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