.jpg)
In Piping Plan 41 there is recirculation from a high-pressure region of the pump (typically the pump dis-charge or the pump discharge piping) through a cyclone separator delivering the clean fluid to a cooler and then to the seal chamber. The solids are delivered to the pump suction line.
Piping Plan 41 is a combination of Piping Plan 21 and Piping Plan 31 and is specified only for hot services containing solids. Contained solids should have a specific gravity of at least twice that of the process fluid. For this seal plan to be used, the seal should require a cool flush. This cool flush may be needed to im-prove the temperature margin over the fluid vapor pressure, or to meet secondary sealing element tem-perature limits, or to reduce coking or polymerizing, or to improve lubricity (as in hot water). A typical use of this plan is in a hot water service to remove sand or pipe slag.
In Piping Plan 41, product is routed from the discharge of the pump into a cyclone separator. Solid parti-cles are centrifuged from the stream and routed back to suction. The seal flush is then routed from the cyclone separator through a cooler and into the flush connection on the seal plate.
If the process stream is very dirty or is a slurry, Piping Plan 41 typically is inadequate and is not recom-mended. The benefits, detriments, and the best conditions for the use of the cooler in the flush stream can be found in the write-up on Piping Plan 21. The use of a pump throat bushing is recommended when a Piping Plan 41 is specified.
Field experience has shown that abrasive wear on the inside of the cyclone may result in reduced reliability.
This plan has not proven to consistently achieve a three-year (3-yr) operating life.
Malavazi NOTE: A differential pressure between discharge and suction of at least 1.5 Kgf/cm² is recommended.
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.