{HEAD ~ One end} of the tube 44 is in communication with a central portion of the tube 45, and {TAIL ~ the other end} of the tube 44 is formed with a gas supply hole 41 
{ HEAD ~ One end } of the tube 44 is in communication with a central portion of the tube 45 , and { TAIL ~ the other end } of the tube 44 is formed with a gas supply hole 41
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH