A case study of stopping humming sound in industrial RO pumps


Client: Soft drink shop owner at Indore, Madhya Pradesh

Complain: Humming Sound in Industrial RO Pump


Vertical Multi-stage Centrifugal Pump - LHR Series
Lubi's Vertical Multi-stage Centrifugal Pump (LHR Series)


Our client owns a reputed soft drink store and requires an industrial-grade reverse osmosis system to obtain clean, filtered water. The system necessitates a robust pump to push water through its various membranes. To fulfill this need, our client has been utilizing our LHR-2 Vertical Multistage Pump.


One day, while an employee heard a humming noise emanating from the RO plant. Suspecting an issue with the pump, the employee promptly shut down the system and notified our client, who immediately contacted us via our toll-free helpline to register a complaint.



  1. Customers can register a complaint by calling our toll-free number, after which they will receive a text message with information about the complaint as well as the contact details of our service engineer.
  2. Our Engineer usually calls up to fix an appointment as per the electricity schedule of the area - as there are frequent power disruptions in some places.


Our service engineer reached the site as per the pre-scheduled appointment. 



Upon arriving at the location, our service engineer promptly initiated his inspection to confirm the reported issue and determine the underlying cause.

  • During the inspection, a humming sound was discernible as our engineer approached the reverse osmosis system.
  • To diagnose the problem, our engineer conducted a series of standard checks, beginning with examining the power supply and investigating for any suction joint leaks.
  • Our engineer then proceeded to examine the suction side of the pump, searching for any external debris that may be causing the issue.
  • Following a thorough examination of the pump, our engineer proceeded to inspect the membranes to further investigate the cause of the problem.


Centrifugal Pump nameplate
Centrifugal Pump nameplate


  • During the pump inspection, our engineer noted that there were no unusual sounds emanating from the pump.
  • Our engineer did not find any leaks in the joints or any kind of debris on the suction side of the pump.
  • Upon inspecting the membranes, our engineer discovered that they were almost entirely clogged with suspended impurities, and he suspected them to be the underlying cause of the humming sound and other issues.


Upon discovering the clogged membranes, our engineer suggested to the customer that they get it cleaned. However, the customer opted to replace the old membranes with new ones.

Our engineer proceeded to refit the new membranes into the reverse osmosis system and conducted a series of basic parameter tests on the pump. After confirming that the system was ready, he started up the RO system once again.

This time, the system ran smoothly and without any sound, indicating that the issue had been successfully resolved.


New Membranes
New Membranes


  1. Abnormal noise from the pump can also be caused by faulty bearings or inadequate water. Damaged bearings should be replaced and an auto-cut off sensor can be installed to prevent dry runs.
  2. The recommended power supply for a single phase Vertical Multistage Pump is 180 to 230 Volts.
  3. Power fluctuations can cause serious damage to all electrical appliances. Use a stabilizer if you are witnessing voltage fluctuations.
  4. The negative suction for the LHR-2 Vertical Stage Pump should not exceed 3 meters.
  5. Make sure to remove all the air from the air plug before installing the LHR-2 pump.
  6. The suction and delivery flange bolts should be properly tightened
  7. Do make sure there are no leakages in the pump apparatus or the suction or delivery pipeline.
  8. Use good quality cable for wiring to avoid voltage loss and pump performance issues.
  9. Make sure your pump operates at the duty point declared by the manufacturer for maximum efficiency. Please contact our customer support team to learn more about duty points.
  10. Test the motor’s continuity, insulation, and resistance using Ohms and Megger Meters.
  11. Regular inspection and servicing of the pump can help detect debris in the strainer or other issues beforehand.


For smooth and uninterrupted working of your pump, always follow the instructions and standard operating procedure issued by the manufacturer in the user manual.