Pump head, often referred to simply as “head,” is a fundamental concept in fluid dynamics and is a critical parameter when selecting and operating a pump. It represents the energy imparted by the pump to the fluid, which allows it to overcome the resistance, elevation changes, and friction losses in the system it is pumping into.
In simple terms, pump head is the height to which a pump can lift a fluid or the pressure it can generate to push the fluid through a pipeline or system. It is typically measured in units of length, such as meters (m) or feet (ft). The pump head consists of three main components:
- Static Head: This component accounts for the elevation difference between the pump’s inlet and outlet points. It is the height to which the pump can raise the fluid above its starting point. For example, if the pump is located at ground level and the fluid is being pumped to a tank on the roof, the static head would be the height of the building.
- Velocity Head: As the fluid moves through the pipeline or system, it gains kinetic energy due to its velocity. The velocity head represents this kinetic energy and is proportional to the square of the fluid velocity.
- Pressure Head: This component represents the pressure energy of the fluid as it moves through the system. It is typically measured in pressure units such as Pascals (Pa) or pounds per square inch (psi).
The total pump head (H) is the sum of these three components:
Total Pump Head (H) = Static Head + Velocity Head + Pressure Head
It’s important to note that the total pump head varies with the flow rate. As the flow rate increases, the pump head also changes due to changes in friction losses and other factors.
When selecting a pump, it is crucial to ensure that the pump’s head capabilities meet the requirements of the system. If the pump head is insufficient, the fluid may not reach the desired location, and if it’s excessive, the pump may consume more energy than necessary, leading to inefficiencies.
The pump manufacturer typically provides a pump curve, which shows the relationship between pump head and flow rate. By analyzing this curve and considering the system requirements, engineers can select the right pump that operates at the desired head and flow rate for the application.