Gear pumps , gear pumps with a wide range of mechanical seals, different models, but the main points of leakage are the following aspects: (l) seal between sleeve and shaft; (2) between the moving ring and the shaft sleeve seal; (3) moving, static seal between; (4) between the static ring and static ring seat seal; (5) seal between the cover and the gear pump body. Generally speaking, it is easy to find out and solve the leakage between the shaft of the sleeve and the seal between the cover and the gear pump. However, careful observation is required. Especially when the working medium is liquefied gas or high pressure, toxic and harmful gas, the relative Difficulties. The rest of the leakage intuitively difficult to distinguish and judge, to be in the long-term management, maintenance practice, based on the symptoms of leakage observed, analyzed and judged in order to draw the correct conclusion. First, the gear pump, gear pump leak analysis and determine 1. Leakage test static. Mechanical seal installation and commissioning is good, the general should be static test, observe the amount of leakage. If the leakage is small, mostly ring or static ring seal problems; leakage is large, then that dynamic and static friction ring there is a problem. In the initial observation of the leakage, to determine the leakage site, based on manual observation disk, if the leakage was no significant changes in the static and dynamic ring seal problems; such as the disk when there is a significant change in leakage can be concluded that the move, Static friction ring there is a problem; such as the leakage of media along the axial injection, the dynamic ring seal there are many problems, leakage to the surrounding medium jet or water leakage from the hole, the more static ring failure. In addition, the leak channel can exist at the same time, but generally there are primary and secondary differences, as long as careful observation, familiar with the structure, we must be able to correctly judge. 2. Leakage during commissioning. Gear pump mechanical seal after static test, the centrifugal force generated by high-speed rotation of the operation, will inhibit the media leakage. Therefore, the test run when the mechanical seal leakage excludes the seal between the shaft and the end cover, basically due to dynamic and static friction ring caused by damage. The factors that cause the failure of friction seal are: (l) operation, due to taking the time, cavitation, pressure and other anomalies, causing greater axial force, so that dynamic and static contact surface separation; (2) The excessive compression when installing the mechanical seal, resulting in serious wear and abrasion of the friction end face; (3) ring seal is too tight, the spring can not adjust the axial amount of floating ring; (4) static ring seal is too loose, when the moving ring axial float, the static ring from the static ring seat; (5) There is granular material in the working medium, and it enters into the friction pair during operation. (6) design and selection is wrong, the seal face lower than the pressure or sealing material shrinkage larger. These phenomena often appear in the trial operation, and sometimes can be eliminated by adjusting the static ring seat, etc., but most need to re-disassemble, replace the seal. 3. Suddenly leak during normal operation. Stainless steel gear pump suddenly leaks in operation due to a few normal wear or life has been reached, and most are due to changes in conditions or larger operation or maintenance caused by improper. (1) evacuating, cavitation or pressure holding for a long time, leading to seal damage; (2) The actual output of the gear pump is small, a large number of medium gear pump cycle, heat accumulation, causing gasification of the medium, resulting in seal failure; (3) return flow is too large, resulting in inhalation tube side of the container (tower, kettle, tank, pool) at the bottom of sediment damage, damage to the seal; (4) for a long time outage, restart without manual turning, friction due to adhesion and tear the sealing surface; (5) Medium corrosive, polymeric, colloidal substances increased; (6) rapid changes in ambient temperature; (7) Frequent changes in operating conditions or adjustments; (8) Sudden power failure or downtime and so on. Centrifugal gear pump in normal operation, a sudden leak, if not found in time, often lead to a larger accident or loss, we must pay attention to and take effective measures.