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