The relationship between head and flow rate of centrifugal pumps
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I would like to ask: what is the relationship between head and flow rate for centrifugal pumps (including canned pumps)? Under what conditions will the flow rate of a centrifugal pump exceed its rated flow rate?
There is an inverse relationship between the head and flow rate of a centrifugal pump; as the flow rate increases, the head decreases； Conversely, when the flow rate decreases, the head increases. This relationship is usually shown on the performance curve of the pump. The situation in which a centrifugal pump delivers a flow rate exceeding its rated value usually occurs when the resistance presented by the system to which the pump supplies fluid is lower than the designed value, or when the inlet pressure is higher than the specified value. In other words, when the actual operating conditions of the system are lower than the resistance conditions for which the pump was designed, the pump’s output flow rate may increase, thereby exceeding the rated flow rate. .
When the pumping height or pressure loss of a centrifugal pump is much lower than the head, the flow rate exceeds the rated value.