Pump noise : causes, remedies, formula, step by step calculation guide
How to reduce a pump noise level ?
How to calculate the noise level emitted by a centrifugal pump ?
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1. Introduction
2. Noise of a centrifugal pump : step by step calculation
4. Manufacturers
1. Introduction
Why are centrifugal pumps noisy ?
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.
2. Noise of a centrifugal pump : step by step calculation
How to estimate what will be the noise emitted by a pump ?
2.1 STEP 1 : Define the type of pump
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 :
- Side channel pump
- Single stage volute or ring section pumps with multi impellers
- Multi-stage ring section pump
2.2 STEP 2 : Calculate the absorbed power
The absorbed power of a pump can be calculated thanks to the procedure given in this MyEngineerinTools page : Pump Power
2.3 STEP 3 : Calculate the noise emitted
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) |
With :
LwA = A weighed sound pressure level (dB(A))
P = Absorbed power (kW)
P0 = 1 kW
3. Noise control : reduction for pumps
How to make a pump less noisy ?
3.1 Noise reduction by design
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 :
- Prefer design leading to low flow velocity in pipes
- Use low noise fittings, have the pump mounted on a base plate with dampers, use vibration reducing pipework
- Avoid sudden changes in cross section of the piping
- Use long radius bends
- Use low noise motors and gear boxes
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.
3.2 Noise reduction by insulation
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.
4. Manufacturers
The reader can refer to the following manufacturers for new pumps :
- GrosClaude pumps (for all kind of pumps)
- Sihi pumps (for side channel pumps)
Note that MyEngineeringTools has no link with those companies.
5. Pump noise estimate free calculator
Warning : this calculator is provided to illustrate the concepts mentioned in this webpage, it is not intended for detail design. It is not a commercial product, no guarantee is given on the results. Please consult a reputable designer for all detail design you may need.
5.1 Excel calculator
You can
download the calculator here : link
5.2 Online
calculator
Pump Noise Level Calculator
⚠️ Important Notes:
- Values are theoretical and may vary in real conditions
- Consider ambient noise and reflections
- Always wear appropriate hearing protection
Results
FAQ: Pump Noise
1. Why are centrifugal pumps noisy?
Centrifugal pumps generate noise due to the high-speed rotation of the impeller, which creates turbulent flow and vibrations. These vibrations are transmitted through the shaft, casing, and pipes, leading to noise in the surrounding environment.
2. How can I estimate the noise level of a centrifugal pump?
Noise level can be estimated using the absorbed power and pump type. The formula varies by pump type: - Side channel pump: \( L_{wA} = 67 + 12.5 \times \log\left(\frac{P}{P_0}\right) \) - Single stage volute/ring section pumps: \( L_{wA} = 66 + 13.5 \times \log\left(\frac{P}{P_0}\right) \) - Multi-stage ring section pump: \( L_{wA} = 78 + 8.5 \times \log\left(\frac{P}{P_0}\right) \) Where \( P \) = absorbed power (kW) and \( P_0 = 1 \) kW.
3. What are the main causes of pump noise?
Main causes include high flow velocities, turbulent flow, cavitation, oversized pumps, and vibrations transmitted through the pump casing and pipes.
4. How can I reduce pump noise by design?
Design strategies include accurate sizing to avoid oversizing, using low-noise fittings, mounting pumps on dampers, avoiding sudden piping changes, and using long radius bends.
5. What role does cavitation play in pump noise?
Cavitation produces a distinct noise. Ensuring the inlet pressure is above the pump’s NSPHr (Net Positive Suction Head Required) prevents cavitation and reduces noise.
6. How can insulation reduce pump noise?
Insulation methods like sound-absorbing panels or enclosures can significantly reduce noise. Ensure the design allows for pump maintenance.
7. What are low-noise pump components?
Use low-noise motors, gearboxes, and vibration-reducing pipework to minimize noise generation.
8. Are there tools to calculate pump noise levels?
Yes, our website offers a free online calculator and an Excel tool to estimate pump noise levels.
9. What precautions should be taken when using the noise calculator?
The calculator provides theoretical values. Consider ambient noise, reflections, and always verify results with real-world conditions.
10. How does pump type affect noise levels?
Different pump types (e.g., side channel, single-stage, multi-stage) have varying noise levels due to their design and operating principles. The noise formula adjusts based on pump type.
Source
[Sihi] Basic Principles for the Design of Centrifugal Pumps Installations, Sihi, 2003