Pump Controllers

A pump curve is a graphical representation of the performance characteristics of a pump. This representation is typically shown as a graph with the “head” plotted on the x axis and the “flow” plotted on the y axis. Head is the height at which a pump can raise water. Connecting a tube or pipe to the discharge end of a pump and measuring the height at which the pump can raise the fluid, is the maximum head of the pump. Flow is the rate at which the fluid can be pumped through a pipe. With this information, the pump curve will display the most efficient way to use the pump. 

The efficiency of a pump is the relationship between the input horsepower required to drive the pump and the water horsepower created by the pump. The pump curve shows the optimal operating range and the allowable operating range. The optimal range is where the pump will perform at its peak, without putting too much stress on the pump. The allowable operating range shows where the limits of the pump are while still being able to safely function. It is best to operate the pump within the optimal range and not the allowable operating range.

It is important to understand that head and flow are directly related to each other. For example, if a pump is expected to move 10 gallons of water per minute (GPM), the head will impact the flow rate at which the water can be pumped. If the pump is expected to move that water 50 feet upwards, it may not be able to achieve the necessary 10 GPM. It all depends on the pump design. If a pump is expected to move 10 GPM, with 3 feet head, it will be easier for the same pump to meet the expected 10 GPM.