The operational stability of mechanical seals directly determines the continuous production capacity of the entire production line,and approximately 30%of pump equipment downtime failures are caused by their failure.Only by identifying the root causes can the leakage problem be fundamentally solved.

-Bonve Pumps Cam Type Twin Rotor Pumps-

Improper installation operation is the primary cause of short-term failure of new seals.When disassembling and inspecting a leaking seal that has been running for a short time,radial concentric scratches are often visible on the end faces of the stationary and rotating rings,with obvious grooves to the touch.This is mainly caused by bumps and scratches of metal parts due to rough disassembly and assembly,as well as hard particles such as sand,welding slag and old seal debris brought in by the unclean installation environment.These particles will damage the nanoscale mirror finish of the seal faces.

Solutions:Operate on a clean workbench throughout the process.Thoroughly clean all parts with anhydrous alcohol and lint-free cloths to ensure that the seal end faces are bright enough to clearly reflect fingerprints.Apply silicone grease to the shaft sleeve for lubrication during installation,strictly prohibit direct striking of seals,and use hot assembly or special tools to press interference fit components smoothly.

Dry running caused by the loss of liquid film on seal faces is the most destructive form of failure.The stationary and rotating rings rely on an extremely thin liquid film of the medium to achieve lubrication,cooling and sealing.Once this liquid film disappears,the seal faces will undergo high-temperature ablation in an instant.Typical manifestations include blackened end faces with attached coked substances,and in severe cases,fusion welding of the stationary and rotating rings and spring annealing and loss of elasticity.Medium cutoff caused by idling or inlet blockage,as well as unopened or interrupted flushing systems such as Plan53/54,are the main causes of dry running.

Solutions:Strictly implement start-stop procedures.Before starting,confirm that the pump chamber is full of medium and the air is exhausted,and ensure that the inlet pipeline and filter are unobstructed.For seals with auxiliary flushing systems,the flushing pipeline must be opened first before starting the machine,and confirm that the flow rate and pressure are normal.

Failure of auxiliary sealing rings is often overlooked but causes persistent leakage.If leakage seeps from the joint surface between the gland and the pump body,or the gap between the shaft sleeve and the shaft,it is mostly caused by damage to auxiliary seals such as O-rings and V-rings.Disassembly and inspection will show deformation,hardening,edge cutting or swelling of the sealing rings.The root causes include material incompatibility with the medium,cutting damage caused by burrs on the installation path,and aging caused by long-term over-temperature operation.

Solutions:Check material compatibility according to the medium composition and temperature,and give priority to suitable materials such as fluororubber(FKM)and perfluoroether(FFKM).Before installation,polish all burrs and sharp edges on shaft shoulders,keyways and thread parts and apply lubricant.Ensure that the operating temperature does not exceed the rated temperature range of the material.

Floating jamming of the rotating ring assembly causes seal face separation and leakage.The rotating ring needs to follow the shaft for small axial movements and swings to compensate for wear and vibration.If the equipment leaks when vibrating but does not leak when stopped,it is mostly due to poor follow-up of the rotating ring.Accumulation in gaps caused by medium crystallization and polymerization,too tight fit between the shaft sleeve and the inner hole of the rotating ring,or excessive compression of the O-ring will all cause the rotating ring to be stuck.

Solutions:For easily crystallizable media,give priority to bellows and large spring structure seals and avoid multiple small spring designs.After installation,manually check that the axial movement of the rotating ring assembly is smooth without jamming.Design special flushing pipelines to continuously flush the area near the seal faces to prevent solid particle accumulation.

Exceeding the design pressure range leads to catastrophic failure of the seal.Each set of mechanical seals has a clear pressure working range.Positive overpressure will cause seal burst and component damage,while reverse vacuum will crush and break the stationary ring inward.System pressure buildup caused by sudden working condition changes,ignoring the actual pressure of the seal chamber during selection,and equipment vacuuming caused by misoperation are the main causes of such failures.

Solutions:Provide suppliers with accurate seal chamber pressure data instead of only the pump outlet pressure.Install safety valves or rupture discs in systems prone to overpressure.For vacuum conditions,use double mechanical seals and introduce barrier fluid.Strictly prohibit starting the pump when the seal chamber is in a negative pressure state.

Abnormal operation of the equipment itself is the core root cause of unstable seal life.If the seal at the same position is replaced frequently and has an irregular service life,priority should be given to checking the equipment itself.Excessive vibration will destroy the liquid film stability of the seal face,coupling misalignment will cause periodic shaft swing,and shock waves generated by pump cavitation will directly damage the seal end faces.

Solutions:When seals fail frequently,first detect the equipment vibration value,bearing clearance and alignment accuracy,and use a laser alignment instrument to control the error within 0.05mm.Optimize the inlet pipeline design to ensure sufficient net positive suction head(NPSH)and eliminate cavitation hazards from the root.

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  

Official Website: www.bvpumps.com  

Business Email: market@bonvepumps.com  

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