The impeller of centrifugal pumps is rotating at very high velocity, in consequence, the different parts of the impeller are hitting the fluid and create vortex, turbulent flow, at a specific frequency which is then transmitted as a vibration through the shaft, pump casing and pipes to the surrounding of the pump. The air is then continuing to transfer the vibration, leading to a noisy environment.
Different types of centrifugal pumps lead to different noise levels. One should 1st define if the pump studied or designed is of the following types :
The absorbed power of a pump can be calculated thanks to the procedure given in this MyEngineerinTools page : Pump Power
The noise emitted by the pump is a function of the type of the pump and the absorbed power [Sihi] :
|Type of pump||Absorbed power||Noise emitted|
|Side channel pump||2 kW < P < 40 kW||LwA = 67+12.5*log(P/P0)|
|Single stage volute or ring section pumps with multi impellers||10 kW < P < 2000 kW||LwA = 66+13.5*log(P/P0)|
|Multi-stage ring section pump||10 kW < P < 2000 kW||LwA = 78+8.5*log(P/P0)|
LwA = A weighed sound pressure level (dB(A))
P = Absorbed power (kW)
P0 = 1 kW
It is necessary to calculate the pump head and power requirements as accurately as possible, indeed, an oversized pump will lead to more noise. In addition, different features can contribute to reducing the noise generated by a pump :
Special case of cavitation
A pump that cavitates leads to a very specific noise. It is then possible to reduce strongly the sound emitted by the pump by ensuring the pressure at the inlet of the pump is higher than its NSPHr and therefore do not cavitate.
It is also possible to foresee an insulation, like an enclosure of the pump within sound absorbing panels. A specific attention to the design of the sound proof enclosure must be given in order to ensure a good maintainability of the pump.
The reader can refer to the following manufacturers for new pumps :
Note that MyEngineeringTools has no link with those companies.
[Sihi] Basic Principles for the Design of Centrifugal Pumps Installations, Sihi, 2003