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 {HEAD ~ gas} which is contaminated by {TAIL ~ magnesium} from entering the feed line 
is contaminated by
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 { HEAD ~ gas } which is contaminated by { TAIL ~ magnesium } from entering 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 HEAD HEAD HEAD HEAD HEAD OTH REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH