Generally speaking, the leakage between the axle sleeve, the seal end cover and the pump body is found and disposed of briefly, but it needs to be investigated in detail. Especially when the working medium is liquefied gas or high pressure, toxic and harmful gas, it is relatively difficult. Other leaks are difficult to distinguish and distinguish visually. It is necessary to investigate, analyze and judge the performance of leaks on the basis of long-term treatment and repair practice so as to reach a positive conclusion.

1. Analysis and Discrimination of Leakage Reasons

1. Leakage of equipment during static test. After debugging of mechanical seal equipment, static test is usually carried out to investigate leakage. If the leakage is small, there are many doubts about the dynamic or static ring seals; when the leakage is large, it indicates that there are doubts between the dynamic and static ring conflict pairs. On the basis of investigating the leakage amount and identifying the leakage location, manual traveling survey shows that the static and dynamic ring seals are doubtful if there is no obvious change in the leakage amount; if there is a significant change in the leakage amount during traveling, it can be concluded that there are doubts in the dynamic and static ring conflict pairs; if the leakage medium erupts along the axis, there are doubts in the dynamic ring seals. Most of the leakage media erupt into the vicinity or leak out from the water cooling holes, mostly static ring seals fail. In addition, leak passages can also exist together, but usually there are primary and secondary differences, as long as detailed investigation, know the layout, will be able to correctly distinguish.

2. Leakages in the test work. After static test, the centrifugal force produced by high-speed rotation of mechanical seal of pump will press the leakage of medium. Therefore, the leakage of mechanical seals during the trial operation is basically caused by the damage of the dynamic and static ring conflict pairs after the failure of the clearance shaft and end cover seals. The main factors leading to the failure of the conflicting pair seals are as follows:

(1) During the operation, because of abnormal appearances such as exhaustion, cavitation and suffocation, the greater axial force is caused, which separates the touching surfaces of the dynamic and static rings.

(2) When the mechanical seal of the equipment is too large, it causes severe wear and abrasion on the end face of the conflict pair.

(3) The sealing ring of the moving ring is too tight, and the tension spring can not adjust the axial buoyancy of the moving ring.

(4) The sealing ring of the static ring is too loose. When the dynamic ring floats axially, the static ring is separated from the static ring seat.

(5) There are granular substances in the working medium, which enter into the conflict pair and detect the sealing face of the dynamic and static rings.

(6) There are errors in the description and selection, low specific pressure of sealing end face or large cold shrinkage of sealing material, etc. The above phenomena are often presented in the trial operation, and sometimes can be eliminated by adjusting the static ring seat properly, but most of them need to be disassembled from scratch to replace the seal.

3. Suddenly leak in normal operation. In the operation of centrifugal pumps, a few leaks are due to normal wear or service life, and most of them are due to large changes in working conditions or inappropriate operation and protection.

(1) Pumping, cavitation or holding pressure for a long time, resulting in seal damage;

(2) The practical output of the pump is too small, many medium pumps circulate inside, heat accumulation, resulting in medium gasification, resulting in seal failure;

(3) The return flow is too large, causing the bottom sediment of the suction pipe side container (tower, kettle, tank, pool) to overflow and damage the seal;

(4) For long-term outage, there is no manual turntable when starting from scratch, and the sealing surface is damaged due to adhesion.

(5) The corrosive, polymeric and cementitious substances in the medium increase;

(6) Rapid changes in ambient temperature;

(7) Frequent change or adjustment of working conditions;

Suddenly blackout or faulty shutdown, etc. Centrifugal pump leaks suddenly in normal operation. If it can't be found in time, it will often become a big problem or lose. We should pay attention to it and adopt useful methods.