First of all, when choosing a water pump, we need to determine the type of pump. First, we need to determine whether the required water pump is for well use or sewage discharge, whether it is for building pressurization or fountain landscape. We need to first determine the direction of use of the water pump and determine the correct operating conditions in order to choose the appropriate pump type.
Determine product parameters
When we know the type of pump, we need to determine the parameters required for the product. For example, we need a fountain pump, which generally has a high head. Our landscape engineering needs to pump 20m3/h of water to a height of 8m. At this time, we need to determine the parameters of the submersible pump, with a flow rate of 20m3/h. However, because the fountain usually pumps water vertically upwards, we need a higher head than the expected water level. When we pump it to a height of 8m, we may need to pump it to a height of 10m or more. Once the parameters are determined, the selection will be more accurate.
After determining the product category and parameters, whether the water pump can meet the requirements also depends on understanding the usage environment. For example, when stainless steel submersible pumps are used for deep well water extraction, after determining the pump type and parameters, we also need to understand the situation of the water well, such as the diameter of the wellhead, dynamic and static water levels, water quality, etc. Only after these issues are determined can we finally install a suitable pump.
Before selecting the pump type, please understand the environmental data used by the water pump.
1、 List basic data:
1. Characteristics of the medium: medium name, specific gravity, viscosity, corrosiveness, toxicity, etc
2. The diameter and content (mass or volume percentage) of solid particles contained in the medium
3. Medium temperature: (℃)
4. Required traffic
Generally, industrial pumps can ignore the leakage in the pipeline system in the process flow, but the impact of process changes on flow rate must be considered. If agricultural pumps use open channels for water transportation, leakage and evaporation must also be considered.
5. Pressure: Pressure drop (head loss) in the pressure pipeline system of the suction pool, drainage pool, and pressure pipeline system
6. Pipeline system data (diameter, length, type and number of pipeline accessories, geometric elevation from suction tank to pressure tank) should also be provided with device characteristic curves if necessary. When designing and arranging pipelines, the following precautions should be taken:
A. Reasonable selection of pipeline diameter. With a large pipeline diameter at the same flow rate and low liquid flow velocity, the resistance loss is small but the price is high. A small pipeline diameter can lead to a sharp increase in resistance loss, increasing the head of the selected pump and increasing the power supply. Therefore, comprehensive consideration should be given from both technical and economic perspectives, as well as increasing costs and operating costs
B. The discharge pipe and its fittings should consider the maximum pressure they can withstand
C. The pipeline layout should be arranged as straight as possible to minimize the number of accessories in the pipeline and minimize the length of the pipeline. When turning is necessary, the bending radius of the elbow should be 3-5 times the diameter of the pipeline, and the angle should be greater than 90 ℃ as much as possible
D. The discharge side of the water pump must be equipped with valves (ball valves or globe valves, etc.) and check valves to regulate the operating point of the pump. Check valves can prevent the pump from reversing and prevent water hammer impact when the liquid flows back (huge reverse pressure will be generated when the liquid flows back, causing pump damage)
2、 Determine flow head
Determination of traffic
a. If the minimum, normal, and maximum flow rates have been given in the production process, they should be considered based on the maximum flow rate
b. If only normal flow rate is provided in the production process, a certain margin should be considered. For large flow rates with ns>100 and low flow rates, the flow margin of the unintentional head pump should be taken as 5%. For small flow rates with ns>50 and high head pumps, the flow margin should be taken as 10%. For pumps with ns ≤ 100, the flow margin should also be taken as 5%. For pumps with poor quality and poor operating conditions, the flow margin should be taken as 10%
c. If the basic data only provides weight flow rate, it should be converted to volumetric flow rate
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