Analysis and countermeasures of leakage phenomenon of mechanical seals for submersible pumps

Grinding shaft phenomenon caused by leakage of submersible pump mechanical seal.

(1) Less than 715kW small pump seal failure often produces grinding shaft, grinding shaft position is mainly the following: Dynamic ring auxiliary seal ring, static ring position, a few springs have grinding shaft phenomenon.

Mechanical Seals

(2) The main reason of grinding shaft: ①bia type double end mechanical seal, reverse pressure state is bad working state, medium particles, impurities are easy to enter the sealing surface, so that the seal failure. The main parts of the ② grinding shaft are rubber bellows, and because the sealing surface of the upper end is in a bad lubrication state, the friction moment between the static and dynamic rings is greater than the transfer torque between the rubber bellows and the shaft, and the relative rotation occurs. ③ dynamic, static ring auxiliary seal due to the sewage in the weak acid, weak alkali corrosion, rubber parts have no elasticity.

Some have rotted, lost their proper function, and produced the phenomenon of grinding shafts.

(3) In order to solve the above problems, the following measures are taken: ① ensure the cleanliness of the lower end cover and oil chamber, and prohibit the assembly of unclean lubricants. The inner oil surface line of ② machine sealing chamber should be higher than that of static and dynamic ring sealing surface. The ③ selects different structures of the machine seal according to the different use media. For high-lift pump should be redesigned machine seal structure, corrosive medium rubber should be selected to resist weak acid, weak alkali fluorine rubber. The machine Feng should be added to the anti-resale.

Industrial Control Abstract: The proportion of mechanical seal leakage accounts for more than 50% of all maintenance pumps, the operation of mechanical seals directly affect the normal operation of the pump, is summarized and analyzed as follows.

Cyclical leakage

(1) The pump rotor axial channeling momentum is large, auxiliary seal and shaft excess, dynamic ring can not be flexibly moved on the shaft.

After the pump is flipped and the dynamic and static rings are worn, no compensating displacement is given.

Countermeasure: When assembling mechanical seal, the axial channeling momentum of the shaft should be less than 0.1mm, the excess of auxiliary seal and shaft should be moderate, while ensuring the radial seal, the dynamic ring is guaranteed to move flexibly on the shaft after assembly (the dynamic ring is pressed to the spring to bounce back freely).

(2) The amount of lubricating oil on the sealing surface is insufficient to cause dry friction or pull the sealing end surface.

Countermeasure: The height of lubricant surface in oil chamber cavity should be added to higher than that of dynamic and static ring sealing surface.

(3) Periodic vibration of the rotor.

The reason is that the stator and the upper and lower end cover are not balanced in the middle or impeller and spindle, cavitation or bearing damage (wear), this situation will shorten the sealing life and produce leakage.

Countermeasure: The above problems can be corrected according to the maintenance standard. 

````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````

JIAXING BURGMANN MECHANICAL SEAL CO., LTD.

Contact: doris@mechanicalseal.com.cn

Phone No: 8615381220188

Skype: kathysunlin