According to the technological process and water supply and drainage requirements, the basis of pump type selection should be considered from five aspects: liquid delivery capacity, device head, liquid properties, pipeline layout and operation conditions.
1. Flow rate is one of the important performance data of pump selection, which is directly related to the production capacity and conveying capacity of the whole device. For example, in the process design of the design institute, the normal, minimum and maximum flow of the pump can be calculated. When choosing a pump, the maximum flow rate is used as the basis and the normal flow rate is taken into account. In the absence of the maximum flow rate, 1.1 times of the normal flow rate is usually taken as the maximum flow rate.
2. The head required by the device system is another important performance data for pump selection. Generally, the head should be enlarged by 5%-10%.
3. Liquid properties, including the name of liquid medium, physical properties, chemical properties and other properties. Physical properties include temperature C density d, viscosity u, solid particle diameter in medium and gas content, etc. This involves the head of the system, the calculation of effective cavitation allowance and the type of suitable pump: chemical properties, mainly referring to liquid medium. Chemical corrosiveness and toxicity are the important basis for selecting pump materials and the type of shaft seal.