{HEAD ~ A brazing oven} includes an arrangement employing {TAIL ~ a gas curtain} or barrier to cover the port or opening of the oven whenever the door is opened 
{ HEAD ~ A brazing oven } includes an arrangement employing { TAIL ~ a gas curtain } or barrier to cover the port or opening of the oven whenever the door is opened
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH