How to rapidly judge whether cavitation has occurred during pump operation,and what countermeasures should be adopted?

Essentially,cavitation takes place when the medium boils due to sharp pressure drop at the impeller inlet,and impact is generated upon bubble collapse.There are three typical symptoms:the pump body emits sharp noises similar to gravel rolling inside pipelines,the outlet pressure gauge needle swings back and forth,and the flowmeter reading is obviously lower than the expected value.When handling cavitation,do not blindly increase suction pressure.More practical measures are:check whether the inlet filter is clogged(clean it if the pressure difference exceeds 0.05 MPa),and verify whether the inlet liquid level is sufficient.For high-temperature media,slightly open the vent valve on the inlet pipeline to release accumulated gas phase.In one on-site case,operators slightly closed the outlet valve to artificially raise internal pump pressure,and cavitation noise disappeared within several seconds;this is only an emergency measure.Fundamental resolution requires calculation of the net positive suction head required for the unit,and reduction of pump installation height when necessary.For Bonve cam-type dual-rotor pumps,cavitation exerts stronger destructive effects when transporting high-viscosity media.Thanks to its relatively low rotating speed,extra attention shall be paid to inlet pipeline diameter design.

How to perform on-site calibration when the actual output of a metering pump deviates greatly from the set value?

Metering pumps are widely used for dosing catalysts or corrosion inhibitors,and accuracy deviation will directly compromise product quality.Calibration shall not rely merely on inverter frequency.The container calibration method is recommended:close the valve from pump outlet to process pipeline,open the return valve,and guide the medium into a graduated calibration column.Run the pump for one minute,close the inlet valve and read the liquid-level drop volume;repeat three times and take the average value.The deviation calculation formula is:(Measured Value−Set Value)/Set Value×100%.If the deviation exceeds±3%,first check whether the check-valve ball is worn or foreign matter is stuck in the valve seat;next inspect whether the diaphragm is deformed.Adjusting stroke length delivers better linearity of accuracy than adjusting rotating speed.It is recommended to set the stroke within 30%~90%of full range.

-Bonve Pump Industry Cam-Type Dual-Rotor Pump-

How to balance factors for seal type-selection under high-temperature working conditions where seals frequently leak?

Seal failure is mostly caused by vaporization of the liquid film on friction pair end faces.For working conditions with temperatures above 150 °C,metal bellows mechanical seals are a reliable option,for their flexible rotating-ring compensation property prevents jamming caused by thermal expansion and contraction.Although packing seals feature low costs,lubricants inside packing will easily drain under high temperatures,leading to rapid increase of leakage volume.During type-selection,clarify medium temperature,pressure and whether solid particles are contained.If medium temperature exceeds 250 °C,besides adopting friction pairs of hard alloy paired with silicon carbide,quench or flush schemes shall also be equipped to lower seal-chamber temperature.

How to implement anti-rust measures for pumps scheduled for shutdown for more than three months?

The most frequent faults during long-term pump shutdown are shaft bending and bearing corrosion.Before shutdown,completely drain residual liquid inside the pump.For crystallizable media,perform thorough purging with clean water or steam.Turn the rotor manually for several revolutions and stop the rotor at a non-stress position.Fill the bearing housing with sufficient anti-rust oil,and perform manual shaft rotation every two weeks(rotate by about 90 degrees)to avoid indentation on bearing rollers.For the exposed shaft extension end,apply industrial vaseline and wrap it with plastic cloth.Place desiccants at the bottom of the pump body when the ambient humidity is high.

Which links should be inspected for excessive pump-body vibration?

Attention shall be paid when the vibration value exceeds 4.5 mm/s(ISO 10816 Standard).Do not directly conduct dynamic balancing during troubleshooting;follow the sequence from simple to complex:Step 1,check whether the tightening torques of anchor bolts are consistent,because loose bolts will lead to insufficient foundation rigidity;Step 2,recheck coupling alignment accuracy,since excessive end-face clearance and radial deviation are frequent triggers of vibration faults;Step 3,inspect impellers for wear of wearing rings or falling-off of dynamic-balance counterweight blocks.If vibration intensifies as flow rate rises,it is mostly related to cavitation;if vibration has nothing to do with load and is accompanied by abnormal noise,bearing clearance shall be inspected.

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.  

Service Hotline: 0574-87588986 13586591794  

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