In the manufacturing process of the Zhongkai pump, the specifications for small, normal, and large flow rates have been provided; large flow rate should be considered.

b. If only normal flow rates are provided in the production process, it should be considered to leave a certain margin.

For low head pumps with ns>100 and high flow rates, the flow margin is set at 5%. For small flow rate pumps with ns<50 and high lift, the flow margin is 10%. For pumps with ns between 50 and 100, single-stage double-suction pumps, the flow margin is also 5%. For pumps of poor quality and under harsh operating conditions, the flow margin should be 10%.

c. If only basic data in terms of weight flow rate is provided, it should be converted to volume flow rate. The drive motor (motor) rotates the impeller through the pump shaft, with the impeller blades causing the fluid to rotate as well, thus generating centrifugal force. Under the action of this centrifugal force, the fluid is propelled along the impeller blade channels towards the impeller outlet. In a single-stage centrifugal double-suction pump, the fluid is collected by the volute and directed into the discharge pipe. The fluid gains energy from the impeller, increasing both pressure and velocity energy, and relies on this energy to transport the fluid to the work location. When a single impeller is unable to provide sufficient energy to the fluid, a centrifugal double-suction pump can use multiple impellers in series or parallel to perform work on the fluid. As the fluid is propelled towards the impeller outlet, a low-pressure area forms at the center of the impeller inlet. A pressure difference is created between the fluid in the suction tank and the fluid at the center of the impeller. Under this pressure difference, the fluid in the suction tank continuously enters the impeller through the suction pipeline and the pump's suction chamber. Thus, as the impeller rotates, it continuously draws in fluid, imparting a certain amount of energy to it, and then discharges the fluid, allowing the centrifugal pump to operate continuously.