{HEAD ~ Heating coils} 63 surround {TAIL ~ tube} 37 to heat tube 37 to a desired temperature 
surround
{ HEAD ~ Heating coils } 63 surround { TAIL ~ tube } 37 to heat tube 37 to a desired temperature
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH