Why does not ATACH recommend using the maximum flow rate point for the pump?

Recently, a customer requested a centrifugal pump with a flow rate of 408 m³/h and a height of 15 m. 

They specified that the pump's inlet and outlet should be 200 mm x 150 mm. During our selection process, we found that when using a 200 mm x 150 mm pump, the pump's flow rate reached the maximum value at that point. 

We suggested to the customer that we change this parameter from 200 mm x 150 mm to 250 mm x 200 mm. 

Otherwise, we would not provide a quotation because even if we received this order, there would be problems with the pump's maintenance and usage later. 

The reasons are as follows:

Firstly, the maximum flow rate and the standard flow rate are two different concepts.

• Maximum flow rate: The maximum amount of liquid that a pump can convey under specific operating conditions. When the pump reaches the maximum flow rate, its head is usually relatively lower because there is an inverse relationship between the flow rate and the head of a centrifugal pump. The maximum flow rate is an extreme value of the pump's performance. 

Operating the centrifugal pump for a long time at this flow rate may cause damage to the pump or reduce its service life.

• Standard flow rate: The designed ideal working flow rate of the pump, also known as the design flow rate or rated flow rate. Operating the pump at the standard flow rate ensures the highest working efficiency, lower energy consumption, and stable long-term operation of the pump. If the actual operating flow rate of the pump exceeds the standard flow rate, it may cause problems such as excessive current, overheating, and cavitation, thereby affecting the performance and service life of the pump.

Therefore, when selecting and using a pump, it is necessary to determine the working flow rate reasonably according to actual needs, avoiding operating the pump for a long time at the maximum flow rate or beyond the standard flow rate.