In industrial production,unexpected shutdown of a pump often leads to interruption of the entire process,and emergency repair costs are far higher than daily maintenance investment.Most faults do not occur suddenly but result from long-term accumulation of hidden operational hazards.Grasping the structural logic,troubleshooting approach and maintenance rhythm of rotary lobe pumps can eliminate the majority of problems in their infancy.

-Bonve Pumps Cam-Type Double Rotor Lobe Pump-

I.Recognize Structural Boundaries for Targeted Troubleshooting

A rotary lobe pump consists of three relatively independent units:the drive unit comprises the motor and reducer,the transmission unit comprises the coupling and synchronous gearbox,and the pump body unit comprises the pump casing,rotors,mechanical seal and bearings.Once the boundaries of these three parts are clarified,the problem side can be quickly located when an abnormality occurs,avoiding blind disassembly.The synchronous gears adopt an isolated design,housed in an independent gearbox with an isolation chamber between them and the pump cavity,so that gear oil will not contaminate the conveyed medium and the medium will not corrode the gears;daily maintenance only requires attention to oil level and periodic oil changes.

II.Causes and Troubleshooting Directions for High-Frequency Faults

When the pump fails to start or cannot rotate,prioritize checking the power supply,wiring and motor windings;if the electrical system is normal,bar the rotor to check whether it is seized due to medium solidification or foreign object ingress,clean the pump cavity if necessary,and confirm whether the motor power matches the current operating conditions.

When the pump does not absorb liquid or discharge material,common causes include reversed inlet/outlet connection,motor reverse rotation,blocked or leaking suction piping,excessive suction lift,and excessively high medium viscosity preventing the rotors from gripping the material.Corresponding handling measures include reconnecting the piping after confirming the flow direction mark on the pump body,swapping two phase wires to adjust rotation direction,checking the inlet strainer and piping sealing performance,lowering the installation height or shortening the suction lift,and appropriately heating the medium.

For insufficient flow or pressure drop,sequentially check whether the inlet piping is blocked,whether the motor speed and frequency converter settings are normal,whether the clearance between the rotors and the pump cavity has increased due to wear,and whether the safety valve is not tightly sealed.

Excessive pump vibration or noise is mostly caused by misalignment between the pump and motor,air entrainment or cavitation inside the pump,bearing damage,or loose foundation bolts,requiring respective measures such as realignment,checking suction piping for leakage and lowering installation height,replacing bearings,and tightening bolts.

Mechanical seal leakage is mainly caused by aging or damage of seal components,burnout due to dry running,or material mismatch due to abrasive particles in the medium.During operation,there should be no leakage and no overheating;stop the pump immediately once leakage is detected to prevent damage from spreading.When the pump temperature rises excessively or the current is too high,attention should also be paid to coupling alignment accuracy,bearing lubrication status,medium temperature,and whether the outlet piping is blocked.The bearing temperature must satisfy≤ambient temperature+35°C,and must not exceed 80°C at maximum.

III.Key Actions for Daily Maintenance

Before startup,barring the pump is mandatory:turn the coupling by hand to confirm the rotors rotate flexibly without seizing or abnormal friction noise,avoiding secondary damage caused by starting with an existing fault.

Lubricant replacement follows a fixed cycle:during the first month,the lubricant must be replaced once after 100 hours of operation(metal debris is generated during the running-in period),and thereafter replaced once every 500 hours of operation;the daily oil level should be maintained at the centerline position of the oil sight glass,and the oil should be replenished promptly when it becomes low or deteriorated.

The mechanical seal is the most vulnerable wearing part of a rotary lobe pump,and it is recommended to keep 1-2 sets in stock;O-ring seals should be regularly inspected for surface scratches or bruises,and replaced together when the pump is disassembled for maintenance.

Continuously monitor temperature,sound and vibration during operation,and stop the pump immediately for inspection upon detecting any abnormality;running with a fault is prohibited.A rotary lobe pump should not be shut down suddenly under full-load operation;the flow should be gradually reduced before stopping to avoid water hammer impact damaging the check valve and piping.After shutdown in winter,unscrew the drain plug at the lower part of the pump body to drain the medium completely,preventing the pump body from freezing and cracking;for long-term decommissioning,disassemble the pump body and wipe all components dry,apply protective grease to rotating parts,and store properly.

IV.Spare Parts Stocking and Operation Taboos

Recommended spare parts for stocking include:1-2 sets of mechanical seals,a certain quantity of O-ring seals,rotors stocked according to operating conditions(different spare parts for metal,rubber-coated,ceramic and other materials),and an appropriate amount of lubricant.

Several operation taboos must be kept in mind:the inlet piping valve must not be used to regulate flow(a rotary lobe pump is a positive displacement pump,and this practice can easily trigger cavitation and severe vibration;flow should be regulated via frequency converter speed adjustment or by adding a bypass on the outlet piping);a stepless speed variator must never have its speed dial turned while the pump is stopped—speed regulation must be performed during operation;for pumps equipped with a water-cooled mechanical seal,the cooling water must be turned on before startup and ensured uninterrupted during operation,otherwise the mechanical seal will be damaged instantly;all inlet and outlet valves should be fully opened before startup,and starting with valves closed is not allowed.

The core logic of maintenance can be summarized in three points:before startup—bar the pump,check oil level,confirm rotation direction,open valves;during operation—monitor temperature,sound and leakage;after shutdown—clean,prevent freezing,perform periodic maintenance.By doing these three things well,the sudden failure rate of rotary lobe pumps can be minimized and equipment service life significantly extended.

Bonve pump always adheres to the philosophy of "Wholeheartedly Making Good Rotor Pumps," committed to providing global customers with customized conveying and mixing solutions. If you have technical inquiries, selection needs, case references, or other cooperation intentions related to Bonve rotor pumps, please feel free to contact us.  

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We look forward to working with you to drive efficiency and innovation in industrial fluid transmission with precision technology.