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