0 1 for structured packing having a specific area within a range of between about 450 m 2 m 3 and about 1000 m 2 m 3 and flow channels oriented at an angle of about between about 30 degrees and 45 degrees the column can be operated at a minimum vapor rate through such packing of about exp 0 0485 ln u03c8 2 0 595 ln u03c8 3 748 0 000421a when u03c8 is within the foregoing range and to about 0 0305e 0 000421a u03c8 0 372 when u03c8 is greater than 0 1 for structured packing having a specific area within a range of between about 170 m 2 m 3 and about 250 m 2 m 3 and flow channels oriented at an angle of about 30 degrees or less a minimum vapor rate for the column can be taken as about exp 0 0485 ln u03c8 2 0 595 ln u03c8 2 788 0 00236a when u03c8 is within the foregoing range and to about 0 0305e 0 00236a u03c8 0 372 when u03c8 is greater than 0 1 lastly for structured packing having a specific area within a range of between about 250 m 2 m 3 and about 1000 m 2 m 3 and flow channels oriented at an angle of about 30 degrees or less a minimum vapor rate from the column can be set equal to about exp 0 0485 ln u03c8 2 0 595 ln u03c8 3 156 0 000893a when u03c8 is within the range.