Difference Between Volute Pump and Turbine Pump or Diffuser Pump

Volute pump

Volute pumps and turbine pumps are types of centrifugal pumps according to the type of casing provided. They have different designs and operating principles. A volute pump has a volute-shaped housing that surrounds the impeller. The liquid enters the pump and is directed to the impeller, where the centrifugal force accelerates it. The liquid then exits the impeller and flows into the volute-shaped housing, where it is directed to the outlet. Volute helps to direct the fluid and reduce the velocity, thus increasing the pressure of the fluid. A volute pump's performance can be improved by providing an annular space called a vortex chamber between the impeller and the volute casing.

Turbine pump or Diffuser pump

An additional element known as diffuser is provided in a turbine pump or diffuser pump. The diffuser is a guide wheel with a series of guide vanes. In a turbine pump, the impeller is surrounded by the diffuser. From the diffuser vanes, the liquid flows into an outer casing that is placed concentrically with the impeller. The spaces between the guide vanes gradually increase; they act as a volute and increase the liquid pressure.

Diffuser pump is called turbine pumps because they resemble reaction turbines. Reversible pump turbines can operate as either a turbine or a pump if their direction of rotation is reversed. A turbine pump does not have this dual capability. It can work only as a pump.

Comparison between volute pump and turbine pump

Efficiency: Turbine pump significantly improves efficiency by up to 75%. Even though these pumps offer significant efficiency improvements, they will work best with a single discharge rate at given impeller speed. This is because the guide vanes are designed for only one discharge rate. For other discharge rates, shock or turbulence could occur at the entrance to the guide vanes, causing low efficiency.

Mode of operation: Both turbine and volute pumps are used in single-stage and multistage operations. However, turbine pumps are known for multistage operation. They are not widely used in single-stage operations. In single-stage operations, volute and vortex casings are preferable. Multistage volute pumps are not common.

Cost: Since the construction of turbine pump is complicated, it is more expensive than the volute pump.

Maintenance: Volute pumps are usually simple and easy to maintain, while turbine pumps are more complex and require more maintenance.

Applications: The volute pump is mainly used for low-pressure and high-flow applications, while the turbine pump is typically used for high-pressure and low-flow applications.