Introduction of Flushing Scheme for Mechanical Seal of centrifugal pump

Mechanical seal is a commonly used seal configuration in centrifugal pump. Due to the particularity of some conveying media, the type of seal is also different. It is called "flushing" to inject liquid directly into the high pressure side of double or single seal.

1. Lower the liquid temperature. In some cases, the liquid temperature is so high that the sealing performance is affected. In such cases, the temperature must be lowered to improve the performance of the liquid.

2. Change the pressure of the sealing cavity. In some cases, it is necessary to increase or decrease the pressure of the sealing cavity to improve performance. This can be achieved by restraining evaporation or reducing the heat load of the seal.

3. Rinse to dissipate heat. The heat generated by the liquid seal must be controlled. This can be achieved by flushing the seal cavity with liquid to remove heat and control the temperature rise.

4. Clean the process liquid. If the process liquid contains inappropriate solid particles or contaminants, the liquid in the sealing cavity needs to be cleaned. In extreme cases, it may also be necessary to provide clean liquid from outside the sealing system.

5. Control the atmospheric side of the seal. Because process liquids come into contact with the atmosphere, they may become dry, crystallized or coked. It is important to prevent interaction with the atmosphere so as not to adversely affect sealing performance.

Classification of machine seal flushing schemes:

1. Double face Seal (Dual Seals)

PLAN 52 (series seal with pressureless buffer tank), PLAN 53A (double face seal with pressure sealing fluid), PLAN 53B (double face seal with forced circulation sealing fluid), PLAN 53C (double face seal with booster tank), PLAN 54 (double face seal with external sealant).

2. Cooling seal (Quench Seals)

PLAN 62 (external flushing or rapid cooling to prevent the accumulation of solid particles on the sealing surface), PLAN 65 (measuring seal leakage with float level switch).

3. Single face seal (Single Seals)

PLAN 01 (single end face self flushing), PLAN 02 (jacket cooling heat tracing), PLAN 11 (self flushing), PLAN 13 (reverse flushing), PLAN 14 (positive + reverse flushing), PLAN 21 (self flushing with cooling), PLAN 23 (internal flushing with circulating sleeve), PLAN 31 (self flushing with suspension separator), PLAN 32 (external flushing), PLAN 41 (self flushing with suspension separator and heat exchanger).

4.Gas Seal (Gas Seals)

PLAN 72 (series dry gas seal with isolated nitrogen for volatile medium), PLAN 74 (double face dry gas seal), PLAN 75 (series dry gas seal with non-volatile medium), PLAN 76 (series dry gas seal with external sealing gas).