Jet Pump Making Noise: A Comprehensive Troubleshooting Guide

Jet pumps are widely used in various applications, from residential water supply systems to industrial processes. However, when a jet pump starts making noise, it can be a cause for concern, indicating potential issues that need to be addressed. This comprehensive guide will delve into the technical specifications, measurement techniques, and step-by-step troubleshooting methods to help you identify and resolve the root cause of the jet pump’s noise.

Technical Specification of Jet Pump Making Noise

The noise produced by a jet pump is typically measured in decibels (dB) using an acoustic level meter analyzer, such as the SVAN971. To achieve level 1 measurement accuracy, the A-weighted acoustic pressure level of the background noise must be at least 10 dB lower than the acoustic pressure level emitted by the measured acoustic source without back-noise correction.

In a study conducted on the noise-induced characteristics of unsteady cavitation in a jet pump, the researchers found that the jet pump produced steady-state noise in each cavitation state. The shortest measurement period for octave or 1/3 octave frequency band measurement was 30 seconds for frequency bands with a center frequency of 160 Hz and below, and 10 seconds for frequency bands with a center frequency of 200 Hz and above. The measurement time was 60 seconds to ensure the accuracy of data collection.

The Pearson correlation coefficient was used to analyze the results of different noise sampling periods, with a two-tailed significance test applied. In this case, the Pearson correlation coefficient was 0.99185, indicating a significant correlation at the 0.05 level.

These measurements and analyses provide quantifiable data on the noise produced by a jet pump, allowing for comparison and evaluation of different operating conditions and potential noise control measures.

Factors Contributing to Jet Pump Noise

The technical specifications of a jet pump making noise can vary depending on the specific model and operating conditions. However, some general factors that can contribute to noise in jet pumps include:

1. Cavitation:
2. Cavitation occurs when the pressure of the fluid drops below the vapor pressure, causing the formation of vapor bubbles that collapse suddenly.
3. This collapse produces noise and can potentially damage the pump components.

4. Cavitation noise typically sounds like a high-pitched crackling and transitions to an intense rattling sound when the effect intensifies (i.e., lower NPSH).

5. Transient Flow and Pressure Fluctuations:

6. Transient flow and the pressure fluctuations associated with it produce noise in pumps and systems.
7. These fluctuations occur when energy is transferred via the impeller vanes to the fluid handled, leading to periodic pressure fluctuations with amplitudes of varying intensity.

8. The flow pattern of the fluid flowing around the vanes, as well as flow separation, make the flow in a centrifugal pump transient.

9. Vibrations in the Piping and Pump Casing:

10. Vibrations in the piping and pump casing can interact with the surrounding air and be perceived as airborne sound.

11. These vibrations can be caused by transient flow and pressure fluctuations, as well as by the drive of the centrifugal pump.

12. Bearing Failure:

13. In some cases, noise in a jet pump may be due to bearing failure, which can produce a loud wind or consistent grinding noise.

To address these sources of noise, various noise control measures can be implemented, such as selecting a pump designed for the task in question and having the correct size, operating the pump at the operating point that provides optimum pump efficiency, using expansion joints in the piping installation, and installing the pump set on rubber-metal or spring mounts.

Jet Pump Making Noise DIY Troubleshooting

If a jet pump is making noise, there are several steps that can be taken to diagnose and potentially remedy the issue:

1. Check the Water Level:
2. If the noise is intermittent and occurs after prolonged run periods or after irrigation cycles, it may be due to a low water level in the well causing the pump to suck air into the system.

3. Check the water level in the well and ensure that the suction line or suction pipe is not restricted.

4. Inspect the Foot Valve:

5. Remove the screen and assure yourself that the foot valve is sealing properly.

6. If the foot valve has become covered in mud or is worn, it may need to be replaced.

7. Check for Sediment or Debris:

8. If there is something lodged or wedged inside the pump or a buildup of sediment material, take the casing apart and inspect the components.

9. Clean or replace any components as necessary.

10. Check the Suction Pipe:

11. If the noise is occurring in a new installation and is not a condition that has occurred over time, it may be due to the suction pipe being too long or too small, causing excessive friction loss before the water reaches the pump.

By following these steps, it may be possible to diagnose and remedy the issue of a noisy jet pump without the need for professional assistance. However, if the issue persists or if there is any uncertainty, it is always best to consult with a professional plumber or pump technician.

References

1. Noise in pumps and systems – KSB: https://www.ksb.com/en-global/centrifugal-pump-lexicon/article/noise-in-pumps-and-systems-1116102
2. Research on Noise-Induced Characteristics of Unsteady Cavitation of a Jet Pump: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9016847/
3. jet pump making high pitched noise when running – DoItYourself.com: https://www.doityourself.com/forum/wells-sump-pumps-septic-sewage-systems/184372-jet-pump-making-high-pitched-noise-when-running.html
4. Research on Noise-Induced Characteristics of Unsteady Cavitation …: https://pubs.acs.org/doi/10.1021/acsomega.2c00684
5. Troubleshooting Jet Pump: Noisy Pump (Cavitation) – YouTube: https://www.youtube.com/watch?v=G9pNhscp7Gw