▁which ▁increase ▁performance ▁by ▁increasing ▁the ▁surface ▁area . ▁They ▁are ▁su ited ▁for ▁low ▁pressure ▁drop ▁and ▁high ▁capacity ▁applications . ▁They ▁have ▁a ▁degree ▁of ▁random ness ▁and ▁a ▁relatively ▁high ▁liquid ▁hold ▁up , ▁prom oting ▁a ▁high ▁absor ption , ▁especially ▁when ▁the ▁rate ▁of ▁reaction ▁is ▁slow . ▁The ▁cross ▁structure ▁of ▁the ▁P all ▁ring ▁makes ▁it ▁mechan ically ▁robust ▁and ▁suitable ▁for ▁use ▁in ▁deep ▁pack ed ▁b eds . ▁ ▁B iał e cki ▁ring ▁ ▁Pat ented ▁in ▁ 1 9 7 4 ▁by ▁Polish ▁chemical ▁engineer ▁from ▁Krak ów ▁Z b ign iew ▁B iał e cki ▁rings ▁are ▁an ▁improved ▁version ▁of ▁Ras ch ig ▁rings . ▁The ▁rings ▁may ▁be ▁injection ▁m ould ed ▁of ▁pl ast ics ▁or ▁press - formed ▁from ▁metal ▁sheet ▁without ▁w eld ing . ▁Specific ▁surface ▁area ▁of ▁filling ▁ranges ▁between ▁ 6 0 – 4 4 0 ▁m ² / m ³ . ▁ ▁D ixon ▁ring ▁ ▁D ixon ▁rings ▁have ▁a ▁similar ▁design ▁to ▁Less ing ▁rings . ▁They ▁are ▁made ▁of ▁st ain less ▁steel ▁mesh , ▁giving ▁D ixon ▁rings ▁a ▁low ▁pressure ▁drop ▁and ▁after ▁pre - w et ting . ▁D ixon ▁rings ▁have ▁a ▁very ▁large ▁surface ▁area , ▁which ▁increases ▁the ▁rate ▁of ▁mass ▁transfer . ▁D ixon ▁rings ▁have ▁a ▁large ▁liquid ▁hold ▁up , ▁a ▁low ▁pressure ▁drop ▁and ▁a ▁large ▁surface ▁area , ▁and ▁have ▁a ▁high ▁mass ▁transfer ▁rate . ▁ ▁D