What is the difference between the centrifugal pump flushing plans Plan02+54 and Plan03+54?

The sealing chamber of flushing scheme 02 is a closed dead space with no circulation of flushing fluid. Flushing Scheme 02 is commonly used in chemical plants where the pressure within the sealed cavity and the temperature of the medium are relatively low. In this flushing scheme, the process fluid should be relatively clean in order to avoid excessive erosion of the seal end caps, seal chambers, or sealing components due to fluid turbulence. When using this flushing scheme, the sensitivity of the saturated vapor pressure of the pumped fluid should also be taken into account to prevent flashing of the pumped fluid within the sealing chamber or between the sealing surfaces. Flushing scheme 02 can also be used in low-speed pumps that pump low-temperature, clean fluids with high specific heat (such as water) as process media. When selecting flushing scheme 02, the product temperature margin should be carefully determined. A heating or cooling jacket can be installed on the pump to control the temperature of the sealing chamber. Cooling jackets tend to scale in high-temperature applications, so caution should be exercised when using them. In flushing scheme 03, the circulation of the flushing fluid between the pump and the sealing chamber is achieved through the structural design of the sealing chamber. Flushing scheme 03 is commonly used in pump design; in this scheme, the inner hole of the sealing chamber is conical, with no throat bushing. The geometric structure of this sealing chamber, or its flow-enhancing properties, enable circulation of the fluid within the chamber, allowing for the cooling of the sealing surfaces while simultaneously evacuating gases or steam from the chamber. This flushing scheme is commonly used in applications where the seal generates little heat, as well as in situations where the sealing chamber is used to collect solid particles. In flushing scheme 54, there is a pressurized external isolation fluid system that supplies a clean isolation fluid to the isolation seal chamber. Flushing scheme 54 is used for the sealing of arrangement mode 3; the pressure of the isolation fluid must be maintained above the pressure in the sealing chamber. The circulation of the isolation fluid is accomplished using an external pump or a pressurized system. The system design includes: instruments, coolers, filters, and other components. Flushing scheme 54 is typically used in situations where the temperature of the fluid being pumped is high, or where the fluid contains solid particles, or when the internal circulation device cannot provide a sufficient flushing flow rate. When using flushing protocol 54, careful consideration should be given to the reliability of the source of the isolation fluid. If the source of the isolation fluid is interrupted or contaminated, it can lead to seal failure, and the costs of cleaning up are also very high. Although a suitable isolation fluid system is very complex and expensive. But with a suitable external isolation fluid system, they can provide the most reliable operation for sealing.

When used alone, 02 and 03 show a significant difference; the difference is smaller when used in combination with 54. Except for 03, the seal chambers used in other configurations all feature a throttle throat design, which makes them unsuitable for media that contain solid particles or are prone to vaporization. When deciding between 02 and 03 when using 54, it is often because the medium contains components that can solidify. 03 has a higher flow rate, while 02 has a lower one. In the presence of such media, even if a flushing scheme using the 02 chamber is employed, the throttle section eventually ends up being removed, otherwise the seal chamber will frequently get blocked by the solidified medium