{HEAD ~ The fluidized product} then passes between {TAIL ~ contact surfaces} 2 following passage through a brief clearance between leftmost weir 13 and the leftmost edge of contact surfaces 2 
passes between
{ HEAD ~ The fluidized product } then passes between { TAIL ~ contact surfaces } 2 following passage through a brief clearance between leftmost weir 13 and the leftmost edge of contact surfaces 2
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL 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