{TAIL ~ An oxidizing gas}, preferably pressurized air, is periodically fed into the exhaust line by an oxidizing gas line for cleaning the drain line and {HEAD ~ the pressure} controlling aperture therein by oxidizing the magnesium 
{ TAIL ~ An oxidizing gas } , preferably pressurized air , is periodically fed into the exhaust line by an oxidizing gas line for cleaning the drain line and { HEAD ~ the pressure } controlling aperture therein by oxidizing the magnesium
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 HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH