In industrial conveying scenarios,many people mistakenly believe that pump idling is simply a matter of"not delivering liquid,"wasting at most some electricity—but the reality is far more serious.Under idling conditions,the lubrication and cooling effects of the medium between the rotors and the pump chamber are lost,which is the root cause of the problem.During normal operation,the conveyed liquid serves dual purposes:it acts as the working medium to complete the conveying process,while also providing continuous lubrication and heat dissipation for the mechanical seal faces,bearing mating surfaces,and rotor meshing clearances.Once the inlet runs dry or trapped gas in the chamber is not fully vented,these friction pairs enter a dry-running state.

-Bonve Pumps Cam-Type Twin Rotor Pump-

Specifically,the damage caused by idling concentrates on four levels.First is the rapid failure of mechanical seals—without liquid film lubrication,seal faces heat up dramatically under high-speed friction,hard seal rings may crack due to thermal expansion and contraction,and soft seal surfaces suffer direct abrasion,leading to leakage in a short time.Second is the clearance issue between rotors and pump casing:rotary lobe pumps rely on extremely tight fitting clearances to ensure volumetric efficiency,and after metal expands under heat,the originally micron-level clearances rapidly shrink until seizing occurs,and in severe cases,the rotors lock directly inside the chamber.Third is cavitation damage:during idling,the pressure distribution inside the chamber becomes disordered,and dissolved gases precipitate and collapse in local low-pressure zones,causing pitting erosion on wetted surfaces.Finally,there is damage to balancing mechanisms and bearings:balance discs in multi-stage structures experience dry friction after losing liquid film support,and bearings also deteriorate prematurely as heat cannot be dissipated.

One point that needs clarification is that the impact of idling on the motor itself is actually limited.Under no-load conditions,the motor load is very small and the current is low,so the motor generally does not burn out—it is the pump head that sustains the fatal impact.

There are three main common causes of idling:insufficient inlet medium supply or low inlet pressure,blockage in the suction line,and incomplete venting of air from the chamber before pump startup.In daily operations,insufficient opening of inlet valves,excessively low tank liquid levels,clogged strainers,and air leakage in pipelines can all trigger idling.Horizontal self-priming pumps operate in a partial idling state during the initial venting phase after startup,which is a normal short-term condition due to the liquid storage design of their chambers.

Preventing idling requires efforts from both design improvement and operation&maintenance management.On the design side,key fitting clearances can be appropriately enlarged within allowable ranges to reduce seizing risk;pump shafts undergo quenching and tempering heat treatment to enhance rigidity and wear resistance;and mechanical seal structures that do not require medium lubrication,along with self-lubricating sealed bearings,can be adopted.On the operation and maintenance side,installing idling detection protection devices is the most direct and effective measure:by real-time monitoring of current,pressure,or vibration signals,the system immediately alarms and automatically shuts down once idling is detected.Strictly following procedures for venting before startup and monitoring inlet/outlet pressures during operation in daily practice can also significantly reduce the probability of idling accidents.

Standardized execution of installation and maintenance procedures is equally important.Pipelines must be independently supported to prevent stress transmission to the pump body;the pump must be manually rotated before startup to check for seizing;during operation,bearing temperature rise should be controlled within ambient temperature plus 35°C and must not exceed 80°C at maximum;and a mechanical seal leakage rate below 3 drops per minute is considered normal.Replenishing bearing grease every 500 operating hours and changing lubricating oil after the first 100 hours of operation are essential maintenance measures for extending equipment service life and avoiding secondary damage from idling.

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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