{TAIL ~ Each} of the sections is separated by a retainer ring having an opening therein smaller in {HEAD ~ area} than the area of the next preceeding scrubber chamber 
{ TAIL ~ Each } of the sections is separated by a retainer ring having an opening therein smaller in { HEAD ~ area } than the area of the next preceeding scrubber chamber
TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH