{HEAD ~ A check valve} in the vent inhibits {TAIL ~ the flow} of fugitive gases to the vent and allows the escape of the fugitive gases to the vent if the pressure of the fugitive gases exceeds a predetermined value 
inhibits
{ HEAD ~ A check valve } in the vent inhibits { TAIL ~ the flow } of fugitive gases to the vent and allows the escape of the fugitive gases to the vent if the pressure of the fugitive gases exceeds a predetermined value
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL 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 OTH OTH OTH OTH OTH