After the
mechanical seal has been used for a period of time, in order to effectively maintain its efficiency, regular cleaning is very important. However, in order to ensure the accuracy of the cleaning operation, the detailed cleaning plan will be introduced.
The flushing of the seal is an effective measure to control the temperature of the seal and prolong the life of the seal. The purpose of flushing is to take away heat, maintain and improve lubrication, prevent vaporization of liquid film, prevent accumulation of impurities, prevent formation of air pockets, etc. According to the flushing form, it can be divided into internal flushing and external flushing. In the internal flushing, the conveying medium is used for flushing, while the external flushing is flushed by introducing foreign substances.
1. Internal flushing, positive flushing
Working principle: The outlet port of the pump guides the sealed medium into the sealing cavity through the pipeline.
Practical scope: used for cleaning medium, p1 is slightly larger than p1, if the temperature of the medium is high or there are impurities, it is necessary to install coolers, filters and other equipment on the pipeline to process the medium.
2. Backwashing
Working principle: Use the sealed medium of the working host to introduce the sealed cavity from the outlet end of the pump, and flow back to the pump inlet through the pipeline after flushing.
Practical scope: used for cleaning media, and<P1<P out, when the temperature is high or there are impurities, coolers, filters and other equipment can be installed on the pipeline to process the medium.
3. Full flushing
Working principle: Utilize the sealed medium of the main engine, the outlet port of the pump is introduced into the sealing chamber through the pipeline, and after flushing, it flows back to the pump inlet through the pipeline.
Practical range: used for cleaning media, and p1 is close to p-in and p-out, and the cooling effect is better than the first two
4. External flushing
Working principle: Introduce the cleaning fluid from the external system to the sealing cavity to flush the mechanical seal.
Practical range: The pressure of the external flushing fluid should be 0.05--0.1MPa greater than that of the sealed medium, which is suitable for high-temperature medium or solid particles. The flow rate of the flushing liquid must not only ensure the cooling effect, but also need to properly control the flow rate to avoid unnecessary erosion of the seal due to excessive flow rate and shorten its service life. For this reason, it is necessary to control the pressure of the sealing chamber and the flow rate of flushing. Generally, the flow rate of cleaning flushing liquid should be less than 5m/s; the flow rate of liquid flushing liquid containing particles should be less than 3m/s. In order to meet the above flow rate, flushing liquid and sealing The differential pressure in the cavity should be<0.5MPa, generally 0.05--0.1MPa, and 0.1--0.2MP for double-end seals. The position of the inlet and outlet of the flushing liquid should be set close to the side of the rotating ring and slightly closer to the end face of the seal. The flushing liquid can be introduced tangentially or flushed at multiple points to avoid erosion of the mechanical seal or deformation caused by uneven cooling. In special cases, hot water or steam can be used as flushing fluid.
