Water pump is a versatile mechanical equipment with a wide range of applications, widely used in various departments such as petroleum, chemical, power metallurgy, mining, ship selection, light industry, agriculture, civil and national defense. The selection of water pumps mainly involves data such as working medium, working medium characteristics, head, flow rate, environmental temperature, etc. A suitable water pump not only works smoothly and has a long lifespan, but also can save costs to the greatest extent for users.

1. If the minimum, normal, and maximum flow rates have been given in the production process, the maximum flow rate should be considered.

2. If only normal flow rate is given in the production process, a certain margin should be considered. For large flow low head pumps with ns>100, a flow margin of 5% is taken. For small flow high head pumps with ns<50, a flow margin of 10% is taken. For pumps with ns ≤ 50, a flow margin of 5% is also taken. For pumps with poor quality and operating conditions, a flow margin of 10% should be taken.

3. If the basic data only provides weight flow rate, it should be converted to volume flow rate.