Tower inspection downcomer seals

To guarantee a proper downcomer seal, the bottom edge of a downcomer should be about V2 inch below the top edge of the outlet weir. This dimension should be carefully checked by process personnel when a tower is opened for inspection. It is quite easy for sloppy tray installation to distort this critical factor. 

Much more importantly, vortex breakers trap rags, gloves, and other trash left in towers during construction or turnarounds. If a draw-off nozzle is equipped with both a downcomer seal pan and a draw-off box, then the draw-off nozzle is difficult, and oftentimes impossible, to inspect. Installing a vortex breaker that is not needed due to low draw-off velocities is just looking for trouble, without any justification. 

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See also in sourсe #XX -- [ ]

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