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May 11, 2022 View:

The Causes And Solutions Of Mechanical Seal Leakage Of Rotary Lobe Pump

The mechanical seal relies on the contact surface of the moving ring and the static ring to always fit together during movement to achieve a seal. A mechanical seal is usually composed of a moving ring, a static ring, a compression element and a sealing element, in which the moving ring and the end face of the static ring produce an appropriate specific pressure and maintain a very thin liquid film to achieve the purpose of sealing.

lobe pump

Analysis of mechanical seal leakage causes, based on practical experience, on-site observation and measurement with the help of instruments, to clarify the intrinsic link between sealing components and sealing performance, all-round inspection of sealing rings, transmission parts, loading elastic components, auxiliary seals, bushings, sealing cavities and sealing systems and other parts, comprehensive analysis, to find out the causes of mechanical seal leakage, as a basis for selecting the correct mechanical seal. The following are the causes and solutions of mechanical seal leakage in lobe pumps.

1、Leakage during static test of lobe pump installation

After the mechanical seal is installed and commissioned, the pump should be related to the static test, so as to observe the amount of leakage of the equipment. If there is a smaller leak, the cause is mostly a problem with the moving ring or static ring seal; if there is a relatively large amount of leakage, it may be a problem between the moving and static ring friction. When the pump seal leakage occurs, the first thing to do is to observe the amount of leakage of the pump, determine the general location, and then manually pan the car to observe.

2, lobe pump test run errors

After the pump has been tested at the above stage, the centrifugal force generated during operation due to high speed rotation will also inhibit the leakage of media. Therefore, the mechanical seal leakage during the trial operation is basically due to the damage caused by the friction of the dynamic and static rings after the failure of the discharge inter-shaft and end cover seal. The main reasons for these phenomena are: 1) the operation of the process of evacuation, cavitation, holding pressure, etc., thus causing a larger axial force, resulting in dynamic, static ring contact surface separation; 2) excessive compression leads to friction surface abrasion is more serious; 3) dynamic ring seal ring is too tight, the spring can not adjust the dynamic ring axial floating amount; 4) static ring seal ring is too loose, when the dynamic ring axial floating, static ring from the static ring seat.

3, due to the corrosion of equipment caused by the mechanical seal failure of the lobe pump: the face of the seal joint corrosion occurred, resulting in the penetration and thus the phenomenon of pump leakage.

4, due to high temperature effect and lead to mechanical seal failure of the lobe pump: at the sealing surface due to long-term dry friction of equipment, cooling water suddenly interrupted, impurities into the sealing surface, evacuation, etc., will lead to radial cracking of the replacement surface; some auxiliary seals in the non-normal temperature, will lead to aging, cracking, after hardening and loss of elasticity. These same phenomena can lead to pump leaks.

Based on the analysis of the above reasons, mechanical seal design and modelling must be combined with the actual situation of production, as far as possible to use reliable sealing, longer life of the friction sub-materials and static seal ring materials.

In general, the lobe pump mechanical seal after installation are subject to static and dynamic tests to confirm that the mechanical seal is installed correctly, when found to have leaks, to facilitate timely maintenance. In addition, leakage may also occur suddenly during normal operation, when a comprehensive analysis can be carried out according to the situation to confirm the real cause of mechanical seal leakage and facilitate the solution.