{HEAD ~ Particulates} accumulate in {TAIL ~ the trap} 2 over a period of time, and, the extent of accumulation of the particulates is detected by the pressure sensors 11a and 11b 
accumulate in
{ HEAD ~ Particulates } accumulate in { TAIL ~ the trap } 2 over a period of time , and , the extent of accumulation of the particulates is detected by the pressure sensors 11a and 11b
HEAD HEAD HEAD HEAD HEAD 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 OTH OTH OTH OTH OTH OTH