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