high requirements on flow rate and the medium transported. Therefore, the selection of pipeline pumps mainly considers the appropriate flow rate and lift. The basis for selecting a pipeline pump should be based on the process flow, water supply and drainage requirements, and should be considered from five aspects, including liquid delivery volume, installation head, liquid quality, pipeline layout, and controlled operating conditions.

It is mainly considered from five aspects, namely liquid delivery volume, device head, liquid properties, pipeline layout and operating conditions.

1. First list the basic data:

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

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

3). Medium temperature: (℃)

4). The required flow rate. Generally, the leakage in the pipeline system of industrial pumps can be ignored in the process flow, but the impact on the flow rate when the process changes must be considered. If agricultural pumps use open channels to transport water, leakage and evaporation must also be considered.

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

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

If necessary, the device characteristic curve should also be drawn.

Secondly, when designing and laying out pipelines, the following matters should be paid attention to:

A. Reasonably select the pipe diameter. A large pipe diameter will have a small liquid flow velocity and a small resistance loss at the same flow rate. However, the price is high. A small pipe diameter will cause a sharp increase in resistance loss, which will increase the head of the selected pump. The configuration As the belt power increases, the cost and operating expenses increase. Therefore, it should be considered comprehensively from a technical and economic perspective.

B. Discharge pipe and its pipe joints

The maximum pressure that can be tolerated should be considered.

C. The pipeline layout should be as straight as possible, and the accessories in the pipeline should be minimized and the length of the pipeline should be minimized. When turning is necessary, the bending radius of the elbow should be 3 to 5 times the diameter of the pipeline, and the angle should be as large as 90 degrees. ℃.

D. The discharge side of the pump must be equipped with valves (ball valves or stop valves, etc.) and check valves. The valve is used to adjust the operating point of the pump. The check valve prevents the pump from reversing when the liquid flows back and protects the pump from water hammer. (When the liquid flows back, a huge reverse pressure will be generated, causing damage to the pump)

2. Determine the flow head of the pipeline pump and determine the flow rate.

Flow is one of the important performance data for pipeline pump selection, which is directly related to the production capacity and transportation capacity of the entire device. For example, the process hypothesis of the Institute can calculate the normal, minimum, and maximum flow rates of the pump. When deciding on a pump, take the maximum flow rate as the basis and take into account the normal flow rate. When the pump is not at the maximum flow rate, 11 times the normal flow rate can be taken as the maximum flow rate.

a. If the minimum, normal and maximum flow rates are given in the production process, the maximum flow rate should be considered.

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

For large flow and low head pumps with ns>100, the flow margin is 5%. For small flow and high head pumps with ns<50, the flow margin is 10%. For pumps with 50≤ns≤100, the flow margin is also 5%. %. For pumps with poor quality and poor operating conditions, the flow margin should be 10%.

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

3. The head required to disassemble the system is another important performance data for pipeline pump selection. Generally, the head must be enlarged by 5%-10% to select the type.

4. Liquid properties, including the name of the liquid medium, physical properties, chemical properties and other properties. The physical properties include temperature, density, viscosity, u, diameter of solid particles in the medium and solid content, etc. This affects the head of the system and effective cavitation. Margin planning and suitable pump type: chemical properties, mainly refers to the chemical deterioration and toxicity of the liquid medium, the important basis for selecting materials for pipeline pumps and which type of shaft seal to use.

5. The pipeline layout conditions of the disassembly system refer to the liquid delivery height, liquid delivery distance, liquid delivery direction, the lowest liquid level on the suction side, the highest liquid level on the overhead side and other data, as well as pipeline specifications and their length, materials, pipe fitting specifications, quantity, etc. , in order to perform system comb head calculation and NPSH verification.

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