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