The inner passage 10 and {HEAD ~ outer passage} 11 are separated from one another by an inner tube 16 and are enclosed by {TAIL ~ an outer tube} 17 arranged coaxially thereto 
The inner passage 10 and { HEAD ~ outer passage } 11 are separated from one another by an inner tube 16 and are enclosed by { TAIL ~ an outer tube } 17 arranged coaxially thereto
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH