{HEAD ~ An apparatus} 8 and further comprising {TAIL ~ a second shutoff valve} in said exhaust line between the connection to said oxidizing gas line and said outlet, said second shutoff valve having a control input connected to said level sensor 
comprising
{ HEAD ~ An apparatus } 8 and further comprising { TAIL ~ a second shutoff valve } in said exhaust line between the connection to said oxidizing gas line and said outlet , said second shutoff valve having a control input connected to said level sensor
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL 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 OTH OTH OTH OTH OTH OTH OTH