There can be several introduction gaps or {HEAD ~ orifices} operating at one time to increase {TAIL ~ the total production throughput} 
There can be several introduction gaps or { HEAD ~ orifices } operating at one time to increase { TAIL ~ the total production throughput }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL