Typically, the supply line for each supply of gas includes {HEAD ~ several safety shut off valves} that may be employed to terminate {TAIL ~ gas flow} into the process chamber 32 either manually or automatically 
employed to terminate
Typically , the supply line for each supply of gas includes { HEAD ~ several safety shut off valves } that may be employed to terminate { TAIL ~ gas flow } into the process chamber 32 either manually or automatically
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH