In larger diameter columns, typical multi-pass designs are limited to four passes. However, for applications that require more than four passes, the proprietary multi-pass downcomer design can be used to reduce weir loading and improve the capacity of the column.
Large diameter columns can use these multi-pass design techniques in 6-pass or 8-pass configurations. Modest capacity increases with these trays are possible in comparison to the best designed 4-pass SUPERFRAC® trays.
The downcomer configuration for a multi-pass design typically is the multi-chordal design; however, almost any other configuration can be used.