Analysis And Maintenance Scheme Of Leakage Point Of Mechanical Seal For Pump

Pump with a wide range of mechanical seals, different models, but there are five major leaks:
  • Seal between sleeve and shaft;
  • Seal between movable ring and shaft sleeve;
  • Dynamic and static ring seal;
  • The seal between the static ring and the static ring seat;
  • Seal between the end cap and the pump body.
In general, the shaft between the shaft, the seal between the end of the cover and the leakage between the pump is easier to find and solve, but the need for careful observation, especially when the working medium for liquefied gas or high pressure, toxic and harmful gases, the relative difficulties some. The rest of the leak is intuitively difficult to distinguish and judge, to be in the long-term management, maintenance practice on the basis of the symptoms of leakage observation, analysis, judgment, in order to draw the correct conclusion.

Analysis and judgment of leakage
Installation of static test leak. Mechanical seal installation and commissioning, the general to conduct a static test, observe the leakage. Such as the leakage of small, mostly dynamic ring or static ring ring there is a problem; leakage is large, then the dynamic and static ring friction between the existence of problems. In the initial observation of leakage, to determine the basis of the leak, and then manually observe the car, if there is no significant changes in the leakage of static and dynamic ring seal problems; such as the amount of leakage when the car can be determined to be significant changes, Static ring friction side of the problem; such as leakage media along the axial injection, the dynamic ring there are many problems, the leakage medium to the surrounding jet or leak from the water cooling hole, then the static ring failure. In addition, the leakage channel can also exist, but generally there are prim

Test run when the leak. Pump mechanical seal After a static test, the high-speed rotation of the centrifugal force generated during operation, will inhibit the media leakage. Therefore, the test machine mechanical seal leakage in the exclusion of the shaft and the end cap seal failure, basically due to the dynamic and static ring friction caused by damage. The factors that cause the failure of the friction seal are:
  • Operation, due to evacuation, cavitation, pressure and other abnormal phenomena, causing a larger axial force, so that dynamic and static ring contact surface separation;
  • The installation of mechanical seal when the amount of compression is too large, resulting in severe wear and tear face, abrasion;
  • Dynamic ring seal is too tight, the spring can not adjust the amount of axial movement of the ring;
  • Static ring too loose, when the dynamic ring floating, the static ring from the static ring seat;
  • The working medium in the granular material, into the friction into the operation, the detection of moving, static ring seal face;
  • Design selection is wrong, sealing the end of the low pressure or sealing material shrinkage larger. The phenomenon described in the trial run often, and sometimes can be adjusted by the appropriate static ring to be eliminated, but most need to re-disassemble, replace the seal.
Normal operation suddenly leak. Centrifugal pump in the operation of a small number of leakage is due to normal wear or have reached the service life, and most of the conditions due to large changes in the operation or maintenance caused by improper.
  • Take time, cavitation or a long time to suppress pressure, leading to seal damage;
  • The actual output of the pump is too small, a large number of media pump cycle, heat accumulation, causing media gasification, resulting in sealing failure;
  • The return flow is too large, resulting in suction tube side of the container (tower, kettle, tank, pool) bottom of the sediment for a long time outage, there is no manual re-starting when the car, the friction due to adhesion and tear off the sealing surface;
  • Medium corrosive, polymerizability, gelatinous material increased;
  • Sudden changes in ambient temperature;
  • Frequent changes or adjustments;
  • Sudden power failure or fault shutdown. Centrifugal pump in the normal operation of a sudden leak, if not found in time, often lead to greater accidents or losses, to be taken seriously and take effective measures.
Second, the pump mechanical seal maintenance in a few errors

The greater the amount of spring compression the better the sealing effect. In fact, the spring compression is too large, can lead to friction wear and tear, instantaneous burning; excessive compression of the spring to lose the ability to adjust the dynamic ring end, resulting in sealing failure.

Moving the ring seal the tighter the better. In fact, dynamic ring seal too tight no harm. One is to increase the seal between the ring and the axle wear, premature leakage; the second is to increase the dynamic ring axial adjustment, moving resistance, changes in the working conditions can not be adjusted in a timely manner; Third, the spring fatigue is easy to damage; Is to make dynamic ring ring deformation, affecting the sealing effect.

Quiet ring seal the tighter the better. Static ring ring basically in a static state, relatively tight seal effect will be better, but too tight is also harmful. One is caused by static ring seal due to excessive deformation, affecting the sealing effect; Second, the static ring material to graphite mostly, generally more brittle, excessive force easily lead to fragmentation; Third, the installation, demolition difficult, easy to damage the static ring.

Impeller lock the tighter the better. Mechanical seal leakage, the shaft between the shaft and the leakage (between the shaft leakage) is more common. It is generally believed that the shaft leakage is the impeller lock mother does not lock, in fact, lead to more leakage between the shaft factors, such as the shaft pad failure, offset, there are impurities between the shaft, shaft and sleeve with a larger shape Bit error, contact surface damage, the shaft between the various parts of the gap, the shaft head thread is too long and so will lead to leakage between the shaft. Lock the mother lock too much will only lead to premature failure of the inter-paddle pad, the opposite modest lock lock the mother, so that the paddle pad always maintain a certain degree of compression elasticity, in the operation of the lock will automatically lock the time, so that the axis is always in good Of the sealed state.

New is better than old Relatively speaking, the use of new mechanical seal effect is better than the old, but the new mechanical seal quality or material selection is not appropriate, with the larger size error will affect the sealing effect; in polymerization and permeability media, Wear, or do not change as well. Because of the static ring in the static ring seat for a long time in a static state, so that the polymer and impurities deposited as a whole, played a better sealing effect.

It is better than the demolition. Once the mechanical seal leakage will be eager to repair, in fact, sometimes sealed and no damage, just adjust the conditions or adjust the seal can be appropriate to eliminate leakage. So that both to avoid waste and can verify their own ability to judge the fault, the accumulation of maintenance experience to improve the quality of maintenance.

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