When the pressure is reduced, the inert gas is exhausted from the casting furnace by an exhaust line, the feed line having a check valve to prevent gas which is contaminated by {HEAD ~ magnesium} from entering {TAIL ~ the feed line} 
from entering
When the pressure is reduced , the inert gas is exhausted from the casting furnace by an exhaust line , the feed line having a check valve to prevent gas which is contaminated by { HEAD ~ magnesium } from entering { TAIL ~ the feed line }
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 OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL