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