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In Piping Plan 32, flush is injected into the seal chamber from an external source.
NOTE Piping Plan 32 is used in services containing solids or contaminants, in which a suitable cleaner or cooler external flush will improve the seal environment. It is also used to reduce flashing or air intrusion (in vacuum services) across the seal faces by providing a flush that has a lower vapor pressure or that will raise the seal chamber pressure to an acceptable level.
In Piping Plan 32, the flushing product is brought from an external source to the seal. The external flush should be continuous and reliable even during nonstandard situations such as start-up or shutdown.
Care shall be exercised in choosing a Piping Plan 32 flush fluid. Since the fluid will flow into the process, it shall be chemically compatible with the process and not degrade the quality of the process fluid. In high-temperature applications, the user should consider the effects of the potential for the Piping Plan 32 flush fluid to flash under pump conditions and degrade pump performance.
This plan is almost always used in conjunction with a close-clearance throat bushing. The bushing can function as a throttling device to maintain an elevated pressure in the stuffing box or as a barrier to isolate the pumped product from the seal chamber.
Piping Plan 32 is not recommended for cooling only, as the energy costs can be very high. Product degradation costs should also be considered when using a Piping Plan 32.
Malavazi NOTE: For better safety it is recommended to install check valve, flow control, filter, flow indicator, pressure gauge and thermometer.
For liquids with crystallization characteristics, Quench is recommended due to micro leakage on the faces, otherwise plug the injection connection leaving the drain free to prevent environmental disasters, since the floating ring will act as a safety point.