assist engineers of its member company in rating and preliminary design calculations of internal devices for mass transfer. The program handles various trays and packings. The trays include sieve, valve, dualflow, baffle, and bubble cap; the program handles both random and structured packings. The program uses the correlations developed using FRI experimental data obtained from two commercial size columns (1.22 m, and 2.44 m inside diameter). The column pressures are ranged from 10 mmHG abs (N-Octanol/N-Decanol) to 34.5 bar (Iso-Butane/N- Butane). The program can handle 1-Pass, 2-Pass, 3-Pass, and 4-Pass sieve trays and valve trays. The multi-pass trays include both the equal bubbling area and the equal flow- path length trays. FRI DRP is a multi-process and multi-device program that enables the users to compare, for a given process, several devices side-by-side, to select the best tray or packing for the specified process. Several correlations for jet flooding, downcomer backup (sieve, valve, and bubble cap), entrainment, weeping, and efficiency are included in the program. The users are able to compare several correlations side by side. For a given process, the users can obtain a preliminary design for a sieve tray including column diameter, number of passes, and downcomer sizes that satisfies requirements for percent jet-flood and downcomer- backup.