{HEAD ~ The apparatus} has {TAIL ~ a hollow body} , with an inflow and an outflow for the fluid  
{ HEAD ~ The apparatus } has { TAIL ~ a hollow body } , with an inflow and an outflow for the fluid
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH