Sagging trays

Figure 18—13 illustrates how sagging tray decks can aggravate the problem of low vapor flows. Also, the preceding discussion is almost as applicable to valve trays as to sieve trays. Valve trays most certainly leak at low vapor rales regardless of any vendor claims to the contrary. 

Figure 4.4 Sagging tray ruins downcomer seai.

The common reason for out-of-levelness of trays is sagging of the tray decks. Sags are caused by pressure surges and sloppy installation. Sometimes, the tray support rings might not be installed level or the tower itself might be out-of-plumb (meaning the tower itself may not be truly vertical). 

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